thread mic??

Jerry,
To use that ring gage will require a plug gage to set it. Also you can't measure the taper in the threads which they all have to some degree. A cheap set of thread mics is all the home smith will ever need. That and an inexpensive program that gives you every number for any thread type or size. Imperial and metric, any style you can think of. See link below. Unless something has changed you can get it for a seven day free trial period. Print off what you need. I would not be without it.

For the home smiths
I've done literally thousands of barrels and never had the action in hand. A thread spec is just a number to hit. No different than hitting the diameter or length of the tenon. Thread wires are a big pain get a cheap thread mic off of eBay or just wait and watch then snag a high end set. life will so much easier.

http://closetolerancesoftware.com/METhreadPal.html
 
Just to share a story with you all...a good friend owned a 2009 model BAT M (right bolt) action he had 3 barrels for it chambered by Lester Bruno...he later switched over and bought a 2012model BAT M action (left hand) none of the original 3 barrels would thread into the old action...the threads in the new action appeared to have a "flat or shallow root" I ordered a tap and we ran it into the new action and all 3 old barrels threaded in perfectly...a change in the threading process at BAT makes ordering a barrel pre-chambered somewhat difficult..

Eddie in Texas
 
Dave Tooley said:
Jerry,
To use that ring gage will require a plug gage to set it. Also you can't measure the taper in the threads which they all have to some degree. A cheap set of thread mics is all the home smith will ever need. That and an inexpensive program that gives you every number for any thread type or size. Imperial and metric, any style you can think of. See link below. Unless something has changed you can get it for a seven day free trial period. Print off what you need. I would not be without it.

For the home smiths
I've done literally thousands of barrels and never had the action in hand. A thread spec is just a number to hit. No different than hitting the diameter or length of the tenon. Thread wires are a big pain get a cheap thread mic off of eBay or just wait and watch then snag a high end set. life will so much easier.

http://closetolerancesoftware.com/METhreadPal.html
Click to expand...

If you set, or reset, a ring gage with a regular plug gage you will be way off. If you want to reset a ring gage 1) set it off a setting gage, 2) Set or off an existing tenon you like the fit of, or, 3) set it off the ID dimension on most gages.


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Dave Tooley said:
Jerry,
To use that ring gage will require a plug gage to set it. Also you can't measure the taper in the threads which they all have to some degree. A cheap set of thread mics is all the home smith will ever need.
Click to expand...

Remember the well known action of a few years back that came with (unintentional) tapered threads?

As to taper in a tenon you just threaded 1) you had too much overhang of the workpiece, or, 2) the threading tool was dull, or,3) you were taking too large of a cut and need to make a few "drag" passes, or, 4) if you find taper with wires or thread mikes, how are you going to fix it???

On typical barrel tenons the first few threading passes can be in the 0.005" to 0.008" per pass then as you pick up more tool load (more surface area) you need to back off each subsequent cut, taking drag passes between feed cuts.

With the average tool room size lathe, American or ChiCom, a skilled operator should be able to cut a tenon without taper.


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I have a couple ring gauges I bought from BAT. They work fantastically. I made a ring gauge for Panda, so I have that covered as well. The Farley actions is where I feel I need a good mic. None of them are the same. Remingtons as well. Wires are all fine and good, but I don't enjoy them one bit!! LOL. Fat fingers I guess?? Lee
 
Been stated many times here and I also support the idea of cheap thread mics. A gage only tells you if part of the thread profile is bigger or smaller than the gage. Proper gaging requires a go and a no-go gage. Then you only know you are somewhere in between. Then you have to calibrate them somehow to know for sure. Even a cheap pair of thread mics will tell you so much more at a fraction the cost.

+++ on the Seco threading inserts! I use them extensively in production machining and they can make some beautiful threads. Seco insert # 16ER 16UN CP500 is exactly what I use on my 16 pitch tenons too. 16ER 18UN CP500 for the 18 pitch tenons. One insert should last you hundreds of barrels if used correctly.
 
I bought a set of carmex that has a bunch of the full profile inserts in it all in a nice box. Got an internal and external set. Pretty sure i got them from msc
 
there's 4 pages of thread mics on EBay. Several 1-2" 14-20 TPI fixed anvil mics for under $50. All you would need is a 1" standard to set and verify them. Don't over look Fowler and SPI brands.
 
SGS said:
Skeet, I have a pair of these in 1-2" and I just ordered another in 0-1" They are nicer than the Chinese but more reasonably priced than the Japanese or USA.
I also use the SECO full profile inserts and I get nice threads even at 200 rpm.

http://www.jtsmach.com/jtswebshop/Measuring/PM099.asp
Click to expand...


Scott, are you having any chatter issues with the full profile inserts? That possibility could exist since there is more contact area when you are at full depth on a full profile insert than a single point insert.



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JerrySharrett said:
Scott, are you having any chatter issues with the full profile inserts? That possibility could exist since there is more contact area when you are at full depth on a full profile insert than a single point insert.
..
Click to expand...

Jerry,

I do sometimes get chatter. If I could thread at higher speed I don't think it would be an issue. I have had success with 18 tpi full profile inserts but I am using standard positive rake inserts for 16 tpi. Some barrels machine better than others, and obviously, the less material out of the chuck the better. I know that manual machining on a Chinese machine is not what these inserts are designed for.
 
I have been watching for a set of starrett 585 thread mics. I think I can get a set bought for under 70$ on flea bay. My friend Chet recommends them. Lee
 
SGS said:
Jerry,

I do sometimes get chatter. If I could thread at higher speed I don't think it would be an issue. I have had success with 18 tpi full profile inserts but I am using standard positive rake inserts for 16 tpi. Some barrels machine better than others, and obviously, the less material out of the chuck the better. I know that manual machining on a Chinese machine is not what these inserts are designed for.
Click to expand...

You are getting chatter because of two issues. 1) Overhang of the workpiece-you can control some of this by running a live center in the outboard end (or shortening the overhang), and 2) Contact area of the cutting tool itself. These full profile inserts are essentially forming tools, and chatter is the nature of that beast. Slower is better than faster. Chatter is a harmonic and speed, surface area passing by the tool (SFM), accelerates chatter.

One of the reamer grinder guys always encourages more speed to eliminate chatter....wrong, wrong!! Speeding up will sometimes change the harmonic but it is not the solution.

http://www.physicsclassroom.com/Class/sound/U11L4d.cfm


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JerrySharrett said:
You are getting chatter because of two issues. 1) Overhang of the workpiece-you can control some of this by running a live center in the outboard end (or shortening the overhang), and 2) Contact area of the cutting tool itself. These full profile inserts are essentially forming tools, and chatter is the nature of that beast. Slower is better than faster. Chatter is a harmonic and speed, surface area passing by the tool (SFM), accelerates chatter.

One of the reamer grinder guys always encourages more speed to eliminate chatter....wrong, wrong!! Speeding up will sometimes change the harmonic but it is not the solution.

http://www.physicsclassroom.com/Class/sound/U11L4d.cfm


.
Click to expand...

Jerry,

Can you explain the "live center in the outboard end" concept, please. I am curious as to how that works to control chatter when you've got the work piece locked-up in a chuck. Will a barrel, or any piece of round stock, not contained in some fashion on the outboard end of the headstock set off a vibration/harmonic that can influence surface finish despite the clamping/holding power of the chuck?

Thanks,
Justin
 
Dave Tooley said:
there's 4 pages of thread mics on EBay. Several 1-2" 14-20 TPI fixed anvil mics for under $50. All you would need is a 1" standard to set and verify them. Don't over look Fowler and SPI brands.
Click to expand...

I use a Accupro thread mike that has the 14-20 tpi range. Seems to work well. If anything using a thread mike does is it saves time. It lets you see how far you have left to go to hit a particular number for a certain action. Don't see that brand listed anymore, but probably comes in as a cheap thread mike. I thread mainly 16 to 18 tpi and a 14-20 tpi range mike works well for those two threads.
 
JerrySharrett said:
You are getting chatter because of two issues. 1) Overhang of the workpiece-you can control some of this by running a live center in the outboard end (or shortening the overhang), and 2) Contact area of the cutting tool itself. These full profile inserts are essentially forming tools, and chatter is the nature of that beast. Slower is better than faster. Chatter is a harmonic and speed, surface area passing by the tool (SFM), accelerates chatter.

One of the reamer grinder guys always encourages more speed to eliminate chatter....wrong, wrong!! Speeding up will sometimes change the harmonic but it is not the solution.
Click to expand...

This is the dilemma many guys run into with carbide tools on manual machines. The carbide cuts best at a much faster cutting speed than the application allows. I haven't tried the Warner HSS inserts because I have been mostly successful with carbide, but many guys really like them.
 
SGS said:
This is the dilemma many guys run into with carbide tools on manual machines. The carbide cuts best at a much faster cutting speed than the application allows. I haven't tried the Warner HSS inserts because I have been mostly successful with carbide, but many guys really like them.
Click to expand...

Could someone explain to me the science behind this HSS/carbide observation? I've heard this before and I'm open to input but I have not personally experienced this in my career. For me, setup rigidity and cutter geometry are the most important factors and cutting tool material only determines maximum surface speed and fracture/wear resistance. The only times I can recall higher speed improving cutting performance is with some high temp stainless materials where high chip heat improves chip flow and in cases where an RPM change breaks a harmonic cycle.

Could it be what you are really experiencing is a difference in cutting tool geometry? There are a lot of carbide inserts out there with less than desirable cutting edge geometry for an engine lathe with marginal rigidity.
 
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