Slot Drill / normal Drill

Hi all, Im sure that in my previous web-wanderings I came across an article/page which described milling, and said that a slot drill is
basically a normal drill sharpened differently. Of course now I need this information I cannot find it... so can anyone confirm this, or point me to a place that can, or even give me pointers on how to turn said drill into a slot drill.
Its for some ~ 1mm slots in brass, and given I dont need to do many, and 1mm slot drills are 8 ea, but 1mm drills are about 1 for 5 there is a reasonable incentive to use drills, especially as I have some snapped 1mm cobalt drills with a bit of helix still on them.
thanks
Dave
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On 19 Oct 2006 04:58:59 -0700, " snipped-for-privacy@bem.fki-et.com"

You've got better eyes then me if you can grind the correct relief angles on the bottom of a old 1mm drill <G>.
The other thing of course is running it fast enough to mill with. Don't know what equipment you have but it would need a *very* high spindle speed.
is there enough access to get a slitting saw in there? Arc Euro have 50dia/1mm thick for 2.50 each.
Petrr
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Peter Neill wrote:

Nope, just more optimism ;)

the mill runs upto 20K rpm, should be enough.

strangely they were on the list of things to buy anyway, but not possible for this job, see other post.
Dave
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wrote:

Nope, just more optimism ;)

the mill runs upto 20K rpm, should be enough.
What sort of mill have you got? sounds wicked!
Steve
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Steve W wrote:

Actually its not mine, but its a Proxxon MF70 micro mill. Its very small, but for tiny cutters its just the thing. About 1/2way down this page: http://www.tool-shop.co.uk/acatalog/Lathe___Milling_Systems.html Im still waiting to get a mill, Id like something bridgeport sized, but dont have the space or money currently.
Dave
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snipped-for-privacy@bem.fki-et.com wrote:

Nope! The flutes on a slot drill, aka a two or three flute milling cutter, are cut at different geometry. You need a tool and cutter grinder to effect the changes.
Drills are not set up to cut on the side. Mills are. Not so say that they will not cut, but they will not cut well.
Any chance you can get a slitting saw in to this job? Much more rugged than a 1 mm mill cutter. Screw slotting saw on an arbor? You might consider grinding up a single lip milling cutter. A little trial and error will get you a working tool.
Slot drills are so called because they will mill a slot to size without widening as a result of cutter deflection. On a two or three flute mill the sides do not get cut while the cutting edge is sweeping across the forward edge of the cut, where a four flute mill deflects to the side from the resultant deflection, with the subsequent widening of the slot or cut.
Cheers Trevor Jones
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Trevor Jones wrote:

Unfortunatly its not possible to use a slitting saw, the slots are between letters on a nameplate for my 5/8 scale traction engine, so not really straight and blind ended. what does a single lip milling cutter look like? I guess i need to build a TCG first, as is always the way ;)
Dave
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snipped-for-privacy@bem.fki-et.com wrote:

Single lip cutters are basically really small fly cutters. http://www.stanford.edu/group/prl/documents/html/gnrlmill.htm I have seen better descriptions on the web, can't find them now. :) Easily made on a bench grinder. ___________ Andre' B.
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snipped-for-privacy@bem.fki-et.com wrote:

Take a look around the web for pictures of D bit cutters and engraving cutters.
If you have a flycutter that takes HSS lathe type bits, think along those lines, but small, one cutting edge swinging around the axis of rotation.
Cheers Trevor Jones
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Trevor Jones wrote:

Ive got the general idea now, ill try and make something at the weekend
cheers
Dave
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