step pulley vs gear head mills

[clippershack]

Hi, I'm looking into making a metalworking mill purchase in the next several months and i'm beginning my "mill education" I can get a PM (precision mathews) for a very good price new with a dro. however it is a step pulley. should I hold out and keep looking for a gear head mill. your thoughts for this old newbie would really help.

thank Mike

[Doc Nickel]

Generally speaking, the belt-drive will be quieter, and more forgiving in a "crash" situation.

The primary benefit to the gear head is simply faster speed changes.

Doc.

[Your Old Dog]

I have a geared head. I wish it was belt driven. It is noisey, unforgiving in a train wreck and I only have 6 speeds on mine and they are slower then I want.

The speeds, at least for me, seem to be slow enough to allow working large cutters which on a table top mill doesn't make too much sense. The faster speeds would have been real handy for the stock size and cutters I use mostly.

Mine is also a mill/drill. Should have gotten a square column so I could loosen it for Z travel without it flopping around causing me to have to line it all up again.

Welcome to the forum, hope you enjoy your stay and good luck with the purchase!

[Just Bob Again]

You're talking about variable-speed pulley or actual gear head? I don't care for the geared machines. Not enough steps. I have step pulley and variable pulley machines. It's a whole lot easier to crank the handle and set the speed where it should be than fiddle with the belts. You end up using the wrong speed because you're too lazy to move the belt. Substantial price difference. You never quite find the machine that's exactly what you want for price and features. If you have to use a VFD to get 3-phase, that makes up for the vari-speed a little but doesn't do the same thing exactly. I'd get the vari-speed if I could afford it. If not, any good mill is miles better than not having a good mill.

[.RC.]

Geared heads outperform belts at low speed high torque situations, other then that step pulley is far better...

[PaulT]

I strongly prefer step head with a VFD for variable speed control, very quiet, flexible and less maintainence headaches than mechanical vari-speed units, especially on import units where parts support gets spotty as the unit gets older. 3 phase motors are also usually a little cheaper than single phase, making the cost of the VFD less than if you would have had to buy a mill with a single phase motor. If you are not familiar with VFD's, in addition to giving you variable speed control they will generate true 3 phase output from single phase input power. You also get controlled braking and reversing, which is really nice for power tapping (no need to buy a tapping head).

These guys - www.dealerselectric.com have good prices on Teco VFD's, which work well. The manuals stink (at least the older ones I got a few years ago) but they have good support via an 800 number.

Paul T.

[McNeillMachine]

+1 for step pulley. I've never used a gear-head, but I have used the step pulley and vari-speed. The vari-speed is convenient - until something goes wrong. Then it gets to be an expensive, monumental PITA. Step-pulley and VFD all the way.

[lakeside53]

I use both.... and my varispeed is now parked awaiting repair. All belt drives are inefficient, but the varispeed is particularly so - it can lose up to 40% of its power in transmission.. which is why those machine had a HP increase over the older step-belt models. Yes, you get a torque multiplier effect as it "gears down", but...

I love the vfd on the step belt. Most of the time I leave it in 1:1, and over speed the motor to a 4000rpm for higher speeds, and as low as 400 . Back gear does all the very low stuff.

I did put on a 2 (3) hp motor onto the step belt. That gives me a lot of power even at 500 [motor] rpm.

The one thing I like best about a vfd... instantly being able to go down to low speeds. Lately I've been needing to machine at 3000, but a lot of edge-finding. One flick of the control and I'm at 200rpm... edge-finder.. then swap in the end mill and back to 3000. Nice. No belts, and not winding the varispeed. I even run the vfd on the varispeed for similar reasons.

[kvom]

My Bridgeport is a 1HP step pulley with VFD. It's a little iffy at 500-800 RPM wrt torque, but otherwise is a good choice.

[clippershack]

Wow I have came to the right place to listen and learn.. You guys are all giving me a bunch of stuff to think about. I have about $2,900 set aside to make my purchase with. I have been looking at both American mills and Imports. Been looking at Grizzly, PM, and others.

I may have to keep saving inorder to get something not ragged out.

I'm all ears
Mike