Vee threads, Acme threads, and buttress threads are cut with significant clearance but I cut square threads pretty snug. Snug enough that grease is required. This, unless the rifle is a take-down. Then I'll figure on a couple thou clearance. WH
Barrel Threads--Tight or Loose?
- Thread starter HTSmith
- Start date
Alex Wheeler
Site $$ Sponsor
Loose threads are a good thing for many reasons. They shoot better and dont rip the threads out of the action 
hoz53
Gold $$ Contributor
i remember that Tenon you showed a pic of, supposedly an award winning barrel. Mine are always loose enough to thread on easily by hand but i wonder how loose is to loose.Loose threads are a good thing for many reasons. They shoot better and dont rip the threads out of the action
Alex Wheeler
Site $$ Sponsor
That one was the loosest one I have ever seen. When you broke it loose it would smack the stock it had so much clearance. Obviously the smith didnt intentionally do that, I still cant figure out how it got that way. It actually looks like it galled into an action and was forced out ripping half the threads away. But if thats the case it was not with the action it was on when if broke records and won a Nationals because that action had no damage. I mean this thing was loose to the point of actually being concerned about safety!
Look at the extremes of a class 2 fit for what is approaching too much.
hoz53
Gold $$ Contributor
thanks Dave—.
ridgeway
Silver $$ Contributor
Kelbly and bat will sell you a threaded tenon that you can utilize as a go gauge when you thread. I simply thread to fit and feel. Thread wires or thread mic will get you a number. Or get a set of high $$ ring gauges for your threa. Machinery Handbook is excellent bedtime reading book.
Ring gauges are great but are sold in classes of fit. There's about .005 between a go/no go for a class 2 and .004 for a class 3. This is for a
1-1/16-18tpi thread.
Thread mics are worth their weight in gold, imho.
Oh, and Machinery's Handbook is the bible of machining.
1-1/16-18tpi thread.
Thread mics are worth their weight in gold, imho.
Oh, and Machinery's Handbook is the bible of machining.
Yep.
Bought all mine (mostly Starretts) on Fleabay, I don't think I paid over fifty bucks for any of them.
hoz53
Gold $$ Contributor
. I don’t know if it’s right but it doesn’t matter to me to know a number of the dimensions of the thread on a tenon. I just thread it to fit that particular action. Mabie I could do better I don’t know. I’ve got wires and I’d like to have a thread mic to measure 1 1/16- 18 cause I’m curious but I thread them to fit. I don’t have to thread things to send them somewhere that has to fit a spec. Should I be doing it different?
hoz53
Gold $$ Contributor
thats what I do to
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Dusty Stevens
Shiner
Get a shars 1-2” thread mic kit. Then start trying to match threads by size first then see how it fits. You gotta have a bunch of tricks- i have to thread barrels for glue ins so theres no checking as you go. Also actions such as a bat mb even if its in hand you cant check it in the lathe. Machining is all about hitting a number on a print. Itll make you a lot better if you practice it.
hoz53
Gold $$ Contributor
Ok Thanks, I will work on that
Thread classes of fit are standards.
Threading to fit a part in hand is creating your own class of fit. Itll work, but no promises that itll fit the next action that was threaded to a standard class fit.
Say you thread a bbl for your own action, to a "perfect" fit..and choose to sell it. Because action makers are doing an excellent job at being consistent, it just might work but there are no guarantees. That's what standards are for. If the Male and female are properly threaded to a particular class of fit standard, you can guarentee fit.
BAT and Kelbly, for example give a more precise spec that is pretty much in the middle (iirc) of a class 2.
This is a great app for your phone or computer.
http://theoreticalmachinist.com/Threads_UnifiedImperial.aspx
Kelblys print calls for 1.071 pitch diameter +0.000/.002...over.032 wires.
That's a proper print.
BAt says 1.023 pitch diameter. The main difference is that BAT does not state tolerances. This is an example of an incomplete print.Everything has tolerances.
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I use a 1" thread mic as the pitch diameter for 1 1/16-16 TPI 2A threads is 1.0203" - 1.0148" That's less than one turn past 1". Also I thread a lot muzzles so I need to check smaller diameter threads. I do have a metric 25MM-50MM and it's easy to do the math. .01MM is .00039". Close enough for government work.
I use wires. Every action I have worked on I have specs for, and tenon diameter and wire measurements are included, as well as where to mark the barrel for caliber. Never need that action again to do a barrel.
A thread mic would certainly be faster than wires, but it's what I started with.
A thread mic would certainly be faster than wires, but it's what I started with.
Looks like a pretty good assortment of ring gauges, to me.
Yes that's only part of them there's a box behind that panel with an abundance of more making our job a little more simple.LOL
I can't disagree with that.
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