Drill speeds and materials

[Captain Al]

I'm wondering if there are any references to appropriate drill speeds for the various materials we drill through, such as soft wood, hard wood, brass, maybe even plastics?  I assume that after a while experience kicks in and you get the feel for it.  As a relative newcomer though, I think I'm burning a lot of my pieces and the bits themselves by using speeds way to high.  Note that this is due to the fact that my Dremel has lost its variable speed ability and now seems to be stuck at around 15,000 rpm, so that's the speed I use for most operations -- not only drilling, but grinding and using the cut off wheel.  A new Dremel is first on my "to buy" list.

 

This question also comes to mind in those other operations -- grinding and cutting through brass rod and sheet.

 

I'm thinking that there must be some table of values to use for the different combinations of materials and speeds.  Maybe thickness comes into play as well.

[Mumin]

The manual of my 'dremel-ish' tool has a neat table with suggested speeds:

 

Soft metal cutting 33,000rpm

Wood grinding 31

Hard metal cutting 29

Metal engraving 25

Smoothing of sharp or uneven edges 21

Drilling 17

Rust removal 13

Tool sharpening 9

Polishing 5

 

You yould also find those helpful:

http://mdm.boschwebservices.com/files/Dremel%20Rotary%20Tool%20Bit%20100,%20105,%20106,%20107,%20108,%20109,%20110,%20111,%20112,%20113,%20_%20(EN)%20r22502v55.jpg

https://www.dremel.com/en-au/customerservice/ManualsAndLiterature/Documents/08-09%20Accessory%20Guide%20Poster.pdf

Edited October 12, 2015 by Mumin

[NMBROOK]

Strictly speaking,every material has it's own optimum cutting speed.This is not an RPM value but measured in feet or metres per minute.Many variables come into play to determine the RPM you require,for modelling,mainly the diameter of whatever the cutting the device and how many cutting faces the tool has.A milling cutter with six flutes will want to run slower than that with two.

When all these variables come in to play,you essentially have many tables of desired spindle speeds.Advances in cutting technology challenge the 30m/min I was taught was the optimum for mild steel.The latest CNC beam saw/drill lines we have at work have drills unlike anything elsewhere and can drill a 50mm hole through 40mm steel in around 5 seconds!!

Sorry I can't be more specific,but the general rule to follow is too fast with wood,you get burning,too slow and you get poor surface finish.This is only with sharp tools,blunt tools can cause either even when the speed is correct.

 

Kind Regards

 

Nigel

[Captain Al]

Thanks guys.  Good information.  The one number that surprises me is the 17,000 for drilling that you show Mumin.  Do you suppose that's for metal or wood?  Reason its surprising is cause my full size Delta drill press which has multiple combinations of spindles for multiple speeds, has a table that shows in the low 1000s for wood (depending on thickness).  If its for wood, the 17,000, then my dysfunctional Dremel is going too slow for even wood at 13000.  Or maybe its running at 35,000 (its original max speed) even though the speed control says less than 15,000.  I'm going to do some additional research.  Maybe Dremel's web site has a table.

[Mumin]

I would guess that 17000 is for very small bit diameter. General rule (as I understand) is the smaller the size and the softer material, the higher the rate.