DRO annoyance

GunsOfNavarone said:
I have a PM-727M mill. When I lock the top gib on the head/z axis I get a MINUS .020 movement on the z DRO. When I lock the 2nd gib on the same gib get a PLUS .010 movement.. (a net of -.01 movement) I've adjusted the slack out as much as I feel isn't causing undue wear. Precision Matthews says it is what it is, I guess like someone else here said, If you know what's gonna happen and compensate for it....
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I know you said you've adjusted it but it doesn't sound like your gib is tight enough. .010" of movement is a lot for a machine that is not worn out. I have a PM-45, my DRO will only show .0002"-.0004" of movement & sometimes none at all but maybe that's cause the head is heavier? I'm surprised PM actually told you that. And if this was the norm/common I figure there would be more people reporting this.

Have you tested with an indicator to see how much it's actually moving?
 
Also to state what other here say, you can't get a Chinese bench top xxxx and expect .00005 slop. I think what many end up fabricating with these machines is amazing. Not that the tools have no weight in the conversation, but skill can make up for the short comings. If you had neither, your in for a bad time. I guess If rather learn on a $2000 mill than a 6k or more machine. With the DRO repair I just did and the new spindle bearings, I'm hoping to have a more pleasurable experience now.
 
darkzero said:
I know you said you've adjusted it but it doesn't sound like your gib is tight enough. .010" of movement is a lot for a machine that is not worn out. I have a PM-45, my DRO will only show .0002"-.0004" of movement & sometimes none at all but maybe that's cause the head is heavier? I'm surprised PM actually told you that. And if this was the norm/common I figure there would be more people reporting this.
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I MIGHT be able to tighten the heads gib more, but I'm starting to detect some drag. I'll just swap one issue for a bigger issue. The PM guys have never sold me a part, just tell me to find them online, help and advice has been pretty funny (depending how you look at it) I'm not knocking them, just sharing what I have experienced. I as about to buy this machine from them and there was a machine reseller that came up with one in town. It was like a sign from God. There has been some things I've had to fix, but it's getting better all the time. Who knows what is abuse, quality control or my stupidity. At any rate, they sure aren't making any money selling me parts.
 
Here is the actual copy paste reply from them...

It sounds like you're saying that when you lock the head down, it's
moving. This would be normal as you're pushing on the head when you lock
it down. You wouldn't be setting up work until the head is locked in the
first place, so this movement should have no effect on your accuracy.
 
I always lock down my table, either X or Y after turning the screw ( handle) in the clockwise direction. Normally I will get zero movement.
 
ddickey said:
I always lock down my table, either X or Y after turning the screw ( handle) in the clockwise direction. Normally I will get zero movement.
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Yeah....not so deep down, I know it's not right, I'll have to dig deeper ...
 
BTW, I think I found the fix to my annoyance here.
When I get close to my target number I'll start turning the X or Y table locking screw until it's fully locked - right when I hit my target number. That seems to be working fine.
 
So it seems to be more mechanical than electrical (DRO)? Perhaps your gibs aren’t tight enough?
 
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