Day 1 Practice - lessons learned. 12/30 update

[GenePoole]

It still looks like you're missing the mark with your thread dial on some of your passes. It looks like you have some cuts going on that are just one notch off either way from your ref.

 

[mram10]

Thanks Gene. Frick! I have been using any number on there since it is 16 tpi, but I think I’ll try one while hitting the same number every time. Could the threads look like that by having slop in any handles? Is the cross slide easier to make nice threads? Is tooling playing a part, or is this mainly me? I keep the machin running the entire time, engaging and disengaging the half nut. Honesty appreciated

That handle never left my hand!

 

[GenePoole]

It could also be that your tool holder is shifting between passes. Is your post good and tight and all the set screws tight?

Do you know what TPI your leadscrew is?

 

[Stan Taylor]

Here's something you might like.

http://www.arwarnerco.com/p-22-kit-18-12-inch-threader-nv.aspx

Plus one on the Warner tool holders if you don't want to grind your own thread tool the work very well easy setting also.

 

[akajun]

View attachment 1029748 View attachment 1029747 I woke up bright and early and decided to thread and cut the bolt nose on some blanks. First two turned out much better than expected. The third I took some measurements. I trued the face then cut the shank 1.000 long and turned it to 1.062. Then cut a small relief cut .295 from the shoulder. Seemed to be going well. I threw on my threading tool at 90 rpm after using my fishtail and did a handful of passes, .005 at a time till the outside threads looked sharp. Turned up the speed and lightly sanded. I measured and they had shrunk to 1.057. Then went on to cut the bolt face. Used a 11/16 cutter just to see how it would do, then finished with a short boring bar. My goal was .150 deep and .705 wide. It ended up .143 deep and .702 wide. I didn’t clean off the face good enough when I measuring the depth and must have got a chip on the mouth cause I was sure it was right at .150 in the shop before I cleaned it up.
Lessons learned:
The compound moves when I’m turning the shank down if it is at 29deg.
The chuck t handle at 505rpm goes across the shop
The bolt nose cutter needs a pilot
I should true the shoulder on the shank then clean off the barrel face. I didn’t true the shoulder.

Any advice welcome guys!!

those threads have some serious burrs and chatter.
What machine are you running? Make sure you’re using the same number each time you close the half nuts on the thread dial.
Also make sure your tool is exactly on center, you can check this by pinching a scale between the tool tip and a centered workpiece , should be straight up and down.
Next check your overhang of your tool in the holder , put it as far back as possible to eliminate chatter.
What tool are you using? If carbide you may be chipping the tip and not seeing it. Try hss tools, either the ar Warner or grind your own with no top rake at all. It’s not hard to do and makes beautiful cuts at slow speed. Also watch out for built up edge and brush on cutting oil each time you cut.

 

[SDWhirlwind]

Looks like your insert is not for that fine of threads and has a 30 degree or so radius? The gent I buy my inserts from at a machine shop/dealer said "just use these same inserts for threading you are using for cutting"! Didn't notice it first couple of threads but with the 30 degree? radius on the tip it removed much of the crest and OD diameter by the time root was cut deep enough to thread on receiver. I needed a V shaped threading insert/tool holder I finally realized. He didn't understand what OD or thread pitch I was wanting to cut. He didn't ask and at that time I didn't know enough to know what I needed/wanted. Anyway with the right tool and insert life and THREADS were much better.lol

Think I typed that as to what I am wanting/trying to convey? Get so d*mn POed with my memory, sentence structure and misspelling from strokes sometimes it looks and sounds like a monkey with same or higher IQ were using my account!

 

[FFEMT]

Learning the tricks of the trade can be difficult and time consuming. It may be worthwhile to look into a nearby trade school to at least learn the basic machine setups (stronger setup, safe shortcuts and basic speeds/feeds (machinists bible)) to get the best finish and longest tooling life possible. please practice good safety for your family. A somewhat long time ago (‘bout 40+ years) I went into the Navy as a machinist, if you were caught leaving a chuck key in a chuck and removing your hand without removing the key, you were awarded a necklace to wear for the rest of the day. The necklace was a piece of chain big enough to fit over the handles of the chuck key. We would have to wear it for a minimum of 12 hours. I only had to wear it twice....... that I will admit to. ;-)

 

[a1712]

Thanks Gene. Frick! I have been using any number on there since it is 16 tpi, but I think I’ll try one while hitting the same number every time. Could the threads look like that by having slop in any handles? Is the cross slide easier to make nice threads? Is tooling playing a part, or is this mainly me? I keep the machin running the entire time, engaging and disengaging the half nut. Honesty appreciated

That handle never left my hand!

Check in your area for a Vocational School. They usually offer night classes and most have Machinist Vocations. You'll be way ahead of starting cold. Brian.

 

[carlsbad]

hate to see you messing up those barrels. Put some scrap in the chuck and cut threads, any threads, until you have perfect threads. You can cut 10 sets of threads in the morning and 10 in the afternoon. just chuck up some scrap and start cutting. Don't worry about the diameter, thread pitch, etc. Just make perfect threads. Then fit them on the barrel.

Looks like you aren't engaging the halfnut correctly. Are these 16 tpi threads? On most lathes any thread divisible by 4 can be engaged on any mark. 18 tpi threads, for example, cannot use any mark. Check your manual to see what marks on the thread dial you have to use. It depends on your lead screw pitch.

Sometimes you can get the half nut hung up between marks. practice engaging until you can get it to fall onto the lead screw smoothly and fully engaged every time.

Make sure the lead screw is well oiled.


--Jerry

 

[Dusty Stevens]

Get some 1.25" bar ends off ebay or from a machine shop. Start with brass and get your actions to fit correctly

 

[mram10]

I am using cutoffs for practice, not barrels
Found the qctp was shifting slightly. Here is a new thread I just did after fixing that hiccup. I think the cutter does have a radius that is too much. They are carbide and I’m only going 90rpm.

 

[carlsbad]

I think you know it but don't use a thread that doesn't have a complete deep 60 deg V.

Example below.



I didn't just post a photo I had on my computer, I took this photo specificly to match your photo and show the difference. Good job posting detailed photos of your work.

 

[mram10]

Thanks Carl.

Just realized my “threading”tool was simply a carbide cutting tool. The iscar will be here soon and we’ll see real results

 

[shortgrass]

Don't know if Iscar makes any HS cutting tools I've used plenty of their carbide, though.

 

[rardoin]

The chuck t handle at 505rpm goes across the shop

Any advice welcome guys!!

I was taught, and almost always remembered, to spin the chuck a half turn or more by hand prior to starting up the headstock. If the wrench is inserted it will fall out or let you know it is there. I did have a 'spring loaded' T wrench that would eject itself when you release hand pressure but never got accustomed to it...but that was a good safety feature.

 

[carlsbad]

I use half HSS and half carbide....I think the threads I posted above were cut with carbide...However, which insert to use is a matter of surface finish. Mram10 is still trying to get he geometry down. you have to put the cutting edge in the right place or it doesn't matter what it is.

 

[hoz53]

I use half HSS and half carbide....I think the threads I posted above were cut with carbide...However, which insert to use is a matter of surface finish. Mram10 is still trying to get he geometry down. you have to put the cutting edge in the right place or it doesn't matter what it is.

what rpm do you run when using carbide?

 

[carlsbad]

Usually pretty slow. It ain't a race. 150 or less. At slow speeds, carbide, like anything else, likes to be submerged in good cutting oil. Also, going too fast while threading makes you susceptible to chatter on the final passes when you are taking a wide light cut. --Jerry

 

[HillbillyLongRifle]

This was cut with Arthur R.Warner HSS threading tool on my South Bend Heavy 10 lathe! Rem 700 16 TPI chambered in 20 Vartarg

 

[sdean]

Google Mr. Pete YouTube's. Watch a few looking over his shoulder.