[zymurgy42]

Thinking of a CNC router build. Doing lots of reading etc.

The stepper end of a ballscrew is laterally fixed. Other end 'floats' supported by a bearing, but why does it have a circlip?

Instead of buying a BF coupler, could one not machine a socket for an appropriate size bearing for ballscrew end to float.

Hope that make sense.

Gordon.

I now understand that the circlip holds the bearing on and bearing AND shaft float in the BF socket.

[aarggh]

Hi Gordon, although you've answered your own question, a lot of people do exactly what you mentioned with the floating end. So long as it's tolerance is good enough to allow for expansion/contraction without sideways slack, doesn't really matter what you use for the floating end, although the BK/BF sets are pretty cheap anyway really.

cheers, Ian

[zymurgy42]

Ian,

Thanks for input.

It's all relative. If I can save on BK's, I can spend more elsewhere

I'm going to start at Z axis and work backwards towards X-Axis. What I learn will be transferable to other axis.

I'm thinking on using either 12mm or 16mm 6061 aluminium plate. I can mount a bearings in this plate (Angular at one end for stepper). Saving on space and cost.

It's still in head and some scribble on paper...

Gordon.

[aarggh]

Ian,

Thanks for input.

It's all relative. If I can save on BK's, I can spend more elsewhere

I'm going to start at Z axis and work backwards towards X-Axis. What I learn will be transferable to other axis.

I'm thinking on using either 12mm or 16mm 6061 aluminium plate. I can mount a bearings in this plate (Angular at one end for stepper). Saving on space and cost.

It's still in head and some scribble on paper...

Gordon.

Hi Gordon, I can understand saving money, but given the very low cost of these from China, I think you'd be hard pressed to devise something as strong or as accurately machined for the price. The beauty of these is also the fact you only have to worry about the alignment of the support bearing along one plane, not two if you make your own. Much easier to get everything perfectly aligned.

I find sometimes that saving a few dollars ends up costing a lot more in grief and a sub-standard result than it was worth.

cheers, Ian

[zymurgy42]

Ian,

A lot of post mention how poorly machined the chinese ones are. Even so, average cost is $69.00. I can get bearing (Angular) and nut/washers for around $20.00.

I will be having major parts machined with a the aid of a real CNC machine, so expect some degree of accuracy

Gordon.

[RICHARD ZASTROW]

I hope you are referring to a pair of angular contact bearings at the fixed (motor) end.

Dick Z

[zymurgy42]

Dick,

I was thinking of these: http://www.ebay.com.au/itm/5201-2RS-ANGULAR-CONTACT-BALL-BEARING-BEARINGS-CNC-BALLSCREW-SUPPORT-BK12-/300751765521?pt=LH_DefaultDomain_15&hash=item46063 3c011 http://.

Referring to here, 5201-2RS 5201-ZZ Radial Ball Bearing 12X32X15.9 they are just called radial bearings.

From what I read, this bearing DOES NOT look like an angular bearing. See: File:Angular-contact-ball-bearing single-row din628 type-b 120.png - Wikimedia Commons

So I may be on the wrong path here....

Gordon.

[RICHARD ZASTROW]

The 5201 series is a double row angular contact bearing. However, it does not have any preload, it has axial clearance that permits axial motion. Also, ballscrew support bearings have 45~60 degree contact angle to be able to handle the axial thrust of the ballscrew. A 5201 has probably 15 degree contact angle, not normal for ballscrew support.

Depending on your accuracy requirements and wallet thickness, I'd look for real ballscrew support bearings. I'd look into a pair of sealed 45~60 degree angular contact angle with heavy preload. Then mount them as recommended by the bearing manufacturer.

There are less expensive substitutions, but each compromise in specification will result in compromised performance. In other words, you get what you pay for or less.

Dick Z

[zymurgy42]

I will have to rethink my original approach. Whilst part of the reason for going the 'bearing only route', was cost. Another was the neatness of incorporating a bearing into the support material.

And since the Ballscrews are the 'key' element, one should do it right.

Hence the reason I posted, but I got so much more information.

Gordon.