Spotting Drills

[Sub MandrelParticipant @submandrel]

Thanks to Mick Knights!

[Sub MandrelParticipant @submandrel]

THanks to Mick for his article in the latest MEW. It came today and earlier this evening I wanted to drill two holes in the side of the valve liners for my little IC engine. I though "what I need now are some of those spotting drills!"

In a flash of inspiration I looked in a little draw for some drills that came with a dremel-type set several years ago, They had short fluted lengths with robust flutes, no lands and 90-degree points. I had assumed they were for plastic.

Blow me down if they aren't the same as the ones in Mick's picture of spotting drills. Seven sizes up to about 1/8".

I tried one out on the valve liners and it went straight in where it first touched, with no tendency to wander and made a neat strat for me to follow up with the full-size drill.

So thanks Mick – without your article they would still be unused in another seven or ten years!

Neil

[Anonymous]

Well spotted Neil – Andrew

[magpieParticipant @magpie]

I bought some cobalt ones from Engineering Supplies after "Bogs" told me about them. The price made my eyes water, but they are superb drills. I have used them lots since i bought them and they are still VERY sharp. ( unlike me)

Cheers Derek.

[_Paul_Participant @_paul_]

After just breaking the tip of a small centre drill in a piece of work with about 10hrs in it i'm off to buy some now, thanks for the tip Derek looking at the Engineering Supplies site now which did you get Cobalt or Carbide?

Thanks

Paul

[John Stevenson 1Participant @johnstevenson1]

Centre drills are a thing of the past.

They were originally made for lathe work on fixed centres when the short parallel part held white lead for lubrication.

Nowadays most run revolving centres and the length of the parallel part isn't needed that long as it only has to provide clearence for the tip.

When I get a new batch of centre drills I always regring them to loose at least half the parallel length, my take on it is I'd sooner loose some life than loose a part thru it breaking in, they are consumables after all.

Other than lathe work I never use them anywhere else and use spotting drills for any other layout work. Take a look sometime in a modern CNC milling shop and you won't see a centre drill at all.

John S.

[magpieParticipant @magpie]

Hi Paul, I bought the cobalt ones. I allready have some very small sizes of carbide and if you look at them the wrong way they snap.

Cheers Derek.

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