Double ball nut question

Hi,

I'm converting my Optimum BF20L mill to CNC. In the Z axis I'm using 2005 ball screw and I have a Taiwanese 4 rows ball nut and a Chinese double ball nut.

While the double ball nut is installed but the pieces are separate from each other they play a lot. Say a play like a 0.5mm. Very slacky. But when I join the pieces together they work fine. No play at all.

Is this the way how a double ball nut is?

On the other hand the Taiwanese 4 rows ball nut alone works fine.

I can't decide whether I should use the Taiwanese 4 rows or the Chinese double ball nut.

Suggestions are welcome.

Thanks

Quote:

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Originally Posted by Azalin

Hi,

I'm converting my Optimum BF20L mill to CNC. In the Z axis I'm using 2005 ball screw and I have a Taiwanese 4 rows ball nut and a Chinese double ball nut.

While the double ball nut is installed but the pieces are separate from each other they play a lot. Say a play like a 0.5mm. Very slacky. But when I join the pieces together they work fine. No play at all.

Is this the way how a double ball nut is?

On the other hand the Taiwanese 4 rows ball nut alone works fine.

I can't decide whether I should use the Taiwanese 4 rows or the Chinese double ball nut.

Suggestions are welcome.

Thanks

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The decent ones have a metal spacer between the 2 nuts and a couple of small straps holding them together like the ones below.
You'll have to have a good shop around for a good seller.

If you have the spacer missing then they are not going to be much cop because the second nut moves freely.

Get the spacered ones, they are much better. And you can tighten them up a bit with thin aluminium foil between the spacer and the slave nut.

You can try to diy the ones you have but it'll be a bit tricky.


With spacer
https://ae01.alicdn.com/kf/HTB1NgVUN...ouble-ball.jpg

Without spacer: (junk)
https://ae01.alicdn.com/kf/HTB19bKsK...IY-Carving.jpg

Hi,

Mine does have a spacer. But without the second nut installed the main nut plays a lot. When the second nut installed they work well together. Is this normal?

Sent from my MI 5s Plus using Tapatalk

Quote:

---

Originally Posted by Azalin

Hi,

Mine does have a spacer. But without the second nut installed the main nut plays a lot. When the second nut installed they work well together. Is this normal?

Sent from my MI 5s Plus using Tapatalk

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Ah. O.k. So far it seems normal with these that on their own they have play. This is why we're using the DFU's because it solidifies them up.
A single Chinese nut is total crap lol.
If Your backlash is still a bit to much get some of the thinnest alu foil you can find (like 0.01mm) and gradually pack it as I said previously.
I went from 0.08mm to 0.015mm on my worst one, any more than that is locked.

it is exactly the way it should work.