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barrel thread guage source?

Toolmaker51

Aluminum
Joined
Jan 13, 2009
Location
Central West Missouri
QT op: [ im gonna get into the barrel threading and muzzle break game ]

I think how you hold a barrel is important.<<<<<snipped>>>>>>>I know how to end a thread on the spot.. anyone doing guns should practice/master doing that. or buy/make a kick-out.

Gun stuff should be perfect.
Gun stuff should be perfect. The muzzle prints provided by member Stirling are interesting, that some threads run out to a relief, others terminate with a pilot. That's near MIL-STD grade of specifying hardware.
There are machinists from here to you know where; some make exotic 5 axis aerospace stuff, there are manual machinists still sinking molds and dies, there are a zillion types of machinists; naval, communications, medical, food service, paper industry, defense, toys, printing, furniture, machinery, utility & infrastructure, petroleum.......
To me, none of those typify Toolmaker as do Gunsmiths.
For that degree of threading, after years of Toolwork, I'd want a good mix of thread gauging implements. It's never wrong to have an alternate means of in-process quality control. Yes having a optical comparator is impressive, even more so when you have to re-index and pick up a imperfect thread. Thread mics, still aren't my first choice, though they are reliable. Wires and ring gauges are the way to creep up on any class fit in every diameter-pitch combination you want. This would include making your own master plugs and rings, need be. You aren't going to spin it so many times to cause wear; tool steels like oil, water hard, A - S - H series all machine nicely, just etch distinct specs, store protected and oiled, including those carefully ground cutters. No worries.
 
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michiganbuck

Diamond
Joined
Jun 28, 2012
Location
Mt Clemens, Michigan 48035
I can’t understand intentionally making your part out of spec so someone else’s out of spec part fits.
Because I would not just trust the maker of the part added to be on spec unless I ran a thread gauge into his part, and the likes of a 2a 5/8 24 you have .004 to play with for feel fit and still be in spec.

Agree if one only installed top name brand parts the threads of the part would likely be in spec..but I would still check.
Nowadays there are hack machinists making gun parts.
 
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300sniper

Hot Rolled
Joined
Nov 14, 2006
Location
Greenwood, Ca
Because I would not just trust the maker of the part added to be on spec unless I ran a thread gauge into his part, and the likes of a 2a 5/8 24 you have .004 to play with for feel fit and still be in spec.

Agree if one only installed top name brand parts the threads of the part would likely be in spec..but I would still check.
Nowadays there are hack machinists making gun parts.
What happens when your customer later on down the road wants to change his muzzle devise and finds out it won’t fit on your out of spec thread?
Personally, my muzzle threads are to spec. My barrel tenon threads are cut to spec, unless the customer any myself agree they will be cut to fit the receiver.
 

michiganbuck

Diamond
Joined
Jun 28, 2012
Location
Mt Clemens, Michigan 48035
Q Op: (What happens when your customer later on down the road wants to change his muzzle devise and finds out it won’t fit on your out-of-spec thread?)

likely it will still be in spec but along that .004 in-spec of tolerance, it will be at the best place.

IF the part to be added is a piece of junk, out of spec, the customer should be told that it should be thrown away, and buy another.
or conference with the customer to let him/her decide.

If the part is high limit big and you make the mate to low limit small, so in spec I would consider that a poor job.
 
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Toolmaker51

Aluminum
Joined
Jan 13, 2009
Location
Central West Missouri
Both arguments are valid. But mass production being what it is, matched to strictly one-off work is a different scenario. If a commercial part proves out of spec, it should be noted and returned. Not always possible when customer is leaving for once in a lifetime trip. Guns, race cars, equipment, maybe even clothing. Ultimately it's up to the customer as michiganbuck describes, under the craftsperson's guidance.
Many (most) of the public do not comprehend what responsibility a shop holds, any better than a clue regarding investment to get rolling. After all, they're showing up to a facility doing what they're unable to do. Once or twice have refused work when they balk at a quote. If near shop door, not one to hesitate while pointing to a machine "Well, yes I suppose you could; you'll need a lathe and tooling, electricity etc for X amount of dollars....just to start".
Usually it's about welding or cutting material. There are not less than 2 generations without ever pushing so much as a hacksaw.
It isn't entirely a fault on them; I believe this whole mess was engineered to separate individuals from not just ability, but exposure to how things originate.
 

wesg

Titanium
In a turning center, I use a partial profile because I am not going to be changing inserts twice per part, nor am I going to take up two plus tool stations with external threading tools.
Understandable. And with a turning center you've got the luxury of going back to make a second pass with the OD and threading tool to knock off any burrs generated. Not remotely possible with a manual lathe. You're reduced to emery cloth or scotch-brite ;-)
 

trevj

Titanium
Joined
May 17, 2005
Location
Interior British Columbia
I think a thread Mic is the berries after one measures a thread of the class you need and writes down that figure.
With not having a comparison number just trying to use a thread Mic is chancy.

Measuring the likes of a grade 8 or better screw is also chancy because one might measure a screw that is at the high or low limit.

Making a thread to wires, and using those numbers for a thread Mic is OK/good.

What I did and taught apprentices to do, was to sit down and calculate, then write the min and max reading over the thread wires, for the spec of thread, usually in the form of, well, it looked like a weird Fraction, with the direct reading that you should get at the Micrometer at maximum spec, on top of a line, and the minimum direct reading at the bottom.
This made thread wires easy to use, for any class of external thread, and you could easily see if you were coming up on the high end or past the low end of the Class you were trying to make. And you only had to do the math with the formula twice, to get the max and min size.
Having a bit of Plasticine to stick the wires in to was handy.

A thread mic is nice, but you do sorta need a couple Standards for it to know that what you cut, actually will fit where it goes, if you do not have the part in hand.
 

trevj

Titanium
Joined
May 17, 2005
Location
Interior British Columbia
Understandable. And with a turning center you've got the luxury of going back to make a second pass with the OD and threading tool to knock off any burrs generated. Not remotely possible with a manual lathe. You're reduced to emery cloth or scotch-brite ;-)
What?

You never learned how to pick up a thread on a manual lathe?
Or l;earned to do spring passes, for cleanup?

It's not that hard to do, and if you are not reliant on the cross slide and compound settings (ie: you are using wires or a thread mic) to size the thread formed, you soon figure it all out.

Personally, I like a single cut mill file and Scotchbrite over emery, as it leaves a nicer finish, IMO. YMMV! :)
 

michiganbuck

Diamond
Joined
Jun 28, 2012
Location
Mt Clemens, Michigan 48035
I could not trust a thread Mic, with not once wire checking and writing down the number with that same micrometer. It seemed that a thread micrometer was/is not easy to set a zero to a master like you can do with a size Mic to a JoBlock.
For finishing a thread I like to flat hone or fine flat file, and then take a finish no stock pass.
Perhaps they have a thread micrometer setting gauge but I have not seen one.
Perhaps one could set a thread Mic to a master thread gauge, but then I don't know if it would be set for other threads. Checking to a bought high-class screw would not work because you don't know if it is high or low to spec.
Getting down to +- .001 ( I think that is for a 12-28) is just too close for me to trust a thread micrometer. I think a 1/2-28 is +- .002 is still too close to check with a thread mic that I have not compared to/with wires.
 
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michiganbuck

Diamond
Joined
Jun 28, 2012
Location
Mt Clemens, Michigan 48035
Here is an interesting subject. Suppressors and other barrel devices might be put on to shoulder up to a lathe-turned step up or set on with a jam nut.

How square is a jam-nut thread to the face, and how square is a suppressor or other device end face? It would seem to me that an un-square end face would stress the barrel and so affect accuracy,
How square is a Deltak jam-nut compared to a no-name jam-nut? How square is a name brand barrel end device to a no-name, or a hack machinist made one?
I guess one could put a jam-nut on a tap that has centers and indicate the end faces for being square to the thread.

I just tried a no-name jam nut (5/8-24) in a 5/8-24 HSS tap and it would only go so far and hung up.at the last tread. (2 1/2 turns and then hang up) so about .089" into the nut.
I will have to 3 wire check the tap, and buy a Deltak jam nut to see if they are better.
I don't have a method to check an ID thread here.

Question: has any match shooter had a barrel end device put on, and then found the gun's accuracy had changed?..for better or worse?

The bargain jam nuts may be 3 to $5 each and the Deltak 12 or $13 bucks each
Yes, I just ordered a Deltak 5/8-24.to compare.
12.50 + ( $9.10 shipping so $22.90)
(A darn shame China can ship stuff like this for free)
-> the no names may go to the dumpster.
 
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wesg

Titanium
What?

You never learned how to pick up a thread on a manual lathe?
Or l;earned to do spring passes, for cleanup?

It's not that hard to do, and if you are not reliant on the cross slide and compound settings (ie: you are using wires or a thread mic) to size the thread formed, you soon figure it all out.

Personally, I like a single cut mill file and Scotchbrite over emery, as it leaves a nicer finish, IMO. YMMV! :)

The comment was regarding production work. Even if you could re-engage the lead screw in the exact place after making a finish pass on the OD, a typical dovetail QC toolpost won't repeat well enough to do this. The Swiss style have a good reputation, and I've heard mixed reports regarding the the Aloris/Dorian 'Quadra' types.

Picking up a thread is easy. An internal, a bit more of a PITA, but I've done a few ...

And the internal, truing a receiver, is another good case for a full form insert. No screwing around getting the ID the right size to match the oddball thread you just generated. And no burrs to remove. Damn hard to get a file in there ;-)

Same goes for an external. In fact, once you know the numbers you can cut a thread to spec' just by measuring the OD.
 

scott-ak

Plastic
Joined
Oct 12, 2021
I can't bring myself to spend that kind of money on gauges and nothing I do requires that. If I need a gauge I make it. I cut the muzzle brake thread using high quality spiral taps and single point the barrel. IMO the thread is important but not as much as some like to say. The shoulders *are* critical. The threads must be concentric and the thread just loose enough for connection to make up within the torque spec of the device.
 
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