Gallery, Projects and General > The Design Shop
An idea for drill sharpening jig
sorveltaja:
--- Quote from: John Hill on September 25, 2009, 03:19:19 PM ---Possible procedure.....?
Put drill in lathe chuck.
Set threading gears for required pitch, 4.65mm?
Set up tool post grinder
Turn spindle by hand to take up any backlash while grinder moves towards first flute
Carefully turn spindle to grind first flute.
Disengage threading feed drive at gears or gear box
Carefully turn spindle back half a turn
Reengage threading feed
Turn spindle back to gather up backlash
--- End quote ---
--- Quote from: John Hill on September 25, 2009, 03:19:19 PM ---Turn spindle forward again and (maybe?) it will be in position to grind second flute. :scratch:
--- End quote ---
Once first surface is sharpened, turn drill back to starting position. Then turn drill holder(not the jig) 180 degrees, and grind the second half.
Jig doesn't move or rotate during the process.
---
Longest pitch available in my lathe is only 1.5mm, so unfortunately it can't be used for that purpose, unless heavy modding is applied.
John Hill:
--- Quote from: sorveltaja on September 25, 2009, 04:22:32 PM ---
Once first surface is sharpened, turn drill back to starting position. Then turn drill holder(not the jig) 180 degrees, and grind the second half.
Jig doesn't move or rotate during the process.
--- End quote ---
There is no jig, the drill is in the lathe chuck and there is a grinder mounted on the toolpost. The requirement is to rotate the drill 180 degrees in relation to the feed mechanisms. You can not loosen the drill in the chuck as that would loose longitudinal position so we have to turn the spindle in relation to the feed. If you have a gear head lathe you could put the spindle in neutral and turn 180 degrees by hand then reengage, if no gear box you could lift out intermediate change gear then rotate the spindle 180 degrees and put change gear back.
---
Longest pitch available in my lathe is only 1.5mm, so unfortunately it can't be used for that purpose, unless heavy modding is applied.
[/quote]
sorveltaja:
It turned out to be too complex to use spring as a guide. So back to the original idea.
Progress so far:
On the left is an old chuck, silver soldered to brass, that has 27 mm(1.06") outer diameter, and 10 mm(~0.4") hole through it.
In the middle are chuck's internal parts. Nothing fancy, but enough to hold the drill bit.
On the right side is the tube that's internal diameter is also 27 mm. Never mind the outer threads, they came as an extra from the scrap yard. Its function is to act as a scaffold.
Essential part is still missing. I'm looking the way to mod my lathe's gears to get 4, or even 4.5 mm thread pitch. Intention is to make two point thread(is that correct term?), one thread/drill side.
Examination is still in process.
sorveltaja:
No luck with lathe's gears. Might be another future (side)project.
I found one thing, that has two point thread and its pitch is ~4.7 mm :dremel::
Next thing is to duplicate threads to brass part.
NickG:
I;ve got one of those cheap grinding jigs too and haven't got it to work properly yet, but i do think it uses the correct method. Having said that, this is very interesting if it can produce more reliable results!
Will be watching! :thumbup:
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