# Clausing 5903 Crossfeed Screw repair.



## Tim9 (Aug 23, 2020)

I ordered a new Acme 5/8”-10 LH threaded rod from Roton Products. Finally getting around to making it work on my 5903 lathe.
The threaded screw has a dowel pin which attaches it to the Crossfeed dial. The biggest issue is that there is a raised part of the Acme thread which is a bearing surface for a bronze bearing in the housing. Anyway, the diameter of this area is 0.62445
cant show a pic of micing it because I only have two hands. But digital Mitutoyo mic gave me those specs. No way would I get that with my other mechanical mics.




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						5/8 - 10 Left Hand Acme Lead Screws & Nuts for Power Transmission - Roton Products, Inc.
					

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					www.roton.com


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## Tim9 (Aug 23, 2020)

My plan is to use the Clausing to cut down the threads on a portion of the new threaded rod, and then make a bronze bushing to have that part which is .62445

  This is going to be more time consuming than I want, but I’m just not at all happy with the way my little South Bend lathe has been performing. Something is wrong with that lathe too.


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## Tim9 (Aug 23, 2020)

So I disassembled the screw.... took a bunch of measurements with some poorly drawn prints I made..... put the screw back together and installed it on the lathe. Then I chucked up the screw. Here’s where I went down a stupid rabbit hole again. I forgot I had some ER25 collets which go up to 5/8”
So I tried to use copper protectors on the Acme Screw. Big fail . The last pic is the “completed” bushing mounted in the ER collet which is surely much better than the soft copper spacers. . I used my Best Test and miced the inner bore. While rotating.... 0.008 out of round. Damned thing would bind when trying to turn the Crossfeed if I left it like this. So....starting over. As an afterthought.... if I didn’t have the collet, I probably could have wrapped some 10 or 12 gauge bare copper wire in the threads. That might have worked better.


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## Tim9 (Aug 23, 2020)

As you can see in the last pic above... I even made a Delrin bushing to hold the back of the screw centered.
But the copper jaw protectors were a fail. I turned a bushing bore to specs and I had turned both sides of the bushing. Then Loctite on the screw in the middle pic with a tailstock live center which I had hoped would do the trick. But when I check for out of round, after waiting for the Loctite to dry....... my inner diameter was wobbling 0.008


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## Tim9 (Aug 23, 2020)

That’s when plan B.....er25 collets and collet chuck. Just amazing how one false start gets a poorly thought out plan put into action. But I’m thinking that the collet 
will make a huge difference.


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## Tim9 (Aug 23, 2020)

I think the final diameter of the screw after turning the threads off, was something like . 4330
i made a little test bushing so I’d end up with a real tight fit for the bronze bushing to new screw. This worked great. I ended up with a super snug fit. Nice popping sound when putting on then pulling it out. So Loctited it with red Loctite and stood up so Loctite fills all gaps. Really hardly any gap in my opinion. Tomorrow I’ll drill and pin the threaded side of the bushing which is Loctited. Then turn outer diameter to accept gear and make that raised mating surface of 0.62445 And then the end to accept the gear which is 0.59595
and also bore it 0.43735 to accept the dial end.
Tomorrow I’ll also disassemble the original screw in the lathe....measure some more to double check my specs... before I  try turning the other end of the bushing. Just want to make sure I’m on the right track. Like I said.... my crappy “prints” even have me guessing on a couple of the spec. Anyway.... the design is a little odd because the gear has to slide over the bronze bushing and the shaft of the dial end the slides in it. A dowel pin locks all three parts together.


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## Papa Charlie (Aug 23, 2020)

Nice work, that ACME thread was a bit on the worn side.


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## Tim9 (Aug 23, 2020)

Papa Charlie said:


> Nice work, that ACME thread was a bit on the worn side.


Yeah Charlie. I was getting like 0.070 backlash most of the time. Tomorrow I’m hoping all goes smoothly. Need to bore the other side of the bronze.... turn outer diameter two different specs, and then drill for the pin. And have to dill pin to line up with the hole in the dial side of the Crossfeed. That’s going to take some thinking before I screw the pup.


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## Alcap (Aug 24, 2020)

I'll be following your repair since the lead screw on my 5914 is worn too . I also saw the replacements made on ebay and figured that would be the way I would go if it got worse but maybe reading your thread will give me  confidence  to try making one


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## Tim9 (Aug 24, 2020)

Alcap. If it goes as planned.... other than the first screw up.... it’s not too bad. My two big mistakes.

first.... must have the screw in the collet. The copper just won’t get the screw centered properly. Especially since it’s 24” long. So the back end inside the spindle is causing the screw to drop in the back and then high in the front.  I didn’t show it yet. But because on the first fail I ended chopping a couple of inches off.... Now the back end of the screw doesn’t come out the other side of the spindle. So I made a Delrin bushing.... 1-3/8 outer diameter and a tight fit for the Acme screw on its inner diameter. I kind of pushed that bushing in the spindle so it’s supporting the back side.
If I were to do it again....I’d buy a 3’ length of Acme screw so I would have hang out on the back side of the spindle which can then be supported with a spider or bushing.
My second screw up was trying to turn the bushing and then mount it on the shaft. This time...I bored the bushing to the smallest diameter to accept my small boring bar....in which I can then bore to final diameter. But it’s not bored to the .4330 yet. I’ll be boring it to the .4330 which is the size of the shaft of the dial end of the Crossfeed .... only after the bushing is mounted on the screw. And I’ll size outer diameters also only after it’s mounted to the screw. This should give me a closer to needed final product.

like I mentioned earlier. The first try was very poorly executed. I turned the bushing separately (or coupling ) to specs and then mounted it on the turned shaft of the screw. That added another unnecessary error in my opinion. Much better mounted to the Acme thread shaft and then turn to specs.


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## ericc (Aug 24, 2020)

Why does the screw need a bronze bushing loctited to it?  Does it make it turn better?


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## Tim9 (Aug 24, 2020)

ericc, it doesn’t need bronze. I could have made a steel bushing. The issue is that the original screw is probably cut from a round stock 5/8”. They cut the screw and then left one end which is the end next to the dial.... they left that part raise about .624”.
  My threaded rod is threaded the entire length. And when I cut the threads off until I have solid steel, I’m left with a spot that’s only about 0.440”. So i need an area which is 0.624” 
The raised area is where the gear is mounted. Like I said, I could have used steel. I prefer to machine bronze. I have a chunk of bunting cast bronze. Zoro sells it. @25.00 for a 13” length. This bushing I made which connects the threaded rod to the dial housing is only @ 2.20” 
Anyway.... Bronze is plenty strong enough. And now it’s just bronze against bronze bearing surface inside the crossfeed.


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## Tim9 (Aug 24, 2020)

So this morning I am ready to machine the other side of the screw.... the bronze bushing I Loctited to the threaded rod. I haven’t put a pin yet. I’ll do that at the end when I’m ready to assemble and have to drill the holes for the roll pin on the gear which also attaches to the dial housing.
  First step. Double check my specs. My original prints I made suck. So I’m going to disassemble everything again and recheck the specs. I also put a couple of turns of blue masking tape on the end of the rod to hold the Delrin support bushing tighter. After I get my specs, I have to bore the bushing to accept the dial housing end which is 0.4373 .
Then, machine outer diameter to 0.6240 and an area .0.8445 long a diameter of 0.5955 diameter to accept the gear. New prints too !!


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## Tim9 (Aug 24, 2020)

So I mounted the threaded rod and  bushing back in the lathe... Which is in the ER 25 chuck . I should have marked the position before I took it out. The collet hasn’t been disturbed, but it’s never good when anything gets removed from a three jaw and then reinstalled.
Anyway, I checked for out of round and was out around 2 thousands. I don’t think its going to affect anything adversely. If I had to do it over again, I would have used my 4-jaw chuck. 
machined outer diameter to0.6240 and then the outer end a diameter of 0.5955” for a length of 0.8445
FWIW, the end which attaches to the dial housing doesn’t contact to small washer on the housing. The gear is a length of 0.8495. And the gear contacts the small stainless washer. I made a small Delrin washer about 0.025“ thick to replace the stainless washer which is 0.005”
I always had some slop in the dial which I could not remover through adjustments. I’m hoping the extra 0.020” takes this slack up.
I also made a test bushing the same diameter as the dial shaft. This shaft is 0.43730”

Of course, my test bushing is really close but no... it’s not .43730”. Me and my Clausing shoot for within a thousandth.
I bored the bushing to specs and checked it with my test shaft.
It did make that popping noise when I forced it in and then pulled it out.


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## Tim9 (Aug 24, 2020)

And of course, nothing is simple. On a positive note....all day yesterday the news was doom and gloom because a storm is approaching. And yet, it was really cool this morning and the sun shined most of the day. The storm has been dumping rain on the Florida Coast.
But, the screw up was when I went to assemble the dial shaft. I didn’t bore the bushing deep enough. And I had to fit the gear so I machined a little bit more length so the gear slid a little more. If I had missed this detail on the gear, then the roll pin hole may have cut into the end of my bronze bushing. I want the gear to extend right past the shaft by a few thousandths since the gear end is a bearing surface to that little Delrin washer. Machined it and then  it slid on a few thousands more.


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## Tim9 (Aug 24, 2020)

Took care of those minor details.... bored the bushing a little deeper. Has to be around 0.850”
Removed the shaft from the collet chuck. Mounted in the mill vise. Just a V block and a supporting group of 1-2-3’s and shims. 
Mounted the gear on the end. First I centered and drilled the other end for the dowel. Then lined up and drilled just one side in line with the gear. The gear is my guide. 
I then mounted the dial shaft to make sure everything was properly lined up and drilled and doweled it.


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## Tim9 (Aug 24, 2020)

So...I’m sorry to say...the excitement got to me. No more pics. Anyway, I just cut the shaft to size and stuck it in the lathe. It’s good to go. My backlash is about 0.014 .

  Much better than the old screw which was always at least 70 thousands. Sometimes worse. The Crossfeed is nice and tight and turns smoothly. I was pretty careful to get everything lined up and true because when I replaced my feedscrew on my little South Bend it wasn’t lined up truly and it had a tight spot on every revolution. No such problem on this repair. I’m really happy with it and the new Acme Threaded rod was only around 35.00 total including the shipping. 
  I bought an acme nut too from Roton. I might try to figure a way to make a new nut. Then I’ll have even less backlash but I can live with this for now.


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## ericc (Aug 25, 2020)

Yay.  Good to hear it worked.  Mine was exciting to put together, and it fought me all the way.  My backlash is now negligible, but things feel a little tight.  Maybe they are supposed to be that way.  Anyway, it seems to work better.


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## Tim9 (Aug 25, 2020)

I figured I’d do a little extra maintenance on the Clausing. I drained the oil and refilled it when I first started using it but never had the headstock cover off. So I pulled off the cover....drained and flushed out the reservoir.  When I first pulled the cover I ran a magnet around the bottom and came up with a little rusty sludge and signs of water. This lathe did sit out in the weather for an unknown amount of time. So I mopped the bottom of the reservoir with some rags to get all that stuff out. 

    I didn’t want to wait for a gasket so I made a new little hammer with a small head and an angled end and flat end to make gaskets. Works like a charm.  Heres’s a few pictures of making the gasket using the hammer. The gasket material is a Corn Flakes box.


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