Drill size form19mm reaming.

[Chris DentonParticipant @chrisdenton53037]

[Chris DentonParticipant @chrisdenton53037]

Not too good with reamers.

What size final drill should I use before reaming 19mm stainless 303?

Thanks.

[HopperParticipant @hopper]

0.25mm under should do you. ie 18.75 or so. Providing you drill pilot hole first and then open the hole out to 18 or so.

For best results, regards location and concentricity, it is best to drill to say 18.00 then bore to 18.75 to 18.90 or so and then ream the final gnat's whisker. The boring bar removes any out of round and wandering resulting from drilling.

Trick with stainless is to keep the cutting speed lowish but keep the feed up to the job. Letting the tool/drill rub on the stainless will quickly work-harden it and make it a regular PITA to deal with.

[Boiler BriParticipant @boilerbri]

I would be tempted to leave more for the reamer to cut, say .5mm to prevent rubbing with stainless steel for once the surface has hardened you will struggle to get under the hardened surface.

Low speed and plenty of cutting fluid with a reasonable feed rate.

Bri

[Ian S CParticipant @iansc]

And when drilling the initial hole, drill say 10 mm, then 18 mm or maybe 18.25 mm.

Ian S C

[Chris DentonParticipant @chrisdenton53037]

Thanks.

It's 303 so shouldn't work harden.

[Ian S CParticipant @iansc]

It still doesn't like very small skims with a clearing drill.

Ian S C

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