Exquisite Automated Build Platform
These are good resources for creating wiki pages. Very Messy Example and Columbus --Sebastien Bailard 07:23, 10 September 2010 (UTC)
this was a wonderful development project, however with any conveyor belt there are issues with warping, lift, and weight issues. If these were overcome perhaps development would continue.
One wiki editor has suggested renaming this page to conveyor belt build platform.
mendel abs (automatic build platform generic)
this is an attempt to make an automatic build platform for Mendel.
the idea, is to have a unit snap into the bed of the mendel and take no more than 15mm in height, that uses a geared motor to move a belt of kapton film with paper base around every so often to clear parts. returns to same surface area as before, and uses vacuum between mulitple base plates to keep film in place especially for tall builds or for fast movements.
theory of operationFile:AbpTheoryOfOperation.doc (beta, not complete yet)
i will be uploading picture of my unit, and diagrams and how to make and machine and possibly print parts for it. note. my unit does not yet work. it does not yet have safety features.
7 essentials of design: 1) must not be two high as to prevent large objects from being built
2) must not be heavy as to slow down y movement and acceleration by more that 10%
3) absolutely must have a flat surface, and be designed sturdy enough to print for 100hrs without warping or adjustment
4) must allow printing of base layer without raft at a minimum of 34mm/s at least for 0.6mm nozzles.
5) must have a built in fail safe so as to not over temp. (fusible linkage, some mechanical fail safe that works no matter what fails)-
6) must be tested by at least another member in the community.
7) must be easy to transport and assemble.
8) must have inline fuse. background. this has been talked about for some time on the reprap forum, although i would like credit for implementing this version, prior credit goes to other people. i will do a search and add those names later.
I also am documenting this here, so it remains a public document, and can serve of proof of prior concept.
heater is 6 10 ohm resistors beneath a copper heat exchanger (pcb copper board) - rated to run at 160C
nylon spacers will be used in front and back for low friction movement of 5/16" (8 mm) rods about 10 inches wide, with polyvinyl tubing to allow it to have grip.
fusible linkage will be hooked up in series to lamp, and will be mounted and kapton taped to bottom surface.
side supports to bolt into the frog of regular Mendel bolt holes. side supports are made of wood because of low warping at high temp. rest are pocket for build surface will be slightly oversize, and gripped from the front inside, with rubber. allowing glass ore backside of copper clad board to expand freely.
here is a picture below of what i have currently. this is just to test the concept. final product will be a lot better looking.
7th design looks like this:
video proof of concept: (basically looks good but does nothing much) <videoflash>yDXkF8dsqMk</videoflash>
video motor working here: (heater is off, plastic is not really secured, and motor is not gear meshed to pull system, yet. Still i found my motor!) <videoflash>s0nOJtCovLk</videoflash>
video of vacuum test research: (simple but shows results)
video demonstrating vacuum pull without airtight container. - shows it may work. not that it actually will. we will see here soon enough.... some errors: i said a few motors, should have said a few batteries.... one of the side effects of doing a video at 3amish... <videoflash>dc8Aq9S-rLU</videoflash>
10/20/2012 - i have a small version of the abp platform proven. it is a common cotton fabric with fine threads tightly interwoven, and it is coated with floor acrylic.
there are still issues with tearing and outside edges lifting. i have work progressing on to full sized beds now for mendel. Still not recommended for prusa beds.
5/8/2011 - after trying to cnc and make support several times, and having int break apart, i have another method. this one involves soldering copper button pins, and using the diameter of the shaft to support it in a layer above. i will try to post images of it in the next few days. the heater works, and on the peg pins it is high enough to allow vacuum between the plates, and also allows area for the space of the heater resistors.
4/2/2011. I've tried to cnc the following top side of the build platform, but it breaks apart being wood. here is the cnc file of the single piece. if you have cnc and cut aluminum, it may work. be aware the thermal expansion rates of the material used. another note, I've had issues embedding stl,dwg files in this wiki, so i will link them to my own server. will have it shortly.
here is stl file of single piece abp_bedboardholder.stl
3/29/2011 here is the file i used to cut the 6.25 x4.5 inch radio shack copper clad boards. if you want to cut boards by hand or redesign here it is in a dxf file boardcutmm.dxf if you hae a cnc and have a 1/8 inch bit, here is the nc file. BOARDCUT.nc
3/27/2011 - more progress, decided to create a video explaining about the heating device of the bed. although it is easy for me to one off a circuit board resistor heater, i will need to talk to suppliers to see if that can be used, until then i decided that least complex method i show in the video below is what i will use. I have tested this heater to 160dec C, but in the video i only get it to about 150dec c. still that is good enough. the system will run at 24v. this test shows 1 heater at 12volts.
3/5/2011 i had a family emergency that kept me away for 2 weeks. here is a revised bed for abp. this one is cheaper to make and allows for the mechanisms required i will post a dxf file in the next few days. i expect for this project to start coming together and to look real nice in the next month or two. here is a video of the laser cut bed base of the abp. what is next is uploading skeleton frame of abp parts, and showing construction instructions. Still having issues laser cutting oak, but I've found acrylic that works OK with abp bed near 160C. I'm worried it may warp, but I'll use it to show its construction.
2/17/2011 this is a beta version of circuit schematic for abp. notice the push button to keep motor going, and the fly-back diodes as well as the 3 Leds. This is a beta design, and a Gerber file will uploaded soon,
2/16/2011 - Try as i might. the abp needs a slightly modified bed. i will try to make a case for this to the community. here is the dxf file and a picture the reason is that thermal stress will crack the acrylic plate otherwise if the abp is bolted on. this allows the abp to be easily removed as well. the abp is made from maple/oak paneling. I'm tuning my laser cutter to test the dxf files, also the pcb board will be in 6 sections. see surface picture below. each section of board will have a single resistor of 10ohms on it, and sliced down the middle, soldered one tab onto each side. the piece will go into tiled spaces on top of the abp, and be set in place. the spaces between are where the vacuum hold down the surface smooth. the paper surface of the belt, will not bend, but will be pulled to the bed thru these tiles spaces. the spaces will be framed on two sides with wood supports. the belt otherwise would stretch and move out of place. the belt is made out of paper and kapton tape. also there will be a notch on the front right of the belt for positioning, so each time the belt is used, it is over the same area of belt. also note the middle slit in each board is just where copper has been removed. it can be removed with a hobby knife. no etching or chemicals needed to make this abp! - just solder skills. i will upload more this weekend.
dxf download -> File:Abp bed.zip
2/13 - i did an edit to this on 2/7 but it seems to be lost. i will be adding back the links to parts. 6 10 ohm resistors heats bed to 160c  thermal cutoff  here are the parts i bought from radio shack motor model zga25rp14.7i gearbox motor
1/17 - since this is an abp for mendel, i decided this weekend to build an actual standard Ed Sell Mendel. it took 2 days to print the parts, and to machine the frog and base plate. still need to do some work with motors and belts. will use custom electronics. here is the mendel video, showing also the abp. it will be designed to work on the standard mendel.
1/10/2011 so far i have been finding some free time i to make it work. i have been thru 7 designs variations, and have decided that heat lamp does not transfer enough energy to the surface. i can easily design a heated platform by etching a board, but this is not cost effective. i will try to make a regular pcb sheet with copper be able to be used. i also had to redesign the outside front a little bit to get the 15mm or less height. the height is now at approx 15mm for platform. but it is 2 inches wider. i will update again by this sunday, hopefully with a version that can be laser cut.
here is version 1 stl files: if you have a cnc 3 axis and have wood handy. these files are in inches. the wood i used was .66 inch thick. it will change, already i am preparing for laser cut version. still investigating Poly(methyl methacrylate) it apparently melts between 85deg and 180deg c that is too low for a bed that can go up to 150c, although that leaves some room for it as a linkage switch.
here is another video showing the motor i am going to ue that is powerful enough. it is going to be a gear mesh later on so it will not use traction, and the motor will be on the inside not the outside, also a slide tray will be in front. video here: http://www.youtube.com/watch?v=s0nOJtCovLk