A while ago, I was inspirited by a nice movie from Oliveira Jose about a DIY SLA 3D printing device, working with a (modified) DLP beamer. I had still a lot of questions, on how this process was working. Finally after reading a building blog on intractables by Tristram Budel, I decided to build my own! :) So this will be my building blog for now.
If you have any questions/remarks about this build or search more info in general, please use this nice forum: www.buildyourownsla.com
I like the "Acer H6510BD", with 1920x1080pixels a lot. So secondly I need to know the projection distances, some measurements:
For having a resolution of 1 [mm] = 10 [pixels], the next distances seems to be best:
Placing the front face of the beamer about 225 [mm] from the printing area. Down side are some sharpness deviations, especially around the corners. Maybe this distance is too close, so the design should have some space to change the beamer distance.
I donít want to modify the (expensive) beamer, so first Iím looking for resins which will be cured by visual light. After searching the web, I found some interesting places to buy resin. A list of suppliers & prices, excl. shipping:
|2engineers.com||€ 45 /Kg (excl)||EU/BE||European reseller of MakerJuice.com|
|FunToDo.net||€ 45 /Kg (excl)||EU/NL||General DLP resin|
|Spotamaterials.com||€ 62..78 /Kg||EU/ES||Nice different resin options! :)|
|Ekmpowershop31.com||€ 137 /Kg||EU/UK||B9creations resin (Red)|
|MakerJuice.com||€ 31..35 /Kg||USA||General purpose, incl. UV & none-UV curing.|
|BucktownPolymers.com||€ 34 /Kg||USA||PS100-V420. Lot of different options. Minimum 1 gallon.|
|Solarez.com||€ 49 /Kg||USA||-|
|Buy3dInk.com||€ 56 /Kg||USA||UV Resin only!|
|MadeSolid||€ 275 /Kg||EU/ES||FireCasting resin :)|
**) Buying outside EU, the Dutch gouverment wants you to pay additional tax (21%) and above € 150 also custom fee (from 4 to 12%).
I'll not regular update this price list, so check out real prices yourself.
I ordered 4 colors (liters) from makerjuice. It took 2 weeks to arrive, getting an additional fee for customs (60e) :( and including transport € ~59/Kg.
Whatever, I've got the stuff, so I'm happy :)
Actually there are 2 types of designs possible:
I cannot really chose, which option will be best. So I like to have both options and I also want to have the 3D printer as small as possible. I decided to use 2 surface coated mirrors. This design will allow the smallest foot print/design possible! :)
My first build will be the bottom-up configuration. Just because thisone is looking much more futuristic.
Because of some spare parts lying around, this results in the next design:
|Top Down||Bottom Up||Bottom Up configuration|
Some places I found so far to buy mirrors:
Glass could be found around the corner. I'll first try standard float glass.
The mirrors came from firstsufracemirror, the arrived after 4 days from the US. Pretty quick & no custom fee's this time.
Almost all the parts are ready. Now the fine-tuning of the mirrors will start. As expected, it's quite hard to align the beamer, the 2 mirrors and the vat in the right way. I think this is the mayor down side of this design. But it needs to happen only once!
I was well surprised about the strength which the simple Z-stage could generate. The stainless steel M6 lead screw is not 100% straight, but still it generates a tremendous amount of force, while just running on 12 [V] & 0.2-0.5 [A]. It's not possible to stop this movement by hand force. Maximum running speeds are currently: 350 [mm/min] (equal to 350 [rpm] in my case). In general (for CNC-milling) not very rapid, but enough speed for doing the 3D printing job.
These options are also connected:
Nevertheless, I want to thank the 'MarginallyClever' team for sharing their ASCII-NC-code converter demo. :)
|CAD:||CAD:||CAM:||SLA 3D Printer:|
|Design||Change format||Real time control||Printing...|
|a: Beamer (b/w images)
b: Arduino (movement z-axis & tilting)
After 225 hours: designing, creating parts, programming the Arduino & testing the Ďdry-buildí, it's time to fill the vat & press the 'printing button'. Hmm, that's a little disappointing, it doesn't do what I had in mind. Settings: 6 to 10 [sec] exposure and 0.1 [mm] stepping height.
Before starting a new try-out, let's get a better understanding what's going on. So I joined the yahoo* group of Graham and asked for help. Why didn't I do this before? This is how it works:
There are two basic "sticking forces" one is adhesive and the other is essentially due to the surface tension.
The resin will stick to build plates and itself adhesively, in the case of sticking to itself the adhesion is very intimate, with the build platform it is wicking into the surface structure like any normal non welding glue.
PDMS absorbs oxygen and this inhibits polymerisation in a very thin layer. This prevents the part from sticking adhesively to the pdms. There is however still a sticking force due to the thin layer of un-cured resin. This is just the same as if you put a drop of water between two panes of glass. Tilting with a flexible vat bottom allows the gap to open gradually allowing resin in, as does pulling up with an even more flexible vat bottom. Sliding is aided by the uncured resin acting as a lubricant.
*) The yahoo discussion forum is now moved to google forum: DIY-AddFab.
I still like the idea for having a vat without any chemical stuff on top. So a flexible floor seems a nice add-on to have, but difficult to make. I'm going for an eccentric tilting vat.
After trying a lot of different vat floor coatings, it's time for some nice pictures.
Some pictures during the printing process (#20):
I'm quite happy about the results so far. At least it's printing something... Now I'm finally in the position of adjusting & improving print quality, try different settings and resin and after that printing different objects...
(Click on the picture for more testing results...)
I'm still very surprised about the nice tiny details! It's amazing to generate such, with a relative simple setup. Down-side is the amount of try-outs. Till today, it's still very difficult to print something like it's within CAD. Maybe I'm expecting too much...
|One of the annoying things is the beamer showing something which it should not do. Like the showing the beamer-close-down-message or while pressing wrong button so PronterFace disappears, so the desktop is shown... When the vat is placed, the resin will cure very fast due to the bright white light, which could even result in damaging the PDMS layer. So I decided to create a mechanical shutter just after the first mirror, including a nice red led & push-button on the front panel.|
Before changing the printer towards top-down, I still have some adhesive FEP foil laying around. So why not try this FEP first. See my 5 [euro] FEP flexvat results below.
I also build a passive tilting system, which could be easialy addapted towards my current vat carrier. It could also be locked, so there is no tilting or only active tilting.|
Like the active tilting, this one can also tilt about 2 [degrees]. So in total 4 [deg], should be sufficient...
This was a very easy update. :)
Great, I've tested the vat again, which was still filled with some resin for the last 6+ weeks. After peeling of some solification and stiring the remaining liquid resin, the black color returns. And after finding an undamaged PDMS location, it's time for some printing again... Due to the lack of air, I expected a complete disaster, but ~20 consecutive (tiny) prints came out very nice... I also activate the passive tilt, but hearing no noises, I don't expect this was necessary during these prints. Maybe the printer isn't that bad after all!!
While continueing some simple test, and refill the vat with FunToDo resin, 2 other prints came out very nice. The first is a quality test between FDM printing & DLP printing. The white object, is the Marvin key chain, which was printed on a 3D Hubs party. It's a very nice FDM print, which is 25 [mm] tall and a layer thickness of ~0.1 [mm]. The black version is my DLP print, which has a layer height of 0.05 [mm]. Like shown, the DLP print is just a little smoother. Now the printer starts listening to me, it's also time for printing a 60 [mm] Eiffel Tower. Yeah, this was worth all those hours: building, testing, adjusting & testing again... :-)
Well, after a long period of no printing progress, time to make a new sylgard floor. While peeling off the old one, there was quite some thickness deviation, from 2.3 to 0.7 [mm]! This is a picture of the old ruined vat:
I don't know how many [ml] sylgard I used last time. Today I'm using 400 [ml], with again a 1:10 ratio. Heating the entire vat in the oven at 50 [dC] for 2 hours, cooling it down for an other 2 hours. This is my fastest vat recovery ever. In the mean while, recalibrating the printer: xy-resolution: 94 [um/pixel]. Smaller resolution is currently not possible w/o moving the beamer/mirrors and chaning vat height. So time to shake the resin for a while and preparing a SVG-file for the next print.
Great, after about 4 hours starting with a ruined vat, I'm printing again :) I disabled both passive & active tilting, printing with some longer exposure times 6 [sec], retracting 1 [mm] and using MakerJuice-Red resin again. Most builds are printed very well!
While having this FEP foil already for half year in-house, it's time to test this! (After seeing this working somewhere else.) This foil has a thickness of 0.05 [um]. |
The printer is getting way more robust:
About costs, you need to buy quite a lot foil (in my case ~2.4 [m^2]), which cost about 35 [euro/m^2], excl. VAT & shipping. So for 1 single resin container you need about 2 [euro] foil. Then you also need a plastic container 1 [euro], a simple wooden frame will work and some bolts. The picture on the right is my 5 [euro] design.
Some suppliers for FEP foil and/or adhesive FEP foil:
Overall: this is a must do!
After a long period believing in a compact 3D DLP printer, I now moved away from the two-mirror approach. Even the pillow-vat didn't solve all the issue's. Without the small mirror I was hoping this would give better precision of projected images and speeding-up the printing process.
I did print some nice FunToDo black prints, but exposure times still remain the same.
Okay, back to square one... The issue with the 2 mirror approach is the necessary length of the light path. It's very difficult making this light path shorter then ~225 [mm].
With the one-mirror approach, I was still printing with a distance of about ~225 [mm], that's why the exposure times didn't go down. Now I changed to direct light and I'm able to shorten the distance to about ~130[mm].
(This took about 5 months of painful physical change in mind set & only 2 hours to rebuild.)
Since the light intensity changes quadratic, new exposure times should be around: 6 [sec] * (130/225)^2 = ~2.0 [sec]. This change in length will also double the printed resolution to ~50[um/pixel].
The down side is buying a longer HDMI cable, because the printer is moved away from the desk & pc. Also need a new shutter.