I tried to build a simple x y system. Looking at the items in the store I chose the mini wheels and a universal build plate. Are they compatible? I can't seem to get the spacing right for 2020 extrusion. I tried to use a spacer on one side and the eccentric spacer on the other. I can get it to work if I use to eccentric spacers. See the last photo.
Sorry but the holes on the standard gantry plate are spaced for the large wheels. The only plate (that I'm aware of) for use with the mini-V wheels is the Mini V Wheel Plate. This should probably be spelled out a little better on the shop's web page and it probably was at some point but currently the only reference to wheel size is for the 20mm plates. If you need to trade back the wheels for the larger ones, please contact the shop. They are generally fairly good about such things. Contact them at http://support.openbuilds.com/support/home.
Can I post a mock up here and get your advice before I trade wheels? I am not sure the standard gantry plate will work with my design.
I can see how the y axis would work with eccentric spacers on the left. I don't see how the x axis would work because there are no holes for the eccentrics. The only other solution I can think of is to put another build plate perpendicular to the first for the x axis.
Tom, If you decide to keep the mini-Vs and need to go with a back to back scenario, you might consider using a mini-V plate on the back. The mini-V plates have threaded holes in the center such that mounting is fairly simple. (Please excuse the condition of the plate. It has had a rough life.) Another thought would be to simply pick up some 1/8" x 3" aluminum squares on ebay and drill your own holes. The holes are 9/32" and 13/64". (7/32 will also work for the latter.)
Thanks Rick. What do u think of 2 mini plates back to back? Small system because no great sideways forces involved. I would put one plate perpendicular to allow the eccentrics to align.
I like this system you have going @Tom Kelly . The spacing seems far enough apart to give plenty of stability for a system with small forces. Good luck with the build Tom and keep up the good work.
That would work fine. The plates are 1/4" thick so you need to make sure the 1/2" thickness of two plates is not a problem. The bolt heads are recessed so the plates will fit flush together and you won't have any interference like you would with the larger plates. The only real issue is that you will need to drill the threads out of holes of one of the plates to pass the bolts through and into the other plate.
I am trying to avoid using a drill press or milling machine so that any artist can make this. Maybe I will break down and $$$ later. Does open build offer any drilling / milling for $? Perhaps this is a good modification for x y (z) tables...
I'm not aware of Openbuilds offering any services like that but you'd have to ask Mark. But those threads can easily be cleared out with a hand drill and a 7/32" bit. This aluminum drills fairly easily and in that you are merely following an existing hole the drill has no problems with wanting to stay straight. The other problem besides not being able to draw the plates together caused by the existing plate threads is not being able to get the screw head all the way down. You might be able to join the plates with 5mm set screws but you will need some form of glue between the plates as set screws will hold them together but cannot tighten them up. If you really need custom plates to make this work, you might get in contact with @Chris Laidlaw.
Continuing with this build. It seems like there is some wobble in the design. Would it be better to add a thin nut to tighten the screw to the plate, and taking tension off the bearing? The screw would also have to be longer.
Found another problem/ solution. It is not spelled out anywhere, but A mini /precision shim (10mm OD * 5mm Bore * 1mm thickness) needs to be put in between the bearings inside the wheel. The bigger shim hits the bearing. Another shim needs to be put between the wheel and the eccentric spacer. Otherwise the bearings are blocked and drag introduced. Since we put one on the eccentric we should also put one on the regular spacer so the wheels are exactly the same distance from the plate. The mini shim (10mm) is better between the wheel and the spacer. For some reason the wheel moves more freely. Small defects in the outside dark plastic of the bearing may rub the large shim.
The assembly order is shown on the wheel kit order page in the store. (Sorry the image is so big.) Got any photos of your progress so far?
saw that today after I figured it out. My other point is that it works better when both shims are minis not the bigger ones shown. Try it and u can feel the slight difference.
I am putting together an order to start connecting everything. I would like to try pivoting the base axis to give change in the z axis. Have u seen a pin and plate combination that 2020 can rotate on? I assume the hole is 4.2 mm. I also assume the pin would have to be 4 mm plus or minus. 4.2 mm is the diameter given for misumi 2020. The sketchup I found for v slot was 5mm ??
