Hi Folks,
As I learn about my new machine, I'm havin' a bad day. Scrapped the same part (in three entirely different ways) in the last three hours.
The first two incidents were stupid mistakes and I understand what I did wrong. The last one has me puzzled and frustrated.
This part has a blind bore in the bottom to fit a plastic KMS bearing. These bearings are difficult to fit correctly -- in the past when we have manuall machined this part, we have had to really sneak up on this ID to get that perfect fit we require -- exacerbated by the fact that the bearings sometimes vary in OD by .001" or so due to the plastic (lower tolerance) construction.
I wrote a program for our Lathe (with fanuc oi-TC) that uses a g71 cycle to rough out the bore followed by a g70 to do a finish cut.
The boring bar is T0404 and is the last tool in the program. In the WEAR offset page, I entered X-.005 for wear on the X value for 04, so that it would cut the bore a little too small, and then I could adjust the wear to "sneak up" on the number and get that bearing fit.
The program ran flawlessly, and terminated without a hitch, including a facing cycle, peck plunging an endmill, then boring, finishing the bore. I measured it to be .003" under the number I'm shooting for for this particular bearing. I adjusted the wear as required, and then selected the g70 block of the program, went to auto mode, started the spindle manually, then pressed cycle start. The X value looked correct and the boring bar started taking a slight clean up cut, but then just kept on trucking on Z! It was supposed to stop at Z-.500 and then face across the bore, but it never stopped moving on Z. This was acrylic rod, so nothing was destroyed other than the part, but I do NOT understand what happened.
Where was it going and why?! In situations like this, (which are common in our shop) when we need a very precise fit for a supplied part/other and need to sneak up on it, where and how do I safely start the program after changing the wear so I don't have to wait for it to cut air before it gets to the finish cut?
Oh yeah...the real kicker -- the chair of our department was watching this one. CRUNCH, SMASH SMASH SMASH GRIIIIINDD....*smack panic stop*
"Was that supposed to happen?"
"No.........."
>_<
As I learn about my new machine, I'm havin' a bad day. Scrapped the same part (in three entirely different ways) in the last three hours.
The first two incidents were stupid mistakes and I understand what I did wrong. The last one has me puzzled and frustrated.
This part has a blind bore in the bottom to fit a plastic KMS bearing. These bearings are difficult to fit correctly -- in the past when we have manuall machined this part, we have had to really sneak up on this ID to get that perfect fit we require -- exacerbated by the fact that the bearings sometimes vary in OD by .001" or so due to the plastic (lower tolerance) construction.
I wrote a program for our Lathe (with fanuc oi-TC) that uses a g71 cycle to rough out the bore followed by a g70 to do a finish cut.
The boring bar is T0404 and is the last tool in the program. In the WEAR offset page, I entered X-.005 for wear on the X value for 04, so that it would cut the bore a little too small, and then I could adjust the wear to "sneak up" on the number and get that bearing fit.
The program ran flawlessly, and terminated without a hitch, including a facing cycle, peck plunging an endmill, then boring, finishing the bore. I measured it to be .003" under the number I'm shooting for for this particular bearing. I adjusted the wear as required, and then selected the g70 block of the program, went to auto mode, started the spindle manually, then pressed cycle start. The X value looked correct and the boring bar started taking a slight clean up cut, but then just kept on trucking on Z! It was supposed to stop at Z-.500 and then face across the bore, but it never stopped moving on Z. This was acrylic rod, so nothing was destroyed other than the part, but I do NOT understand what happened.
Where was it going and why?! In situations like this, (which are common in our shop) when we need a very precise fit for a supplied part/other and need to sneak up on it, where and how do I safely start the program after changing the wear so I don't have to wait for it to cut air before it gets to the finish cut?
Oh yeah...the real kicker -- the chair of our department was watching this one. CRUNCH, SMASH SMASH SMASH GRIIIIINDD....*smack panic stop*
"Was that supposed to happen?"
"No.........."
>_<