Choice of 2 Mill speed groups...which would you go with?

Hey,

So my milling machine (which I'm currently reconditioning) has 2 sets of 9 speeds. Each of the 9 is easy to select between, but to jump between groups I'd have to change the 2 main top pulleys. It's not a 5 min job.

So for someone who's going to be milling mostly mild steel and aluminium...which would you say has the most useful range?

Group 1: 79 | 104 | 162 | 178 | 213 | 222 | 293 | 365 | 500

Group 2: 316 | 416 | 648 | 712 | 852 | 888 | 1172 | 1460 | 2000

Very interested in you choice

Thanks for your answers.

what machine, what power what dia cutters etc etc etc we need more info

The selection of materials that you say you'll mostly be working with point to using "both". You'll want the higher speed range (which isn't really very high by modern standards) for machining aluminum whereas the lower range would be more in line with steel. Here's a link to one of Melin's feed/speed charts for HSS and cobalt cutters: http://www.endmill.com/pages/training/Speed and Feed - HSS End Mills.pdf

Probably decide which you'll do more of, aluminum or steel and go with it. Plan your projects ahead of time to minimize having to switch back and forth.

That's all I got, hope it helps,

-Ron

Thanks Ron. Yeh, will most likely be more steel and simple milling. Now the 60 year old pulleys have been released I guess it'll be easier to swap them around for projects.

Limy: My tooling will grow but I'll be starting with end Mills around 10mm. Just simple stuff but by the time I'm pushing myself I'll know exactly what I need It's an old Archdale milling machine.

Symon said:

I'll be starting with end Mills around 10mm.

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? Some among us would class that more as engraving than milling, and suggest the higher of your two ranges isn't even quite fast enough. But ne'r mind. Your shop, your machine limitations, your choices..

Thanks for your thoughts

Symon said:

Thanks for your thoughts

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Carbide end-mills have become good, cheap, and tough enough it is hard - really hard - to want to limit yerself to HSS-only.

Easiest upgrade is to boost the motor RPM. VFD for the masses. Dee Cee my choice.

Challenge in that for "Old mills" is their bearings.

Take the Burke #4. Came into existence around 1903 with 'plain' bearings. Used more than one type of those, 'drip' lubrication with oil for all.

Then went-over to Timkens, grease-packed OR oil. Then also BALL bearings for higher speeds, yet.

Not a lot to modify to migrate my one to higher RPM capability, IOW.

Asquith may or may not have evolved though a similar progression, but you get the idea.

You can probably take advantage of options already proven and known about amongst at least the Blighty-based crew with not a lot of risk or spend. Re- search needed. Re- engineering, not so much.

That's some post! Thanks very much.

It's currently only rocking a 2hp motor!

There's a lot of greased deep ball bearings in the main shafts (drive shaft to gearbox to pulley shaft to spindle). Most others (not all) are thrust type.

But a lot still have the drip fed lubrication, too.

I got this for an excellent price and will cut my teeth on it. I'll see where I'm at and then decide on upping is rpm. Your suggestion is sound

will you be using a coolant of some sort and if so how will you apply? it can make a difference on how aggressive you machine. I use my lowly Bridgeport in more of a job shop application and for the most rarely get over 1000 rpm usually less.

Yeh, it has a white water pump which is drawn up to the table

Hodge said:

will you be using a coolant of some sort and if so how will you apply? it can make a difference on how aggressive you machine. I use my lowly Bridgeport in more of a job shop application and for the most rarely get over 1000 rpm usually less.

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As I'm sure we all recognize, RPM wanted has a great deal to do with cutter diameter at the working edge of the flutes (or inserts).



My Burke #4 is a horizontal. Only. So far, anyway.

The Quartet is a 'combo' mill with both H and V spindles. Each has entirely separate drive motor as well as totally independent drivetrains and ratio selections.

Low RPM is essential to the survival of HSS cutters in 3" to 12". Inserted goods are not cheap, even at 3".

Endmills, OTOH, I'd be far more likely to want carbide, so need higher RPM, even if using ones a good deal larger than 10 mm. In my case - I already HAVE that on the Quartet - DC motors will just improve it.

The Burke's OTOH, once away from line-belt drive and multi-step cone pulleys, generally left the factory with Lima, Century, or Master integrally geared-head motors with as many as four ratios. Long gone as new. Few used around. Heavy bastids anyway.

The move to a DC motor in this case is not for field-weakened extended higher RPM, but rather for far greater low-end torque than a VFD'ed 3-Phase motor can ordinarily deliver, even up-HP'ed and fed off a VFD several times as costly as a basic NEMA 4X enclosed KB-Penta DC Drive.

Mind - even THAT would be terribly costly if I had to pay the current prices for Reliance RPM III Type T DC motors I was fortunate enough to find in good order for about 2 or 3 cents on the dollar vs new price. I'm just NOT into effing 'treadmill' grade Dee Cee motors. Not even close.

If ever I add a vertical head, it would probably be a VERY high RPM 'router' type, small diameter carbides only.

Have the heavier mill already, and the Burke has silly-small travel, X, Y, and Z anyway.

For a 10mm cutter or under i would want north and well north at that of 500 rpm. Bottom speed of 316 would still get you above and well above a 1/2" drill chuck's capacity in mild steel would certainly be usable with most MT2 shanked drill bits probaly a few of the smaller MT3's if you were generous with the coolant and did not mind sharpening em a bit more oftern in mild steel. In alu the extra speed is no problem at all.

Whilst monarchist is right about the advatages of dc, bear in mind it comes at one hell of a cost premium, the drives are eye watering expensive over here unlike good VFD's which are around - just under the £250 mark depending on model and features.