October 1, 2018 at 2:24 pm #70826
This is where I got the idea. It seems to work pretty well. You could mount 608ZZ bearings around the edge of the turntable to support more weight.October 2, 2018 at 12:57 pm #70871
The article says “mount a high-torque rotisserie motor” to turn it. If you have a front-wheel drive car, jack up the back end and rotate one of the rear wheels by hand and you’ll see why the article says “high-torque”. You’d need a really big stepper motor to drive it.October 2, 2018 at 2:11 pm #70880
Wheel hub assemblies from a car might work for axis bearings. They would be too heavy to mount on the head, but would work fine on the table.
I was actually wondering the same thing. I just recently put something similar to these on a small trailer I was rebuilding: https://www.amazon.com/CE-Smith-13110-Replacement-Accessories/dp/B003NTM1C0/
They spin very freely by hand, especially before you pack them with thick wheel bearing grease, and at the loads we’d be talking for something like this, I’m sure you could get away with a light weight grease like white lithium. They’re 1″ inner diameter too, which could potentially work out well for people using 1″ SS tubing in their build (depending on the overall design of course).
It does seem to me like you’d be better off doing both the 4th and 5th axis on the table, that’s how the majority of large industrial 5-axis machines I’ve seen do it. But doing it that way does mean that the 4th axis has to be able to rotate (and accurately position/hold) the entire work piece and the 5th axis rotary table, which might start pushing the requisite motors and drivers into a range outside the usual MPCNC build.October 15, 2018 at 10:32 am #72101
Lazy Susan bearings still have my interest. The better ones support a few hundred pounds, turn with little effort, have large diameters which will increase stability, and are common and cheap.
I have most of the 4th axis working, except I don’t think nema 17 motors have enough torque to hold this thing strait during cutting. I have to see what I can get in a geared stepper. Speed should not really be a problem here.
I’ve seen smaller geared motors, but I haven’t started to compare torque or detent holding specs. If I can get it to hold, I’ll make a few cuts with it strait up and down. If that works, I’ll add an endstop. If all goes well, I’ll go for the last axis.October 15, 2018 at 11:27 am #72121
I was hoping to find those “puck” style steppers, and see what kind of specs are on those. Anyone know of a source?October 17, 2018 at 10:55 am #72401
I have an idea. If this ends up not having enough power on the 4th axis mounted on the z, maybe I can mount a camera on it, and still make the rotary table, and use it as a 3d scanner.
I’ve seen you can take a lot of photos and stitch them together to get a 3d image. Just wondering if cnc’ers would find something like that useful.
You must be logged in to reply to this topic.