Practicing thread cutting

[DCP]

So I cut my 1st Threads on my Logan today.

I was really proud of myself and everything went well.

I used a S&W flash hider that was 1/2 28 for a gage.

I Threaded until it went on easy. [smilie=1:

Then :violin: I took it out of the lathe.

I took out my fake 22 silencer for my gs5 22lr and it only goes in 1 thread. :groner:

So guess I should have taken at least 1 more pass.

So what to do now? (I want to use this as a gage)

It would very hard to put it back in the lathe. [smilie=b:
Should I get a 1/2-28 die and just chase the threads?
or
Just leave it alone and mark it oversize?

Any help will be appreciated.

[drhall762]

Okay, good lesson learned. It sounds to me as you are starting as I did and that is self taught. First question is: What angle was your compound set at? Should have been 28 degrees. If so, you can put the barrel back in the lathe and pick up the threads where you left off and cut them deeper. Also, you can chase the threads. If you use an adjustable die you will get a tighter fit than if you use a Sears & Roebuck special which is intended to chase class 2 or even 3 threads. I spent several years teaching machining in the local community college. If I can help, let me know I still have a lot of student handouts on my hard drive.

[MtGun44]

Dr. Hall - I have a mill and a lathe and have been learning to use them. If you have some
good handouts that are "stand alone" - i.e. don't depend on the normal accompanying lecture to
make sense, I'd love to have them to study.

Thanks!

Bill

[Bret4207]

A die would certainly be simpler, but picking the thread up isn't that hard. It's a trade off- learn to pick up the thread (with the resultant hair pulling, swearing, stomping and throwing of things till you get it right) or buying a die you might only use once. Your choice.

DR (Dr.?) Hall, I'm sure your experience will be a welcome addition here!

[deltaenterprizes]

Unfortunatly I think drhall's memory is failing, the compound is set at 29.5* or 30* to the right for external 60* threads and to the left for internal 60* threads One half of the angle of the thread.
Your problem is different manufacturers use different tolerances for thread fit and tooling wears during production causing variences in sizes.
Acme threads require 14.5* compound angle since they have a 29* thread angle. Square threads require 90* compound angle.
Excuse the spelling errors.

http://littlemachineshop.com/Info/MiniLatheUsersGuide.pdf Page 30

[theperfessor]

After having to make several threaded items for which I had no mating part to use as a thread gauge I bought a set of thread wires and learned how to use them. Turns out to be easy to do and so far it has worked out just fine.

Wish I'd spent the money (not very expensive at ENCO by the way) a long time ago. Doing it right the first time is easier than doing it over.

[tomme boy]

Are you sure that thread on the GSG is 1/2-28? I thought it was Metric.

[tomme boy]

M9X.75 is what I am finding.

[DCP]

It came with an adapter from Gemtect and the 1/2 28 fake suppressor, its a kit



Are you sure that thread on the GSG is 1/2-28? I thought it was Metric.

[roysha]

First off the tool is ground to 60 degrees. For single pointing threads to reduce the tendency for the tool to tear the threads the compound is usually set at 29 degrees and the compound is used to feed the tool into the work piece with the cross slide always being returned to zero. This is so there is a bit of clearance during the cut, until just a couple thousandths from full depth then the cross slide is fed in to clean up the back side and true up the thread. This is why the double depth thread tables list 29 degree and normal double depths.

Picking up the thread is VERY easy! After the work piece is mounted in the lathe turn on the lathe and engage the threading nut with the cutting tool just clear of the workpiece. Leaving the thread nut engaged shutoff the lathe and then using a combination of the cross slide and compound align the cutting tool in the existing thread. Reset your dials to zero. Back out the cutting tool and disengage the threading nut. Start the lathe and take a trial run with the cutter a few thousandths from full depth to make sure you are properly aligned. Adjust if needed Then proceed to deepen the threads as required. Even threads use any number or mark, odd threads numbers or marks only and 1/2 threads the same number or mark when engaging the thread nut.

[Cap'n Morgan]

Since the GSG-5 is German made, I would think the threads are 1/2-20" Almost all European made .22 silencers are using that size, but it could be M12x1 as well.

[DCP]

It came with an adapter from Gemtect that is 1/2-28

and the 1/2 28 fake suppressor, its a kit




Since the GSG-5 is German made, I would think the threads are 1/2-20" Almost all European made .22 silencers are using that size, but it could be M12x1 as well.

[DCP]

I went down and re threaded it.

It just a 5in piece of 1/2in of round stock

The threads were about 1in long

So I started by trying to pick up the last 1/4in

Everything went fine.( beginners luck )lol

[nanuk]

......
I used a S&W flash hider that was 1/2 28 for a gage.......
I took out my fake 22 silencer for my gs5 22lr and it only goes in 1 thread. :groner:



Are you sure that thread on the GSG is 1/2-28? I thought it was Metric.


M9X.75 is what I am finding.


Since the GSG-5 is German made, I would think the threads are 1/2-20" Almost all European made .22 silencers are using that size, but it could be M12x1 as well.


It came with an adapter from Gemtect that is 1/2-28

and the 1/2 28 fake suppressor, its a kit


Just wondering.... are you all talking about the same part?

[DCP]

That we are.[smilie=s:




Just wondering.... are you all talking about the same part?

[JIMinPHX]

I agree with the perfessor about thread wires being the way to go. You can learn a little bit about using them by looking at the picture I posted at the bottom of this page - http://castboolits.gunloads.com/showthread.php?t=105185. You can see them in actual use, & get an idea of one way to hold them, in a picture that I posted in post #32 around the middle of this page - http://castboolits.gunloads.com/showthread.php?t=76079&page=2

The 29.5 degree infeed angle trick is really only needed on coarse threads. Most lathes that are less than 50 years old & have a swing in the 10-13" range & are in good condition, can cut threads down to about 18 or 20 tpi before they start to chatter & need the angled infeed to reduce the amount of cutting edge surface that is in contact with the work piece. Ideally, the perfect compound infeed angle should be 29.999 degrees on a 60 degree thread, but a half a degree is pretty darn close. It only leaves a little saw tooth edge on the back side of the thread & that usually comes off pretty easily with a few passes of a triangular file.

Lining back up in a preexisting thread to take another whisker thin cut can be a bit tedious, but it can be done. It's a lot easier if your compound is set parallel to the spindle axis.

If you just need to take a very small amount off, then try running a triangular file or a piece of folded sand paper inside the thread as the spindle turns. If I need to take off less than .0005", that's how I do it.

[theperfessor]

Having a set of thread files is also nice. I have two, they're square and have four standard pitches on each end. There are two pitches that overlap on mine so I have 14 pitches covered. A triangular file is also really nice to have, especially a jeweler's size for very fine pitches.

Thread files aren't really all that expensive, check Enco or MSC.

[Artful]

One of the problems you'll run into is that treading for a size like 1/2x28 isn't very standardized - I have several hosts threaded and my Barsto was largest with others being several Thou under that size - Also make sure you leave enough shoulder for the can to butt up against as most don't have in internal shoulder to butt up against the muzzle.

This may be helpful
http://www.silencertalk.com/AAC-thread-guide.pdf

[Bret4207]

Having a set of thread files is also nice. I have two, they're square and have four standard pitches on each end. There are two pitches that overlap on mine so I have 14 pitches covered. A triangular file is also really nice to have, especially a jeweler's size for very fine pitches.

Thread files aren't really all that expensive, check Enco or MSC.

Not many people even know thread files exist. Good on you, must be why you teach the class instead of sitting int he class! I just ran into my thread file the other day. Found it right where I "stored it safely so it won't get lost" some years back. When you fins something you forget you lost...it's been awhile.[smilie=1:

[DCP]

Lots of good info here.
I hope even more gets posted.
Thanks to all

Now I would like to address Bret4207

Your the man. I though I was the only one that has "stored it safely" LOL
Now I must go find my hole gages that have been safe for a month now.
I do know they will be in the last place I look.[smilie=1:[smilie=1:




....... I just ran into my thread file the other day. Found it right where I "stored it safely so it won't get lost" some years back. When you fins something you forget you lost...it's been awhile.[smilie=1:

[JIMinPHX]

One of the problems you'll run into is that treading for a size like 1/2x28 isn't very standardized

maybe it isn't very standardized, but it should be. 1/2"-28 is a specified UNEF thread. There are published standards for it.

The PD on an external should be 0.4757-0.4720" & the internal should be 0.4768-0.4816" for class 2.

For class 3 - external 0.4768-0.4740" & internal 0.4768-0.4804"

Anybody that cuts that thread outside of those limits should be asked to make good on their out of spec parts.

[riorider]

Dr. Hall I too would like to have a copy of your handouts just let me know how we can do it.
Thanks

[white eagle]

not going thru a bunch of trouble
run a chaser head on them
just have to ask :
why didn't you use your go/no go gauges before you unchucked it ????

[DCP]

I dont have any.

From what I read you would need 2 different sets.

I thought the flash hider would be close enough.



not going thru a bunch of trouble
run a chaser head on them
just have to ask :
why didn't you use your go/no go gauges before you unchucked it ????

[andremajic]

I tried to use thread wires but haven't got the hang of holding them on right. It's pretty frustrating.

Went by a pawn shop and found a starrett thread mic for 30 bucks. Problem solved.

Andy.

[JIMinPHX]

I tried to use thread wires but haven't got the hang of holding them on right. It's pretty frustrating.


Some people use a pair of rubber bands to hold them in place while taking a measurement.

[DCP]

:popcorn:

Aigain with another good idea. :awesome:


Man I need to think outside the box.

:Luvcastboolits:


Some people use a pair of rubber bands to hold them in place while taking a measurement.

[theperfessor]

I'll try the rubber band trick. I've just been using a dab of some thick grease to hold them in place. By the way, I've learned to clean out the chip pan in my lathe before using thread wires. Dropping one or more wires into a big pile of chips really slows down the measurement process while building your vocabulary.

[JIMinPHX]

Dropping one or more wires into a big pile of chips really slows down the measurement process while building your vocabulary.

Yep, I just did that two days ago. I'm now short one .024 wire. I really don't want to go out & buy another set, but I might need to.

[andremajic]

Some people use a pair of rubber bands to hold them in place while taking a measurement.

I appreciate the tip. I wish I grew up around some of you guys! Everything I've learned so far has been through video.

[DCP]

I talked to a retired Machinist today about using thread wires.

I told him about the rubber bands.

He said you might bend them on the small ones.

He said use some heavy grease they stick right in the threads. (Thats 2 now for thick grease)
Thanks theperfessor

He said he had some luck using a styrofoam block also

Thanks for all the good tips

[Buckshot]

.............Just for fun if you have a bit of spare 'fool around time' try your hand at making a couple 2 and 3 start bolts and nuts :-)

............Buckshot

[DCP]

This sounds like a good idea.

If I could only figure out how to make the sides or flats of the nuts.

Then how to make a adaptor mount for a octagon barrel. [smilie=b:


.............Just for fun if you have a bit of spare 'fool around time' try your hand at making a couple 2 and 3 start bolts and nuts :-)

............Buckshot

[Blanket]

A couple of more suggestions from a new guy here;

make sure that if you are turning threads on a piece that is already at the major diameter ie 1/2- 28 on a .500 blank, that it is indicated in dead nuts or your threads will not be concentric to the major dia axis

Thread wires are cheap and accurate, especially when chasing higher classes of threads. I have several sets and use wheel bearing grease as a stickum to hold them, have also used a small magnet stuck to the side of the work as a holder. They also have many uses for other things and I keep partial sets from the ones lost to make odd pins, small pin punches, oriface and jet cleaners, slave pins, screw holder and starter gizzies by rubber banding the ends of 3 of them together and sliding over the threads of a screw, measuring bore slugs to determine minimum land diameters and the list goes on.

Have set my lathes up with a positive stop rod to return to zero before infeeding for the cut on the cross slide. This can be as simple as a threaded hole in the end of the cross slide that you can screw a piece of threaded rod with stop nuts on it and a bracket with a hole for the rod to slide thru and stop nuts to hit mounted on the carriage.

Learning to either set the threading tool upside down and the compound swung to 29.5 degrees at 1 and 7 o'clock or at 11 and 5 o'clock and the tool mounted on the backside of the part and thread in reverse is very usefull for turning against shoulders such as a barrel shank or a screw head. doing this the cutter travels from left to right and off of the workpiece instead of having to disengage and back out as it approaches the shoulder

I always use several witness passes without any infeed to clean up any inconsistancys due to lathe wear or cutting pressure. I use black sulpher cutting oil as a lube and a very fine bristle wire brush mounted in a low rpm air buffer to polish and clean the threads when done.

I grind my threading tools with a surface grinder but always stone the face of both sides of the point and the chip face and cutting edge by hand. Hand ground ones also benifit from this as well

Forgive my spelling as I am a toolmaker and not a scholar and hope some of these tips help out. ..Russ