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Author Topic: Why Is this happening?  (Read 6187 times)

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Offline ger21

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    • The CNC Woodworker
Re: Why Is this happening?
« Reply #10 on: September 08, 2015, 09:42:01 PM »
When mach 3 first loads up the feerate is set to zero.

Doesn't it always default to 6ipm?

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JointCAM Dovetail and Box Joint software

Offline RICH

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Re: Why Is this happening?
« Reply #11 on: September 08, 2015, 10:02:00 PM »
Hmm...thought it was 6 ipm also

I will need to check something in ver 62 as I have noticed, but ignored while testing my screen set, that  at times that a slow feedrate
occurs,  when,  "I think" I have used the mpg and then want to rapid jog. So his use of the mpg in the script kind of rang a bell.
I may be all wet......but will try to check it out.


Re: Why Is this happening?
« Reply #12 on: September 09, 2015, 10:44:48 AM »
HI BR549

Thanks for the help.

When I did what you suggested the feed value does appear in the feed rate DRO but is not used

in either the fast or slow cycles. At the end of the cycle the feed DRO reverts back to this value.

However I have noticed something very strange.

When it does the fast cycle I thought it was following the feed rate in the macro.   It is not.

It is actually following the value I have set up in motor tuning for axis A acceleration.

I have tried altering this for low to high values and it does appear to be using the acceleration value

as the feed rate.

Does anyone have any idea what could be causing this?

For information

The stepper driver I am using for the turret is a Leadshine   DM422C

I have the steps per set to 93.333333333

the steps per rev of stepper is 1600
the turret gear ratio is 1:21

so     (1600 x 21) / 360 = 93.3333333

also the manual states that  t3 the pulse width should not be less than 7.5 us

(page 12 of manual)

I have tried the step pulse width at both 5 and 8 dir pulse width 5

with no change

I have tried several different acceleration values but for most of the time

I had it set at 900 which was the same feed rate value I had in my macro

and why I didn't realise it wasn't using that value

the velocity I have normally set to about 1/3 the accel value

let me know if you think this may be part of the problem?

cheers George

Offline BR549

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Re: Why Is this happening?
« Reply #13 on: September 09, 2015, 05:05:37 PM »
First I would NOT use the A axis for a turrent . It has special features that allow it to radius sync to the XYZ motion. I would use one of the other axis B C.  You also need to start with a more normal setup I would start with VEL =200 and acel =20 as a test. THEN run the code and see how it responds.

ONCE you get it running smooth THEN you can play to find max vel and accel settings.

You could also be having trouble with the POKEYS ??

Just a thought, (;-)
Re: Why Is this happening?
« Reply #14 on: September 12, 2015, 11:33:26 AM »
Hi Guys

Sorry about the delay in responding but I have been working away for a few days.

Have done what you said ie changed axis over from A to B and it has made some improvement .

When the system is initialized it does start up at 6  (although my selected units are mm not inches)

Now when the turret moves in the fast cycle (either macro or MDI) it does follow the feed rate

(not the acceleration value in motor tuning as before)  set in the code.

(or at least it seems to compared to the DRO I haven't actually timed it)

But I still have the problem that after start up coming out of ports and pins

it runs the first cycle slow (occasionally it will be two cycles)

This is true if the code is entered via the macro or MDI.

One thing I have noticed is that when the cycle is running on the slow

cycle the feed increase/ decrease buttons never work. When it is running in the

fast cycle some times the feed  rate change buttons sometimes work!!

(but I haven't been able to spot the pattern why sometimes it does and sometimes

it doesn't)

I don't know what else to try.

Any suggestions would be greatly appreciated.

Cheers George

(ps I am contacting pokeys so see if the issue may stem from

pokeys but not holding my breath as I have tried without using

encoder readings or pokeys controlled button but just via MDI.

but we shall see what they say)
Re: Why Is this happening?
« Reply #15 on: September 13, 2015, 10:49:12 AM »
Hi Guys

Good news.  I've cracked it.  (well it seems to be working so far)

But I have absolutely no idea why it's working.

Stumbled across it by complete accident. I noticed that if I zeroed

the axis DRO immediately after start up or after coming out of ports and pins

it didn't go through the slow cycle.

What is strange is the first line of my macro zero's the DRO using


The button on the screen zeros the DRO using

Call SetDRO(4,0)

when I put the   Call SetDRO(4,0)   line at the start of the macro I don't get the slow cycle

The vb manual says SetDRO is just a legacy command and it's use is not recommended

So I tried putting an extra line of  DoOEMButton(1012) but that didn't work

But at least I have a solution which seems to work so far.

If anyone has any has any theories why it is behaving like this I would love to hear them.

Cheers George