Threading barrels

[xr650rRider]

Joe Pie Threading Myth busted

 

[AccelR8]

I had ground a HSS bit with the geometry very much like the tool in the post above. I can thread very close to a shoulder with it. As I wrote about once before here, I did some barrel shanks for a gunsmith without a relief groove and got ripped by him for being lazy. These for Remington 700'sso...

I've been hearing so much about this threading away from the spindle with an inverted tool I decided to try it. But, paying so much attention to getting set up I forgot to actually run the lathe in reverse! Turns out that's one of the key things for this method to work. Huh. Busted my (somewhat expensive) threading insert.

I would have to buy new tooling in order to thread away from the spindle with an inverted tool on barrels or anything with a shoulder because my tool holders will not allow the insert to get anywhere near the shoulder when inverted. I honestly don't see enough advantage to justify the cost,

Anyway, I feed in with the compound at 29 degrees Disengage the half nut at the thread termination, back out with the cross slide, run the carriage back, run the cross slide back in to zero and then advance the compound however much I want for depth of cut and re-engage the half nut. Basic threading 101 type stuff.

If I've cut a relief groove, that's about all there is to it, just let the tool run off into the groove. If no relief groove, sometimes I will simply let the tool dwell a bit after I disengage the half nut before I retract the cross slide. And sometimes I'll cut a groove with the tool before starting to cut the thread as someone mentioned above I think. Or, I can quickly take the tool out with the cross slide just as I disengage of just before I disengage the half nut. It all depends on the job, the thread depth, the material, you learn by doing.

Getting old, getting tired of measuring threads with three wires. Adopting a new method whereby I set my compound dial to zero before cutting the thread, go to the thread termination and cut a groove with the cross slide to the depth of the minor dimeter - I use my cross slide dial for this which on my lathe is accurate, you need to verify that. DRO would be better. You can also verify your depth by measuring with two wires in this groove which is a whole lot easier than three on the thread...anyway...now back out your compound (not cross slide, leave that where it is), go start your thread and feed in with the compound. At the termination point, disengage half nut and back out with the compound, not the cross slide. Go back to start another pass, feed in the cross slide to where it was on the last path plus your new depth of cut. Repeat until your last pass, that's when you've arrived back at zero on your compound dial. Measure your PD with the three wires to verify and find you pretty much nailed it.

Still getting used to that method. Old dog, new tricks and all that. One day I'll buy a good thread mic even though I believe the three wire method is more precise. However, and I'm not a gunsmith, but I think if you're ding a barrel and you have the action in hand, just cut your thread to fit your action.

I'm not gonna go back and proof read that so, I apologize for spelling errors or what not

 

[LVLAaron]

@AccelR8 I laughed... but only because that's something I would do.

 

[xr650rRider]

For external thread away from the chuck, you run a left hand holder upside down.

 

[ronsatspokane]

Joe Pie Threading Myth busted

So this is an extended exercise in the obvious. Of course the right side of the tool cuts when the compound is set to 29.5. Simple arithmetic answers that question. It does not cut much and results in beautiful threads with minimal heat. What he did in the video was a waste of time. I want my time back.

 

[AccelR8]

ronsatspokane brought up a good point earlier about how much to advance the tool for each cut. I think good general rule is, when you get close to final dimension, advance by half of what you think you need for example if you think five thou cut will do it, cut two or three and then measure. It's real easy to cut a thread too much.

 

[GenePoole]

ronsatspokane brought up a good point earlier about how much to advance the tool for each cut. I think good general rule is, when you get close to final dimension, advance by half of what you think you need for example if you think five thou cut will do it, cut two or three and then measure. It's real easy to cut a thread too much.

...and always do a spring cut.

 

[INTJ]

Since I use only the compound, I set it to zero and know about how much to feed it in. I usually check as I get close with the action, brake, or ring gauge.

 

[Kiwishooter]

All you people with imperial lathes are lucky, when using a metric lathe you can't disengage the half nuts, so technique has to change.
I would like to try threading with a HLV that has the thread stops and the quick retract compound slide, but until I get a lathe with those features this is how I do it using the below threading tool.

No thread relief, all the infeed is done with the compound set at 29 deg, except the last two passes.
Set up a dial indicator that reads off the carriage, set it so the dial coincides with "0" where I want the thread to finish.
Feed the tool in and start the cut, when the dial indicator needle reaches the 0 on the correct rotation flip the lever on the threading tool which withdraws the tool approx 0.150" (4mm) more than enough to miss the shoulder, just as I flip the lever I flip the carriage feed from forward straight through to reverse....one of the benefits of a 3phase motor. Back to the start and flip the lever to move the threading cutter forward and apply the cut with the compound.
For the last two passes I feed straight in .001 to achieve final depth, then a spring pass.

From what I understand if I was using a HLV the only thing I wouldn't need to do is reverse the lathe, the HLV does that for you by just moving the threading lever on the headstock which reverses the carriage while the motor is still running forward and it doesn't lose position.

 

[Carl S]

All you people with imperial lathes are lucky, when using a metric lathe you can't disengage the half nuts, so technique has to change.
I would like to try threading with a HLV that has the thread stops and the quick retract compound slide, but until I get a lathe with those features this is how I do it using the below threading tool.

No thread relief, all the infeed is done with the compound set at 29 deg, except the last two passes.
Set up a dial indicator that reads off the carriage, set it so the dial coincides with "0" where I want the thread to finish.
Feed the tool in and start the cut, when the dial indicator needle reaches the 0 on the correct rotation flip the lever on the threading tool which withdraws the tool approx 0.150" (4mm) more than enough to miss the shoulder, just as I flip the lever I flip the carriage feed from forward straight through to reverse....one of the benefits of a 3phase motor. Back to the start and flip the lever to move the threading cutter forward and apply the cut with the compound.
For the last two passes I feed straight in .001 to achieve final depth, then a spring pass.

From what I understand if I was using a HLV the only thing I wouldn't need to do is reverse the lathe, the HLV does that for you by just moving the threading lever on the headstock which reverses the carriage while the motor is still running forward and it doesn't lose position.

Haven't you got a threading dial that engages the lead screw.if so you can disengage the half nuts.then re-engage them when the dial gets round to your desired number.

 

[Ksracer]

Haven't you got a threading dial that engages the lead screw.if so you can disengage the half nuts.then re-engage them when the dial gets round to your desired number.

I wonder if his lead screw is a metric pitch?

It sounds like he's doing the same thing you need to do while cutting a metric thread with an imperial lead screw. I.E, leaving the half nuts engaged and reversing to the start.

 

[xr650rRider]

So this is an extended exercise in the obvious. Of course the right side of the tool cuts when the compound is set to 29.5. Simple arithmetic answers that question. It does not cut much and results in beautiful threads with minimal heat. What he did in the video was a waste of time. I want my time back.

That video was a follow up to the one below. You said you'd never heard of anyone feeding straight in with cross slide while threading. At around 14:50, Joe states he always has but your machine has to be rigid enough. Mine is. If you already know everything, then it probably isn't of benefit. The original poster was asking about threading away and 29-1/2 degrees. Joe has a lot of videos if your waiting on a lathe.

If you run tools upside down with QCTP, you might need a spacer to be able to get on center.

 

[Bamban]

What is the micrometer below the carriage for?

Proximity sensor, micrometer to fine tune where you want to stop. With thread relief I have threaded at 400 rpm.

Thing with prox, once the rpm is set, you may not want to change it.

 

[Hal]

All you people with imperial lathes are lucky, when using a metric lathe you can't disengage the half nuts, so technique has to change.
I would like to try threading with a HLV that has the thread stops and the quick retract compound slide, but until I get a lathe with those features this is how I do it using the below threading tool.

No thread relief, all the infeed is done with the compound set at 29 deg, except the last two passes.
Set up a dial indicator that reads off the carriage, set it so the dial coincides with "0" where I want the thread to finish.
Feed the tool in and start the cut, when the dial indicator needle reaches the 0 on the correct rotation flip the lever on the threading tool which withdraws the tool approx 0.150" (4mm) more than enough to miss the shoulder, just as I flip the lever I flip the carriage feed from forward straight through to reverse....one of the benefits of a 3phase motor. Back to the start and flip the lever to move the threading cutter forward and apply the cut with the compound.
For the last two passes I feed straight in .001 to achieve final depth, then a spring pass.

From what I understand if I was using a HLV the only thing I wouldn't need to do is reverse the lathe, the HLV does that for you by just moving the threading lever on the headstock which reverses the carriage while the motor is still running forward and it doesn't lose position.

Kiwi who make your threading tool.
Hal

 

[Kiwishooter]

Kiwi who make your threading tool.
Hal

Ifanger is the manufacturer, I think they are pretty hard to get now, although the basic threading holder and cutting blades are available and I'm partway through making a retractable tool holder.

Multifix also made a tool holder for their toolpost with it built in both for internal and external threads

Thread cutting device FE, Multisuisse

With the thread cutting device FE by Multisuisse a thread can be produced without adjusting the plan support. The retraction lever can be used to move out of the thread. For the next cut only the new cutting depth has to be adjusted....

www.fwt-gmbh.de

Thread-cutting device FI, Multisuisse

With the thread-cutting device FI Multisuisse can be made a thread without adjusting the face support. The retraction lever allows the thread to be withdrawn without any problems. With the next cut, only the new cutting depth has to be...

www.fwt-gmbh.de

It's a pretty easy to copy design as it works on an eccentric pin for the movement, I've thought about making a toolpost holder for my quick change toolpost so I can use carbide threading tools

Retractable Threading Tool Holder !!!

Well after questions and ordering some dove tail cutters etc. I finally got this holder put together. Not that there wasn't a few issues with the making of the tool. Had to work really slow with the dove tails as was suggested to make sure I didn't destroy the cutters, as I also only have a...

www.hobby-machinist.com

 

[Kiwishooter]

I wonder if his lead screw is a metric pitch?

It sounds like he's doing the same thing you need to do while cutting a metric thread with an imperial lead screw. I.E, leaving the half nuts engaged and reversing to the start.

Yes, on a metric lathe the leadscrew is metric, the threading dial works for metric threads................Kiwi

 

[urbanrifleman]

So you flip the threading tool upside down and thread in reverse?

I suppose you have to thread straight in?

 

[WSnyder]

I suppose you have to thread straight in?

No, not necessarily. You would flip the compound around and use the "other" 29-29.5° mark. You always want to be pushing the compound back into itself when threading.

 

[urbanrifleman]

No, not necessarily. You would flip the compound around and use the "other" 29-29.5° mark. You always want to be pushing the compound back into itself when threading.

By the time I did all that I could already have the tenon threaded.

 

[LVLAaron]

If your lathe can go slow it's easier to just get comfortable working up to the shoulder than it is to do all of that upside down and backwards setup.