Rigid tap alarms

[heeler]

We have some bridgport 3020 with a fanuc 21i control. We are getting alarms 740 and 741 rigid tap alarm: excess error. In the discription of the alarm it say for 740 "During rigid tapping, the position error of a position at which the spindle stops exceeds the specified value". For 741 "During rigid tapping, the position error during spindle movement exceeds the specified value". I was wondering if I could adjust some of the rigid tapping parameters (5200 group) to help with this error. I feel that this machine should have the power to run the tap cycle. When I finished the tapping by hand it didn't really seem that difficult.

 

Thanks

 

Glenn

[crazy^millman]

If you can thread mill it and be done with it.

[Guest]

Thread milling might work to get thru this job but you can't threadmill everything.

 

Is this a new problem?

 

Have you ever rigid tapped on this machine previously?

 

Is there a sync code that the machine is looking for before it reads the G84?

[heeler]

They have had this problem before, but nobody talked to me about it. They felt that the machine lacked the horsepower to do it. We have to put an M29 before the G84. We have done rigid tapping before. Some worked and some didn't. The reason that I felt there is a parameter problem is that it will do this with a 3/8 28 tap. When you can break 3/4 or 1" endmills, why wouldn't it break a 3/8 tap? This tells me that I should have plenty of torque to tap this hole.

 

Thanks

 

Glenn

 

P.S. Ron, We have never used thread milling. Where is a good place to read/learn more about it?

[Guest]

If you can rigid tap smaller holes ok, then you just might not have enough torque to do it on that machine.

 

As far as thread milling goes it is fairly easy to do, anything you need to know this is the place to ask.

 

Threadmillings biggest fallback is depth of thread, if you need and excessively deep thread, it can be tough to do it. Most stuff though it is a piece o' cake.

[fboike]

Have you tried peck tapping?

I use it on our 3020 almost daily.

it helps with the tougher steels.

[heeler]

fboike,

 

 

I think that they have tried both. What size of holes have you tapped in your 3020? And in what? I havn't been able to find the rated horsepower for our machines yet, we have the 8000 rpm spindle. In our manual, it has a rigid tapping setup proceedure. Have you done this? Would you know where to find the program O0040 at?

 

Thanks

 

Glenn

[fboike]

I've tapped 5/8-11 in d2,m4,a2,s7 and some alloys. I wont go any bigger becuase its a 12hp motor. it just dont have the torque.

The only thing ive done is put a m29 in the post.

but I program G95 for my taps so the feed for 11 pitch would be F.0909.

The only O# programs are the ones we put in.

hope this helps

[Matthew]

On your M29 line, do you specify a speed also?

[fboike]

no, spindle and speed are on a line. so I can find them easy.

m3 s500

[heeler]

quote:

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On your M29 line, do you specify a speed also?

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Yes

 

fboike

 

According to my Kennemetal book, in 1010 mild steel, a 3/8 24 tap should take 60-120 inch lbs of torque, and a 3/4 16 should take 300-800 inch lbs with a min of 1 hp. You should multiply this by say 1.2 for HB 70 mild steel which would be 360-960 for the 3/4 inch. Which I believe converts to 30-80 ft lbs. The 12 hp bridgport should have 110 ft lbs @ 468 rpm. This seems like it should have plenty to run this 3/4 tap. Could anyone help explain why/why not for me.

 

Thanks

 

Glenn