# Oops. Lathe workholding issues.



## Mauser lover (Mar 29, 2019)

Got the whole project figured out, then upon starting, can't figure out how to hold it. 

Trying to make a socket head cap screw. Because I despise flathead screws. Figured the easiest way to get a 1/4-22 Whitworth screw with a socket head was to order some bigger screws (5/16-24) and machine down the shank and thread to my needed diameter/pitch/form. Obviously a beginner here, as a real machinist's first thought would be "how am I going to hold it", and I didn't even think of that part of the project until basically right now. Not sure how I can hold it securely without chopping off the head (which was the part I particularly wanted!) without some sort of gymnastics. 

I've got six inch three jaw and four jaw chucks, and drill chucks in case I just want something smaller. Ideas? Not looking to spend several hundred dollars on some sort of specialty chuck just for a screw. 

Thanks for the help!


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## darkzero (Mar 29, 2019)

I've had to do something similar except it was a countersink screw & LH thread. Here's how I would do it.

Center drill the end of the screw. Skim the OD of the head so you can hold it securely in the chuck or chuck up a hex bit & use that to drive the screw. Support with live center, then single point the threads you need. If you rather not have a center drill in the end, start with a longer bolt, do the machining, then cut off the center drilled section.


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## darkzero (Mar 29, 2019)

Found the pics (don't mind the live center ext thing, I didn't have an extended point live center at the time & I needed to get the screw done).






M5 LH screw I made in the middle. On the right is what I started out with (M6).


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## Mauser lover (Mar 29, 2019)

> chuck up a hex bit & use that to drive the screw.



Thank you! Blessings upon your head! If I had ever needed to turn something between centers with a dog I might have though of it, but I never have needed to. So... Thanks!


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## 4ssss (Mar 29, 2019)

I see a 5/16-22 but the 1/4 sizes are 26 threads. You sure about the sizes?

https://britishfasteners.com/index....ainless-steel-bsf-socket-head-cap-screws.html


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## Mauser lover (Mar 29, 2019)

Absolutely sure about the sizes. It's one of these.





__





						Guard Screw, Rear, Commercial, Replacement | Gun Parts Corp.
					

Shop for your Guard Screw, Rear, Commercial, Replacement with Numrich Gun Parts - the world's largest supplier of gun parts.




					www.gunpartscorp.com


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## MSD0 (Mar 29, 2019)

darkzero said:


> Found the pics (don't mind the live center ext thing, I didn't have an extended point live center at the time & I needed to get the screw done).
> 
> View attachment 291452
> View attachment 291453
> ...


The hex bit in the chuck is genius.


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## Mauser lover (Mar 29, 2019)

MSD0 said:


> The hex bit in the chuck is genius.



Yes, pure genius.

And I even have one that is set in a socket for a quarter drive. Being round, I might be able to manipulate that to fix any concentricity  issues. Of course, that might not work, but it's a possibility. I'm a little concerned about slop between the bit and the socket in the screw, but I'm guessing it will work out fine.


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## mikey (Mar 29, 2019)

That there is a simple, elegant solution, Will. Makes perfect sense, too. Funny that in all the years I've been doing this stuff I never saw anyone come up with that. I agree with MSD0 - that is genius!


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## NortonDommi (Mar 29, 2019)

1/4" BSW is the same pitch as 1/4" UNC - 20 tpi.  Only the thread form is different and for the most part due to normal tolerance are interchangeable at that size.  Either way knocking the tops off the UNC threads and/or running through the appropriate die cures all.
It may be a Whitworth _form_ thread but at 22 tpi is not BSW or BSF.


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## Mauser lover (Mar 29, 2019)

Right. Whitworth form, 55 degree thread, but 1/4-22. 

I believe Mr. Mauser used the same screws as the Gew 88 in his 1891 design, his 1893 design(s), etc. all the way through his iconic 1898 rifle, and perhaps even beyond that. In 1888 I think there were significantly fewer notions about standardized threads. And switching tooling anytime between 1888 and 1945 (and even beyond) when these rifles were produced would simply have been inconvenient. Why bother? Well... Now I'm fabricating an entirely new screw because the commission in 1888 was two threads per inch off! 

And I don't have the right die tooling, and have no intentions of either chasing down or purchasing at this point.


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## NortonDommi (Mar 29, 2019)

Interesting discussion on Barrel threads on Mauser's here:http://bbs.homeshopmachinist.net/archive/index.php/t-12291.html 
Also could have been 7 mm Lowenhurz? That has a pitch of 1.1 mm and is actually only 0.001" bigger than 1/4" is reality.  There are some old obscure Metric threads that use the Whitworth thread form just because it is so nice.


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## NortonDommi (Mar 29, 2019)

P.S.  Nice job on the screw!


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## Mauser lover (Mar 29, 2019)

NortonDommi said:


> Interesting discussion on Barrel threads on Mauser's here:http://bbs.homeshopmachinist.net/archive/index.php/t-12291.html
> Also could have been 7 mm Lowenhurz? That has a pitch of 1.1 mm and is actually only 0.001" bigger than 1/4" is reality.  There are some old obscure Metric threads that use the Whitworth thread form just because it is so nice.



That could be, I suppose. My calipers read .252 inch on my original screws. Which are beat up enough (and a hundred years old!) that I don't want to be dogmatic, but I suppose it is possible. I'm pretty sure the gun was actually built in imperial measurements though. Everything else is nicely configured for English measurements. A hundred years (or more) after his guns were built, I don't think Mr. Mauser could have foreseen the problems I'm having with his gun! If he thought it would even be around!


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## NortonDommi (Mar 30, 2019)

Regardless you have got it done and I'm sure Mr Mauser will shower blessings upon you for your diligence in keeping it original.
One of my greatest challenges and greatest joys is finding out what obscure thread may have been used.  Still a lot of very industry specific ones in use to keep life interesting even if annoying in that you can't just pop down to the local hardware store for a replacement.  Where I live I am increasingly encountering fastner salesmen that don't know anything but ISO Metric exists, let's hope they never buy a Peugeot!


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## markba633csi (Mar 30, 2019)

It's true, there were literally dozens of thread pitches in 1/4" size, most never seen now according to my pocket reference


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## Suzuki4evr (Mar 30, 2019)

darkzero said:


> Found the pics (don't mind the live center ext thing, I didn't have an extended point live center at the time & I needed to get the screw done).
> 
> View attachment 291452
> View attachment 291453
> ...


Clever idea of holding the screw on the chuck side.


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## Mauser lover (Mar 31, 2019)

Okay, made some chips. And one of my screws goes in the recycle bucket (that's okay! They are cheap, and came in a ten pack  )

Any ideas on how to hold the socket head tightly enough not to wobble and still have room to get in there with a tool to do some cutting? I thought about my steady rest but it is WAY too big to stick on the head of the screw and still get a cutting tool in there.

Also, how do I make sure the socket head is concentric with the rest of the screw? My first operation was to cut the head down to the size I wanted. I chucked the threaded shank in my three jaw (and some of my problem is here, no doubt), and then when I pulled it out and looked at it, it *looks* like the socket is not quite in the center of the head. I put an indicator on a chucked reamer shank close to the diameter of my screw to look at my chuck runout, and I've got about .0025 between high and low, and my guess is that the "normal" human eye would never notice that much (or little) lack of concentricity. I'm thinking the screw threads are not really perfect, but I don't know what else I can trust. I've got to hold it somehow to center drill it (chucked, held by the threads, ostensibly) and I'm thinking that even if the threads aren't perfect, they are probably better than the sloppiness between the driver bit and and socket head.

Using the bit to drive the screw worked majestically, by the way, so I'm not trying to spit on that idea or anything, I just need an idea to make it tighter! Or another way to center it and still use the hex to drive it. Like maybe a hex bit with a point on it. Although I've breathed out anathemas upon Phillips and his screws before, I'm beginning to see the advantage his design has for driving screws on lathes!

Or, maybe it's just an optical illusion having to do with the domed head and six points of the socket and the lighting. Or maybe I just need to get over it even if it isn't an illusion.

But... PERFECTION! AAAHHH!!!!

What do ya'll think?


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## darkzero (Mar 31, 2019)

Mass produced screws aren't machined, the threads are rolled & the heads are hot formed so they won't be perfectly concentric. You can use tape or paper to make the hex bit fit tighter. Not sure how much play you have. Can even super glue it, heat will release it afterwards.

If you really need it to be precise, make your own hex mandrel to drive the screw. That way you can machine the hex to be a tight fit & chuck it in a 4-jaw if you want it to run true with the OD of the head.


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## Mark Needham (Apr 1, 2019)

Mauser lover said:


> Yes, pure genius.
> 
> And I even have one that is set in a socket for a quarter drive. Being round, I might be able to manipulate that to fix any concentricity  issues. Of course, that might not work, but it's a possibility. I'm a little concerned about slop between the bit and the socket in the screw, but I'm guessing it will work out fine.



Set it up in the lathe, and hit it with some Locktite  Superglue, or some of the girlfriends ( or your own) fingernail polish. Acetone/heat will release when done.

and darkzero, I'll have your baby, you clever thang you. Brilliant.


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## Suzuki4evr (Apr 1, 2019)

Mark Needham said:


> Set it up in the lathe, and hit it with some Locktite  Superglue, or some of the girlfriends ( or your own) fingernail polish. Acetone/heat will release when done.
> 
> and darkzero, I'll have your baby, you clever thang you. Brilliant.


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## Mauser lover (Apr 1, 2019)

darkzero said:


> ...make your own hex mandrel to drive the screw.



Sounds good. How? I don't have a dividing head at the moment for my mill. Any other way? If not, I might just have to be happy with it. 

There is a little bit of a center mark in the head of the screw. If there is a way to hold it between centers, and still drive it somehow, I think that would be ideal. Ideas on that one?


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## ThinWoodsman (Apr 1, 2019)

Mauser lover said:


> Sounds good. How? I don't have a dividing head at the moment for my mill. Any other way? If not, I might just have to be happy with it.



Hex collet block.

But really you can just buy some hex rod, and shave it down as needed to tightly fit the socket cap screw. The more important bit is the concentricity you'll get turning part of the hex rod down to a round shaft in the lathe.


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## Tozguy (Apr 1, 2019)

Sometimes a Torx bit will fit the hex head tighter than a hex wrench does.


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## darkzero (Apr 1, 2019)

Mauser lover said:


> Sounds good. How? I don't have a dividing head at the moment for my mill. Any other way? If not, I might just have to be happy with it.



Collet block would be the quickest but if you don't have any type of indexing device it can still be done easily a number of ways. Here's a few methods off the top of my head.

Piece of round stock, drill & tap one end for a hex head bolt, diameter of head smaller than the round stock. Heck you could even just drill & glue the bolt in, as long as it's secure. Clamp the round stock in the vise using the hex bolt to index. Eyeball & line up one flat of the hex head with the top surface of the vise. Make the cut, rotate & repeat. You could even remove the endmill after each cut, put a piece of round stock in the spindle with the end faced flat & use that to touch off on the next flat of the hex head. Of course you could even indicate it in but I would just eyeball, much quicker & it doesn't need to be precise.

Or don't even need to use a hex bolt to index. Cut the flat, rotate, use a protractor touching the flat & say the table surface to cut the next flat.

Get a bigger hex head bolt & with enough length, use a piece of stock to support the shaft of the bolt, clamp the head in the vise with 2 V-blocks, cut the flat, rotate & repeat. if you don't have v blocks you can quickly make some by just making a cut with an endmill at 45°.


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## Mauser lover (Apr 1, 2019)

ThinWoodsman said:


> Hex collet block.
> 
> But really you can just buy some hex rod, and shave it down as needed to tightly fit the socket cap screw. The more important bit is the concentricity you'll get turning part of the hex rod down to a round shaft in the lathe.



Ah! I think we've got a winner here! I don't have a collet block (yet. Budgets are inconvenient, aren't they!), and my mill is probably less precise than the screw I've already got anyway! It's a well-loved Rong-Fu round column benchtop machine. Will probably upgrade sometime in the distant future, but a surface grinder is on my list before a Bridgeport. And a concrete shop is on my list before that! Anyway, back to the idea at hand!

I'm puzzled by what you mean by "The more important bit is the concentricity you'll get turning part of the hex rod down to a round shaft in the lathe."

Are you saying that I buy 3/16 hex stock (the size I need for driving my screw) and turn part of it down, put the round part in my chuck while noting which side is "up" so the runout cancels itself out?

I'm also contemplating getting 3/16 hex stock and machining a steep taper on the very end of it so it contacts the head of the screw in the shallow taper inside the socket while also providing enough contact with the socket to drive the screw.

Just to be clear and restating my goals...
I'm center drilling the threaded end of the screw while holding the threads in the chuck. I move the screw out of the chuck to be driven by a hex tool bit (either something I make, or something made across the sea) and held by a live center and finishing the machining there. I'm taking material off the diameter of the head as well as the shank, and my goal is to have everything be concentric with the socket in the head and the center drilled shank.
Did I miss anything? I did mention that I am a beginner, right? In case you couldn't tell.

Also, I did try the Torx bit. It is just a hair tighter. It is about .002 bigger across the flats than the hex bit. If all else fails, I might go for that, but it is still too wobbly for my tastes.


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## brino (Apr 1, 2019)

Is there a metric hex driver bit that works out to fit a little tighter?
-brino


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## Mauser lover (Apr 1, 2019)

Nope, tried the metrics already. Goes from spinning freely inside the socket to not fitting.


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## ThinWoodsman (Apr 1, 2019)

Mauser lover said:


> I'm puzzled by what you mean by "The more important bit is the concentricity you'll get turning part of the hex rod down to a round shaft in the lathe."
> 
> Are you saying that I buy 3/16 hex stock (the size I need for driving my screw) and turn part of it down, put the round part in my chuck while noting which side is "up" so the runout cancels itself out?



That is pretty much what I was suggesting. Put the hex rod in the chuck, get it to run true (basically do something clever with a plunger dial indicator to verify that all six sides are at the same measurement - a bit tricky to know when each face is true to the previous, but you can prob use a machinist's square on the lathe bed to square up each face), then turn down to a cylinder. Hold the cylinder in the chuck. That should make it easier to re-chuck the thing. I might be over-simplifying here and it may be better to just use the hex rod without turning it. If the rod isn't centered when you turn it, the end result will be worse than just using the hex shape.

And of course you will probably need to skim the flats of the hex with the mill, which probably should be done before chucking the thing, just make sure the newly-milled end is inside the chuck a bit so the jaws don't mar it.

Sounds like you pretty much have the idea. What you described in your restating-of-goals should work.


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## Mark Needham (Apr 2, 2019)

Did you try Superglue, nail polish, or locktite, shoot even wood glue, PVA, shellac, dopping wax even bondo. Spit on the mother.
Nail polish, et al, would even allow you time to attain your concentricity.
Just need to know if you have tried it yet?


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## Mark Needham (Apr 2, 2019)

Then again. A Set or Grub Screw, at 1/4" ww is readily available here in Australia. Screw a nut on locktite the sucker.. Machine it to the diameter for head. Set screw Hex socket would be considerably smaller than a 5/16" screw Hex! Shoot you could even do a parallel knurl if you wants to.
Could slip a couple in the mail. pop.


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## Tozguy (Apr 2, 2019)

Mauser lover said:


> Also, I did try the Torx bit. It is just a hair tighter. It is about .002 bigger across the flats than the hex bit. If all else fails, I might go for that, but it is still too wobbly for my tastes.


Then maybe just peen the end of the Torx bit a tad to get it snug in the screw head.


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## ThinWoodsman (Apr 2, 2019)

I should probably point out, as nobody else has yet, the existence of the Lantern Chuck. It's usually used for finishing a screw (e.g. after you've shortened it), but it should be suitable for re-threading if you don't mind a large groove at the top where the head is held.

I haven't made one yet, but it is high on my TODO list. For now I've got some 1/4" plate that I mount in the vise with drilled and tapped holes in it for the common thread sizes I encounter.


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## bpimm (Apr 2, 2019)

How about use a spot drill to put a small center in the bottom of the hex socket on the screw, then turn a matching point on the hex bit. should center it up and drive it.


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## Mauser lover (Apr 2, 2019)

Mark Needham said:


> Did you try Superglue, nail polish, or locktite, shoot even wood glue, PVA, shellac, dopping wax even bondo. Spit on the mother.
> Nail polish, et al, would even allow you time to attain your concentricity.
> Just need to know if you have tried it yet?



AAH! I step away for a few hours and I'm overwhelmed with ideas! Which is a great problem to have!

Okay, no, I have not tried any adhesives. I'm at a loss as to how that would help. It seems to me that due to the play between the hex bit and the socket I would just end up gluing it off-center. Unless I missed something. Which I might have.

I'm not sure to what you refer in post #31. Probably just my inexperience with this hobby, but I'm failing to see what a grub screw will do.


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## Mauser lover (Apr 2, 2019)

bpimm said:


> How about use a spot drill to put a small center in the bottom of the hex socket on the screw, then turn a matching point on the hex bit. should center it up and drive it.



I'm thinking along these lines. I'm going to order some 3/16 hex stock here in the near future (like, next fifteen minutes) and I might do that with this, unless they fit just perfectly. I think the S2 tool bits I've got would be pretty difficult to turn down, but cold finished 12L14 or 303 stainless should be pretty easy. 

I'm going to have to look at the lantern chuck sometime too. Not exactly sure how it works yet, but worth looking into.


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## Mark Needham (Apr 2, 2019)

Set screw.
Grub Screw.
Took me 3 minutes.


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## ThinWoodsman (Apr 2, 2019)

Mark Needham said:


> Set screw.
> Grub Screw.
> Took me 3 minutes.


Ah, you mean as an alternative way to produce the screw, not as a workholder. I was wondering.


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## Mark Needham (Apr 2, 2019)

other thing is, I have reread your OP, and note the thread @ 22tpi. Sure is a mongrel thread. Maybe, not available as a set screw!

edit. again, cut down a 5/16, cut your thread, and a nut..............yabba.....yabbba...............


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## Mauser lover (Apr 3, 2019)

Yeah, definitely mongrel! That's a good term for it. 

I've got some hex stock coming from Online Metals that is supposed to be .1875. That's about .004 bigger across the flats than my tool bits measure, so hopefully that will work. If not, I'm going to turn a taper, glue it in, and drive it that way and see if that works. We will see when the stock gets here. 

I sure picked a complicated project to learn all the basics!


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## dulltool17 (Apr 5, 2019)

I'm late to the party, as usual...IIRC, the 1/4-22, 55-degree Whitworth was used by the Mauser Bros because their original machinery came from Britain.  

Good luck!


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## Mauser lover (Apr 5, 2019)

Yeah, I think most of the world's machinery came from Britain in that era! Just about all the european rifles were built in mainly Imperial English measurements. 

I'm going to try to carve out some time this weekend to work on this, but might not be able to... so it will probably be another week before I do anything substantial. I know you are just waiting with bated breath to know about my minuscule project.


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## seasicksteve (Apr 5, 2019)

No message


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## darkzero (Apr 5, 2019)

seasicksteve said:


> No message



I guess whoever called didn't wait till after the beep?


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## seasicksteve (Apr 6, 2019)

darkzero said:


> I guess whoever called didn't wait till after the beep?


I was going to add a link to hex cap mauser action screws and then I read the fine print that they had been discontinued
I tried to delete but couldnt find the button sooooo......
It sucks that they dont make the hex screws anymore


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## Mauser lover (Apr 6, 2019)

Yeah, the B-Square ones? I've seen the discontinued ones, and would have purchased them, but this is more fun anyway. It's not the destination, it's the journey. Or some smarmy excuse like that for never getting anything done! I'm a hobbyist, after all.


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