Re-sharpening 0.9mm HSS drill bits - diyAudio
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Old 13th March 2007, 06:34 AM   #1
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Default Re-sharpening 0.9mm HSS drill bits

I have several 0.9mm HSS drill bits that are worn out.
How can I re-sharpen them ?
Is there any jig to hold them at the right angle and sharpen them against a small grinding wheel ?
Any other short cut methods ?
Thanks,
Ashok.
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Old 14th March 2007, 05:01 AM   #2
dangus is offline dangus  Canada
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A ceramic cased EPROM or microprocessor case works about as well as a real ceramic sharpening stone for sharpening small drill bits and knife blades.
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Old 14th March 2007, 06:00 AM   #3
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Thanks. However I want to know at what angle the tip should be ground and how (angle ) should the drill bit be held.

Doesn't anyone on the forum do this ?
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Old 14th March 2007, 09:08 AM   #4
EC8010 is offline EC8010  United Kingdom
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Quote:
Originally posted by ashok
Doesn't anyone on the forum do this ?
Probably not. Try looking closely at a 1/2" drill bit. You have an included angle of about 120 degrees between the cutting edges, working back from the cutting edges is the rake to allow the drill to cut. In the centre is the web that starts the drill. I have watched a toolmaker sharpen drills over 1/4" but even he couldn't get as good a result as a machine-sharpened new drill. The slightest imbalance between the cutting edges and you will get oversize holes. Now scale that problem down to 0.9mm. Grin it and bear it, drill bits have to be looked after, but are disposable.

I like the EEPROM suggestion, mind...
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Old 14th March 2007, 11:18 PM   #5
dangus is offline dangus  Canada
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I just eyeball the angle when I use the EPROM sharpening stone. HSS bits in small sizes (like #70) go dull very quickly when drilling glass-epoxy boards, like maybe after a few dozen holes, so any improvement in sharpness helps.

I prefer to drill boards using 1/8" shank carbide bits; after buying a couple new for an appalling price (and breaking them), I was lucky enough to score a heap of them at a swap meet. There's several vendors selling assortments of them on eBay very cheaply, or your friendly local tool/hobby stores may have them. You must use a drill press since the bits are so brittle.
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Old 15th March 2007, 12:59 AM   #6
Bert_R is offline Bert_R  Netherlands
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A normal drill has a angle of 118 degrees (factory made)
drills for aluminium do have an angle of 135 degrees, because aluminium is a softer material, 135 degrees cuts more controled.
Machine drills do often have an angle of 90 degrees.


I re-sharp my drills just bij hand. Most importand is to keep both sides te same.
Depending the material you want to cut you can alter the angle. Just give it a try you lose nothing
Unless you have shakey hands
And all non machined sharpend drills will give you an unround hole so if that is importand for you, buy new ones.
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Old 15th March 2007, 01:02 AM   #7
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After seeing a post on drilling circuitboards last week here I decided to build this
http://www.powerlabs.org/railgunprogress.htm
What I couldn't find at Home Depot I borrowed from my wife's Honda Civic and a 1972 Zenith console television set.

I set it up with a laser guide and am cranking out perfect holes with micro slugs and matching barrels/rails sized from .001 mm on up to 1.5 mm - as fast as I can hit the foot pedal.

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