Is there online char for drill press RPM

Is there any online chart for right RMP speed for different drill bits size and different metals? I know the cutting speed formula but having chart by drill press is easier than calculating RMP every time.

Thanks, Alex

Reply to
Alex
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You may find it good metal exercise to calculate for every size. You really don't have to be too close anyway. Are you using the (4 x CS)/Ø formula? This one's easy to do in your head and it keeps the gears up there greased...

Regards,

Robin

Reply to
Robin S.

There have been several such graphs published over the years in HSM, PM, etc.

GWE

Rob>>Is there any online chart for right RMP speed for different drill bits

Reply to
Grant Erwin

True. Many of our radial arm drill presses at work have them. I do think there's something to be said for keeping that skill fresh in one's mind though.

Regards,

Robin

Reply to
Robin S.

Just off the top of my head, I'd say the "right" speed of the Royal Mounted Police... oh, never mind.

Reply to
Steve Ackman

What do the symbols in the formula represent? Thanks Karl

Reply to
everyman

I went through this exercise a while back. Didn't really find anything extraordinarily useful.

I threw up the following page with conservative numbers for others' use

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Regards, Joe Agro, Jr. (800) 871-5022 (908) 542-0244 Automatic / Pneumatic Drills:
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Spindle Drills:
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V8013-R

Reply to
Joe AutoDrill

Also,

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but I haven't really finished that page yet and it looks a bit ... well... unfininished.

Reply to
Joe AutoDrill

RPM = (4 x CS)/Ø

Where:

CS is the cutting speed of the work piece given a certain cutter material in Surface Feet per Minute. When cutting mild steel with a HSS tool, 100 is about right. Aluminium with a HSS tool is about 300. When using a carbide tool, multiply said numbers by 3-5x.

Ø is the diameter of the cutter when the cutter is spinning (drilling and milling), and the diameter of the work when the work is spinning (lathe).

For instance, 1/4" HSS drill bit drilling aluminium:

RPM = (4 x CS)/Ø = (4 x 300)/.25 = 1200/.25 = 4800

Note: These cutting speed numbers are under ideal conditions. If you're feeding by hand using a single-phase drill press, you'll probably have to go slower to get a stable cut. I usually go 60-80% of whatever number I get using the formula. YMMV.

HTH.

Regards,

Robin

Reply to
Robin S.

According to Robin S. :

[ ... ]

One minor complaint about this one. While reading it in the newsreader, it shows up as a zero with a slash through it, in my editor, it shows up as an octal value (330) preceded by a backslash ''.

It is one of those "extended ASCII" characters which cannot be depended upon to be the same on all systems. You probably had to do something strange on the keyboard to generate it.

It is better to use something like "(Dia)" instead, so the weirdness of the character's display does not become a problem.

Enjoy, DoN.

Reply to
DoN. Nichols

Thanks I learn something new every day I read this group. Thanks Karl

Reply to
everyman

Hi Robin,

Using the formula you posted above, I took the liberty to create a small spread sheet and publish it to pdf. I went from 1/32 to 2 inches via 1/32 steps.

The hard work (yeah right...) is done. If anyone spots an error or has a suggestion to make it better say so.

See:

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If someone wants to host this it would be fine by me, that is if Robin approves too. I'll leave it up for a week or two. My webspace/traffic is really limited...

Reply to
Leon Fisk
100's a little hot for MS using HSS tools, I learned to use 60 ...

GWE

Le> >

Reply to
Grant Erwin

Dave, Who also uses 60 sfm.

Reply to
Dave Lyon

Hi Grant,

That is easy enough to change in the formula. I'll wait a bit and see what other comments come in. Like I said the main work is done, changing formulas, more sizes and stuff won't take much. If anyone wants other materials added, I do need the formula for them though...

Thanks for the comments!

Reply to
Leon Fisk

Grant,

I agree with you. Unfortunately any value in the machinery handbook (or otherwise) is an estimation.

I find that the rather brutal entry into, and exit out of the material the drill bit makes severely decreases its edge life (manually fed). Similarly, it's actually very difficult to tell when an endmill on a CNC mill is dull by looking only at the cutter. They don't look burnt or chipped as when they are used manually. I attribute this phenomenon to the entry, exit, and their inconsistent feed while in the work.

I have the luxury at work of using massive radial arm drill presses with geared power feeds and huge cast iron bases which make for very powerful and rigid machines. Using flood coolant and a quality bit, one can feed appropriately for 100fpm in mild steel. Similarly, it is easily possible to burn the same bit at 60fpm because the feedrate is set too high.

Perhaps Leon should change his spreadsheet to reflect values suitable for a hand-fed tool in mild steel (60fpm). I'd be inclined to leave the aluminium and the mild steel w/ carbide the same though as the cutter tends not to fail in the same way.

/rambling

Regards,

Robin

Reply to
Robin S.

Why not just post it to the dropbox once it's finalized?

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Best Regards, Keith Marshall snipped-for-privacy@progressivelogic.com

"I'm not grown up enough to be so old!"

Reply to
Keith Marshall

Well after looking at Joe's (of Auto Drill) I completely changed it to reflect HSS only and added more materials. I also increased its coverage. It starts at 1/32 and continues to 2 inches via 1/32 steps and then continues to 8 via 1/4 inch steps. The latter sizes I think could be useful for lathe work. I decreased the speeds, leaning to the low side (thanks Grant) which most of us would find of use with smaller machines.

This is the link to the new pdf:

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This is the link to the pdf and xls spreadsheet zipped:

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This zip archive has the pdf and the spreadsheet I used to create it. The spreadsheet is Excel (xls) and I can't guarantee it will work. It is an export from Quattro Pro (ancient version). I don't have anything else that can load it and I didn't figure anyone would want it in Quattro format... You can easily change the SPM (surface feet per minute) values in one spot for each material and get your own preferred output via the spreadsheet.

Let me know what's wrong now ;-)

Reply to
Leon Fisk

Hi Keith,

That should work. I just re-read the rules and I see that I could zip the spreadsheet and submit it that way. I knew there were some restrictions on file formats and I couldn't remember just what it was.

Waiting to see what is thought of my last attempt now in another thread...

Reply to
Leon Fisk

You folks are makeing this way more complicated than it needs to be Using a mild steel work piece & a high speed steel tool, if th round thing is 4" diameter it should turn 100 RPM, if it'

1" diameter it can turn 400 RPM. Aluminum can go faster exotics like stainless & tool steel way slower. In a home/ hobb situation you can reduce the spindle speed by 1/2 and still be tim ahead by not having to sharpen as often. In a production situatio all formulas, tables ,etc. are only a starting point any way as ther are infinite variations due to material alloys, tool alloys shapes, coolants, machine rigidity ad infinitum so that optomizin spindle speed is a matter of experimenting to push the edge of th envelope If youre only doing one or two pieces, the vast majority of your tim is spent in other than the actual cutting process any way
Reply to
Lee Reed

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