Boring bar

I need a special purpose boring bar and have a simple question. I suppose I
could just try it and see what happens, but...
I'm thinking of making a steel bar, cutting an appropriate notch in the end,
brazing a piece of tool steel into the notch and grinding it as required.
I have a couple questions:
1. What will brazing do to the temper of the tool steel? Should I quench
it after brazing in water? Oil? (What kind of oil?)
2. I've been told that brazing won't adhere very well to tool steel. Does
anyone know for sure? Tried it before?
Thanks.
Jerry
Reply to
Jerry Foster
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if the bar is large enough you can make it hold small cemented carbide bits
when it is too small I just tig weld a piece of high speed steel on the end of a bar , grind to desired size and use it ,
have done it for threading, grooving and other internal detail work where a special was needed, in mild steel and 4140 mostly
Reply to
williamhenry
Drill and ream "a hole" .001" so "oversize" crosswise in the bar near the end. Tap a set screw hole in the end, on axis. Use a drill blank whose diameter corresponds with the "hole".
Same idea, but broach a square hole for a lathe bit.
Randy
Reply to
Randy Replogle
Ruin it.
Use what the tool steel uses. Water for W1. Etc. Then temper around 350°F for an hour.
Tool steel is 95% (except for special grades) mild steel, it works just fine.
Use brass braze, quench immediately after the filler solidifies - or while still molten if it'll hold in place (capillary action will probably secure it nicely in a recessed pocket).
Tim
-- "California is the breakfast state: fruits, nuts and flakes." Website:
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Reply to
Tim Williams
And anneal it in the process. Assuming he does indeed have common tool steel, and not HSS. If it is HSS, silver solder is the way to go of course.
Tim
-- "California is the breakfast state: fruits, nuts and flakes." Website:
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Reply to
Tim Williams
If you have silver solder, make that your choice. Do not quench. You can also heli-arc the tool in place using silicon bronze filler. Either of those procedures work fine.
Harold
Reply to
Harold and Susan Vordos
Thanks, Tim. Yeah, make sure you use HSS, not other types of tool steel.
Harold
Reply to
Harold and Susan Vordos
I have to ask, even at the risk of looking dumb -- have you considered one of the import boring bars with square holes broached? The ones with the hole at one end broached at 90° and at the other 45°? These are very inexpensive and the ones I have purchased from Enco have been made very well even if they were made in India. I have rarely been as happy with a purchase. - GWE
Reply to
Grant Erwin
See my page, "Making a Boring Bar for the Lathe":
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Reply to
Richard J Kinch
It's the only way to go for specialized boring bar bits. You don't even have to notch the end unless you plan to really abuse it. Brazing or silver solder works fine. Bugs
Reply to
Bugs
I have made a number of special purpose tools by silver-brazing bits of HSS to mild steel shanks. Bits of broken HSS slitting saws make nice narrow parting tools and grooving tools for snap ring grooves. I once made a form tool for making round-bottomed threads by silver-brazing a steel ball to a shank and then grinding the top half away to leave a perfect hemisphere. Made a boring bar similarly. The application was a shop-made ballscrew. It was a little rough at first. I filled it with 400 grit clover compound, ran it up and down about 200 laps with a half-inch reversable electric drill. It put up a fight at first, but got over it. After I took it apart, cleaned it, lubed it and loaded it with new balls it ran very nicely indeed. The trickiest part was the ball return tube, made of copper tubing.
Reply to
Don Foreman

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