# Lost dial lock screw - 10K large dials



## DavidR8 (Apr 19, 2021)

In cleaning up the shop yesterday I noticed that the locking screw for the  compound dial was missing. It must have been loose and vibrated out. I swept and ran a magnet through the sweepings but no luck. 
My Starrett thread gauge goes to 28 TPI and the locking screw for the other dial is finer than 28 so maybe it's 32TPI.
I guess I can make a new one but wonder if anyone has a spare.
Thanks in advance


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## C-Bag (Apr 19, 2021)

Man that sux. Double wammy that it seems fine thread. I replaced one of them on my RF30 but it wasn't an odd thread. Did it in brass and I think it looks classy, but it's certainly not something I'm trying to keep stock. Hope somebody can help you out.


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## DavidR8 (Apr 19, 2021)

Thanks mate, I was/am kinda bummed about it.


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## John O (Apr 19, 2021)

Is the size a #8 or #10 screw?


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## DavidR8 (Apr 19, 2021)

I just measured the OD of the remaining screw and it's .178 or 11/64".
That doesn't seem to correspond to a #6 or #8 so that's perplexing.


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## Janderso (Apr 19, 2021)

DavidR8 said:


> I just measured the OD of the remaining screw and it's .178 or 11/64".
> That doesn't seem to correspond to a #6 or #8 so that's perplexing.


David, are these original South Bend or did someone retro fit?
If it's SB, you know it has to be an Imperial thread. If retro?? who the heck knows.
That is the szhitzz


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## John O (Apr 19, 2021)

thread chart from 1916 shows #9 screw with 24,30 and 32 tpi


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## DavidR8 (Apr 19, 2021)

Jeff they are definitely original. Definitely the szhitzz 

#9... I did not know such a thing existed John. Thanks!


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## Janderso (Apr 19, 2021)

John O said:


> thread chart from 1916 shows #9 screw with 24,30 and 32 tpi


Me either. #9 is a new one to me.
What year is your lathe David? I had the small dials. They were terrible.


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## DavidR8 (Apr 19, 2021)

Janderso said:


> Me either. #9 is a new one to me.
> What year is your lathe David? I had the small dials. They were terrible.


It's a 1975. I can't imagine having small dials, I have a hard enough time reading the large ones


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## Janderso (Apr 19, 2021)

1975, that is a late model. I would enjoy looking at that lathe close up. The difference between my war production 13 and your late 10 would be interesting.
Flame hardened ways right?
Double lever gear box. What kind of spindle bearings? Roller or did they stick with the brass/bronze?


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## Manual Mac (Apr 19, 2021)

My small SB9 dial is 10-32. Yes small dials are the ****z 
Any good hardware store is your friend.
Cheers


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## DavidR8 (Apr 19, 2021)

Janderso said:


> 1975, that is a late model. I would enjoy looking at that lathe close up. The difference between my war production 13 and your late 10 would be interesting.
> Flame hardened ways right?
> Double lever gear box. What kind of spindle bearings? Roller or did they stick with the brass/bronze?


Sadly the ways are not flame hardened. I think because a 10K is basically a 9 with a taller headstock and tailstock. Many 9" parts are a direct interchange. It has bronze bushings with a roller thrust bearing like yours I imagine. I'll post some pics.


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## DavidR8 (Apr 19, 2021)

More sleuthing revealed that the screw is a 10-32. 
What so bizarre is the diameter difference between the existing screw at .179" dia and the 10-32 at .189" dia.
The 10-32 is definitely more snug, so maybe the old screw is just worn?


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## Shootymacshootface (Apr 19, 2021)

Check to make sure that you didn't lose the small spacer that resides under the screw. The screw itself is not long enough to engage the leadscrew.


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## DavidR8 (Apr 19, 2021)

Shootymacshootface said:


> Check to make sure that you didn't lose the small spacer that resides under the screw. The screw itself is not long enough to engage the leadscrew.



By some miracle the spacer was still in the hole. Lottery ticket time?


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## Mechanik (May 25, 2021)

I recently bought a 10K  (1959 I think). I have a different problem - My compound has a knurled slot head like the one pictured, but it doesn't lock the dial, seems too short. I found a longer matching thread in my huge stock of misc bolts - that locked it.  I was wondering if there is suppose to be a little slug in the hole that the screw pushes?
thx!
A


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## Mechanik (May 25, 2021)

Shootymacshootface said:


> Check to make sure that you didn't lose the small spacer that resides under the screw. The screw itself is not long enough to engage the leadscrew.


Aha! just as I suspected! Previous owner lost it! Can anyone offer the dimensions of said spacer?
thx


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## DavidR8 (May 25, 2021)

Mechanik said:


> Aha! just as I suspected! Previous owner lost it! Can anyone offer the dimensions of said spacer?
> thx



I’ll see if I can extract mine and I’ll measure it. 
Other than diameter, I suspect it’s a non-critical dimension.


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## C-Bag (May 25, 2021)

Mechanik said:


> Aha! just as I suspected! Previous owner lost it! Can anyone offer the dimensions of said spacer?
> thx


Under certain set screws etc that went directly onto a threaded shaft my old Atlas 7b had lead shot under the screw. I thought it was kinda genius as it locked the shaft without marring it.


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## Mechanik (May 26, 2021)

DavidR8 said:


> I’ll see if I can extract mine and I’ll measure it.
> Other than diameter, I suspect it’s a non-critical dimension.


thanks!


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## Mechanik (May 26, 2021)

C-Bag said:


> Under certain set screws etc that went directly onto a threaded shaft my old Atlas 7b had lead shot under the screw. I thought it was kinda genius as it locked the shaft without marring it.


y'd think lead would get mashed.I thought I'd make one out of brass


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## C-Bag (May 26, 2021)

Mechanik said:


> y'd think lead would get mashed.I thought I'd make one out of brass


That’s why I thought it was genius. It’ll lock the shaft and not mar it. Brass will deform threads.


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## Shootymacshootface (May 26, 2021)

This is the original pin that I thought that I had lost. I made a new one out of steel. When I found this one I threw it in a drawer.
So, this one, I believe to be an original Southbend part. It's aluminum, it measures .126 dia × .242 long. I'm going to put this one where it belongs!


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## SLK001 (May 26, 2021)

For the pin, don't use steel - it will mar the shaft.  Also, don't use lead - it will deform and flow into the threads so that you won't be able to get it out (without drilling).  Aluminum may work, but I would be worried about mushrooming the head and getting it jammed into the threads like the lead.  The original part was brass - it's hard enough to not deform, yet soft enough to not mar the shaft.

McMaster sells the knurled thumbscrew to replace the one you're missing.  As for the size, it is a common thread (I don't remember the size - it was a #10 something), so just find a screw that fits and order that size.


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## Mechanik (May 27, 2021)

SLK001 said:


> For the pin, don't use steel - it will mar the shaft.  Also, don't use lead - it will deform and flow into the threads so that you won't be able to get it out (without drilling).  Aluminum may work, but I would be worried about mushrooming the head and getting it jammed into the threads like the lead.  The original part was brass - it's hard enough to not deform, yet soft enough to not mar the shaft.
> 
> McMaster sells the knurled thumbscrew to replace the one you're missing.  As for the size, it is a common thread (I don't remember the size - it was a #10 something), so just find a screw that fits and order that size.


thanks all
I found a short piece of copper fuel line in my endless junk boxes, about 3/8 - that did the trick, at least for now. I suppose it'll work harden, but it'll still be softer than the steel - or brass.


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## Mechanik (May 27, 2021)

Shootymacshootface said:


> This is the original pin that I thought that I had lost. I made a new one out of steel. When I found this one I threw it in a drawer.
> So, this one, I believe to be an original Southbend part. It's aluminum, it measures .126 dia × .242 long. I'm going to put this one where it belongs!
> View attachment 367266


thanks! - yeah, i'd get the steel one out of there...


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## Mechanik (May 27, 2021)

C-Bag said:


> That’s why I thought it was genius. It’ll lock the shaft and not mar it. Brass will deform threads.


Really? Maybe there are some very hard brass alloys, but I've never heard of brass being harder than  steel, even iron.


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## Shootymacshootface (May 27, 2021)

Bronze maybe.


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## C-Bag (May 27, 2021)

Mechanik said:


> Really? Maybe there are some very hard brass alloys, but I've never heard of brass being harder than  steel, even iron.


Yes. This is all first hand observations. Of course brass is not harder than steel or iron. But i think you are thinking you have to smash a thread flat to foul it. On a typical 60deg thread it takes very little to smash the tip of the thread. If a small ding or piece of dirt will foul a thread...brass is nowhere near as soft as lead.

I’d never seen the lead shot done before going through my old Atlas shaper. I basically thought screwing anything against a thread was a bozo nono because of just the shearing action of screwing against the thread at the least is going to leave a chip of brass in the threads if it hardened. A reg hardness screw the ends of tips of the thread will be deformed. Seen it. in the case of the Atlas I took out the set screw seeing it was on a threaded shaft and expected to see smashed threads but in maneuvering to get light down in there the lead bb fell out and I could see the thread impression on one side and the set screw on the other, and no deformation of the threads at all. And none of the supposed sticking and fouling the thread. YMMV.


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## SLK001 (May 27, 2021)

There seems to be some confusion here.  The brass slug I was talking about is tightened between the bottom of the thumbscrew and the cross feed or compound lead screw.  Where it goes on the lathe is in an area where there are NO threads - the jam area is just a smooth part of one of the lead screws.  When tightened, simple friction prevents the dial from turning freely.


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