Need Tool For Internal Threading

Hope I can explain this trick a machinist showed me.
For your 3/4 -16 fine thread, take a 3/8-16 course tap, (damaged if you have one), grind away the teeth on 3 of the 4 flutes, if its not a bottoming tap grind away the end till your into full teeth, leave 2 or 3 teeth at the end then grind away the rest back to the top. Presto you have a full form boring bar.

Greg
 
Those look like good tools on Vargus, but then again your relying on proprietary inserts just for those tools.
 
i have the mesa threading tool ... i happen to like it very much .
as to the inserts it takes ... i have not used the carbide that came with it , i coughed up a few extra bucks and ordered hss inserts for it from ar warner .
zero complaints i have cut a lot of threads with the inserts and have done nothing more then to give them a quick hone on a stone every now an then to keep them razor sharp .
i think with care the inserts will last many years .

the downside to the mesa tool ... if you have a 4 way tool post still you will not be able to get the tool on center . on my g0602 with the 4 way turret post i had to shim the entire post up 1/8 inch to get on center
and the require a minimum hole of around .620
 
Why not just get a brazed cutter, or one like this? Seems that if an insert is not lasting too long, especially a threading insert, it is being abused.
 
stupoty said:
It might be the initial drilling to size that wandered off line or was the hole bored?

Stuart
Click to expand...

This has been my experience... If the hole is correct... and the tap is started 'straight' (which should be the case with a tailstock as opposed to by hand)... then you should have relatively 'straight' threads.

The issues I have had with threading that was not 'straight' was either the hole was off or the tap was started off.
 
Thanks guys.
That Mesa tool looks reasonable but I see how the tool height may be a problem. I assume these are made for larger tool posts? Or for use with a QCTP where you could set the height? Doesn't sound like it will work on my 4 way toolpost.
Maybe I should forget inserts and go with something like this as suggested:
10320495.jpg

R
 
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Trying to get insert tooling that small especially if you want to get down to 1/2" is a fairly hopeless case. You will most likely have to go down to solid carbide threading tools like Micro100 or something. There just isn't enough room when you get that small for a fastener for an insert. They are not "that" bad. About $37 a pop. You can also grind your own if the price is too much.
 
Here's a very small Everede boring bar that I've used to thread a new cross feed nut for my 9" SBL.

DSCN2576.JPG
 
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