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The standard IH motor is only like 640oz/in. belted 4:1...
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Ok with the huge size of the head on the IH machine. As anyone ever thought of doing a counter balance on the head so that you don't have to use a bigger motor to drive it????
DJ
The standard IH motor is only like 640oz/in. belted 4:1...
I ended up swapping my 640 oz/in motor for a 850 oz/in motor. i have thought about counter balancing the head and really think that its a good idea. most larger cnc mills have the counter balance. you would have to remount the motor drive of the z axis so it runs front to back as opposed to off to the side. had i thought about it sooner i would have counter balanced it.
So would you balance with a gas cylinder or with pulley and weight? Pulley and weight would be ok because the weight of the head pretty much stays the same. I have seen a couple of bigger Bridgeports mills with hydraulic counter balances. There table weight is always changing. But i think thats a little complex for this small of an aplication. Just curious but what is the reduction on the x and y axis?? if anyone knows.
I was looking for a counterbalance too for these mills. One advantage of having a counterbalance is that with the power off or heaven forbid a broken belt on the servo drive the head stays in place instead of crashing into the table or whatever is underneath it at the time.
I kinda ruled out a weight due to the bulk and ...well the weight. Lifting the head into place is enough of a challenge. Also a weight adds to the mass that needs to be accelerated in either direction. I'd like a gas spring but finding one with a 20" un-damped stroke and enough force to use 2 (ie 125lbf) has been fruitless so far. Anybody have a source that won't break the bank? Next in line for consideration is a garage door spring hidden on the floor at the back with cables and pulleys. Over the 20" or so travel the force should be fairly linear. One advantage of the garage door spring is it is adjustable.
Thoughts anybody? Any examples?
Mike
the reduction on the x and y is 4:1 as well.
in terms of the counter balance i would use a weight and pulleys. and in terms of accelerating mass, the current motor, has to accelerate the mass of the head, the friction of the ways etc and it has no problem. static friction is a very high force, i haven't calculated it but i bet its more than the head so adding a counter balance would help offset that to some extent. i mean really the counter balance weight offsets the weight of the head so that really your only fighting friction, but you can then go easier on the gib tightening and the head should move more freely.
Would be nice to keep all of the servo's the same size instead of upsizing on the head. I would think also that the weight would work great. If it is a ballanced load accleration should not be a problem. But im no engineer. Is there room in the colum to install a compression spring? I dont have my mill yet... Hopefully this week.
Thanks for your input
DJ
Originally Posted by letmefixit
All this, and you don't even have your machine yet ! I won't say it ! but I really really want to !
If I were to decide my IH mill needed such a contrivance I would go with a live hydraulic assist. It would be expensive to some extent, but once it worked in unison with the servo it would be the ticket. But, it isn't really needed and the extra expense can be spent somewhere else.
Don
IH v-3 early model owner
what can I say... just trying to plan ahead.
I've been day dreaming about this as well (all I can do since my delivery date is probably a month away at least). Has anyone ever mapped out the extension force over the length of extension on one of these gas shocks? I was concerned that it would vary dramatically over the full 22" of travel. I assume the Z ball screw has zero backlash like the others (CNC version), but it still seems like we'd be best served with a constant balance force.
I thought about running a cable up to a ceiling mounted pulley to leave the sides clear. I also thought about using a pneumatic cylinder with a pressure regulator attached to one side (opposite side open). The pressure would remain constant over the full range of motion and it could even be mounted to a cable/pulley for inverted operation. I happen to have odd things like long cylinders floating around, but the smooth bore tube is the only obstacle I could see to making one pretty easily.
Ken
i have an RF-45 that started to get drag problems on the Z even with an 1290oz stepper. i then fitted 76Kg of steel on the back and the problem went away. Z axis seems to run smother now as a result of the counter balance.
well worth the mod.
Got Pictures???? I want to see what you did.
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