[leix_99]

Thank you for sharing your experiences, as said above feel free to post comparison pictures!

[Padrino]

Bigspike,
you touched on a topic earlier about purchasing off shore end supports for your ball screws and replacing the bearings with single row angular contact bearings.

Just wondering if you could explain why this is a better choice over a similar sealed bearing.

Thanks again in advance,
Cheers

[leix_99]

Angular contact bearings, provide a tight fit in all the directions, unlike common bearings.
This prevents the little movement (and not so little)normal bearings can have, and this could induce a source of backlash in your system.
The offshore supports, come with AC bearings , but they are common cheap bearings, and worth your time and money to change them.

It's dificult to explain this, i found an image, it's not the best but it helps.

[Padrino]

Angular contact bearings, provide a tight fit in all the directions, unlike common bearings.
This prevents the little movement (and not so little)normal bearings can have, and this could induce a source of backlash in your system.
The offshore supports, come with AC bearings , but they are common cheap bearings, and worth your time and money to change them.

It's dificult to explain this, i found an image, it's not the best but it helps.

Lets say I was planning to utilize a FK fixed support on one end and a FF floating support on the other. Would you suggest to also use an angular contact bearing on that floating side as well?

Here is what I was thinking of replacing it with:
7004B Bearing Angular Contact 20x42x12 Ball Bearings

However it doesn't tell me the accuracy grade. I'm looking for minimum C3

Thanks
Rob

[SCzEngrgGroup]

Using an AC bearing on a single-bearing floating support make absolutely no sense at whatsoever. AC bearings make sense ONLY where *axial* load-carrying is required, AND they can be pre-loaded, which is almost always accomplished by using them in pairs.

Regards,
Ray L.

[Padrino]

Using an AC bearing on a single-bearing floating support make absolutely no sense at whatsoever. AC bearings make sense ONLY where *axial* load-carrying is required, AND they can be pre-loaded, which is almost always accomplished by using them in pairs.

Regards,
Ray L.

Perfect! That's what I initially thought. Thanks for confirming this.
Cheers

[steve123]

I have been following this thread because I also want high accuracy ball screws for my project and thought the Chinese C7/T7 screws were worse than they are. I think the Nook screws are a very good match for your mill. My project is different though. It's a 3x4' router. That means that the critical speed of the ballscrew (max RPM for the length of screw) becomes a factor. I decided to go with linearmotionbearings2008 2010 or 2510 screws with double nuts because of the following: 1. Longer lead of 10 mm will give me faster movement over the 150 ipm I would get from the .200 lead on the Nooks (you can't get an accurate Nook with a longer lead). 2. C7 accuracy is .0018 per 12", and that will be fine for me. 3. They will do the end machining. 4. I can get everything from one place (screw, nuts, end supports, bracket to attach nuts to axis, probably motor mounts). Thanks for starting this thread, and good luck.

[skray775]

I have been following this thread because I also want high accuracy ball screws for my project and thought the Chinese C7/T7 screws were worse than they are. I think the Nook screws are a very good match for your mill. My project is different though. It's a 3x4' router. That means that the critical speed of the ballscrew (max RPM for the length of screw) becomes a factor. I decided to go with linearmotionbearings2008 2010 or 2510 screws with double nuts because of the following: 1. Longer lead of 10 mm will give me faster movement over the 150 ipm I would get from the .200 lead on the Nooks (you can't get an accurate Nook with a longer lead). 2. C7 accuracy is .0018 per 12", and that will be fine for me. 3. They will do the end machining. 4. I can get everything from one place (screw, nuts, end supports, bracket to attach nuts to axis, probably motor mounts). Thanks for starting this thread, and good luck.

I can vouch for the quality of the end machining! They have done 2 sets of ball screws for me and both times the end machining was exactly what the drawings I sent them called for. !

[sudip]

If you need high accuracy ball screw you can try this

Ball Screw In CNC Machine.

[Contract_Pilot]

Roton double ball nuts... Made by milling 1/8" slots into the ballnuts then making a carrier with tangs to go in between them.

Carrier with tangs would like plans if anyone has them.