Openco

Copam chatter - old problem - new description.

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I've seen this issue recurring with various descriptions on vinyl forums.  This is how I would describe it.  Please help if you can.

As I face the out feed side of the cutter it chatters on cuts from right to left.  Those left to right are very smooth.  It also chatters on right to left "lower right to upper left" cuts like those on the inside upper climbing left cut of a "Y" or "N", or  the two inside upper climbing left cuts of a "W".  It looks like a perforated tear off sheet.  Yes, I loosen up the roll so the machine does not have to pull it - more blade, less blade - more pressure, less pressure - yada, yada, yada...  I thought the loud chatter that causes the blade to skip might be an issue with something not moving freely within the machine in the right to left direction.  So I plotted out the same cut on paper with pen - no chatter - almost perfect.  The other odd thing that I do notice is that even though I have the machine set to the slowest speed setting, it will speed up at certain points.  I realize complex cuts will cut slower than lines but, for example, I may have a twenty inch line and the first half it cuts slow and the second half it speeds up.  I've seen it go fast - slow - fast (etc...) on the same line.  I've tried setting it to cut in steps instead of full lengths.  I only mention the speed issue because if it is a long right to left cut the speeding up makes it worse.

Also - this always happens with WHITE vinyl.  Not so much with darker colors.  Go figure...

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put a drop of oil or graphite in the blade holder and make sure all the vinyl is cleaned off the inside of the blade and holder

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Thanks man.  that's not it.  When I start messing with this, by the time I can get more solid cuts, I get the dreaded peel ups on small stuff.  I can solve for one - not both.  Even with "harder" cutting, the weeding box on the right to left cut is a chatter cut.  I'm sure it's due to my inexperience.  When I teach woodworking the hardest thing to get across to the students is that "the difference between not enough and too much is not very much."

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I enjoyed the advice about the difference about too much & not enough  :thumbsup:

Thinking about what you said & what I have read in this forum for several years now , this is my guess . Have you determined if it chatters more at slow speed than fast ? The blade may be a bit dull & not cutting as smooth at either slow or fast . I have read different color vinyl sometimes have different thickness , but I'm sure you did the adjustments on what you are having the most problems with . Other than what you have tried & what I am guessing , it may be the stepper motor vs servo thingy . ( from what I have read here again ) Steppers as in Co-Pams don't cut a long smooth line like a servo .. they jot out in whatever increments programmed .

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Thanks roger.  I was hoping it was me and not the machine.  I did the blade change, but don't know that the new blade is perfect - except for the great cuts at other times.  I sharpen chisels sharp enough to shave, but these are tiny to see...  :lol:  I've ordered some clean cut blades for my next try.  Also, one thing I've read was less blade more force (others recommend less force).  Though this seems counter intuitive (since I sometimes have the dreaded peel up problem), but there may be a happy in between here...

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I was scratching the backing strip because of the blade out too far . I must have thought I had it right a 1/2 dozen times , just to realize I needed to have less blade exposed . Now I cut some vinyl by hand until just the vinyl gets cut & barely an indentation in the backig paper , then take the blade in some more & install it . Thinking about you post , I remember my Co-Pam chattering when the blade was going thru the backing paper . Good Luck

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I had exactly the same experience. Everything OK except for cuts from right to left with a screaming chatter noise with a perforated cut. Numerous adjustments to blade depth and pressure without results. In my case the problem turned out to be a rough blade holder tip.

Here's how I diagnosed cause of my problem:

First, I created a simple test plot to cut a wide and short box which would force the cutter to traveled all the way across my vinyl sheet without wasting a lot of material. With the blade and blade holder installed, I got a great cut from left to right but got an unusable perforated and noisy cut when the cutter moved from right to left (looking at the machine from the front). Then, I removed the blade from the blade holder, reinstalled the blade holder without the blade in the machine and tried the cut again. Same smooth slide from left to right, but same noise and chatter from right to left!!

Therefore, the problem must be with the blade holder. I inspected the bottom (contact area) of the holder and it was hard to see anything wrong outside of a little circular ridge (almost invisible). But it had to be the holder because it would chatter with the holder in (without the blade), but not with a pen and pen holder instead.

Here's how I confirmed the diagnosis and solved the problem:

I took the holder and ran the contact end over a fine file until the ridge disappeared. Then I took some automobile polishing compound on a cloth on a hard surface and polished the filed end (vinyl end) of the blade holder until it was very polished. Take your time and make sure it is super shiny! After the blade holder end is polished, clean the holder carefully inside and out as the polishing compound is abrasive. Try the holder without the blade again. Same machine, same vinyl, no noise, and no chatter!!!

Put the blade back in the holder, set the depth, and say goodbye to chatter, perforated cuts and weeding nightmares. I hope this is helpful.

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Anyone have any solutions to this problem? I have a CP-3050, purchased from US Cutter last year. Same exact issues as above...chattering right to left on long straight cuts and angled cuts. Have oiled holder, changed blades, set blade depth and adjusted downpressure six ways to Sunday to no avail.

 

It only happens when the stepper motor accelerates. If it a short enough cut to not accelerate to the higher speed, it generally cuts fine...and it only happens right to left. Which brings up another question...If I set a cutting speed, why does the cutter do the acceleration at all? Can it be turned off?

 

I have been operating vinyl cutters for 15 years and think using an X-acto to finish the machine's work is quite ridiculous, and I am getting pretty tired of it. It does seem to happen more on silver and gold metallics. Spent an hour and a half on different blade depth/downforce settings last night for a job and then another 2 hours finishing the silver by hand when none of it worked.

 

When I use Oracal 751, 951, it seems to do a little better (or I have less issues with the chattering). I don't have a local Oracal dealer, which is unfortunate. Their vinyl is heads and tails above all others IMO. My local supplier sells 3M/Gerber Scientific, so we use that predominantly...their silver in series 220 is a nightmare to cut with the Copam acting up. 

 

I am going to try Bridg Hunt's technique on the blade holder, but I don't have high expectations. Anyone else have any ideas? 'Bout ready to spring for a new Summa to save me the aggravation.

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check your cutting strip first and might think about a new blade holder - my copam never gave me any problems.  on finishing the cuts if you use flexi add to your overcut in production manager will fix that.  on the chatter I would normally start with blade length adjustment but after 15 years I am sure you are adjusting properly and not using the 1/2 credit card that is 10 times too much blade

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I noticed this last night on my copam cutting white 751C. I'm actually running a Roland blade holder in mine. I had a hell of a time getting it to cut this vinyl properly. I removed the blade holder to swap the blade from a 60 to a 45 to see if it helped. In the process of changing blades I decided to clean and oil the holder. As I was cleaning I felt what could only be described as a burr on the tip of the blade holder. I used a four way nail polisher to remove the the burr and polish up the tip, oiled the tip, bearing and blade tip. Upon reassembly I test cut one piece of the 38 I was trying to cut and it cut much better. It was late so I did not try the full cut.

 

I recalled seeing this post and decided to look at it this morning to see if there was a solution to the chatter. Looks like I may have solved it inadvertently.

 

Think about it, it makes perfect sense. The cutting head is driven by a belt. Being so, the motor should be pulling the head no matter which direction it travels. This leads me to wonder if there is not an adjustment that can be made to the carriage allowing some of the slack to be taken out of the carriage. It seems like maybe the head may tilt a bit when changing direction and has more resistance traveling one direction than the other. It makes more and more sense as I type. This probably explains why the machine seems to have spots where it does not cut and repeats it on every copy unless the vinyl is changed and re-registered. (which really only relocates the trouble spot)

 

The other thing I noticed while trying to weed this crap was that it was nearly impossible to pull it back against itself while trying to weed cursive lettering. It tended to stick to itself like cling vinyl does. I assume that's because of the gloss finish.

 

So when I get home this afternoon I'm going to pull the blade holder out and polish the poo out of the tip, re-oil it and manually manipulate the carriage to see if there is any play in it. If so I will look for an adjustment. If not, hopefully polishing the tip and putting a bit of oil on it will get me by until I'm done with this project. Fortunately, I do not cut a bunch of glossy stuff. 

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Behind 1 of the end caps will be an adjustment for the belt if it's loose.

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I thinking a belt tension issue would affect both directions of travel. It's more than likely where the belt and carriage interface or something that allows the carriage to slightly pivot one direction and not the other. My guess is the latter. 

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