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Mtns2Skies

Final Approach
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Mtns2Skies
Anyone have any small (sub $10k) CNC Mills you'd recommend? Ideally something that can handle steel.

I see that Haas has a desktop CNC mill, but I'm not sure it's either rigid enough or torquey enough to handle steel. It's fairly new and I'm not able to see much information that's out there about it yet.

Tormach has the PCNC 440, however it's somewhat pricey and a bit heavy once you add on the necessary features.

Bantam makes a pretty cheap-highly refined CNC mill, but it's too light and weak to do steel.

Anyone know of anything else out there?
 
Rigidity and torque requirements are dependent on the cut. If you want to cut 1/4 inch steel plate in one pass, you are going to need a big machine. OTOH, multiple light cuts do not require a lot of horsepower or rigidity. I have a manual desktop mill and it handles steel no problem.
 
The other issue is tolerances and vibration. I can’t imagine a desk top machine without a lot of vibration.
 
I wouldn't probably mess with the desktop solutions if space isn't an issue. You should be able to find Haas VF1 or VF2 mills used for under 10k all over the place. Make sure it's got a CAT40 spindle and it'll cut most anything. They aren't the best machine out there, but dollar for dollar they are a great value. I run a VF2 at work and with some finesse and time I can hold <.001" tolerances and make some pretty parts. We're moving to Mazak mills now and will be getting rid of the Haas' mills. I'm betting we won't get over $10k for any of them and they are all in great shape.
 
Joe_B1 said:
Rigidity and torque requirements are dependent on the cut. If you want to cut 1/4 inch steel plate in one pass, you are going to need a big machine. OTOH, multiple light cuts do not require a lot of horsepower or rigidity. I have a manual desktop mill and it handles steel no problem.
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You do need spindle torque to operate at lower RPM or you'll end up burning up tools left and right. Especially if it's CNC I don't need to be making heavy passes - just want to make sure I'm making the right choice with such a large purchase.
 
Then consider a tormach. They seem to have a pretty good following for a compact machine.
 
You would probably benefit from a machining class before you buy anything if you have no experience. Machining steel correctly requires more than passing knowledge. Speeds and feeds, proper tooling and process is important. Programming the cnc is usually the easy part. Are you making one offs or loads of the same part? One offs are almost always more efficiently done in a manual Bridgeport type machine. They can handle as big a piece of steel that you can fit into it. And have the hp to drive some fairly large tools.
 
PaulS said:
You would probably benefit from a machining class before you buy anything if you have no experience. Machining steel correctly requires more than passing knowledge. Speeds and feeds, proper tooling and process is important. Programming the cnc is usually the easy part. Are you making one offs or loads of the same part? One offs are almost always more efficiently done in a manual Bridgeport type machine. They can handle as big a piece of steel that you can fit into it. And have the hp to drive some fairly large tools.
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I'm a mechanical engineer and at a previous job programmed CNC machines for a living. I'm well aware.

I'm just not familiar with the small hobbyist scale stuff.
 
I have an older Jet tabletop machine (JMD-15), usually termed a mill/drill. Not CNC, and not a high end machine, but it does what I need it to do.
 
Have a Tormach PC 1100 at school - works well if you don't push it. But it ain't gonna hog metal and it's not that stiff.
 
Mtns2Skies said:
I'm a mechanical engineer and at a previous job programmed CNC machines for a living. I'm well aware.

I'm just not familiar with the small hobbyist scale stuff.
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Hmmm, I misread your first post as "I'm fairly new'. Meaning you.

Did you set them up too? That's where the skill is. I suspect you will be very disappointed with the hobbyist stuff unless you are making trinkets.

I'm a mechanical engineer too. I used to spec and buy machines for production parts, multi axis CNC machines for milling and turning. I had two guys who would program and tool. I went through about 10 to find the second one.

What you are trying to do has a big impact on what machine you need, with out that info, no one can really give any good advice.
 
..so what are ya building? :)
 
You might try looking at the Hobby Machinist forum, lots of discussion and good advice about small machines and not snooty like the people on the Practical Machinist forum.

PaulS said:
I suspect you will be very disappointed with the hobbyist stuff unless you are making trinkets.
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You can do a lot with a basic machine. I've made engine parts, landing gear parts for my Starduster, a complete new tailwheel assembly for my Fisher, lots of stuff. You just can't be in a hurry, and of course you can't handle really big parts.
 
Are you sure that has enough power for what you're looking to do? Not second guessing, just wondering. I've been shopping around for a manual mill to cut steel, and am looking at models in the 1000 lb range, 2HP or so, to have the ability to run normal tooling. Even at that, I don't think it would necessarily run carbide tooling well.

My experience with small CNC is not high. I designed a one-off little one a long time ago, for cutting parts for musical instruments. Normally, I see open loop done with steppers, fairly conservatively driven, and closed loop with servo motors, for smoother motion, generally higher speeds, and with bigger mills more power and efficiency. So closed loop server seems a little bit odd, but perhaps not.
 
Thanks for the response Tom. I think the difference is that all I'm looking to do is be able to reliably take off 0.030-0.100" of mild steel with fairly small cutters, which frankly if the computer is doing it I'll just let it do some more passes it's no skin off my back. The mills you're looking for can hog a significantly higher quantity of steel and run larger tools like fly cutters and shell mills, vs small endmills so the quantity of steel is far higher. If you're doing pass after pass by hand you're not going to want to sit there all day going back and forth with a 0.25" endmill, so the hand machines would want more power.

The biggest step seems to be getting a mini-mill with enough torque to spin a cutter slow enough and with enough rigidity to take any steel off. The majority of these small mills are running 10k+ spindle RPM's which is great for soft materials but will just burn out tools when cutting steel.
 
That's kind of what I was wondering. For a mill around the sizes I'm looking at, I think they'll be fine for steel, but they top out around 2K RPM, and from what I can tell that's not a good thing for any smaller cutters for aluminum. I don't know if it helps any, but I've been looking at Precision Matthews version of import mills. They have a model PM-25MV that some companies have made turn-key CNC mills from. https://www.precisionmatthews.com/shop/pm-25mv/

Under the description section, there are links to 3rd party companies doing the CNC from them. No affiliation at all, just one type I've been looking at.

I've never done any machining work in steel, only soft materials, but the concern about torque makes sense to me. I do know that tool wear goes through ceiling if you can't load the cutter properly, and end up dragging it rather than cutting with it, and I think that's what you mean about needing that torque.
 
FWIW department...

I machined most of this on a Tormach 1100 (1.5 hp spindle) and a manual EMCO Maximat Super 11 lathe. I ended up using a Bridgeport to deck the base - hard spots in the casting were giving me a hard time. Milling was a mix of CAD/CAM generated code, built in "Wizards", hand written G code, typing in commands one at a time, and just using the jog pendant.

https://www.pmmodelengines.com/shop/steam/steam-engines/steam-engine-4/

20211105_080606.jpg
 
That's beautiful! Steam, but setup to demo with compressed air?
 
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