Recommendation for an internal threading tool please

[darkzero]

Anyone recommend a good threading bar or indexable tool for it? I don't really get the LH/RH part of it when I look for tooling. I plan to cut these feeding from the right towards the headstock with the tip of the tool facing me. Not planning to run in reverse with the tool tip facing away from me cutting on the far side of the stock.

These are the Carmex tools that I mentioned. Notice my internal threader is mounted upside down.




Another way of cutting internal thread (besides using a LH tool running backwards) is to mount a RH tool upside down like I have pictured, run the spindle forward, & feed in with the compound from the right as if you are cutting external threads. I prefer this method since I can actually get somewhat of a view of the cutting & I don't have to have the compound off to the left.

These pics are from my 8x14 but I use the same tools & same methods on my 12x36

 

[darkzero]

a 1/2 by 28 thread tap would be even better, more ridged. and you already probably have a boreing bar holder that would fit a half inch tap. The natural taper of the tap allows each tooth to take a little and reduce the chip load per tooth. You do have to drive it in at 90 degrees not at the usual 29.5 degrees as usual. Because a tap has very little relief on the threads. but with such a shallow thread i doubt that will pose much of a problem.

That's very interesting & I've never even heard of this method. I will definitely have to try it one day. Thanks for sharing!

 

[cmv]

Not sure what kind of setup you were using when you said you made a tool from hss, but on a hole that large I would use an hss tool in one of these bars:
View attachment 44297

Should go pretty easy. Also make sure you clean up the inside of the tube first to the proper diameter with a boring tool.

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Ground a HSS blank to something like that. Didn't work well.

Someone needs to make an expandable tap - turn a set screw on the end until you get the OD you want While I wait for that to hit the market, will check out some of the other tools you guys recommended.

 

[stevecmo]

cmv,

I'm totally confused as to what you are trying to do. Are you really trying to cut 28TPI internal threads on ID's ranging from .900 - 1.120? What are you then going to try to thread into those holes? Are you going to make custom external threads to match each internal thread???

There is nothing magical about cutting internal threads. Just grind a HSS bit to 60*, put it in a boring bar and have at it. Help us understand what we're missing in your project and we'll gladly help you thru it. Do you have any pictures?

Steve

 

[Tony Wells]

Smaller ID threads can pose problems, but there are (of course) tools on the market for the job.



There is also a single point, carbide insert made by Kennemetal I believe that is good for smaller ID threads. I can't locate a picture of it at the moment.

 

[darkzero]

Smaller ID threads can pose problems, but there are (of course) tools on the market for the job.

There is also a single point, carbide insert made by Kennemetal I believe that is good for smaller ID threads. I can't locate a picture of it at the moment.

True, Micro 100 also makes great carbide tooling for boring & threading small holes. But IMHO .900 - 1.120 is not a thread size I would consider to be small. For that size I personally wouldn't even think of using a tap, if the OP's thread had been a standard size, unless the material was something very soft. With the boring bar I have, I use it for any thread 1/2" & bigger.

 

[Tony Wells]

Mopar, that may be smaller holes to some of us.

 

[ptgord]

Mesa Tool has an interesting threading tool.

It can do internal, external, right or left hand.

Pretty inexpensive also for $32 or $36 depending on size.

Check them out HERE.

He also sells inserts for grooving either square or radius bottomed grooves.

Gary

View attachment 44309

++++ on the Mesa tool products. Very easy to use & great results