Coventry dies

[IntrestinParticipant @intrestin]

Re-sharpening

[IntrestinParticipant @intrestin]

Does anyone know where I can get 3/8" BSF Coventry dies re-sharpened for my 3/4" die head

[MWParticipant @mw27036]

You might need to ask around a few engineering works to see if they can do it, locally ideally, but not the sort of thing that tends to be advertised online.

To be honest though, I think I've see a few demonstrations of people re sharpening threads in home workshops. 

Michael W

Edited By Michael-w on 27/02/2018 10:46:02

[Mick B1Participant @mickb1]

I'd think you could sharpen the chasers by grinding across the top using the side face of a fine bench grinder wheel – carefully. Probably hold the chaser with a mole wrench or parallel clamps.

[Rik ShawParticipant @rikshaw]

I would not attempt to sharpen by hand – if you want to take advantage of the accuracy of your die head that is. You would increase your chances of finding some one who would do the job if you invested in a die sharpening attachment – they quite often come up on ebay though not always cheap.

Then all you need to find is someone with a surface grinder.

Rik

[Howard LewisParticipant @howardlewis46836]

To do the job properly you really need the proper jig in which to hold the dies for sharpening.

If you get the hand grinding wrong, you may well end up worse off than if you left well alone.

My advice FWIW is find someone with the kit to do the job correctly.

Howard

[lug lordParticipant @luglord]

i have the die grinder jig for setting all the angles but do not have a surface grinder i often wonder if i could maybe touch them up by rubing a stone accross the top whilst there in the jig

[Bill Davies 2Participant @billdavies2]

I have a pdf of The Book of the Coventry Diehead (25th Ed). It mentions UNC and UNF, so is post-1949, perhaps late-50s to 1960s. I don't know where I downloaded it, so can't post a link.

It mentions several jig types, including one for 12 degrees rake angle. It also mentions M-type dies are ground parallel to their back. I enclose a couple of pics from the book for a type which allows different rake angles.

It shows the clamps on the left for grinding top rake, and on the right for grinding the 'throat' or lead-in of the die.

My recollection from long ago (unreliable) is that the die rake angle was zero degrees, and that there was a simple jig, perhaps shop-made, not a branded one, for use on a cutter grinder or surface grinder.

Larger copies are my album.

Bill

[Bill Davies 2Participant @billdavies2]

A couple of more images from the book, showing the grinding of the die rake angles.

Bill

[Steamer1915Participant @steamer1915]

Try John Dunn Engineering. Advertises in ME magazine.

I believe he has the jigs.

Best regards,

Steve.

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