When is a new 90 degree drill not 90 degrees?

When is a new 90 degree drill not 90 degrees?

This topic has 6 replies, 5 voices, and was last updated 6 July 2026 at 20:09 by old mart.

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6 July 2026 at 16:31 #855004
Bill Phinn
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@billphinn90025
I recently bought a new spot drill (pictured) off ebay.

Can anyone explain the lack of correspondence between the marked tip angle and the actual one?2
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6 July 2026 at 17:06 #855009
Diogenes
Participant
@diogenes
Used, reground, put back in it’s packet, and sold? ..the box looks a bit ‘handled’..
6 July 2026 at 17:41 #855030
Bill Phinn
Participant
@billphinn90025
I think that’s unlikely, Diogenes, though I understand your cynicism; the drill is its full 75mm in length, the tip grind looks factory-like for its evenness and smoothness, there are no signs of use on the shank or the lands, and the seller tells me all the stock of these drills he has have visibly the same tip angle.

82 degree spotting drills do exist (presumably in both LH and RH), but I’d expect them to be marked as such, not marked 90 degrees. I can only assume this was a batch that got marked 90 but was ground to 82 degrees.

It can be used for screw extraction and to countersink for UNC/UNF screws if nothing else.

Now I just want some 140 degree spot drills, which seem to be rare as hen’s teeth in HSS, and ludicrously expensive in carbide.
6 July 2026 at 18:17 #855040
not done it yet
Participant
@notdoneityet
I would think that left-handed ‘spot’ drills are not a regular item?
6 July 2026 at 18:27 #855042
JasonB
Moderator
@jasonb
Presto only seem to list 90deg so less likely to be marked wrongly, have you contacted them and asked why?
6 July 2026 at 19:19 #855053
Bill Phinn
Participant
@billphinn90025
The seller can’t explain it, but offered a refund, which I declined.

He said the other three he has in stock (“had”, actually, because he appears to have sold another two since lunchtime today) have the same angle as each other and as mine “from the look of it”.
6 July 2026 at 20:09 #855059
old mart
Participant
@oldmart
Apart from several spotting drills in HSS and carbide which are a pretty good 90 degrees, I have a 5 or 6mm carbide with the 140 degree end. It rarely gets used as the shallow angle makes it more of a blind spot drill.
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