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Older HMCs with scales?

huleo

Hot Rolled
Joined
Feb 12, 2014
Location
UT
Looking for another HMC. We have been pretty OK using older equipment that has been maintained right and such. Our current machines have scales. I think after using them, we just don't want to go back. Curious if Makino, Mori, Okuma, etc, any of the bigger players either did scales as standard? I know some of the bigger (800mm+) HMCs came with standard scales but we are probably looking for a 500-630mm machine.
 
I have used HMC's with scales and without, and have never really formed a preference for one way or another. Yes the machines with scales were accurate, but so were the machines without. They were also more work to keep running reliably than the machines without scales. For the type of work we were doing it made almost zero difference in quality. A machine that is geometrically in square and straight, with recently pitch comped screws without backlash is plenty accurate in a climate controlled shop without scales. It takes many many many hours of hard abuse without lube to ruin the screws in a Makino, Mori or Okuma. We had a Mori with grease lube, that had well over a thousand hours with the grease pump turned off. Still could interpolate a circle within .0002", still was able to accurately located features in the entire envelope. Mind you it had scales, but when we had it evaluated, the first thing we did was turn the scales off, it performed just as well without the scales as it did with them. We had bought it used and nobody put two and two together that it wasn't using grease for about a year of use. Previous owners had turned it off.

I would be curious what your experience was without scales that makes you think you need them.
 
Scales are a fairly commonly selected option. Machines with dual drives (dual motors, screws, etc.) on an axis almost always use scales on each drive. Most machines from the builders you mention work well enough without scales in many production environments. Scales often improve accuracy when thermal variables are not well controlled. Scales can also be the cause of weird troubles on a machine too. On an HMC with full 4th axis, a scale on the rotary axis is more important than scales on the linear axes.

One final thing to consider...

Scales are standard on a Yasda. If they were not adding a performance improvement, would they have them as standard?
 
On an HMC with full 4th axis, a scale on the rotary axis is more important than scales on the linear axes.

One final thing to consider...

Scales are standard on a Yasda. If they were not adding a performance improvement, would they have them as standard?

I agree 100% on having a scale on a rotary axis without a curvic coupler, even then, they aren't as repeatable as a good curvic.

As for Yasda putting them on as standard. I believe a Yasda on a bad day is actually geometrically accurate enough where having scales actually means something. Having .0005" of out of square, coupled with .0002" of machine movement error by not having scales is still basically .0005" of error. You get the squareness and straigness down to less than .0001" and now having scales is cutting your error in half or more. Just saying. I can't see scales doing that on a used HMC which new out of the factory is likely two to three times worse (minimum) geometrically than a Yasda.
 








 
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