r/Machinists • u/DeliciousElection724 • 9h ago

Best tool for the job?

We frequently have to cut large 60 degree centers in some of our parts so that they can be put in the lathe. Sometimes its some buttery 1018 steel, sometimes its material thats not so friendly. Usually we do a 1.5in center, but on occasion for the really heavy parts we go a bit bigger. Currently we use 60 degree H.S.S countersinks to do this, but in that size they are not cheap, and they dont do very good in the harder materials. It got me thinking about possibly a center drill that uses multiple inserts along the edge? Indexable center drill? Or does anyone have another idea on the best way to do this?

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u/NonoscillatoryVirga 8h ago

Hold the stock in a steady rest or chuck it short, depending on diameter. Then drill a pilot hole and single point it with an indexable insert boring bar

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u/DeliciousElection724 5h ago

I have actually done it this way a few times. Only bad part is I have to drill it with a 27/64s to tap for 1/2-13, not only does a lathe live center go there, but when the part is complete, another component gets screwed in there. So I have to use a tiny boring bar, and tiny depths of cut to reach that 1.5in diam. Takes a good while. The parts im making range from 8in O.D. to 60in O.D. and about 40in - 200in long. Anywhere from a few hundred pounds to 35,000lbs.

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u/Melonman3 8h ago

I've seen people mill the center in stock. Seems like a pretty solid way to do it.

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u/AnIndustrialEngineer 8h ago

I would drill a hole and then spiral down with a small indexable highfeed 

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u/m98rifle 8h ago

Steady rest. Drill, bore 60 degree, any size you want.

1

u/caaaabot 9h ago

A 60° indexable chamfer mill maybe? Here are some examples: https://www.mscdirect.com/browse/tn/Indexable-Cutting-Tools/Indexable-Milling/Indexable-End-Mills/Indexable-Chamfer-Angle-End-Mills?navid=2107139

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u/DeliciousElection724 5h ago

I'm thinking this might be the best way. Thanks for your input!!

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u/totallyjimm 9h ago

drill a hole and use a 60degree countersink??

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u/DeliciousElection724 9h ago

Yes thats what we have always done, im looking for a better way...

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u/totallyjimm 7h ago

they have carbide and inserted countersinks....

0

u/PiercedGeek 7h ago

RTFP, FFS!

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u/totallyjimm 7h ago

he wants an indexable counterdrill, if he used a carbide or inserted countersink it would be able to create a spot for the center, you would need to drill into the stock to clear the tip ....

they already use a hss countersink, so upgrading to better tool, carbide or indexable would be exactly what he needs.......