Drill sharp­en­ing

The Shed - - Letters -

I was most in­ter­ested in Andy Wil­son’s re­quest for in­for­ma­tion about drill sharp­en­ing Is­sue No. 74).

Pic­tured is the drill-sharp­en­ing jig [that] I use. It is the Eclipse 39, a Bri­tish­made de­vice whose in­ven­tor won the In­ven­tion of the Year com­pe­ti­tion for it in 1970. I have seen it de­scribed as “the best-value bit of kit ever”.

The abra­sive ma­te­rial is sand­pa­per glued to a flat sur­face. I use the plate-glass top from a dam­aged set of bath­room scales and sprayon ad­he­sive.

The drill bit is ac­cu­rately po­si­tioned in the jig and pushed over the sheet of abra­sive.

Af­ter a few pas­sages across the sur­face the drill bit is repo­si­tioned and the other facet of the cut­ting sur­face is sharp­ened. The process is re­peated un­til two good cut­ting edges are pro­duced. It is rather a long and de­mand­ing pro­ce­dure, but has the ad­van­tage that a com­pletely in­ex­pe­ri­enced ama­teur can trans­form a blunt drill bit into a use­ful item.

I have seen sea­soned me­tal­work­ers sharpen drills free­hand on a bench grinder in just a few sec­onds and pro­duce qual­ity re­sults. That is ob­vi­ously a bet­ter way, es­pe­cially for large bits, but re­quires skill which I sus­pect was hard won; there be­ing plenty which can go wrong.

Steve Harris, Christchur­ch

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