Thread pitch micrometer

[NewGunPlumber]

Hi guys,

I'm looking to buy a thread pitch mic for measuring barrel tennons. From what I can see most average tennons range from about .8 to about 1.125 which according to my supplier would require two seperate mic's being a 0-1" and a 1-2".

Do you know of anything that is in the magical sweet spot for gunsmithing, buy both or use wires?

Thanks in advance

 

[cstrickland]

Why not buy a 0 - 2" micrometer and use wires vs buying a 0-1 & a 1-2 ??

 

[Jim Kobe]

Barrel threads are not that hard to duplicate using the original barrel if you have it. I use my Mitutoyo dial caliper to measure the original pitch diameter and then cut the new one to that dimension. Not rocket science but it works for me. I see no reason to thread to such critical tolerance. If I need to thread to fit a new barrel to an action I don't have, I will have a print if I did it before and use wires to measure pitch diameter.

 

[BSCustoms]

The offshore Pitch Dia Mics are economical and plenty accurate for any gunsmithing type work you'll encounter. Buy both sizes.

 

[Pete Deal]

What are your quantities? I think for for very occasional work just use thread wires. They are hard to beat for versatility and price. I do a lot of small dovetailed stuff so I have also used them for checking dovetails. For dovetails I have switched to dowel pins though.

I recently bought a few mitutoyo thread mics for 0-1 and 1-2" diameters. These are really nice. I actually bought the pana mics which have non rotating spindles and grooved anvils for measuring threads. Nice! Pretty expensive option but when making quantities of parts the tread wires are a pain. Also reaching into a cnc lathe with the issue of dropping stuff and never finding it the thread wires are not so appealing.

 

[Mike1974]

I have these up to 3"

https://www.amazon.com/Anytime-Tool...734434&sprefix=THREAD+PITCH+MI,aps,165&sr=8-7

Plenty good for the work I do. Of course I bought them years ago and only paid about $100 for all three of them...

 

[michiganbuck]

They are very good but not perfect ..and even better if you keep track of measurement of a wired measure thread and keep that number in your note book.

 

[BruceS]

You can also use a 'Screw Thread Comparator'. They can be found cheap.

If you keep records, they are almost a thread mic.

 

[Clive603]

Yep.

A thread micrometer is best treated as a calibrated comparator rather than an independent measuring device. When using the snazzy ones with interchangeable anvil sets its most important to be meticulous about getting the anvils properly seated.

Beats the heck out of mucking about with thread wires in a machine when your carefully worked out thread cutting comes outa shade too tight or a shade too loose. Most especially so if you are using the Zero-to-Zero method on a manual machine as the thread micrometer gives you the error which can be transferred directly to the set-up with no mental maths beyond remembering if your cross slide dial is direct diameter reading (which I hate) or just travel.

Clive

 

[MilGunsmith]

You will need both 0-1" and 1 -2" , but if you can only get one, start with the 1-2" as most barrels are in the 1.062" area. The offshore copies are good for gunsmith work.

 

[wesg]

Pitch diameter of a 1-1/16-18 is 1.025. 16 TPI a bit less. A 1" thread mic should do just fine a turn or so off the end of the scale. My $60 bought at auction Tesa matches thread wire measurements within a half thou ... on a good thread. Any significant roughness and you've probably got no idea what you've really got either way. Which is probably why they use ring gauges for critical parts.

Still kicking myself for not paying attention. The 1-2 inch sold for $50 right before this one.

I've played a bit with this and a Pana-Mic. I like the non rotating spindle, but not sure the wedge vs cone male anvil is better or not. Easier to get centered, but not the same feel for going over center to find the 'high point'.

 

[theperfessor]

Several years ago we bought a 0-1 and 1-2 SPI thread mikes. They both use the same interchangable anvils, the 1-2 comes with a gage standard to check after changing anvils. Accuracy is fine, wish the anvils didn't rotate but it does let you use the mike "out of position". Price was reasonable when purchased but who knows now?

Beats the hell out of using wires, especially when you have to make money on a job. Maybe that isn't the OP's main problem.

 

[Illinoyance]

I own 0-1 and 1-2 thread mikes with interchangeable anvils. I would never consider using wires in the 0 to 2" range. The convenience of thread mikes makes them worth the investment.

 

[theperfessor]

It should be pointed out that the anvils for most thread mikes are for a 60* thread form. Some barrel tenon threads are not 60* thread forms, wires might be more useful for these if you know how to do the proper calculations.

 

[NewGunPlumber]

I'm only doing a handfull rather than hundreds but losing wires doesn't appeal to me so hoping to find a comprimise with a cost effective thread mic.

All work will be done with the actions on hand and if I haven't fitted a barrel to it previously I will likely make a stub gage to allow measuring before going to the barrel. So it will be used mainly as a comparitor and nothing leaving my workshop is going to need to bolt up to a space ship in the next state :-)

 

[kustomizer]

I'm only doing a handfull rather than hundreds but losing wires doesn't appeal to me so hoping to find a comprimise with a cost effective thread mic.

All work will be done with the actions on hand and if I haven't fitted a barrel to it previously I will likely make a stub gage to allow measuring before going to the barrel. So it will be used mainly as a comparitor and nothing leaving my workshop is going to need to bolt up to a space ship in the next state :-)

I think I have a 1-2 and a 0-1 with anvils, in good shape Foreign made. If you want them pm me and we will make a deal

 

[wesg]

I generally cut to fit, for whatever POS M-70(0) is in hand. Cutting a stub first gives me something to write down for reference, as well as something to stick the action on to see how much I might have improved it after truing . It also gives me something to shoot for, by mic dim, on a $300+ barrel.

A .002 increment on the compound is .0035 on PD, I think. So I've got a couple passes at least after it starts looking like a thread before I scrap it.

Usually.

 

[GenePoole]

A .002 increment on the compound is .0035 on PD, I think. So I've got a couple passes at least after it starts looking like a thread before I scrap it.

Usually.

That sounds right if you're using a direct reading compound dial: 0.004 * cosine 29.5° = 0.003481423... My compound reads twice as much or how much is going to come off the diameter, but that doesn't make any sense unless you're compound is always at 0°.

 

[wesg]

The Monarchs I've used are like that. Quite confusing. I never came up with any reason that made sense either.

 

[Peter.]

The Monarchs I've used are like that. Quite confusing. I never came up with any reason that made sense either.

It can only be because the cross slide has a built-in threading stop so for straight-in threading you swing the compound round to zero, use the cross-slide stop for fast repeated threading pass sets and add in-feed with the compound using the diameter-reading dial.