# Milling speeds for brass?



## Cap'nBill (Dec 27, 2008)

I 'built' a milling attachment to go on my little 7 x 10 lathe. Therefore, I chuck the end mills in the lathe chuck which has variable speeds. I'm able to use the very small mills...1/16" and 1/8".... at slow(est setting) speeds and do o.k., but with 1/4", it wants to chatter and 'grab'. Wondering if someone can advise how best to do this? Not sure either if I should be useing ball ends for 'plunging', or if end mill bits are o.k. Bill


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## xo18thfa (Jan 2, 2008)

Brass generally machines at a higher speed than steel. But it is really a matter of trial and error. Another thing is tightening up the gibs on the attachment. I don't know how you built the attachment, but it has to be rock solid. On my little mill-drill, I had to really tighten it up. Almost to the point where the handwhees would not turn. Check the cross slide and carriage, make sure those gibs are tight. Also how are you holding the mill bit in the headstock? Regular drill chucks are surprisingly loose and make for chatter. Use a collet with a draw bar. The headstocks on those 7 x lathes seem to be very solid, should be no trouble in there.

Bob


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## Michael Glavin (Jan 2, 2009)

A two flute end mill @ 500-1500fpm is typical IMO, harder material slower speed. If your chattering reduce speed and increase feed.

Michael


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## coyote97 (Apr 5, 2009)

for tools in little dimensions (2mm or so) mostly there is no question about speed:
u dont reach it!

The other thing that was said is the really important one:
absolute stability in tool-clamping AND tightening the work-piece!!!

When this isnt sure, all u can reach is just a matter of chance. 


Frank


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## steamboatmodel (Jan 2, 2008)

Hi Bill, 
For drilling Brass the Machinery's Handbook recommends 9170 rpm for a 1/8" high speed steel drill, and 4585 rpm for a 1/4". For milling they recomend 150 feet/minute, or about 2200 rpm. You can use Ball Mills for Plunge cuts, but a Slot Mill (Center cutting) works better. If the End Mill is Center cutting you can plunge with it, if not you stand a chance of snapping the mill or getting a poor finish. Make sure you are using conventional milling not climb milling as climb milling will grab. 
Regards, 
Gerald.


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## Cap'nBill (Dec 27, 2008)

Thanks Gents for the info. Yes, I am using the headstock, and yes, I will tighten up on the gibs. I made mine up 'ala' 'Varmint's Mini lathe' site. The little 1/16th endmill I've used to form a 'step' in the cylinder for the steam port, and then drill from there. The angle I used is not' braced', which holds the machinist's vice, and that may be my problem....that is some miniscule movement. Need to weld on a web, or two, I guess! Bill!


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## bill grif (Dec 27, 2007)

Hold the end mill in a collet in the head stock spindel make a draw bar for the collet. The 1 ro 2 thousands the chuck is off makes a **** of a rumble.


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## mocrownsteam (Jan 7, 2008)

Better than a collet is a 2MT (usual size for mini-lathes, might be 3MT) end mill holder with a drawbar. Milling tends to pull the cutter out of a collet. An end mill holder has a set screw to firmly hold the cutter in place. 

Mike McCormack 
Hudson, Massachusetts


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## Jack - Freshwater Models (Feb 17, 2008)

Capt Bill, 

My first lathe was a worn out South Bend and I had a milling attachment. It was OK for very light cuts that were made by a small diameter end mill. The problem with milling attachments in general is that there is a lot of leverage and the slightest amount of play in any of the gibs will produce movement that you don't want. It's the nature of the beast. Best strategy is super sharp end mills of small diameter run as fast as the spindle will turn taking very light cuts. Been there done that and don't want to do it again! 

Another way to do it that is better but a lot of fussing is to forget the milling attachment altogether and hold parts directly on the cross slide or compound. This eliminates the leverage and puts your part on a solid footing. This was commonly done on the myford in the UK but can be done on most lathes with a little inginuity. On the 7X10 it should be a bit easier than other lathes since the compound and cross slide are both flat and square. I have mounted aux tool posts on my 7X12 quite easily and mounting a part to be milled would be similar. 

Hope that helps, 

Jack


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