The Breakroom > The Water Cooler

So muchfor pilot holes

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vintageandclassicrepairs:
Hi All,
Going back to Will's original link,
In the video, the speaker says the the 3/4 drill has a split point
This would certainly help the drill to start without wobble, Although when used in a decent milling machine
the need for spotting or centre drilling is reduced

An interesting variation on drill sharpening is shown on one of Brian Block's videos where he demonstrates a "spiral point" drill grinder


John
 

sparky961:

--- Quote from: AdeV on September 13, 2017, 07:00:09 AM ---Presumably the SFM is measured at the edges of the spade? I'm trying to convert that into RPM in my head, without a lot of luck :D

Edit: OK, think that's between 28 and just under 38 RPM?

--- End quote ---

I get 130 to 172 RPM, which sounds about right to me.

AdeV:
Bugger, I forgot to convert feet into inches when I divided the SFM into the circumference. Blast these complicated mathematical thingmajigs!  :smart:

sparky961:

--- Quote from: AdeV on September 13, 2017, 05:56:27 PM ---Bugger, I forgot to convert feet into inches when I divided the SFM into the circumference. Blast these complicated mathematical thingmajigs!  :smart:

--- End quote ---

LOL... I cheated.  I used an app. ;)

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