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Author Topic: Help with stoppage mid cycle  (Read 458 times)

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Help with stoppage mid cycle
« on: August 14, 2018, 07:11:19 PM »
Hey everybody.  I'm hoping for some guidance in troubleshooting a problem I've had for some time.

Basically something unpredictably freezes during a run cycle.  It's always while the bit is engaged and mostly (but not always) occurs while taking a heavier cut (but nothing crazy).
For instance, I was cutting a small part out of 1/2" Baltic Birch Ply yesterday. Feed rate 15 and full depth with a 1/2" spiral roughing bit.  About 1/2 way through it stopped. At this point I need to restart Mach 4, and restart the machine. Next I ran the cycle with the bit high (cutting air) and all was fine. Next I re-ran the part again. When it got to the place where it failed earlier it stopped just after making contact with the wood. Next, I re-ran the part and slowed the feed down to about 7. The machine finished the part.  This is a typical experience when it fails. But it doesn't always fail....
One thing to note, when the program stops, the Cycle Time clock keeps running. I'm also able to enable/disable Mach 4, but can't jog the machine or get it to move at all.

One of the problems is that I can't tell what the problem is. Is it Mach 4? Is it noise interference from the router/bit causing problems with the PC or with the BOB? (I bought a shielded ethernet cable to see if this was the problem, no dice). A water cooled spindle is the last piece of the puzzle that I didn't want to afford during the build. Could it be this?

Honestly, I just don't know where to look...

Here's my set up: It's a home made chassis with commercial parts...

Cad/Cam Software is BobCad V29
Mach 4 - V.4.2.0.3481
Ethernet smooth stepper with latest drivers (shielded Ethernet cable)
PMDX 126 Break out board
Kelling stepper motors, stepper drivers and power supply.
Dewalt DW618 Router (For now)
Aluminum Extrusions as the chassis and ball screws/linear bearings as the mechanicals.
Toshiba Laptop running windows 10-64bit and 8GB ram (set to never sleep!)

Any and all thoughts are much appreciated!
Bob
Re: Help with stoppage mid cycle
« Reply #1 on: August 14, 2018, 07:19:25 PM »
Did you look at the bottom line on the Mach4 screen to see if it provided
an error message?

My guess is that you got a false trip on a limit switch input due to the
load on the spindle. This can happen if you have a spindle motor with
brushes, and especially if the brushes are worn. Sometimes you can
help avoid this by using a shielded power cable to the spindle.
Steve Stallings
www.PMDX.com
For PMDX product support, please use PMDX forum or direct email for quickest response. We do not use this forum as our primary product support site.
Re: Help with stoppage mid cycle
« Reply #2 on: August 14, 2018, 07:25:57 PM »
There was no error message. But if it was a false limit switch trip, would it force a re-start?  You say spindle, but I'm not using a true DC spindle. I'm using a regular router.
« Last Edit: August 14, 2018, 07:30:25 PM by Soxfan963 »
Re: Help with stoppage mid cycle
« Reply #3 on: August 14, 2018, 08:23:38 PM »
Re-start? You mentioned a freeze, which is what happens when a limit is tripped, but it does
cause Mach4 to provide an error message at the bottom of the screen. You might click on
the History button to make sure that one did not scroll past.

Brushes in a line powered router like the Dewalt can cause plenty of problems if worn.
Steve Stallings
www.PMDX.com
For PMDX product support, please use PMDX forum or direct email for quickest response. We do not use this forum as our primary product support site.
Re: Help with stoppage mid cycle
« Reply #4 on: August 14, 2018, 08:28:50 PM »
No. Everything stops (except for the cycle time clock). I can't overide limit switches, jog the machine, or move it in any way. the only way to get back to work is to power down the CNC, shut down Mach 4 and start over...

The PC is otherwise operating normally.

Offline Stuart

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Re: Help with stoppage mid cycle
« Reply #5 on: August 15, 2018, 02:28:19 AM »
Ok

Sorry mid read the op post

« Last Edit: August 15, 2018, 02:31:32 AM by Stuart »