Mill parts

ABS would not work as it doesn't make a very good bearing surface.

Delrin works well for thermally forming a nut on an existing metal leadscrew. There are many you-tube videos.

Joe

Delrin works well for thermally forming a nut on an existing metal leadscrew. There are many you-tube videos.

Joe

------------------------------- Generic acetal cold-formed to sharp points when I knurled it.

Maybe Jet has something. Their JT9 and JMD45 mills look similar:

This might be the part you're looking for but you won't like the price😬

Yup , that's what it looks like . But I don't know what pitch the threads are ... They don't all use 8 TPI , some use 10 . I saw a comment about making a brass/bronze nut to thread into the original , I may end up going that way . I've got just over .020 lash , which isn't a problem with most projects , but my current project of making tool holders for my QCTP is having problems .

Guessing by the part Description Size "TM23.7-10" it's likely to be

Just an off the wall thought... could you use Babbit and a home brew mold to catch the pour for a shape you could use?

Would have responded sooner, but I do not have a proper Usenet client installed on the house computer.

My first response would also be to sleeve the existing nut. This addresses your request. I would suggest very tight sliding fit and use sleeve and bearing locker.

The search for a new one is what it is. A search. I have no special insights other than as you clearly already know that these machines may be sold under different labels. I suggest may be ask Matt at Precision Mathews. Admittedly he may be more responsive on parts to a customer than somebody who just wants parts, but he is very good at supporting customers.

Now for the tangents.

Backlash should not be a huge issue if your gibbs are adjusted, you use your gibb locks, and you mostly conventional mill. Accuracy probably is not a huge issue, but if it is take all measured moves using the hand wheel dials in only one direction. If you really need to be able find a postion accurately in two directions there are two solutions. The nice one is a DRO with glass scales. The alternative is some dial indicators mounted to the table. I have a dial indicator mounted semi permanently on one of my lathes.

As was already mentioned ABS is a terrible idea for all the reasons stated. Acetal (Delrin is a trade name) is used for bearings, axis nuts, and a variety of other things. Its pretty tough and there are commercial products made form the stuff. HOWEVER. Acetal does not accept any common adhesive well at all. It would not be a good option for boring and sleeving the old nut. Bronze or even brass would be better. I do not know if adhesives would stick to oilite bronze. Maybe another rabbit hole to research there.

I looked. I do not have an acme tap that big. You will have to cut it on your lathe (or buy a very expensive tap) after grinding a suitable inside cutting tool. It will probably chatter pretty bad, so it might be time to consider making a solid tool post that bolts directly to the cross slide.

Yes. So do it warm.

By thermal forming I mean melting.

Here is a related posting, but one would not want to take the real leadscrew and make it into a big self-tapping screw. I haven't found the videos on doing this on the actual leadscrew without damaging or risking it.

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And as others have said, no glue will stick to delrin, so the attachment must be mechanical.

Joe

I could cast it with bronze/brass ... I'd have to make a pattern and a core ... I have the material and the flasks and green sand . Actually it would be easier to make a lost foam pattern to cast it .

I just a few months ago ditched the Shumatech DRO and capacitive scales for a nice glass scale DRO that reads to tenths ... and I have a dial indicator on a mount that clamps to the front v way on the lathe in addition to one on a magnetic mount . Also have a couple of Starrett back plunger indicators with hardware and one NIB indicator for a backup in case I break one .

If I sleeve the original it'll be with bearing bronze or some Ampco

I already made a post type boring bar holder that bolts directly to the compound . I can use the lathe leadscrew as a pattern to grind the tool since it too is 8 TPI . Actually I have another leadscrew that's in very good condition that I would use .

Yes. So do it warm.

By thermal forming I mean melting.

Here is a related posting, but one would not want to take the real leadscrew and make it into a big self-tapping screw. I haven't found the videos on doing this on the actual leadscrew without damaging or risking it.

.

And as others have said, no glue will stick to delrin, so the attachment must be mechanical.

Joe

-------------------------------------------- I would try making a mild steel tap that closely resembled the leadscrew to pre-form the Delrin before compressing it onto the heated original. Possibly if the nut blank was tapped slightly tight and both heated the original could be screwed into it. Annealing might relax the plastic to a sliding fit. The tap could give ID and OD clearance so only the thread flanks are snug. The lathe will ensure the correct pitch and the tap's thread form doesn't have to be perfect.

I would try making a mild steel tap that closely resembled the leadscrew to pre-form the Delrin before compressing it onto the heated original.

----------------------------- I just discovered that the metric equivalent to Acme has a 30 instead of 29 degree thread groove angle.