Well there are some constraints for us (FRC Team 1989) to be involved
1.) It has to be completely open source
2.) It has to fit around our other projects. Right now we got to get “BumbleBot” along as far as possible before the ERRF as we want to show it there and if its not completely finished by then it got to be finished asap as we want to take it to a competition in the beginning of November to test how well a 3DP robot can compete so we kow for next season. All items for the 3DP robot are open source too as with FIRST we need to share everything otherwise nothing even close to it can ever be used by our team again.
I - Martin Pirringer - am the head mentor. I am retired - I can design a lot of parts. My restrictions/bottle neck is 3D printing it. My printers the PULSE which is currently not operational and the CHIRON are the only printers currently working for team 1989. The team has a makerbot replicator + the school was going to throw out cause it was too expensive to fix and we fixed. The school also has an airwolf but we can’t use that one cause we “print too much” and it might break. I currently have the parts that connect the 2020 for the base frame and the legs. Bumblebot is designed by the kids and sometimes I get a little ahead of them printing (they make the STLs under my guidance). The Pulse is apart cause when it ran out of warranty I decided to fix/update it. It has some “features/quirks” that annoyed the heck out of me. Like an underpowered powersupply which means if you try to run the E3D V6 at over 255 and the bed at 100 like for some ABS and definitely hobby king HIPS the 12V is 11.1 cause well the draw is too great and if you turn the fan on like for bridiging you get a thermal runaway. The Mini rambo its running therefore is running too hot and right now I got a fan strapped to it so it gets a new electronics case and wiring with fan and a 30A power Supply and an enclosure the Chiron will get one too right now the enclosure is this
A piece of plastic draped over it and the Print dry which is a converted food dehydrator next to it which ups the “chanber” temp to somewhere within the high 40C a little over 50 at the nozzle level if the bed is at a 100ish. plus it keeps the HIPS smell under wraps. Granted that smell is way less than ABS but still noticeable. Right now I am printing plates for the Rack and Pinion like this
That is about (depending on config) between 400 and 700g of filament as its pretty much solid.
Our standard print settings for Hobby King HIPS - frame brackets is (we print with a .8 nozzle) between .9 and 1.0mm outside perimeter between 1.2-1.5mm inside perimeter layer height .4mm 6-12 perimeters (the piece displayed has 9 with a 1.3mm inside perimeter 1mm outside perimeter) and 3mm floor and ceiling so its pretty much a solid piece of plastic as close as you can get 3DP to it being casted. At that print it almost never breaks along layer lines anymore. Dialing it in right is important and so are the other parameters we print a little hot so we get a little stringing but in most cases that is ok like the piece in the picture will take 12 ea 1 1/8in od bearings (We print those too)
Now to the CNC. We have a 1/2HP hand router donated that we will fit but pretty much any spindle setup will do we got to use that one as we dont have the $$ currently for another one. The Y is probably going to be like th Z on most printers with 2 steppers the X has 1 stepper and the Z will have 1 stepper. Initially we intend to run belts - maybe double belts on some . Eventually we would love to replace the belts with Rack and pinions. The 2020 extrusion we bought in 1200mm length as we need to cut pieces as big as 36x36 in mostly hardboard,. lexan and hopefully Aluminum up to .125 in thick And maybe other plastics like sheets of ABS or HIPS or PVC etc the repeatable accuracy we are looking for is +/- 0.5 mm If we get to about 0.1 tolerance we can do pc boards too. In electronics we were thinking in the direction of the Bigtree 32 bit board with TMCs to do “sensorless” homing. But right now its kinda on hold for about a month. All the parts so far and in the future are designed to be printed in HIPS. We love HIPS we print it easier than PLA on the makerbot (which is a PLA only printer) Is realy tough and we buy it at between $8 and $12/kg. Only thing we (the kids) don’t like its very limited in the range of colors it comes in Hobby King sells Black,yellow, orange, red and not all colors are in stock all the time and toner plastics sells natural (white) only. I will make a separate post on printing that HIPS. Some other minus which we don’t care about is that according to some people the Hobby King and Toner Plastic variety do not dissolve in limosene as fast as other brand name HIPS (we never tried it ) cause if we had a 2 head printer and would use a dissolveably support material we would print in HIPS and use ABS as the support material we call HIPS the better ABS smells less, is tougher, easier to print (less warp, better layer adhesion) and its the filament so far that according to our Volumetric max extrusion determination can be printed faster than any other material,