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dwneumann

random cuts part way through file... driver issue or cutter?

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Argh!!

I have been using my Creation Pcut CT630 with a licensed copy of SignGo successfully for a long time without problems.

Now (after 6 months of not using it) I am trying to cut a dxf file that I successfully cut 6 months ago, but now I get random cuts occurring part way through the file. The cuts are random but they always occur exactly at the same place int he file. I checked my communication settings and flow control settings. All appear to be correct and identical to what they were when everything was working (9600 baud, 8/1/none, hw flow control). The program communicates with the cutter for about 10 minutes before the random cuts start happening. (This is at a cut speed of 20mm/sec.) I can reproduce the random cuts at *exactly* the same place in the file over and over again.

Suspecting a flow control problem (buffer underflow or overflow) I sped up the cut speed to 30 mm/second to drain the buffer faster, and indeed the program gets further along in the file, but then the random cuts happen, and again, it happens repeatably at exactly the same place in the file. I can try the same file over and over again and the random cuts happen at the same place (but a different place at 30mm/sec than for 20mm/sec). If I increase the cut speed even further to 40 mm/sec the program gets even further, but eventually generates random cuts.

If I switch to pen plotiing I can increase the plot speed to 60mm/sec and then the file gets all the way through without any random cuts (or pen lines in this case).

The USB virtual serial port driver had been updated to FTDI's latest, so I suspected a driver bug causing problems with flow control. so I rolled back to 2.6.0.0 which worked for a long time, but no change.

I ran a serial port monitoring utility and observed that no RCS/CTS control signals are being logged. I don't know if the serial port monitor program is supposed to log them or not. I have attached the first bit of the serial port monitor log file to show what settings the computer and cutter negotiate.

I have RTS/CTS enabled, DTR disabled and XON/XOFF disabled in the SignGo package and driver. I am using USB port on cutter to USB port on PC (Windows XP).

I have spent 2 days trying everything I can think of to explain this.

Do these symptoms sound familiar to anyone?

THanks for any and all suggestions.....

Dean

rave-bear-totem @ 20 speed hw flow cntl.htm

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Put it on a keyspan adapter or a serial cable. It is always the best way to go. Also, Is your cutter grounded to the stand if, you have a stand? A sheet of dryer sheet in the roll, or wipe down the vinyl with it. Spray Static Guard around your machine.

Static Electrical Interferance and what to do!

Posted by Hugo on 06 July 2010 10:49 AM

The value line cutters (specifically the MH series) are a great choice when first getting into business, starting your hobby or generally when dealing with a tight budget. In some instances and in some environments, your cutter can be subject to a higher susceptibility of Static Electrical Interference. You'll know static is interfering with your cutter by performing this simple test: Disconnect the cutter from the PC and turn it off for 20 seconds, then reconnect and power on. Remove the vinyl and blade holder from the machine and run a cut job through the cutter that would typically fail or stall. If it completes, run it 2 or 3 more times. Did it fail? If yes, probably not static. Finally, (still w/no blade) run the same job the same way WITH the vinyl. Does it fail? If yes, Static.

Vinyl is an insulator which is negatively charged; this is where the problem begins. During the process of simply un-rolling, your vinyl gets a strong negative charge. Because it's an insulator you cant simply wipe off the charge (as with anti-static wipes) unless you cut the sheet from the roll. The other point where this is an issue is when the media feeds out of the machine and lays on the floor (ESPECIALLY CARPET!) and then the cutter rolls it back in. Again the peeling away motion creates more static. Grounding the cutter ( or "bonding" to be precise) is your best option for helping to discharge the static that has built up on the cutter. Grounding can be done by running a copper wire/speaker wire from a screw on the base of the cutter to a point on the stand. Contact points should be metal on metal, which might require you to scrape away some paint. You can also try a humidifier to dampen the amount of environmental Static Electricity in the immediate area.

The only real solutions: 0.5) Ground the machine. 1.) Get an ESD blower. You can find them by simply doing a Bing search (or visiting: http://www.gndzero.com/neutralization.php). ESD blowers deliver a balanced stream of ionized air which neutralizes object surfaces and insulated objects that are charged. 2.) Think about upgrade your cutter! Anytime is a great time to get a professional piece of equipment that is built on a superior design.

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Thank you skeeter. My cutter only has a USB port (no RS-232) and my laptop only has a USB port so unfortunately I cannot try using a real serial interface. I have not changed the cable, laptop, or port since it last worked. There is no USB hub, router, or any other device between the cutter and computer.

My cutter is not on a stand but I did try grounding to the metal legs of the table it sits on. This had no effect. I also pre-cut the resist from the roll to avoid static buildup (I use a rubber sandblast resist, not sign vinyl), and I power cycled and unplugged the cutter and the laptop many times during my troubleshooting. The random cuts also happen on regular paper when plotting with a pen at less than 60mm/sec cut speed. This, plus the fact that the random cuts always happen at exactly the same point in the plot, makes me think it is not a random effect such as static charge but rather something that happens after a certain amount of data has been transmitted, or perhaps whenever a specific memory location in the cutter's memory buffer is read.

I'm still stymied....

Regards,

Dean

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does this problem happen on every thing you cut, or just this file? If this file only, maybe the file got corrupted...stray nodes on it .. Have you zoomed the file up really good and looked at it?

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hmmm,that's an interesting question.... It doesn't happen on smaller files that only take a few minutes to cut. This file is quite an intricate design. It takes almost an hour to complete cutting at 20mm/sec. I had not thought of file corruption because it does complete successfully if cut fast enough. But I will test a different similarly intricate file and see what happens....

Thanks.

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Some times when I run into this I just restart the laptop and it fixes the issue I might have. I have always used my cutter with a laptop and usb connection. Just a thought.

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