cutter comp fail

[hsoldo]

Hi,

 

I need to mill eliptic hole 20mm x 8mm. I am using 8mm mill to do it. Basically I would need the mill to enter 4mm from one side, travel 12mm and exit.

 

How to do this?

 

Thx

[SpacePilotPro]

sounds kind of straight forward....you pretty much described what you need to do.

[duckdogers]

create a point 4mm from one side then chain the point first then the hole use point as starting point

[crazy^millman]

Hi,

 

I need to mill eliptic hole 20mm x 8mm. I am using 8mm mill to do it. Basically I would need the mill to enter 4mm from one side, travel 12mm and exit.

 

How to do this?

 

Thx

 

You can't comp this. You need to go to a 6mm, 6.5mm, 7mm or worst case 7.5mm endmill. Rule of comp got to have room to apply it. How are you going to cut an exact 8mm slot and comp it with a 8mm endmill?

 

Want to comp and just cut it then that is one thing, but with comp not going to work unless you are not giving us all the facts and want to cut it .002mm bigger then possible if the machine allows .001 comp adjustment.

[Reko]

What Ron said... or if you have tolerance... draw it ( machine it ) to the high side and that will create some room for comp to turn on and off as well.

[Müřlıń®]

If you have the tolerance, lie about your cutter size.....make it slightly smaller than 8MM....then it will comp.

 

Otherwise it will not like some have said.

 

You cant put a 1/2" pin in a 1/2" hole...there has to always be clearance......clearance is clearance...no matter how small.

[Mjölnir]

What Ron said... or if you have tolerance... draw it ( machine it ) to the high side and that will create some room for comp to turn on and off as well.

when there's no room, turn on ccomp in the air. on the lead in lead out page there are options for plunge after first move and retract before last move. i use those frequently to invoke ccomp when there isn't enough room to do it near the cut.

[BCW]

Another option would be to create a straight line thru the center of the slot and do a standard 2d contour move on it with cutter comp turned off.

[crazy^millman]

Another option would be to create a straight line thru the center of the slot and do a standard 2d contour move on it with cutter comp turned off.

 

The poster specifically said they wanted cutter comp. I could cut this all day long if that were not part f the original topic. 

 

I was given a test on a Bridgeport back in 93' to cut a sample part. I had 2 hours to make the part and I was done in one hour. I had to make a .250 slot by 1.000 +.001/.000 as one of the 20 features on this part. I was only given a 1/4 endmill to machine the slot. I went over to one of the machinist and asked for a 3/16 endmill. I trusted my readout and cut the part. My slot was +.002 and the person who was given me the test said you are the 5th person to cut that slot wrong. Why didn't you use a smaller endmill. I told him I did and who ever laid out the tool was not thinking because they only had a 1/4 endmill to cut the slot with. I told him about getting the smaller endmill. He asked me how did I cut it over size. I said there is something wrong with your machine. He was not going to hire me till the machinist I asked the endmill from walked over and told him you know that DRO is messed up and is .005 off in Y. We have asked for you to fix that for a year. I looked at them both and I was hired. The guy giving me the test was the shop forum and he was replaced the week I was supposed to start. Seems he had been setting up all the people taking the test to fail and I was the first one to figure it out.

[BCW]

The poster specifically said they wanted cutter comp. I could cut this all day long if that were not part f the original topic. 

 

I was given a test on a Bridgeport back in 93' to cut a sample part. I had 2 hours to make the part and I was done in one hour. I had to make a .250 slot by 1.000 +.001/.000 as one of the 20 features on this part. I was only given a 1/4 endmill to machine the slot. I went over to one of the machinist and asked for a 3/16 endmill. I trusted my readout and cut the part. My slot was +.002 and the person who was given me the test said you are the 5th person to cut that slot wrong. Why didn't you use a smaller endmill. I told him I did and who ever laid out the tool was not thinking because they only had a 1/4 endmill to cut the slot with. I told him about getting the smaller endmill. He asked me how did I cut it over size. I said there is something wrong with your machine. He was not going to hire me till the machinist I asked the endmill from walked over and told him you know that DRO is messed up and is .005 off in Y. We have asked for you to fix that for a year. I looked at them both and I was hired. The guy giving me the test was the shop forum and he was replaced the week I was supposed to start. Seems he had been setting up all the people taking the test to fail and I was the first one to figure it out.

 

He only said cutter comp was failing not that it was required. Not using cutter comp is the only solution unless you use up some tolerance.

 

Edit: In fact if you read OP he mentions only wanting to move in one straight line.

[guitar]

Apply cutter comp with an entry move above the cut.