Daewoo/Doosan threading on sub-spindle

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pdexter1210

Aluminum

Joined

Oct 21, 2014

• Oct 20, 2017

• #1

We're trying to run some double sided 1 1/2-8 studs on the newest Puma 230MSB to test it out and we're having trouble with the 2nd side threads on the sub. It's a proven program from our other machine. Each threading pass on the sub is equally out of time/clock(not sure of the correct term) with the previous and we end up with a very nearly flat looking surface at the end of the threading cycle. There is no backlash in the machine, and the collet is holding accurately, but our sub is out of sync by the same amount with each pass. Front side threads on the main are perfect. 1st pass on the backside using the sub looks great, then gets out of sync. Any ideas?

 

WILLEO6709

Diamond

Joined

Nov 6, 2001

Location

WAPELLO, IA USA

• Oct 20, 2017

• #2

using a g76 compound cycle or individuals?

 

Y

yardbird

Titanium

Joined

Jul 3, 2013

Location

Indiana

• Oct 20, 2017

• #3

Are you sure the part isn't spinning a little in the collet as the cut gets deeper?

Brent

 

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pdexter1210

Aluminum

Joined

Oct 21, 2014

• Oct 21, 2017

• #4

The program is currently running correctly on the like kind machine sitting next to this one, so I don't believe it's a program issue, but we'll check the program again. We've checked the collet and the clamping pressure and do not think the part is spinning in the sub. If it were spinning I would expect to see non uniform passes in the threads as the tool went deeper. However, the subsequent passes after the first threading pass all seem to increment by the same amount. It's appears that the spindle is locating to a different position at the start of each pass, although the spindle is always running, so maybe there is a parameter in this control somewhere that is telling the machine to increment each threading pass?

 

litlerob1

Diamond

Joined

Nov 4, 2013

Location

Utah, USA

• Oct 21, 2017

• #5

Post the code.

 

WILLEO6709

Diamond

Joined

Nov 6, 2001

Location

WAPELLO, IA USA

• Oct 21, 2017

• #6

Its possible a newer machine will require a code tweak.... I think I would do this:
1. sharpie/ paint marker at clamp but before you thread it.
2. put a live radial tool in for sub work
3. do an mdi orient to zero
4. mill a little key
5. go back into programm mode- tell it to mill that same keyway same orient 12 times.
if its not repeating the c mark its either a parameter or a flubbed up encoder-is the sub belt drive or integral? could be belt slack. could also be x or z drive lag/ following error

 

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pdexter1210

Aluminum

Joined

Oct 21, 2014

• Oct 23, 2017

• #7

Threading cycle posted below, but again, we're running good parts on the exact same machine right next to this one, so I'm pretty sure it's not a code issue. I'm leaning towards an encoder issue on the sub, we'll try milling the slot in MDI and then repeating with a program and see what that produces. Thanks for that idea. Sub is belt driven, as is the encoder. Maybe its possible that the encoder belt was changed at some point and didn't get put back in proper time with the sub?

(TOOL - 3 OFFSET - 3)
(SANDVIK 266RG-16UN01A080M GRADE 1125)
(1.5" - 8 UNC 2A THREADS)

G55 G40
G18 G98
G0 G53 X10.
G53 Z10.
G53 B0.
T0303
G97 S400 M103
Z-.236
X1.69 M08
G76 P020029 Q10 R0
G76 X1.3366 Z1.594 P767 Q145 R0. F.125
X2. Z-.2
M09
G97 S400
G0 G53 X10.
G53 Z10.
G53 B0.
M105
M30

 

Ox

Diamond

Joined

Aug 27, 2002

Location

Northwest Ohio

• Oct 23, 2017

• #8

Well I don't see how belt "timing" is an issue - other than for the case of picking off shapes. (sqr, hex, interlocking 3 jaw chucks, etc..)

Maybe the [encoder] belt is loose?
Maybe the encoder is giving up the ghost.

If it has a belt drives encoder, then this thing is 20 yrs old or more?



---------------------

Think Snow Eh!
Ox

 

litlerob1

Diamond

Joined

Nov 4, 2013

Location

Utah, USA

• Oct 23, 2017

• #9

Okay, the code you posted looks fine to me. A couple things I will say it sounds a lot like what happens when you accidentally have a G96 in there instead of G97. I know that is not what the code reflects, just saying.

Another thing to explore beside the Mechanics, is that in your first post you say; "It's a proven program from our other machine." If it were me I would try writing a stand alone threading cycle just for a test, different Pitch, different start points and finish points, different DOC, retract, finish allowance all that Jazz and just see if you can possibly get a good thread off the sub. That is what I would do before blaming the Mechanisms.

R

 

S

sinha

Titanium

Joined

Sep 25, 2010

Location

india

• Oct 24, 2017

• #10

Seems a hardware problem.
For the sake of further checking, may try P----00 which is straight plunge.

 

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pdexter1210

Aluminum

Joined

Oct 21, 2014

• Oct 24, 2017

• #11

WilleO6709, thanks again for the comment here, we ran your little exercise and the sub is not coming close to returning to zero on each pass, sometimes close, sometimes far, but definitely random. I was stuck looking at the threading cycle and couldn't see the forest for the trees. We definitely have some sort of sub-spindle encoder issue, so I'll spend some time on that and see what I can dig up. Appreciate the comment.

Ox, the encoder belt is tight, I've already checked that, but I do agree this isn't a timing issue. The machine is a 2001 model, so not quite 20yrs old. If I'm not able to get the encoder issue diagnosed, I'll start a new thread so that it more closely describes the problem.