« Posts by tj


There is a slew of projectors out there And I am sure that you will find one the fits your budget size,and likes. There is also a lot of controversy about projectors its bulbs etc….

Lets start by just looking at a few different types of projectors that might work for 3d printing.

1-Digital Light projectors.



2-Light Spectrum charts for DLP’s


CS-1 PCB’s and schematics

This page was last updated on Jun 18, 2012 

Eagle Cad files of the CS-1Top copper trace trace layout (Done in EAGLE CAD) below:
Bottom copper trace trace layout (Done in EAGLE CAD) below: 





Populated view below:


CS-1  Assembly manuals:

Main Cs-1 Assembly manual here:

 Chemshield_assmbly_ instructions.


 CS-1 30 way Ribbon Cable  Assembly here:



 CS-1 Opto Interrupt PCB’s assembly manual here:





CS-1 PIN LAYOUTS_Apr8_2012

CSR-1 ,UV Rapid shot modeling

The CSR-1  is only in conceptual stage and pretty much a hypothesis for now. The concept   carries a lot of merrit and  hold it’s own category because nothing like this has ever been attempt or build before. ChemShapes is the only company that we know of that is in development of  this technology .It is called the  “RAPIDSHOT” This method is truly unique and will put ChemShapes on the forefront of rapid prototype technology. It will be called the (CemShapes Rapidshot) ,   CSR-1 Model.   The CRS-1  will do a one time  8 to 20 seconds cure for for  a 1 cubic foot model. then just like the CS-1 post curing.

What is it?

more coming soon.

UV cured modeling

Last updated JUL 14, 2011

This is a very controversial subject defended by a lot of  purists. Here is our take on it.

For most application the Ultra Violet or visible light curing  method is by far superior and much faster to any other rapid modeling methods. The name 3d-printing is actually a misnomer. a Better  title for it is ” Layered UV cured modeling” . Even though this method uses resin for every layer buildup it is not mechanically applied at every layered  level. Becaus it is a liquid at low viscosity ,it uses gravity to fill the building  gap for the next layer of curing. For that reason we do not categorize it as deposition modeling . It has great resolution , and uses  minimal moving parts.

Fig. 1. The basic concept of UV light curing,1-Stage (building platform),2-The model being build,3-The Vat containing the resin,4-horizontal beam,6-Main Z-Axis collumn,7-Stepper motor,8-Carriage plate,10-Base,11-Projection beam


So what is a rapid prototype  modeling by light projection  and how does it work?

The purpose of it is to rapidly ( a few hours)fabricate/grow  an exact replica of a 3 dimensional computer aided design drawing(CAD). It is normally a conceptual or working  model for the industry. Scientists ,architects,dentist ,jewelelers etc. make very good use of it and for the first time this will now be available to the hobbiest,the D.I.Y’s  and tinkerers . Any type of model can be build with it with no limitations to undercuts ,hollow structures or curvature. It builds a model in a 3 dimensional  hard durable  solid layered  format in resin ,rubber or wax. (now other materials also became available). The model is build upside down with the base attached to the hatced blue platform.

The software interface (see link below) starts  the process by slicing a 3d CAD drawing into thousands of horizontal sliced layers and generate a photo image for each  cross section in a seqential order. For example if the model was a sphere ,the images would start as a small tiny round white dot on the bottom and grow sequentially bigger per layer until it gets to the center  slice(the biggest) .Then it will get smaller again (per layer) as it goes to the top of the sphere. . The last sliced image wil be small again.  Each image is used to seqentially build  a one layered cross section at a time. Each layer is formed by hardening  a layer of resin by the printer  as decribed below:

Refer to the above illustration Fig. #1 : A Light curing resin  (usually Ultra violet(UV)  sensitive) is poured into a shallow  square vat/container (shown in blue color).The bottom of the vat is made of clear glass .  A building platform  (Yellow) is lowered into the liquid resin until it almost touches the bottom glass (hairline space above). A projector projects the first image sliced (cross section #1)  of the 3d CAD drawing in white light (or uv) through the glass onto the building platform surface for about 8 seconds. As the thin sandwiched layer of resin between between the glass and the building surface recieves  the light, it cures to a plastic consistency(polymerize). This first layer is importand ,It forms the base of our model wich is now glued to the building platform surface. The printer  stops projecting and  let the computer know to move the platform up another hair thickness (0.01mm) .The printer calls for the next image and projects the next layered image.The process repeats itself over many thousands of times with a new image every time…….. Layer after layer the model is build up ( like a thick stack of paper)  to form the solid model.

This process continous until the whole model (green) is extruded from the resin vat.The model is build upside down, as it extrudes from the base first.

A highly  detailed model (high resolution) of 2 inches high (50mm) usually consist of thousands of layers. Needless to say that the whole process is  computer controlled and can take up many hours to build a small 2 inch model.



Ultraviolet (UV) light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than X-rays, in the range 10 nm to 400 nm.

There are three types  of Ultra-violet light :
UV-A : With wavelength 400-320 nm is less intense than UV-B, but is more penetrating  to the eye reach and damage the retina easily

UV-B : Wavelength 320-286 burns the skin   and damages the cornea and ocular lenses.Half of it does not go through window glass as far as I read and researched.

UV-C : filtered off by ozone layer

Here is the a the lightwave  spectrum ,we are going to focus on the Ultraviolet


The Electromagnetic VISISBLE LIGHT Spectrum

Fig. 1 The Electromagnetic spectrum


Other links:


2-….Here….. is a good link if you want to dig really deep in the definitions.

Companies that does RP modeling




Rapid prototyping by deposition

We will include all other deposition methods on this page. Almost  all rapid prototype method includes the depositing or build up  of  a material added in a layered buildup of some sort. The most comon ones are:

1-…3-Dimensional Inkjet Printing (mostly pure wax buildup),

2-Fused Deposition (mostly extruded waxes, glue and plastics)…In this method the one layer gets fused by heat to the next layer by a microscopic plastic, glue or wax  extrusion from a round or square nozzle.

3-Laminated modeling  by  layering (mosty paper layering)

4 -Laser Sintering (layered powder,mostly metal, deposition bonded by a micro laser ). 

5-Jet printed resin on layered Powder  deposition…..Even though this process is very similar to laser sintering(without the laser)  we will categorize it by its own .It uses a curing resin printed printed on top a layered  powder buildup. Big advantage of this method I can be done in colors.

UV web links

Last updated MAY 16, 2012



1-Prof .Nicholas Fang





Chemistry and suppliers  links:

UV Resins,waxes ,epoxies,rubbers and ink:






6- http://www.deco-coat.com/uv.html















UV  Inhibitors/absorber/blockers/stabilizers:






UV Patents:





Beakers, graduated cylinders,pipets, scales etc.





Links of similar interest :


Model CS-1,Rapid prototype shaper/printer

This page was last updated Aug 13, 2011


Model CS-1

We have come a long way Since we kicked off with the SNYGRO. It all evolved into the Our first model The ChemShaper(CS)  model 1 or  Model CS-1 .

we are not going to post the whole evolution Of the CS-1 . You can read more about it  here.  , the history and where it was born.

We will just post the final stages  and troubleshooting that we do .

Here is where we left off:

The CS-1  project will be based on a digital light projector solidifying a photo sensitive wax/resin  layer on a growthplate (as described above.). What makes our printer stand out from the rest is the fact that it is MODULAR. Meaning ,in just one printer you can have much  more versatility and choice in stage (building platform)  size and height .

 This MODULAR aproach will allow the resin vat to be raised or lowered for bigger or smaller models. (See fig.)

You overcome the limitations of  one small fixed growth cubic volume. One thing to keep in mind is that as you enlarge the projected area you loose a lot of resolution (see VAT  construction). The quality of the resolution will be relative to the size of your stage.

The main reason for this aproach is versatility.One  printer can cover a much wider field of interest in the industry, from the jewelers that makes a small 1″ rings to a sculptor that makes  18″ sculptures.

Shown here is a monochrome rendering of the SNYGRO that transitioned into the CS-1. When all the hardware glitches is sorted out we will post a fresh up to date 3D drawing of the CS-1


The solenoid cam tilt mechanism.Shown here is just one of the mudular features of the CS-1.The adjustable stainless steel collumn can telescope out to give a 350mm focal depth.The three opto limit switches. I kept these modules all the same for simplicity.It slides inside the main collum and the final calibration is done from the outside with the white abs plastic slide nuts (see fig xx) .1- Square nut. 2- Opto switch.

Shown here is just one of the mudular features of the CS-1.The adjustable stainless steel collumn can telescope out to give a 350mm focal depth.

The three opto limit switches. I kept these modules all the same for simplicity.It slides inside the main collum and the final calibration is done from the outside with the white abs plastic slide nuts (see fig xx) .1- Square nut. 2- Opto switch.

Inside view of the main collumn. 1-Middle Opto slowdow switch(not wired yet) . 2-V-Groove rail. 3-Main collumn.

The external adjustable ABS plastic slide nuts for the opto-limit switches. 1-Plastic slide nut. 2-Hex Capscrew


Shown is the horizontal beam (3), bolted to the carriage plate(1).The four small holes are for the leadscrew nut block that slides inside the main collumn

The carbon impregnated nylon anti baclash nut(5) inside the nut block(4) wich will be bolted to the the carriage plate. The Main collumn(1). Acme thread leadscrew.3/8" x 12 (3)

For now I made adapters for the leadscrews,But I am working with a company in china to get steppers with300mm leadscrew shafts.We want to eliminate any backlash possible.


While I am on the Anti- backlash nut,  here are the specs for the acme nut thread:

I used a Carbon impregnated nylon and a Tandem (3/8-12)  tap from :  Link:  Mc Master car

ACME TANDEM from Mc master carr 3/8-12 (12 turns per inch). Thus 25.4mm/12=2.116mm per turn. thus 2.116/200 steps = 0.010 mm per step(wich is 10 microns for each full step.

Diameter 3/8″
Thread Size 12
Type Acme Tap
Helix Angle 29[DEG]
2lbs of force for every ounce of torque  (for plastic nuts)
1.8° Motor 200 steps per revolution x 12 turns per inch (3/8″-12 rods) = 2400 full step or 4800 1/2 step
be prepared to open your wallet(wide) for the TAP (..in 2010 the Tandem tap cost  $80.00(us) from mc master carr)
It is honestly a lot of work to make a anti backlash nut. ….Link:  Hayden Kerk sell them for around $ 50  and is truly there moneys worth.

The ChemShapes model1 (CS-1) ,with latest revisions as of AUG 13,2011

Outside view of keypad

Inside populated and Viewsonic keypad installed

Hardware links

Here is a list of hardware links that is mostly geared towards our Machines:


Aluminum Profiles:

1- The first is a product that just got off the ground in June of 2011. “Mark” refered us to them when we were still on the old SNYGRO website a few months ago . We submitting our idea . When the project got funded,we won a “Makers sponsor award”  from them .

Makerslide by Bart Dring,We plan to incorporate this great carriage and slide into our kit soon.

We are very excited about this for the deveopment of our kits. This was developedon Kikstarter  By Bart Dring, and is  very well designed product , Please check it out …..MAKERSLIDE . . If all goes well with our prototype this will probably be our main collumn of choice .

2- http://www.bonlalum.com/pdf/products/sd-135.pdf






8-GRAINGER linear rails




12-Bosch Rexroth

13-Easy Systems

14-80/20 Inc



UV Block plastics sheeting :






UV Glass  for vatfloor-Let UV light through :





Tips and techniques for doing the electronics

Updated on June 7, 2011

June 1, 2011

Let me just clarify first ,None of us are electronic  engineers or electronic gurus.  We all learn by trial an error and in the process we always discover  inexpensive  ways to make our life  a lot easier .Also good innovations  pop up as we learn,and  we are willing to share all our experiences with you.

The breakout/signal distribution board plotted with a SHARPIE ULTRA FINE point ready for etching


I am going to post the first tip here about Printed circuit board ( PCB) etching. We all need to etch a PCB at some point .If you do it as much as I do you always look for faster ways . A  few days ago I had to  etch a breakout board for our developing  rapid shaper/printer

I have been making circuit boards since I was a kid. I even remember  making a circuit board with  my mom’s hat glue and copper , and it worked!!! and very good that is .

So now that I am old (a little older …lol ) I use a little more profesional (still primitive) methods to make PCB’s.  But I have to be honest ,nowadays there  is such a saturation of PCB  makers on the market from China , that is has to be a very special application before I will etch a board. It’s mostly for the  R&D stages.

You can buy boards silkscreened, varnished with the whole works for a fraction of the price of what just  the etching chemicals cost….None the less …why take the fun out of it right? I had this idea for some years now .I did a little researched on it , and found a few guys that does the exact same thing here :  http://grandahl.net/feed/?p=19

So lets dive right in and discuss how I did it( and still developing it) :

 What you need in this method:

To make a printed circuit board (PCB) you need a copper clad (one or 2 sided) fibreglass or phenolic copper  board , a mask of some kind and an etching solution, its thats it simple,  really it is!

So lets break it up sequentially:

1-The copper layered board , single or double sided

There is a slew of them online,  just google all kinds of electronics and surplus supliers, I am not gonna get into that here.

2- The Masking

We will plot/scribe our mask straight to our PCB with a small little A4 Penplotter ,Like the HP7475A (get them on ebay for $50(US)). So why a penplotter?…..After years of etching I find myself more and more impatient. I want to draw the schematic on Cad or EAGLE , etch it and silkscreen or plot the component side all in 30 min.   Yes it can be done that qiuck. Here is video plotting  the pcb. 


 It’s  plotting straight on pc board in 5 min and ready to be etched  (No photo sensitive exposing process etc.) . Use your favorite cad program export in HPGL (Hewlett Packard Graphic Language)  and print/plot.

In the video I am plotting with a SHARPIE ULTRA FINE point.Sharpie don’t stand up too well against ferric-cloride etching . so I am going to experiment a little more with other inks like inda ink. Maybe the muriatic and peroxide will work better with the SHARPIE.( Later I switced  to the scribing method)

3- The etching

Various chemicals can be used ,I like ferric chloride acid,  available everywhere,but yesterday I ran accross   this link   wich I will definitely try next time.Its cheap and readily available. Just be very carefull not blow yourself up in the process,read the whole post and comments carefully. … WARNING!!: …We take no responsibility for any of these formulations,  use it at your own risk,discretion and common sense!!!…And DISPOSE of the acid  in a proper legal way!!!

4-Plotting the component side

After etching ,the board can be re-inserted into the plotter.This time with the component side up and re plotted with all the colors of your choice. Now plot all components ,names and revision notes  on top. .Thats about it.

Happy plotting/etching……TJ.




June6, 2011

We expanded on our research and development on the plotter-etching method this weekend .And  with a lot of hard work and dedication we had a good breakthrough!! . Here  at CemShapes we go through all the grunt  and pitfalls so you dont have to be aggravated with it. We will only extract the best and provide you with the right techniques and information to make you life easier . ( without breaking the bank.)  And as always ” opensource is our motto ” so you will also know about all our mistakes and how we correct them.

Before this weekend we had no consistency in the final etchings (some came out good,  some bad). The pen  plotting  straight to the PCB  was  not satisfactory  yet.  See Fig. 1 , for some of the bad etchings .

FIG 1, #1-Shows bad masking ,#2- shows deteriorated mask, #3- Angled view, Got a lot of bad etches like these while experimenting with many different pens and paints , Many times it worked but not consistent enough.

 The acid breaks down/deteriorate  the ink and paint masks before the etching  is properly done. This was mostly due to the thin ink deposit on the boards.  , Sorry , ….not consistent enough for  success!

After Dozens of etchings I stopped and analized each  board. I regrouped , brainstormed and took a whole new aproach. Right of the bat,this new method worked great, and it only took a few tries to perfect  this method . And here is the best part …..We need no ink pens!!  that can get dry!!!!  ,only a scribe pen. Wich means you are ready to etch at any time!! .The new method is also just as quick and involves a thin coat of black spraypaint from a can for the mask, and scribed trace outline  from the pen plotter.  Explained here , step by step :

The cad drawing does need a few more curves or lines to create , but this by far outweighs the clogging of the plotter pens.( wich is a big pain after a few weeks of no plotting).The scribe is ready to go 24/7 …I LOVE IT!!!   Here is the cad drawing in RHINOCEROS 5

A RHINOCEROS 5 CAD Drawing,Export to HPGL (Hewlett Packard Graphic language) and plot.

1- THE PEN SCRIBE…. I used a regular felt tip plotter pen to make a steel scribe.

(A)…Remove the top inkplug. 

(B)….Remove the fibre core ink container inside and push the felt tip out of the pen.Wash with soap. 

(C)….use the shank of a drill bit a few thousands of a inch bigger in diameter  than that of the felt tip inside the pen (this is for a nice tight fit in the plastic pen housing) , Sharpen to a 60 degree cone point ( very sharp tip) . 

(D)….Push the cone sharpened drill shank into plastic pen housing  and thats it!!  it  took me two minutes! and $1  for a 3mm  drill bit.

Fig 2. The modified plotter pen to a SCRIBER. Shown with the sharpened drill inside where the felt tip used to be..The line is for the same pen insertion/orientation every time.

.Because I only scribed once per curve , some traces did’nt get isolated because of paint burrs that got stuck in the grooves.So here is one more important tip when plotting:…scribed each otline twice. The way I did that was simply copy and paste the drawing right on top itself one time. That way you do a double plot without having to re-register your paper , It is the quickest and most accurate way to get a double scribeline. Also make sure the outline is one polygon all in one direction.This eliminates open corners.

IMPORTANT:…After scribing dont wipe of any paint burs. Leave them as is, otherwise you’ll push them back in the grooves,remember the scribeline is only about 0.1mm or so thick

2-PREPPING THE PCB… (A) Cut the PCB About 12mm oversize than your plot outline…. (B) Sand clean and get all tarnish off with 220 or 400 grit sandpaper so the paint have “teeth” to grip onto.  Important: after sanding, wipe clean with acetone….  (C) Spray just one thin layer of paint to cover the whole board with enamel spraypaint. I used RUSTOLEUM OIL GLOSS BLACK , but any oil brand can be used. While waiting to dry (tack free in about 5 min) go to step 3 .

3- Plotting the A4 Paper ….  (A)  Use a thick piece of paper (photograph thickness or poster board) . The plotter moves pretty rapidly and the thin paper sometimes bend a little when changing Y-AXIS directions.  Do a position plot with a regular pen or pencil . Leave the paper in the plotter …. (B) Tape your PCB right over that plot so it sticks over on  all 4 sides about 6mm. …You are ready to scribe.

4-Plot/Scribing……  Scribe at a really slow speed ( on autocad the pen speed is 4 , I think it is 4cm / sec.) and make sure you do it twice on every curve or line and leave the paint burrs alone , just give a light blow of air to blow them off the board.

Fig 3.The first scribed board etching -First off ,I used an (already used)old acid mixture,the mask deteriorate and and some traces etched away and also pitted the copper cladding bad!


5-The etchant……  I used a “new” formula , 50/50 by volume …One volume unit of MURIATIC ACID(31.35% concentrate)  @ $5/Gal. and one volume unit of HYDROGEN PEROXIDE (20% concentrate)@  $3/bottle .  The MURIATIC you get at the pool and hardware supply and the PEROXIDE at a salon /beauty supply store.

Fig 4, #1-MURIATIC acid (31.45% concentrate) (VERY CORROSIVE!) for pools,... #2-HYDROGEN PEROXIDE (20% concentrate) available at salon suplies

6- Etching process……When the board is ready to be etched move the whole process outside for good ventilation.  add the plastic stand-off clips (See FIG 5. ) to the side to elevate the board of the contaner bottom . Have a second container ready with fresh water to rinse imediately.  Add the MURIATIC ACID to the PEROXIDE  in a flat container of your choice. Swirl for a few seconds to get homogenous  and lower the board in the mixture …SLOWLY!!!..I did mine trace down,but trace up work just as good, this way  no bubbles get trapped under it . Use a pencil and fan the PCB up and down  in the mixture slowly to agitate the mixture even more.This also keeps good flow over the board to  wash off the etched copper on top. 

Fig 5. Use plastic PCB clips elevate the PCB above the container bottom.


NOTE: THIS IS THE MOST AGRESSIVE ETCHANT SOLUTION I HAVE EVER EXPERIENCED  BE CAREFULL IT IS EXTREMELY CORROSIVE!…. Watch your board being etched in 2 to 4 minutes (pending on your copper clad thickness). As it bubbles and activates you literally see the copper being washed of the PCB like fine dust. As soon as you see through the board,take out imediately and rinse of with fresh water. …..Believe me every second count…. its actually so fast its funny to watch …lol

Eureka Good etch!!


Traces Isolated and very clean!!


With a backlight...., nice and clean.... (the backlight diffracton makes the traces disapear in this picture). It does show how clean that tiny little scribe line can etch.


(A)  It is a always a good idea to have a neutralizer like baking soda  and extra water handy for your eyes and skin….

(B)  wear glasses and nitrile gloves ,This is nasty stuff!! and extremely corrosive!!!….

(C) Even though you can use this mixture more than once ,  it looses it’s effectiveness after the first etch. It turns green into copper chloride , and the  second time it takes too long to etch and the mask starts to deteriorate. I also don’t have the time and patience to sit there and stare at the PCB for  30 min……

 (D)   Dispose off properly(Definitely not into the kitchen sink or any plumbing for that matter) also  I don’t like to store this mixture, I think it’s very unstable,so I use it only one time (it’s cheap enough)….

(E)   Use your brain and COMMON   SENSE when you do this kinda stuff and keep kids and pets away!!!…far away!!!

Till next time!!! Happy etch’n


The VAT & STAGE construction

This page was  last updated on Sept 1 ,2011

The vat (resin holder)  and stage(the building platform)  is such a controversial subject that I gave it its own category.Discussions are always  going deep into all kinds hydrophilic and hydrophobic  materials and methods , Good ideas and bad ideas. This connection plane or first adhesion layer ,so to speak, is also the heart of the whole project .This is where ” the rubber literally meets the road”.  This is the point where the software and hardware meets to produce our nice models.

The design of the vat  was harder than I thought,and it took a really long time to figure out the vat removal ,Pivots and tilt mechanism.It has to be removable for easy cleaning then put back at exactly the same plane as before removal. Still in the rough now,but I will finish off nice when I know all is working good. The tilting mechanism at this stage of our development is a solenoid pull .I did allow space on the breakout  pc board for this polulu DC MOTOR DRIVER and 2x extra opto switches.Just in case we need more torque we will use a  worm gear with two opto limit switches. It is also good just to have that option built in. The amount of force we need so seperate the stage and vat wil be the final desicion on the hardware.

The VAT Floor coating:

This is where everyone have a opinion(icluding me…lol…..(and a product that he think will work best ) this one , that one …lol…makes your head spin. The final outcome will be very interesting. I cant wait to see  who the final survivor will be. After reading all you input so far ,here is my 5 cent take on it:

Before we go on let us a quick look at what Ultra violet light is….UV LIGHT and how it effect our  vat  floor

Ultraviolet (UV) light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than X-rays, in the range 10 nm to 400 nm.

There are three types  of Ultra-violet light :
UV-A : With wavelength 400-320 nm is less intense than UV-B, but is more penetrating  to the eye reach and damage the retina easily

UV-B : Wavelength 320-286 burns the skin   and damages the cornea and ocular lenses.Half of it does not go through window glass as far as I read and researched.

UV-C : filtered off by ozone layer

So let us analyzing the the Vat floor first  ( material, thickness and filtering) and the criteria it has to  meet to work with our UV exposure:

1-The vat floor ,as thin as possible.

We probably want it as thin as possible to avoid filtering . UV does not have very good penerating power and it is easily stopped by most transparent materials. Plain soda-lime glass is a BAND PASS FILTER.  Most incident UV  is absorbed as heat in the glass. Glass absorbs short wavelength ultraviolet light, but it does pass 350 to 400 nanometer ultraviolets wich is where most of exposure to the stage would take place.For now we will try that because it’s readily available .

QUARTS GLASS…While both standard glass and quartz glass use SiO2 as its main ingredient, the difference between standard glass or “soda-lime glass” from quartz glass (may be fused quartz or synthetic fused silica) is in the manufacturing process.

Soda-lime glass uses SiO2 and adds sodium carbonate to lower the melting point and allow working the material at lower temperatures. Since the addition of soda makes the material somewhat water soluble, calcium oxide is added to have better chemical durability. Depending on the use, other substances may also be added (lead for luster, boron to have Pyrex, iron for heat filtering, etc.)

Quartz glass, on the other hand, is usually made from pure silica (either by fusing SiO2 or from other sources of Si and O).

Thus, the purity of quartz minimizes interaction with UV, whereas standard glass have additives that can absorb or disperse UV.

Available here: http://www.sydor.com/flatopticsbasics.asp

2-The vat floor as rigid as possible ,  right!…OK…lol..Some argues flexibility here??..lets see.

My personal opinion : I believe that the floor , coating and walls  should be as rigid and as  thick as the exposure will possibly allow. You guys have to remember that  “ microns ” is a small!! ,small!!  distance!! any flex in the floor will eventually lead to permanent bending and bowing.Especially after 1000’s of times bending per inch. But I have to give your “FLEX” arguement credit ,that  this does take place gradually over many many layers,so the next layer will just be build on the same curved plane  as the previous.Parallelism wil  be continued throughtout the model.  For those of you that will go that route ,you will have to prove me wrong. I think I will stick to metal and glass for the vat materials for now until proven wrong.Wich brings me right to the next point..Size!


I know we all want build  big models with mini microns of resolution!..But, before you decide on a stage size (big or small) for exposure area , consider these points.  (a lot have to be sacrifice to make a big stage):

1-Resolution …Resolution decays ( just like exponential scattering of a light sourceinverse-square…. law of light)  , it decays exponentially as it gets bigger so  a 2 x 2 inch is not merely just half the resolution of  a 1×1 inch,… its a lot less!.Your projector only have X -amount pixels per square inch it can give you. No matter how you look at it, ….Use it wisely and and abundandly ,apply the most pixels you can to the smallest footfprint neccesary for your model!

2-Focal height gets longer as the stage gets bigger ,so more lens distortion. Depth of field (focus plane)gets longer (harder to focus)

3-The vat floor gets big and flex much more as it gets pulled away from the floor.This goes for the stress on the glass and the horisontal beam.

4-The  adhesive force grows exponentially between the Stage  and vat floor

I am sure more will pop up ,and I will post more as we ran into more problems.

4-Vat floor-Hydrophilic or hydrophobic surface?

Lets define the three chemical and surface interactions  that we deal with here  (in simple plain english )  :

In its simplist form :  The Stage should stick to the resin and the vatfloor not!. simple …huh…   |:-)..Here’s a little more expanded version:

Hydrophobicity … Refer  to the repellent of a element by the charge /non charge  of that element towards another. Hydrophobic molecules (usually non-polar)  thus prefer/attrack  other neutral molecules and non-polar solvents..(Water is electrically polarized ) …..At first  when I read this,  of course the oil/water concept came to mind wich did put us on the right track.but..lets throw in one more action  that we deal with (just to stir up the pot even more ) …lol….That is lipophilicity….huh!!??…. Yeah that’s what I first said too.

Wiki explains lipophilicity  very good: …

Lipophilicity (fat liking), refers to the ability of a chemical compound to dissolve in fats, oils, lipids, and non-polar solvents such as hexane or toluene.[1] These non-polar solvents are themselves lipophilic — the axiom that like dissolves like generally holds true. Thus lipophilic substances tend to dissolve in other lipophilic substances, while hydrophilic (water-loving) substances tend to dissolve in water and other hydrophilic substances.”

While hydrophobic substances are usually lipophilic(Oil or fat liking) , there are exceptions—such as the fluorocarbons and silicones they are hydrophobic but not lipophilic (fatty). When you open a tube of pure 100% silicone sealant ,that strong  smell is the toluene (also known as methylbenzene) solvent………(also see Silicone vs silicon here)…..


This is basically just the remainder or inverse of Hydrophobicity . The Hydrophilic-lipophilic balance of a surfactant is a measure of the degree to which it is hydrophilic or lipophilic.

So to sum up back to plain english again:

Hydrophilicity (attrack) is the remainder of  Hydrophobicity (repel) , So one should  stick more than the other (a lot more) . To reduce stress on the machine parts, the stick /release ratio  should have high opposing coefficients. Meaning  have a good “release” on  the vat floor , and  a good “stick” on  the stage.

We will  probably at some point have different surfaces to accomodate different resins. ..Time will tell. . Chemistry is not my strong point at all  ,but I know,  not all resins and waxes are going to dislike just one surface.

Some fall right in between these categories and is way beyond the scope of this discusion.  It can  get really deep into chemistry.way beyond the comprehension of my li’l brain. We will just stick(or not stick…lol)  to silicone for now, simple hydrophobic , keep it simple and see what the outcome will be. It  will  probably repel   80% of all resins anyway.

Other “NON STICK” Surfaces

We will also try some of the  plastics and surfaces that you guys reccomended. A non-stick material that I have used in the past with much succes is   …MYLAR ..  It is a hard polyethylene sheet .As a matter of fact that is exactly what I am using to put the silicone on the glass vat floor . I smeer a thin layer of 100% pure  “DAP” silicone (from Ace hardware) on the glass 1mm thick, then cover it with a MYLAR sheet .(Do it within  seconds to prevent the evaporation of the toluene ) Squeeze out all the bubbles .Then take the silicone layer (sandwiched between the glass and mylar) down   to a few microns.I do that by pressing and iron  with a flat cold surface object like a machined metal block or cold clothes iron . After a hour pull of the Mylar off and you are left with a crystal clear shiny surfaced silicone layer stucked to the glass like crazy! .I have tried many ways before ,But this one seems to be the only way that you can get the toluene to catalize the silicone. If you leave it just thinned out  and exposed (without mylar) it never cures properly. I have tried probably 5 different kinds of pure 100% silicone but “DAP” and the “ACE Hardware brand” is the purest ,clearest and finest ground. ACE Hardware sells both.

The clear Mylar sheets can be obtained at any Office supply/stationary  store as binding covers (some are perforated). get the extra thick ones ,as it gives a much more even surface.I was surprized how smooth and clear the silicone surface was.

Links for good “Non-stick” surfaces


July 25,2011

Aug 3 ,2011

I finally got around to post some pics of doing the vat floor.

After many ,many attempts with many different aproaches and many diferent kinds of silicones, I got this this method down to where it gives me consistent and very satisfactory results:

1-I Have used about a dozen different kinds of silicones.The one that I found to work the best is “DAP”. 100% PURE SILICON”.For some reasson it just flows smoother and the consistency is just right.Maybe they use a different kind of toluene…? . Another one that works good is the ACE HARDWARE Brand.

Some types of silicones I have used, "DAP" and " ACE Brand "was the winner!"

2-This Mylar /Silicone idea  stems  way back to a old DACRON / EPOXY  technique that’s  used on Experimental Aircraft.   You press a dacron sheet on a still “wet” Epoxy surface to soak up any unnecesarry and extra epoxy and it gives  you a almost type of knurled surface when the dacron is peeled off after the epoxy is set.

So  I figured ,Mylar will give me a super nice glossy finish. I just did not know what the toluene will do to the mylar. Anyway to my surprize the mylar  helped  “catalyze” the silicone to a cure.On previous attempts ,before I used the  mylar, I would try and smeer the silicone  to a very thin layer over the glass,but the silicone never set to a dry/hard state,it always stayed sticky.The toluene would evaporate too fast for the silicone to catalyze or set to a dry/hard state.

So the MYLAR sheet was the solution to two problems,One was the curing (It was just thick enough for the toluene to slowly evaporate.) and the other was obtaining a shiny surface,it also helps to even out the thickness of the silicone strata.

3-What do we need ?

3a-Thick MYLAR Binding cover sheets(81/2 x 11″),  $10 for (20x) of them at Office Depot,Get the thickest you can find.

3b-Tube of “DAP” or “Ace  Hardware” Silicone

3c-A Straight edge that has a little flex to it.

3d-Skotch tape,to mask the edges(if you want)

3d-A thick piece of posterboard to work on.

3e-VERY IMPORTANT!……,A dust free environment……..remember one spec of dust will block out one pixel on your model (even more if you print small)

3f-Acetone ,soap and water. paper towels (a full roll).

3g-The VAT Glass floor and the vat frame.

81/2 X 11" Mylar sheets

4-Start by washing your hands at least twice(WITH SOAP) to get rid of all skin oils.Clean the glass, first with Acetone(as clean as humanly possible and NEVER touch the surface of the glass),Now wash it with dishwashing soap and hot water,dry with papertowels until it starts to squeak.(I used up about 20 paper towels in the process.).Also make sure to use the most lintfree papertowels as possible.

5-Tape the glass sheet to the  posterboard,go in about 2mm around the perimeter of the glass.This does two things,it holds the glass down on the board but more importand it keeps the silicone from squeezing in under the glass,you want to keep the bottom of the glass now  clean until all the silicone  is set.

6-Start with a nice blob right in the middle of the glass. Use your judgment ,it should be enough  to give you a layer of at least a layer of 10 or so microns over the whole surface of the glass.

7-Put the mylar sheet on top .Gently start to squeeze from the contre outwards until you get a 3″ diameter blob .If any bubbles is trapped at this point lift the mylar all the way to bubble and gently iron it out with your fingertips.Dont use  your nails or any  any sharp edges ,it will bend the mylar sheet.

ALL BUBBLES SHOULD BE OUT BY NOW! I there is still any trapped ,clean and start over again.

8-Keep ironing all the thick spots outwards evenly with your fingers until the sislicone is about a 3mm thick.Now switch to a straight edge with rounded corners  that flexes a little.

keep working the the silicone outward with the straight edge.Make sure to  cross over 90 degrees in all direction, go down evenly until you feel that the silicone is not moving anymore and you should be right 20 to 40 microns thick now .Very important! .

9-The mylar will probably have a lot of stains of silicone and scratches at this point. Don,t worry about that. WHAT IS IMPORTANT IS THIS: Make sure at this point you did not press any divots in the mylar,Divots can still be somewhat be rescued at this point but bubbles not.The corners have a tendancy to suck bubbles in under the mylar.

10-After your satisfactory ironed surface,  leave at least 24hr. to dry and catalyze (and leave it alone now!).If you lift a corner when its still wet you will totally ruin the surface. After 24hr. It wil peel off very easy. And you will be amazed at how shiny that silicone can get!!

11-After the glass is done .Line the inside of the vat walls with a thin layer of silicone ,Smeer the silicone with your finger until completely covered then  put  your  vat frame upside down on the posterboard .

Squeese a bead of silicone alongs the frame edge (just enought to get a good seal) .Lleave the frame on the Board upside down.VERY CAREFULL TO NOT GET SILICONE ON THE GLASS NOW!! ,Lift the glass and put it down  on top of the frame with the silicone surface  facing down.The reason you glue this upside down , is so you can see if the silicone bead seal and fill in  the surface between the frame and glass.It is very easy to see it through the glass.If there is any shortage at some spots where it didn’t fill in.Press some in with your finger from the ouside, BUT DO NET GET ANY SILICONE ON THE BOTTOM SURFACE OF THE GLASS .  Silicone adheres tenaciously to glass and can not be cleaned afterwards.Leave for 24hr.

You can trim any acces silcone now and even wash the vat floor silicone surface now with a soft spunge and soap,Take care not to put and scrapes in it though…I will also post a video of the hole process soon…

Aug 12, 2011

I did a adhesive release test for the vat floor with  small piece of U-aluminum  bracket and a pull scale. The bracket had a hole on top to pull straight up.

131 square mm gave me a pull of 1.5-2kg until it released of the vat floor.The sideways for breaking it loose was only a few tens of  grams.

I glued it with a 2- part 5 min. epoxy to the vat floor. It gave me pull of 1.5 -2kg before it released.Wich had me kinda woried.The side ways pull is only a few grams,wich tells me that it is mostly suction/vacuum I am pulling against.I tried it five times with about the same results .(As it will later turned out , the resin ‘s adhesive strength was not near as tenacious as the epoxy.)

I did a strain test on the stage that went very well., 6KG (13,2LBS) pull on the side of it showed very little flex.

Aug 19 ,2011

I just love research and development its full of surprises around every corner….. I couldn’t wait for the sudan 1 ( on backorder) so I mixed up  a batch of HEXANEDIOL DIACRYLATE and PHENYLBIS (Dr Fangs) to try and and at least put all the theory to practice..(And play of course)…. Whell this was a very ,very educational exercize.The following test I have done manually and advanced the stage up by hand. It was mainly to try the vat floor silicone’s  hydrophobicity to the resin.And also get a feel for the cure time.I had no intention to make a super high resolution model.This was just an experiment,(that went very well).I also pulled of a lot of little test cured plates  of the vat floor by hand to get a “hands on ” feel for it. It is very difficult to determine the strenght needed if a high torque stepper does the job.

I made a small vat inside the big vat and build a small stage to replace the standard one.(see pic)

OOPS!.....lol..Tripple exposure on the first few layers made the small centre stage stuck to walls and cracked the floor glass.(Way too overexposed...as found out later)

So here is what happened:
After filling the little vat , I started of 0.25mm (250 microns)above the vat floor with the small stage. Now keep in mind we  have a 2000 Lumens projector focused  down to a 50 x 30 mm image (window) . Exposed for 8 seconds,advanced yp another layer and  did it again( for a few times) .Still all was well. But little did I know I was just bending the glass of vat floor as I was raising the first few  layers.(Also for my first trial run the room was somewhat dark dark, because I had no idea how that stuff will react to ambient light) ,  So at the 3rd try or so,I heard the snapping sound of  glass….see pic. ……..It could bend no more..
The conclusion:
With no UV inhibitor in it , the first layer was  way over exposed ,the light  probably went up the sides of the vat  and glued the stage to the side walls of the little vat.(here is another lesson:  Do not make your stage material out of any white or translucent material……Then to make matters worse I overexposed the 2nd and 3d layer without the vat ever releasing the floor(meaning I fried the first layer with 3 over exposures).

Shown is the small stage and cracked vat floor.

So after the cracked floor I switched on all the flourescent lights (GE.cool white) in the workshop re-evaluate what happenend and then started playing (exposing) with  the rest of the batch on the vat floor .

Fig.Vat-Playing with the resin revealed a lot of the mystery about the curing, exposure and aggressive nature of the resin.Shown here is just the letters ChemShapes that was exposed through the puddles of resin left over on the vat floor.

See fig. VAT
A-The Capital C wich is 1mm thick
B-The crack in the floor
c-The cured vat walls

The main picture shows how nice and clean the it build the edges. The resin is a light transparent see-thru yellow on black/plate. This was on a 50 x 30mm exposure window.All compared against a mm ruler. Note some of the letter is 0.25mm wide

So What have I learned from this:
1-Number one…The CS-1 Is doing exactly!…exactly it’s job designed for, It works awesome!.It is way strong enough and rugged enough to handle a big exposure. As far as the cracked glass….aaah!  no biggie ,  I can make hundreds ….and it doesn’t cost me hundreds of $ either. )
2-Over exposure wil lead to damaging the glas(break…lol…..) and burning the silicone surface  white/milky (Yes It gets hot man!, At the end of the test I thought I might as well finish of the floor and super over exposed it. I smoked it good! It only took about 15 seconds in 1.5mm of resin. …That stuff is aggressive!
3-it look like the magic exposure time is about 3-5 seconds on a 50 x 30mm window for 1mm thick resin . (I will try thinner on the new vat floor).
4-The hydrophobic  silicone surface works fantastic!! with just the right exposure time it slips right of,pushing it sideways,It is the vacuum in the upwards pull that makes it stick more.
5-Dr fang’s recipe works very good,almost too good…lol.
6-This stuff gets hot!
7- The stinky fumes are bad, guys you were all right! …. this recipe does call for  ventilation or air extraction.Granted that it  would not be normal to smoke it like I did . I only worked with a 150 sq mm surface.(I can imagine a 2 x 2 foot section) . Hope the other resins  are better.
8-I was really surprised at burning the vat floor a little milky at some spots.(wich was not a good thing).But then on the other hand,  those temperatures should never be reached otherwise shrinkage would be a real problem.
9-Use eyeware,…lol..At one point I was rubbing the corner of my eye,the slightest invasion in your eyes  burns like fire.
10-After I switched on all the flourescent lights the ambient light it had really no affect on the resin.I did not  know what spectrum all the flourescent  bulbs were, thats why I started of in the red room first.
11-You definitely need a UV inhibitor/blocker , when those radicals run free for all ,those molecules just have an grand o’l time , a molecule feeding frenzy ,and  the reaction  is way too aggressive.
9-You can cure a thick layer probably about 3-5mm thick (or more) without an inhibitor.
Once it starts it goes quick.You can probably do even a lot thicker than that even ,But for now , I don’t want to waste too much  resin ,It is a little on the  expensive side just to waste.
10-Another thing That I realised was that I have to switch to a completely dark opaque /non translucent stage material. That 2000 lumens light beam penetrate the white plastic  stage block, It lights it up like a Ice castle at Chrismas!. (not good for those hungry molecules.)
11-So all in all This mornings trial a was very ,very good learning lesson. The resolution is awesome and I can shorten my cure time.The silicone works great ,so the only variable that did not work was the release.
In the future I will have to raise it up more(or lower the vat more) past the release height,Then bring it back down again to make sure it broke completely.The “break loose ” height will of course be determined by the exposure time…….It’s  a ” wich comes first, chicken or egg”   thing..

Aug30, 2011

Today I combined two previous batches I had mixed before .It  contained the following:
1-HEXANEDIOL DIACRYLATE (for faster reactivity)
3-UV-24 FROM CYTEC (as a uv blocker)
4-TRPGDA WICH IS NOW TPGDA (for lowering viscosity)
5-TMPTA (for better flexibilty)
5-ADDITOL -TPO  initiater ( This was mixed in with the first batch,and had not much of a catalysing reaction at all,I think it was for the wrong spectrum). I also think the   PHENYLBIS caused most of the reactivity here is the “cake I baked or rather “extruded” .
This time my main goal was (1)… to  get enough developed..andto extrude it out of the resin , and  (2) …to be able to remove it from the stage when I was done.
I did not go for  high resolution neither sharp edges this time (as before) . I know the CS-1 can do that now. AS matter of fact I layered it in 0.25mm layers (250 microns). wich is really thick layers. You can also see on the black and white images that did not utilize all the pixels either.(See black and white  images).
I did succeed in both.I also overcome the tenacious adhesion  strength of the Hexanadiol Dyacrylate to the vat floor by addin other polymers. I also added a sacrificial scoffold support this time  for the main model. It is use to break the main model loose from the base

Aug 30 , 2011 the first model to be taken off of the stage.Still needs lots of work,but closer .

The arrows shows underdeveloped spots,wich could be because of too much uv blocker or under exposure.Because I time it manually the exposure and advance height is not consistent on every layer.

This was the longest extrusion so far, about 15mm plus the base.

Another close up note the x- scaffold support on the bottom.

Note the under developed spots at the arrows.

There is still  flaws in the lettering and some spots that did not  develope. Probably because some layers were thicker than others(I still advanced the z-axiz  by hand to get a feel for the adhesive strength  of the resin.)This was only my second try , and at least this time I got the model raised/extruded  out of the vat .Also,even though I had to cut halve of the scaffolds off( it  was molded together) ,The other halve was perfect and would have snapped off easy.
I had to brake almost all of the previous models of the stage, cause I could not build a scaffold supports for the main model yet.
This trial run definitely proofed some more success ,especially with the addition of the TPGDA and TMPTA AND THE CYASORB UV-24 by CYTEC ,There was much les cohesive forces involved,…(I pushed the vat down by hand to feel the force) …,And this recipe was a lot more gentle on the Silicone floor too.
(Speaking of the reaction of polymers on rubber,….I ran across …..these awesome tests….. they did on rubber gloves and polymers)
Here is some points that still needs attention:
1-The UV light is still not blocked enough ,it went through the flat base and into the suport scaffold and formed  a  solid spot in the middle (where the light is the most intense).
2-The thin widths of the letters underdeveloped. (see red arrows)
But to conclude  ,  I would say this was definitely another advancement in chemical recipe , mixing, developing and extrusion.
I am going to switch to new glass stage again.
At least now we have elimated these few variable:
1-we know that the vat  and stage works well together
2-we can extrude this polymer recipe
3- The previous test proofed to have high resolution.
One variable that  wil always linger is the duration of exposure ,for this one , 8 seconds seemed to the the golden rule,For the very first batch (Dr. Fangs) it was 3 to 4 seconds but that was on a very small image 30 x 50(intense light exposure)
So my next goal is to combine all three ,stregth, high resolution and shorter duration per layer.
Once I have that established i will focus on the  shrinkage and color.

Sept 1 ,2011

Here are steps I followed to build the Model shown above:

1-For the  firts layer of any model you want to “Grow” I thought it would bewise to have the very first few  layers as a solid image area. This will give us very good adhesion to the the stage. So I exposed a full image  area of 3  layers.

(See Model image #1) .This startup base would also be good for the  Sacrificial Scaffold Support( SSS) to hold onto  ( see image #2) ,  three layers deep @ 0.25mm per layer. Used Image #1 that was  just a plain white base .

MODEL Image # 1 ,for the first 2 layers.

2-The… Sacrificial Scaffold Support ..(SSS)…came next.(see  image #2) This  is also something to develop a feel for.It has to be strong enough to hold the model in place,sturdy an rigid,but also thin enough to break the main model loose  from the base ,otherwise the model have to be destroyed to take it of the stage. This was built with” cross a section “.You can use prety much any shape for the collumns,as long as it can be sacrificial. (see image #2)  About 20X Layers @ 0.025mm=5mm high`

MODEL Image # 2 The cross scaffold support .Design to break loose.

Without the right amount of  UV blocker I got over exposure through the base of  MODEL image #3  so my SSS was “grown”  together in the center  area (Had to use a Hack saw to cut off). but  the SSS around the outer perimeter worked fine.
3-Now it was time to start the model. I did just a plain block base for the lettering to stand on, and used used MODEL image # 1 again
Did about 15 layers again @ 0.025mm .
4-Then started the lettering ,Used MODEL Image # 3, for about  50 layers wich gave me about 12 mm or so. mabe  a littlle higher. I could have kept going at this point to 300mm if I wanted to.

MODEL Image # 3 ,The text

5- the whole proces took probably an hour (manually)


I am going to post the rest of the chemical research and development  in the CHEMISTRY  menu on top , look under RESIN or  … Click here…. ( Just to keep information in their right categories) .I will focus on the UV Blocker first cause UV inhibition causes problems in a few  areas :
1-under/over  developing
2- duration of exposure
4-Crazing of base layer
All of these  in turn will require different settings and formulations  for different size images because of the inverse-square…. law of light,All it means is that the further you go away from your light source the weaker and more scattered the lightrays are.Wich have to to compensated for.
I will also post the images I used for this last model too..