Backlash on SX2p mill

[BOB BLACKSHAW 1Participant @bobblackshaw1]

[BOB BLACKSHAW 1Participant @bobblackshaw1]

My SX2p mill has .2mm backlash on X and Y, is this normal or is the screw on the way out.

My lathe which has had good use over four years has .05mm backlash,

Is any adjustments that can be made for the mill, or any other type of screw that will give minimal backlash.

If I don't climb mill it can be a bit light on the handle and can jump the .2mm backlash, so Im always aware of the problem.

Thanks Bob.

[JasonBModerator @jasonb]

Have you tried adjusting the two grub screws in each of the nuts, they will take some backlash out.

Nuts that hold the handles on can also affect endfloat of the screws may want nipping up a fraction

[HOWARDTParticipant @howardt]

As Jason said adjust the leedscrew nuts. If you wind the axis out to its maximum the adjusting screws can be seen. Adjustment stretches the split nut to apply some tightening on pitch. You have to do it at the end of travel then see what happens at the mid position, which is were most slack probably is. Mine is only three years old and reasonably worked but still adjusts ok.

[BOB BLACKSHAW 1Participant @bobblackshaw1]

Thanks for the replies. I didn't realise that grub screws are on the nut, Ill have ago in the morning.

Thanks Bob.

[Neil WyattModerator @neilwyatt]

+1 for adjusting the leadscrew nuts.

Neil

[Alan VosParticipant @alanvos39612]

I found that even wth the leadscrew nuts adjusted, there was still more backlash than I liked (I don't recall the numbers). This was traced to float at the hand wheels. Adjust out the float, too tight to turn. Easy to turn, too much float. Much improved by boring out the bearing blocks to add needle roller bearings. Smoother as well. There is plenty of metal. If you mess up, the blocks are cheap enough to replace. I could probably come up with a photo or two if interested. SX2P Bearing Block

[Russell EberhardtParticipant @russelleberhardt48058]

Like Alan, I added thrust bearings to the support blocks. Here is a DXF file of my working drawing for the modification along with a slight mod to the leadscrew:

**LINK**

Russell

[Alan VosParticipant @alanvos39612]

Posted by Alan Vos on 29/04/2019 18:36:38:

needle roller bearings.

Correction, thrust ball bearings. The thrust needle roller bearing is helping clamp the tool post.

[BOB BLACKSHAW 1Participant @bobblackshaw1]

Can you tell me what bearings I need, and where to get them.

I got the backlash down to .05mm, had no idea that those small screws were there.

Thanks, Bob.

[Alan VosParticipant @alanvos39612]

Posted by BOB BLACKSHAW on 02/05/2019 08:47:27:

Can you tell me what bearings I need, and where to get them.

I used F8-16M (2 per axis) from ARC. (Do ARC keep order history for ever?) Russell's drawing showed the same size and the same general arrangement. Though I did not modify my leadscrew. Diagram 4, part 23 of the SX2.7 looks much the same.

IF I recall correctly, the fiddly bit is getting the outside bearing slightly proud so that the handwheel neither binds, nor shows a large gap.

[BOB BLACKSHAW 1Participant @bobblackshaw1]

Hello all, any idea how I can open the link on Russell's thread, its Drop Box file. I cant open it on my computer, haven't a clue what Drop Box is.

Thanks Bob.

[JasonBModerator @jasonb]

her you go as you will need something to open the DXF file that is on dropbox anyway.

[Russell EberhardtParticipant @russelleberhardt48058]

Hi Bob, I'm not sure if you will need to modify the end of the leadscrew. I was fitting a stepping motor for CNC so possibly needed a bit more length at the end.

Yes, the thrust ball bearings came from ARC.

FYI a DXF file is one that can be opened by almost any CAD software or just a DXF viewer.

Russell

[Alan VosParticipant @alanvos39612]

One additional note. To avoid binding, you need to align the centre of the bearing block with the centre of the leadscrew nut. When you re-assemble, leave the bearings and two bolts attaching the bearing block slightly loose. Crank the handwheel so that the bearing block is as close to the leadscrew nut as it goes. Tighten the two bolts. Now you can set the bearing pre-load.

[Author]

Posts