Starting small drills
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Lakc
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A 00 center drill is .025 on the small end. How small are you asking about? Against a round or flat surface, at an angle?
GWRdriver
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Small is relative but if it's small enough a drill will start in a center pop mark, and if one is carefull enough a center pop mark can be placed within the limits of accuracy of a twist drill, but I keep a few #00 center drills on hand just in case.
Mosey
Well-Known Member
I recently started using center drills down to size 5/0 for my tiny drilling, and it helps quite a bit when boring miniature carburetters, etc.
You might try using an optical centering punch "Optimark" for laying out small stuff. It lets you center punch at about a couple of thousandths without difficulty. MSC has them and they are now about $45.00
Those little buggers are breaky when you get down to #70-80.
You might try using an optical centering punch "Optimark" for laying out small stuff. It lets you center punch at about a couple of thousandths without difficulty. MSC has them and they are now about $45.00
Those little buggers are breaky when you get down to #70-80.
Get yourself some smallish (3mm) spot drills. They just can't be beaten for putting the start dimple in the right place.
Centre drills are for drilling the recess for a centre, for turning between centres, and are just a standard drill tip on the end, so most probably no better than the drills you are trying to use. Plus they will snap the end off at the least excuse.
Bogs
Centre drills are for drilling the recess for a centre, for turning between centres, and are just a standard drill tip on the end, so most probably no better than the drills you are trying to use. Plus they will snap the end off at the least excuse.
Bogs
Lew Hartswick
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I've had it happen only once but that was one time too many. :-(walnotr said:I can attest to that! Had it happen to me just yesterday . . .
Steve C.
...lew...
Hi Colin,
I think you need to re-read Bogs post, The drills he recommends are SPOT drills a different animal to the Centre Drills referred to in the Sherline ad. I don't know where you are based but they are pretty much available from most reputable tool suppliers.
Regards
Terry
I think you need to re-read Bogs post, The drills he recommends are SPOT drills a different animal to the Centre Drills referred to in the Sherline ad. I don't know where you are based but they are pretty much available from most reputable tool suppliers.
Regards
Terry
These are about the cheapest place in the UK, and where I obtain mine from.
http://www.engineeringsupplies.co.uk/drilling-c-160.html?9=172&10=&11=192&12=&13=
Unless you are drilling right thru a piece, the largest size you really need is about 5mm, that would be for starting off drills of about 15mm and above. I mainly use 3mm x 120o, and that will do most smaller sizes. By careful downfeed, you can get a spot much smaller than a standard centre pop, ideal for those really tiny drills.
Bogs
http://www.engineeringsupplies.co.uk/drilling-c-160.html?9=172&10=&11=192&12=&13=
Unless you are drilling right thru a piece, the largest size you really need is about 5mm, that would be for starting off drills of about 15mm and above. I mainly use 3mm x 120o, and that will do most smaller sizes. By careful downfeed, you can get a spot much smaller than a standard centre pop, ideal for those really tiny drills.
Bogs
I looked at the spot drill bits end view and it looks like the same profile that my Drill-Doctor sharpener calls a "split point". With the "split point" profile the instructions claim that the bits are self starting.
SAM
SAM
You are quite correct there Sam.
The only difference I think is that the spot drills are ground a lot finer and to a very sharp point.
Most of the 138o four facet ground drills are classed as sort of self starting, but I have had a few that have wandered.
John
The only difference I think is that the spot drills are ground a lot finer and to a very sharp point.
Most of the 138o four facet ground drills are classed as sort of self starting, but I have had a few that have wandered.
John
