Awesome New Mill- Is it worth it?

[JetMech]

Hi guys,

Another post in the stream of noobs asking "which machine?" I have an introduction post here if you wnat to know more about my situation.

In this case, I have a pretty narrow question:

I have an opportunity to buy a mill, very similar to a G0704, for example. My plan is to use it for small hobby work, primarily in aluminum.


Issue is, I have a tough choice:

I can get the variable speed model, with speeds from 40-3000 RPM, or I can get the non-variable version, with 6 speeds from 115 to 1700 RPM.

If it was a matter of a small premium, then it's a no-brainer and you get the variable speed!

However, there is a catch-

I can get a discount on the 6-speed. A big, big discount. Think 2/3 price.

So, my question is, if I'm working aluminum with small bits, am I goin to miss the higher speed capapbility?

Is 115 to 1700 rpm sufficient range for a mill?

What price-premium would you put on the variable speed and wider range?

What capability, if any, do I lose from choosing the much cheaper 6 speed?

Any thoughts appreciated.

 

[higgite]

Doesn't matter what price-premium anybody else would put on it. You can obviously afford either one or we wouldn't be having this conversation. IMHO, get whichever one you want or you will regret it later.

Tom

 

[Bob Korves]

Don't know how much torque it would deliver, but I like the lower speed even more than the higher speed.

 

[Randall Marx]

Not only do you loose the higher range in speeds, but also the lower range. The lower speeds is what I would miss, but I often need to put somewhat large holes in steel without burning up my twist drills. Using small bits in aluminum, you might miss the high end of the range more. Look at the speed-feed charts for the materials you want to cut and the size of cutters you plan to use, then consider how close you can come to the desired surface speed with the ranges you might have. Another option would be to get the 6-speed model and add a VFD and 3-phase motor to gain a much larger speed range than the variable speed model. Depending upon the price difference, the upgrade may or may not make sense.

 

[Reeltor]

I don't know how to advise you but my mill has speeds from 50 to 1,400. There were times when I would have liked to go even slower than 50 rpm but I don't recall ever regretting not being able to go faster than 1,400 rpm

 

[JetMech]

Doesn't matter what price-premium anybody else would put on it. You can obviously afford either one or we wouldn't be having this conversation. IMHO, get whichever one you want or you will regret it later.

Tom

Good advice, thanks.

 

[JetMech]

Don't know how much torque it would deliver, but I like the lower speed even more than the higher speed.

Cool, one vote for low speeds being desirable- very good, this is the kind of info that helps!

 

[JetMech]

Not only do you loose the higher range in speeds, but also the lower range. The lower speeds is what I would miss, but I often need to put somewhat large holes in steel without burning up my twist drills. Using small bits in aluminum, you might miss the high end of the range more. Look at the speed-feed charts for the materials you want to cut and the size of cutters you plan to use, then consider how close you can come to the desired surface speed with the ranges you might have. Another option would be to get the 6-speed model and add a VFD and 3-phase motor to gain a much larger speed range than the variable speed model. Depending upon the price difference, the upgrade may or may not make sense.

Awesome, another vote for low speeds and a wonderful explanation and recommendation besides. I appreciate the idea to look up feeds/speeds of anticipated cuts, will do so. Some definite info about what I should expect would come of that. Thank you, Sir.

 

[Eddyde]

If you are going to be milling aluminum with smaller tools, I recommend you get the variable speed as you will want the higher rpm.
This hobby always costs more...

 

[mikey]

The way to look at speed is to consider the material and cutter size and then look at the recommended cutting speeds for that material. For example, aluminum is rather soft and requires pretty high cutting speeds. A 1/4" finishing end mill taking a shallow profiling cut of 0.02" deep would have a cutting speed of 800 sfm. This translates to a speed of about 12,000 rpm.

To make this useful, remember that you calculate the rpm required by finding the listed cutting speed of the material and using this formula: RPM = SFM X 3.82 / D, where SFM is the recommended cutting speed for the material in sfm and D = diameter of the cutter. You can look up cutting speed charts on the net.

You will need lower speeds when cutting hard materials with larger diameter cutters. If you plan to do smaller work primarily in aluminum then lower speeds is not as important as the higher speed range. This is especially true if you ever use carbide tooling that requires higher speeds to cut well.

Personally, I would go for the variable speed with the higher range.