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From: Bob La Londe <none@none.com99>
Newsgroups: rec.crafts.metalworking
Subject: Re: Mill parts
Date: Wed, 20 Nov 2024 09:44:12 -0700
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On 11/19/2024 4:27 PM, Snag wrote:
>    I'm in need of help finding a part for my bench top mill , RF45 
> clone . It's the same as the Grizzly G0484 and they show the part as 
> discontinued . I'm looking for a replacement X axis lead screw nut . The 
> Grizzly part number is P0484032 , maybe someone is making a replacement 
> since there must be 10's of thousands of these machines around . The 
> thread is Acme 15/16 (24 mm) diameter with an eight TPI thread . I've 
> seen articles about people making replacements using plastic - maybe 
> ABS? - and heat/pressure forming the threads but I'd lots rather find a 
> direct drop-in replacement .


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.




-- 
Bob La Londe
CNC Molds N Stuff

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