Quote:
Originally Posted by Jared
We measured on a CMM. Here are the results, listed as nominal, measured
1.1250, 1.1249
1.1245, 1.1250 (our first try, incorrect cutter comp)
0.8750, 0.8747
I did the math for how much temperature affects diameter, and for a 1.125" hole, it was around 20 degrees F to get a change of .0003. It's likely there wasn't a 20 degree change, as the machine's coolant is at room temperature, the part was machined at room temperature, the bearings were installed at room temperature, and the measuring was done at room temperature.
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Well, machining is rarely at room temperature. If it was you wouldn't really need coolant (yes I know that coolant primarily carries chips away).
But that's really impressive that you got such high precision on a machine like a Tormach with an endmill measured with calipers. The PCNC 1100 is not that precise of a machine though, and the only way you can achieve those numbers is with repeated adjustment to dial it in. The inspection sheet for this machine allows for .00118" of spindle runout alone, the axis repeatability is specced at .00078". I don't disbelieve that you got the numbers that you did, but it certainly shouldn't be expected behavior from a machine like this and a dimension like that should take numerous attempts to dial the machine in. I wouldn't think twice if you told me you got that from an Okuma or Mori Seiki.
Quote:
Originally Posted by Mark_B_4545
Wow! Thanks for all the info, this is great.
Gary: What about the Tormach Tooling Setup makes it so you don't have to zero the Z-axis each time? From what I've learned on MasterCAM so far, you can tell it which tool you're using, and program an offset for the tool. I think I agree about the .250" end mills. As for the 4th axis- I agree, it doesn't seem super useful, but we got it for free, so I at least plan to check it out sometime. As for coolant flow you mentioned, I don't think it should be a problem. They've installed their own pump instead of the factory one. I like your idea with the oversized stock. I was just planning to use tabs and cut them out.
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The holders have a straight shank that slides into a 3/4" collet and ring on the outside of them that sits nice and flush with part of the spindle. Its always the same length tool as long as you don't remove the cutter from the holder. You measure it once, set the offset, and then call up that offset every time you use the tool. This is part of why you should have a tool library of tools that never leave their holders.
If you have an upgraded pump that should help a lot. The one I used to work on needed to be basically full of coolant and even then the pressure was low. If your tank started to run down due to evaporation, coolant flow would be horrendous.