Quote
nicholas.seward
@uncle_bob: Won't you have carriage interference if you mount bearings in the middle?
Yes indeed you would have interference. That's a very real limit to how high you could put the bearings. I'd have to do some modeling to figure out how high they can be (or if it makes sense at all). My motors are pretty tall. The same issues may apply to mounting them above the build plate. I’m guessing the motors plus “stuff” will be 8” to 10”.
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Plate with dowels:
Somehow I missed the comments on the stack up. I suspect :)-D:)-D:)-D:)-D but will deny it if pressed...
I'd rather keep the build plate free floating from the support if possible. That way I can fiddle it with three screws to get everything close.
My alternative plan is to go with the better grade of Home Depot plywood (the Columbia PureBond stuff). I'd probably stiffen it with a couple pieces of poplar 2x2's. I can easily get three of my horizontal plates out of a 4’x8’ sheet. More or less it’s a 3 plate or 6 plate design if I go this way.
[homedepotpurebond.com]
Anything that involves major machining of 20" diameter objects is going to cost me something (beer or what ever). A few holes here or there with a drill press - no problem.
Coupler:
The only real CNC item that is still on the list is the coupler between the bottom of the drive shaft and the top of the motor. With high torque motors and no flat on the shaft, I’m not real sure that a printed part is going to get the job done. I’m guessing that epoxy will do fine for attaching one of the bronze nuts to the bottom of the shaft. That leaves me with a fairly simple round piece to go to the motor shaft and to glue in the other end of the nut. I’d love to find an off the shelf 8mm coupler that would drop into the nut. So far no luck.
..... of course this could be the perfect excuse to buy a small lathe....