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From: Snag <Snag_one@msn.com>
Newsgroups: rec.crafts.metalworking
Subject: Re: Mill parts
Date: Wed, 20 Nov 2024 12:19:19 -0600
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On 11/20/2024 10:44 AM, Bob La Londe wrote:
> 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.

   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 .


> 
> 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.


   If I sleeve the original it'll be with bearing bronze or some Ampco 
45 aluminum bronze . I have both on hand ...


> 
> 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.
> 

   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 .


-- 
Snag
Voting for Kamabla after Biden
is like changing your shirt because
you shit your pants .