From Newsgroup: rec.crafts.metalworking

The X axis leadscrew nut on my ZX45 bench top milling machine is
loose . Very loose , like .025 lash loose . I read up on making a new
nut since I can't find a replacement . So I bought this big chunk of
Delrin and a piece of aluminum to build one . Got the delrin threaded
and now I'm figuring out how to machine a nut/holder without a milling
machine since I have to disassemble to get the dimensions for the new
nut holder ...

Last night I was considering getting one of those mini mills to do
the job and while shopping around I found the solution to my dilemma . I ordered a small X-Y table . I can lock down the mill table and bolt this little one to it to machine the nut and holder . Since it's only like 4
inches tall I won't lose much Z travel . I'm thinking I'll mount the
small screwless vise I made on the small table , much easier to dial it
in instead of having to dial in the part every time I move it .
--
Snag
I appreciated foreign cultures more
when they stayed foreign ...
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From Newsgroup: rec.crafts.metalworking


Snag <Snag_one@msn.com> posted:

The X axis leadscrew nut on my ZX45 bench top milling machine is
loose . Very loose , like .025 lash loose . I read up on making a new
nut since I can't find a replacement . So I bought this big chunk of
Delrin and a piece of aluminum to build one . Got the delrin threaded
and now I'm figuring out how to machine a nut/holder without a milling machine since I have to disassemble to get the dimensions for the new
nut holder ...

Last night I was considering getting one of those mini mills to do
the job and while shopping around I found the solution to my dilemma . I ordered a small X-Y table . I can lock down the mill table and bolt this little one to it to machine the nut and holder . Since it's only like 4 inches tall I won't lose much Z travel . I'm thinking I'll mount the
small screwless vise I made on the small table , much easier to dial it
in instead of having to dial in the part every time I move it

A few of those inexpensive import XY tables have been noted to have inconsistently lead screws.

That is not a deal breaker. Just use a mag base and your dial indicator for positioning.
--
Bob La Londe
CNC Molds N Stuff
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From Newsgroup: rec.crafts.metalworking

On 5/31/2026 6:30 AM, Snag wrote:

On 5/31/2026 7:39 AM, Bob La Londe wrote:

Snag <Snag_one@msn.com> posted:

-a-a-a The X axis leadscrew nut on my ZX45 bench top milling machine is
loose . Very loose , like .025 lash loose . I read up on making a new
nut since I can't find a replacement . So I bought this big chunk of
Delrin and a piece of aluminum to build one . Got the delrin threaded
and now I'm figuring out how to machine a nut/holder without a milling
machine since I have to disassemble to get the dimensions for the new
nut holder ...

-a-a-a Last night I was considering getting one of those mini mills to do >>> the job and while shopping around I found the solution to my dilemma . I >>> ordered a small X-Y table . I can lock down the mill table and bolt this >>> little one to it to machine the nut and holder . Since it's only like 4
inches tall I won't lose much Z travel . I'm thinking I'll mount the
small screwless vise I made on the small table , much easier to dial it
in instead of having to dial in the part every time I move it

A few of those inexpensive import XY tables have been noted to have
inconsistently lead screws.

That is not a deal breaker.-a Just use a mag base and your dial
indicator for positioning.

-a The only critical dimension is the distance from the mounting surface
to the center of the leadscrew . If I do this right I'll be using the Z
axis DRO readout to set that dimension . If I mess it up , I have enough aluminum to make it over ...

I know bronze is expensive, but it might make a better long term quality replacement. Maybe even brass if you add an oil line. Its an import
mill, but it will still cost a few thousand dollars (minimum) to buy a
new machine. Why not improve what you have. If backlash is your
concern you might also play with the idea of a split nut you can adjust.

Every manual machine I have played with has some backlash. I bet with a
split nut (if the screw is good enough) you could get it down under a thousandth. Certainly under 5 thousandths. If the screw is badly worn
you may have to adjust it at the ends and accept some more backlash in
the middle.

A split nut (the ones I have seen) is split down one side with three
screws both holding it together and pushing it apart. When the nut
wears you just loosen them up, pull it together some more, and then snug
up the screw/s that push it apart. The little Taig mill was that way.
If I was willing to to accept low speed and acceleration (it was CNC) I
could adjust it to better than .001 backlash. It just had high precision 1/2-20 v-leads. (I swapped Z out for a ball screw).

To increase the life of your nut you might also run a simple oil line to
it so you can give it a shot of oil to lube it and flush the dust out
once in a while.

One caveat. I think they leave a lot of things loose on a a lot of
import machines because alignment isn't great. If you get everything
tight, you may need to add some adjust-ability for alignment purposes to prevent binding. Maybe just slotting or wallowing out the holes that
mount the lead screw bearing blocks.

Wow! Listen to my arrogant ass acting like an expert. LOL. I am just
making suggestions. Only you know what is best for you.
--
Bob La Londe
CNC Molds N Stuff
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From Newsgroup: rec.crafts.metalworking

On 5/31/2026 9:13 AM, Bob La Londe wrote:

One caveat.-a I think they leave a lot of things loose on a a lot of
import machines because alignment isn't great.-a If you get everything tight, you may need to add some adjust-ability for alignment purposes to prevent binding.-a Maybe just slotting or wallowing out the holes that
mount the lead screw bearing blocks.

Oh, yeah. Some of your backlash may be coming form the lead screw
bearings. In better CNC machines they mitigate that with back to back
angular contact bearings machined as a pair that when tightened together
take out virtually all of the slop in the bearings. It can be done with v-groove bearings and a shim or spacer. That's typically a lot cheaper,
but maybe not the same ease and longevity.
--
Bob La Londe
CNC Molds N Stuff
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From Newsgroup: rec.crafts.metalworking

On 5/31/2026 11:18 AM, Bob La Londe wrote:

On 5/31/2026 9:13 AM, Bob La Londe wrote:

One caveat.-a I think they leave a lot of things loose on a a lot of
import machines because alignment isn't great.-a If you get everything
tight, you may need to add some adjust-ability for alignment purposes
to prevent binding.-a Maybe just slotting or wallowing out the holes
that mount the lead screw bearing blocks.

Oh, yeah.-a Some of your backlash may be coming form the lead screw bearings.-a In better CNC machines they mitigate that with back to back angular contact bearings machined as a pair that when tightened together take out virtually all of the slop in the bearings.-a It can be done with v-groove bearings and a shim or spacer.-a That's typically a lot cheaper, but maybe not the same ease and longevity.

This machine has split nuts ... The X nut has the adjustment
bottomed out . I could make one out of bronze casting stock I have on
hand , but I think the delrin nut with 3 times the threaded length will
last longer . I never really noticed excessive - in my opinion -
backlash until after I added the power feed 4 or 5 years ago . I have eliminated 99% of the bearing backlash with the design of the extension
I had to make to adapt the power feed unit . I'm not too surprised with
this happening , I've had this machine for like 25 years and it's made a
LOT of parts .
--
Snag
I appreciated foreign cultures more
when they stayed foreign ...
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