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:
|Spotamaterials.com||€ 62..78 /Kg||EU/ES||Very nice different resin options! :)|
|FunToDo.net||€ 45 /Kg||EU/NL||General DLP resin, incl. VAT: € 54 /KG|
|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!|
**) 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! :)
Because of some spare parts lying around, this results in the next design:
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.
Since the tilting system is working, it's time for some more testing.
This time I'm using resin from FunToDo.
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... 2014 will be an interesting year!
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...