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Centec pressure buildup

I'm fitting a DRO to my Centec 2B. On the RHS of the body there are two unpainted nicely machined raised rectangular surfaces, each with 4 tapped holes, that were clearly intended at one time or another, to have something bolted to them.

Not wanting to drill any more holes than necessary, I have bolted the display gantry to the top surface, and am fitting part of the Z-axis scale to the other. This involves bolting on, doing some machining, and then removing it to check fit etc. Now here's the funny thing; when I remove the first bolt from the lower surface there is a noticeable puff of air from the tapped hole. It lasts only 1/4 second or so, but its very noticeable. It only happens if all the holes have been occupied and the machine used. I'm of the opinion that its trapped air that has been heated by the gearbox that is just above the top surface. Any other ideas?

Reply to
Gary Wooding
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I have similar surfaces on my 2A, but with tee-slots in them. I've always believed they're for attaching the motor, if bench-mounting the machine.

Perhaps there's a heating effect from the motor underenath, as well.

Wilfrid Underwood

Gary Wood> I'm fitting a DRO to my Centec 2B.

Reply to
tenacitygoogle

No, its not the motor; that's in the cabinet on the 2B.

Reply to
Gary Wooding

Yes, mine's in the cabinet, too. But if you wanted to take the machine off the cabinet and stand it on a bench, you'd either have to cut a hole in the bench for the belt - or bolt the motor on the side.

The DROs sound like a good idea - you're putting the Z axis on the knee rather than trying to measure the quill movement? Not that I can figure out how you'd attach to that!

Wilfrid Underwood

Reply to
tenacitygoogle

Yes, the Z-axis is on the knee. A friend also has a 2B with DRO and Z-axis on the knee. He's fitted a depth stop to the quill and it would be a relatively easy job to add a Chinese scale to it too. Ideally, the quill movement would be added (subtracted really) to the knee movement, but I can't see any way to do that.

My DRO has the ability to vector-add 2 axes together (intended for combining the cross and topslide movements on a lathe), but then it would lose the X or Y movement on the mill.

Reply to
Gary Wooding

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