Harold Hall’s Tool and cutter grinder rest (the more sophisticated model)

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Harold Hall’s Tool and cutter grinder rest (the more sophisticated model)

This topic has 4 replies, 2 voices, and was last updated 22 June 2011 at 23:06 by dcosta.

Viewing 5 posts - 1 through 5 (of 5 total)

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18 June 2011 at 00:45 #70489
dcosta
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@dcosta
Hello all (specially Harold Hall’s grinding rest user)!

A while ago I build the Harold Hall’s grinding rest and then I ground some drills with it. However didn’t make a teste of my work as deep as I should. So, now, I find that the drills I grind with the grinding rest do not show the expected geometry I can see in the book (Tool and cutter sharpenning pages 120, 121, 122) and they don’t cut metal in a smooth way. One of the 8mm drills sharpened with grinding rest even cut steel (cold rolled steel) in chips instead of two spirals and the vibrations of the drilling machine were as if the drill were hammering the metal…

The cause may be because I have some doubts in reading and interpreting (my mother tongue is the Portuguese) the “Tool and cutter sharpening”.

In referred pages, Mr. Hall states the following steps:

1 – table tilted down 27 degrees

2 – table rotated about one degree so the grinding only takes place in front edge of the wheel

3 – put the drill in the vee support with the cutting edges parallel with jig’s base

4 – adjust the drill end stop

5 – with the positioning bar against the edge of the end stop base fasten it to the drill shank ensuring the two halves are parallel

I have a doubt about this step: which edge? The left or the right? Is the side irrelevant? There are two possible edges usable for the purpose.

6 – start grinding de first face using the fence as a guide

7 – rotate the drill 180 degrees in the jig for sharpening the second facet

8 – set the angle of the table to 10 degrees and grind the third and fourth facets until the chisel has changed to a point with all four facets meeting at the same spot.

I’ve been facing dificulties in producing facets with a geometry equal to the image in page 122 of the book.

Is there any advice You can give to me in order to obtain better results? Can You clear my doubt in point 5?

Thanks in advance

Dias Costa
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18 June 2011 at 00:45 #38053
dcosta
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@dcosta
Doubt about a step in the sequence of usage for sharpening drills
18 June 2011 at 08:16 #70491
Nicholas Farr
Participant
@nicholasfarr14254
Hi Dias Costa, the edge that is shown being ground in Harold Hall’s book is the right hand side as you look at it with the point upper most. (See sketch below)

The parallel drill positioning bar is touching the left hand side of the drill end stop base, as viewed from the back of the drilling jig.

Hope this helps.

Regards Nick

Edited By Nicholas Farr on 18/06/2011 08:41:26
19 June 2011 at 00:55 #70535
dcosta
Participant
@dcosta
Hello Nick.

Thank You for Your help. Your advice was very well explained.

So, finally, I sharpened a drill satisfactorily.

I made some more modifications to the rest.

Soon I’ll load new pictures of it to my album.

Once again thank You for Your help

Dias Costa
22 June 2011 at 23:06 #70695
dcosta
Participant
@dcosta
Hello Nick (and all interested).

I uploaded a group of pictures showing some modifications I made to my Harold Hall’s grinding rest.

They complete some other pictures of the grinding rest in my album “Accesories and tools”.

Nick!

The best results I get in sharpening drills is with 30 degrees.

Once again thank You for Your help

Dias Costa
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