english to metric for single point threading

[BrianP.]

Question about single point threading. We are doing a job in a Haas ST10 lathe. This job has a fine pitch metric thread but is programmed in inch. My question is can you change to metric for just doing the thread and then back to inch? G21 before threading block and then G20 after? Just before the G76 line? Anyone ever do this and is it possible? Thanks

[DODGERFAN]

I think you can post all operations except the thread in inch, then do a separate program in metric just for the thread and do the copy & past thing.

[jeff]

Why would you need to change it to metric at all? Just curious.

[Hardmill]

Why would you need to change it to metric at all? Just curious.

 

Thats what im thinking too.

Just do the conversion and post it in inch

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

PEACE

[BrianP.]

Why would you need to change it to metric at all? Just curious.

 

The guy here was thinking that a .5mm pitch is .019685 so he rounds it to .0197 and that could be an issue. I do know that Haas setting 9 is there for metric or english. Was just wondering if you could change on the fly as described above with a G20 and G21.

[Guest]

you would never catch that amount of error unless "maybe" it the thread was very, very long

 

Will the control do 5 place, if not, 4 really is close enough for almost all applications

[Guest MTB Technical Services]

You can do the switch to metric in the middle of a program.

Dangerous thing to do unless you check everything because your offsets are already in Inch.

The Haas should have no problem with 5 place decimals for the F address for the lead.

If it doesn't, program it as an expression F[0.5/25.4] and let the control handle the rounding.

 

Keep in mind that all CNCs today are using metric screws to begin with so all inch programming contains some inherent rounding.

[BrianP.]

Thanks guys. Like I told him that amount of rounding will not matter. It was more along the lines of one of those thoughts that pops into your head and makes you go ....Hmmm I wonder?

[within a thou]

Leave the G20 in your safety line. Add a G21 before your tap cycle. Feed in IPR. Put a G20 before your M30 change your z to something safe hit start. You will see if the thing is feeding at .500" ipr as opposed to the .0197" ipr. You can also watch your current commands to see if the G20 modal changes to G21 and then back just by watching the control screen.

 

Now you got me wondering next time my machine stops I am going to check myself.

 

Its actually a really good idea if it works since it will be one less calculation that will need to be made and it also puts the proper pitch that will be the same that is written on the Tap to help out operators. But the .00002 pitch error would never matter you would never be able to thread it deep enough to cause enough error.

[Watcher]

Keep in mind that all CNCs today are using metric screws to begin with so all inch programming contains some inherent rounding.

 

Like in Claus Terp (CIMCO founder) signature, "The real world is metric" -