Threading barrels

[Ksracer]

Nobody has mentioned measuring the threads yet. I know a lot of people despise the 3 wire method and I've heard 2 dozen hacks on how to do it easier. This is how I do it.

Set the mic .005 over your expected measurement.

Put 2 wires on top, holding the third in your mouth.

Hold the top 2 in place with the mic's spindle.

Place the third one in the thread occupied by the LH wire and trace it down until it slides in place over the anvil.

If you set your mic close enough, the wires are now trapped and can't fall out while your hands are free to take your measurement.

 

[Doug Beach]

Thread mics aren’t expensive. ~$100 from Shars. They work great.
When I use wires, I hold them in place with my fingers, all parallel to one another, then stick a piece of tape at each end. Now I have a rectangle, with two wires on one long side, one wire on the other long side, and tape for both short sides. I can take it on and off the threads, and move it around to my heart’s content.

 

[xr650rRider]

Thread mic, or if you have to use wires, little dab of wheel bearing grease. Lucas red & tacky.

 

[WSnyder]

Thread mic’s. Have wires but almost never use them because the mic’s are just easier. One for the breech and another for the muzzle.

 

[INTJ]

I like ring gauges. Only need a few sets.

 

[INTJ]

Which is a relief groove. I know for a fact that is what Bruce and Daryle are saying. They have said it to me directly.........

So one the Bros BAT came in the shop last Friday and I asked him about their drawings and how they didn't say "relief groove." He gets a grin on his face and says that "technically" it wouldn't have to be a relief groove, but that on a manual lathe it's hard to thread to within .100" of the shoulder and to get the action to thread all the way to the shoulder. Thus their recommendation and practice.

I thought it was a diplomatic way to not take sides. It also means I can't be as definite about their recommendation any more.........

 

[shortgrass]

I like ring gauges. Only need a few sets.

If the "GO" ring won't thread on, it won't tell you how much you need to take off before it will. Likewise, if the "NO-GO" will thread on, it is not telling you how much undersize the thread is, only that it's undersize. These are used in production, where the 'part' that is not within tolerance is scraped or repaired, if its an expensive part that can be repaired. What do you do, INTJ, if the "NO-GO" threads on? Cut it off and try again? Thus making that barrel 5/8 shorter than the customer requested. If the "GO" won't thread on make a 'spring pass', and if that doesn't do it, guess at how much to take off with the next pass?

 

[LVLAaron]

Thread Triangles w/ Holding Loop - 13-109-4

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[INTJ]

If the "GO" ring won't thread on, it won't tell you how much you need to take off before it will. Likewise, if the "NO-GO" will thread on, it is not telling you how much undersize the thread is, only that it's undersize. These are used in production, where the 'part' that is not within tolerance is scraped or repaired, if its an expensive part that can be repaired. What do you do, INTJ, if the "NO-GO" threads on? Cut it off and try again? Thus making that barrel 5/8 shorter than the customer requested. If the "GO" won't thread on make a 'spring pass', and if that doesn't do it, guess at how much to take off with the next pass?

That's never an issue. I know about how much to cut for each thread pitch. When I get close I check with the gauge. I also know about how much more to cut based on how the go gauge feels.

Easy peasy.

 

[Tod Hendricks]

So one the Bros BAT came in the shop last Friday and I asked him about their drawings and how they didn't say "relief groove." He gets a grin on his face and says that "technically" it wouldn't have to be a relief groove, but that on a manual lathe it's hard to thread to within .100" of the shoulder and to get the action to thread all the way to the shoulder. Thus their recommendation and practice.

I thought it was a diplomatic way to not take sides. It also means I can't be as definite about their recommendation any more.........

As someone mentioned earlier, you may want to a try thread specific insert. It made a big difference in how close I could thread to the shoulder, eliminating the need for a relief.

Assuming my math is correct, using the dimensions from the picture and that I pull out .020” from crash would put the root at the end of the thread .051” from shoulder.

 

[shortgrass]

That's never an issue. I know about how much to cut for each thread pitch. When I get close I check with the gauge. I also know about how much more to cut based on how the go gauge feels.

Easy peasy.

When I was setting up and running multiple spindle 'screw' machines and turret lathes, I operated like that. An 'educated guess' would do it. Of course I was making 10,000+ parts on the multiple spindle automatics or a couple of hundred on a turret lathe, each worth only a few dollars. 'Scraping' a few was expected and built into the cost. Doing 2nd operations on the turret lathes ment not taking as many 'educated guesses', as there were $$$$ already invested in the 'part' being made. Once I started doing more "one-offs" , and on more expensive 'parts' and tool room work (where tool making & sharpening actually took place), I started using thread mics more to prevent possible 'loss'. Now, I set-up and 'trouble-shoot CNCs where most threading is internal, and I depend on my 'educated guess', as it's usually a NPT with lots of tolerance between GO and No-go. I do almost all the 'manual' work in the shop (20" swing Summit or the 36" swing Sydney) and that's 'one offs', so I use mic when I can. Any barrel work I use thread mics, because it's a 'one-off' on an expensive 'part', and I've got no ring gauges for those threads. I'm not bold enough to call myself a "master machinist", but I've learned a few things over the past 48yrs (and a graduate of MCC 2yr gunsmithing program). And yes, I had a 2nd shift job in a machine shop tool and repair dept. while I was going to school full time during the day. One of these days I'll have had enough machine shop and just work out of my gunsmith shop as I see fit. At my age, the day's a comin'!

 

[WSnyder]

Which is a relief groove. I know for a fact that is what Bruce and Daryle are saying. They have said it to me directly.........

And here’s the 22CM Bruce threaded in his shop for the Ult Reloader video. Check picture and step 6

 

[INTJ]

And here’s the 22CM Bruce threaded in his shop for the Ult Reloader video. Check picture and step 6


View attachment 1396869

Bruce likes to leave a little tenon right next to the shoulder. Then he cuts a relief groove. This gives him lots of space to thread. Space he needs for threading at 450 RPM.

I like to have the groove go all the way to the shoulder. I also like small lathes and Bruce likes big lathes. However, I am self taught and Bruce is a master machinist.

 

[INTJ]

When I was setting up and running multiple spindle 'screw' machines and turret lathes, I operated like that. An 'educated guess' would do it. Of course I was making 10,000+ parts on the multiple spindle automatics or a couple of hundred on a turret lathe, each worth only a few dollars. 'Scraping' a few was expected and built into the cost. Doing 2nd operations on the turret lathes ment not taking as many 'educated guesses', as there were $$$$ already invested in the 'part' being made. Once I started doing more "one-offs" , and on more expensive 'parts' and tool room work (where tool making & sharpening actually took place), I started using thread mics more to prevent possible 'loss'. Now, I set-up and 'trouble-shoot CNCs where most threading is internal, and I depend on my 'educated guess', as it's usually a NPT with lots of tolerance between GO and No-go. I do almost all the 'manual' work in the shop (20" swing Summit or the 36" swing Sydney) and that's 'one offs', so I use mic when I can. Any barrel work I use thread mics, because it's a 'one-off' on an expensive 'part', and I've got no ring gauges for those threads. I'm not bold enough to call myself a "master machinist", but I've learned a few things over the past 48yrs (and a graduate of MCC 2yr gunsmithing program). And yes, I had a 2nd shift job in a machine shop tool and repair dept. while I was going to school full time during the day. One of these days I'll have had enough machine shop and just work out of my gunsmith shop as I see fit. At my age, the day's a comin'!

What got me on the ring gauges was a customer requirement that both the 27x1.5mm shank threads and 5/8-24 muzzle threads to pass 6G and 3A respectively, ring gauges.

I am still not doing things like a production shop. I like hand fitting everything and double checking. When we get the new Kingston lathe, it will be set up more like Bruce does things. Should be faster, at least on the easy stuff. I'll still do all the weird stuff on the PM 1440GT.

 

[WSnyder]

likes to leave a little tenon right next to the shoulder.

If I’m turning a relief I leave a small step as he does. It’s partly a time saving measure for me with less tooling changes. I turn the tenon to my desired OD. I then setup my threading tool which typically uses a full profile insert. I use the threading tool to create my relief. I infeed X until it reaches full depth to the point that the inserts shoulder touches the tenon OD which leaves a step at the barrel shoulder. I then traverse in Z for desired width of the relief.

Picture of some action stub gauges. I make them up every time I get a new to me action. The top two show reliefs made with the full profile insert and the bottom is threaded to shoulder with no relief just to prove I can do it

 

[LVLAaron]

I do the same if I'm using a full profile insert. Easy mode.

 

[Rich S]

So one the Bros BAT came in the shop last Friday and I asked him about their drawings and how they didn't say "relief groove." He gets a grin on his face and says that "technically" it wouldn't have to be a relief groove, but that on a manual lathe it's hard to thread to within .100" of the shoulder and to get the action to thread all the way to the shoulder. Thus their recommendation and practice.

I thought it was a diplomatic way to not take sides. It also means I can't be as definite about their recommendation any more.........

I've done some with the relief and some without. On the ones I didn't cut the relief, I reduce the OD to 1.040 within 0.100" of the shoulder and thread fairly close to the shoulder. On the BATs I've checked the ID of the action is bored about1.062 ID for 0.100" at the shoulder. I haven't seen a functional difference either way.

 

[jelrod1]

Nobody has mentioned measuring the threads yet. I know a lot of people despise the 3 wire method and I've heard 2 dozen hacks on how to do it easier. This is how I do it.

I use mics, ring gages, and three wire depending on what I'm doing, but these things get used most often on tenons. They are size specific and fairly expensive for what they are but pretty foolproof to use.

 

[LVLAaron]

Wow those are cool.

Also… stupid defiance actions!

 

[tobnpr]

^^^
Ditto, never seen spring gages before. Definitely less headache than wires, but they're diameter and pitch specific so you need a bunch of them- and won't work on a non-"standard" diameter. I'll stick with my handful of thread mikes. Three mikes 0-1", and two 1"-2" measure every pitch and diameter I need.