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Old 02-23-2017, 07:08 PM   #11
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You really need to determine the material, hardness.

Yes, a masonry bit will work,on hard materials. But! and or if.

You really need to have a means to sharpen and size the carbide.

The geometry of the cutting edges of carbide will determine how well the tool cuts, how long the edge will endure. There is a great deal of heat generated and a ridgid set-up ideally needed for good results.

The thread size that you are mentioning, 8-10 pitch is mighty small, to try thread mill.
That is : to interpolate threads.
I don't know if there is a tool that small, in carbide to do thread interpolation for inside threads.

But as mentioned by dnalot, If it is permissible, drill a hole larger than needed, allowing plenty of wall thickness, over tap size.
You can tapper the hole or step it. Then you can plug the hole with a mild steel, brass or what ever you want for the application.

Then you can: peen,glue,weld,braze the plug in, then drill and tap.

There are a number of applications for this type of repair, just use your imagination.


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Old 02-23-2017, 07:59 PM   #12
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Drill an oversize hole with a sharpened masonry drill.Any old oversize. Press and locktite in a soft steel plug and drill and tap the plug. The same kind of idea as Danalot, What does the screw hold? I have sparked threads with an adjustable eccentric rotating holder. It is a bit of a fiddle but it works.
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Old 02-23-2017, 10:21 PM   #13
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For drilling hard materials, search around where you live for hard plate drills. They are mainly used by locksmiths and don't cost much.

The ones I use can drill through spring steel with no problems and do really drill accurate sized holes.

http://www.leofixings.com/Hardplate-...ped-p/9892.htm


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Old 02-23-2017, 11:43 PM   #14
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As Blogwitch mentioned hardplate, drills , these would be called Die maker or toolmaker drills.

These are available in couple of configurations. A die makers drills can be a solid carbide spade , there are spotting drills and carbide tipped.

These are a lot more expensive for doing a infrequent job. The spade shape drills are very nice to use.

I'll have to check into the hardplate drills, that are common to the UK.
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Old 03-11-2017, 04:35 PM   #15
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I needed to drill a 4-40 hole in a 2" Ball Bearing x 6. First ground a small flat spot, then using a carbide twist drill 3/16" about 1/2" deep, into this I pressed a pre-drilled spud, then tapped the 4-40 hole.

Pre drilling the spud gives the metal somewhere to expand when pressed into the ball.
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Old 03-11-2017, 07:54 PM   #16
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Has anyone noted the OP is talking about a 6-32 thread = 0.108" = 2.6 mm?

So far Buchanan has offered the only practical solution.
If this is a DOE or a NASA project then there are more options.
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Old 03-12-2017, 08:19 PM   #17
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Quote:
Originally Posted by tornitore45 View Post
Has anyone noted the OP is talking about a 6-32 thread = 0.108" = 2.6 mm?
Yes, I have a Thread Mill or two in the drawer for that size range ;-)
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Old 03-12-2017, 09:17 PM   #18
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Quote:
Yes, I have a Thread Mill or two in the drawer for that size range ;-)
And the 10,000 RPM lathe spindle to do it. In that magic drawer.
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Old 03-12-2017, 10:52 PM   #19
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A little more info with photos and description would not go amiss
How hard is the material.You mention S/S that is not hard.Is it file hard
if so it can only be drilled and a softer plug fitted to drill and tap
If its S/S hard then it will be difficult to tap at that size but not impossible
I personally have never heard of spark eroding a thread that small
What is the item?,can it be remade in drill rod and then rehardened
Can it annealed to work and the hardened.Again I say not enough initial info
that is why you are getting some weird and wonderful ideas most of which
can be ignored for our type of work
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Old 03-13-2017, 09:36 AM   #20
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If it is very important I will spark erode the thread in for you. But we need more information. What does it hold and what are the stresses and in what direction.
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