Thread: Angular contact bearing source for ball screw supports?

Here's some 'eye candy' for anyone who'd like to retrofit their bridgeport :P. Looks a bit terrifying.
https://www.youtube.com/watch?v=NdaX-tvVHl0
Cost? If these servos are reliable, $450 each ex-postage. Obviously there are more costs involved - power, controller, etc. STILL.
https://www.aliexpress.com/store/pro...7a1dacd6QuPYPJ

Originally Posted by rcaffin

most hobbyists give steppers a bad rep from overdriving them and losing steps.

I will irritate a lot of very good people here and suggest that more than half of the comments in this area are made by people who have not actually got any practical experience. They are just channelling other peoples' comments.

Cheers
Roger

Not sure if you mean me (though I must admit to having been guilty of this before), but that's a quote from Tormach.

Does the stepper control system sometimes lose steps?

Proper engineering of a stepper system is not trivial. The fact that stepper-driven motion control is commonly used on mission critical systems, such as medical equipment, is testament to the reliability and accuracy of the technology. The technology has been given a black eye by a few poorly designed machines offered by others, as well as a large number of hobby CNC projects. PCNC mills and other properly engineered machinery will not lose position in the designed operating envelope. The PCNC 1100 axis system can deliver 850 lbs of force before missing a step, more than enough to break most cutting tools. Step loss is simply not an issue."
https://www.tormach.com/technical_qu...#stepper-motor

I was just pointing out steppers are probably adequate for my needs, though servos can offer superior performance (here I am rechannelling) and provide an interesting experience if you like PID loops and such.
The big issue in my mind is as I've said before reliability. See my post on cnczone.

Not sure if you mean me
No.
Generic comment, alluding to the vast number of confusing recommendations on the web, compounded by the huge number of enthusiasts with little or no knowledge of either engineering or electronics who try to build 'perfect' machines for <$1,000.
In fact, I agree with Tormach.

Would steppers suit YOU? Very possibly, subject to you (or anyone else) understanding their limitations. Go for it.

Cheers
Roger

Open loop steppers are used in millions of applications around the world without issue. I don't think I can recall ever having a missed step on my 3D printer other than with the extruder motor when overloaded.

Originally Posted by jhovel

Maybe it was just pure luck. But the two bearings I fitted both exhibited the 'ground in' preload behaviour. I think I said that they were both automotive wheel bearings.

I really don't know. The specs I found for single race 4 point bearings was the smallest clearance was 0.002".

I do not know anything about them other then what I found.

Oops, I didn't make it clear: I have used automotive wheel bearings - which are two angular contact bearings with a common outer race as shown in the first picture. There was no clearance at all after assembly. I have no practical experience with 4-point bearings other than having one in my bearing draw.... that's how I knew they existed.