Vinyl shifting after design is 90% cut

[taisho 0]

I have a 28" SC2. I'm trying to cut a large logo for a vehicle graphic. It is 6.5' x 1.5' and I'm using Avery Dennison SW900. I've wasted a lot of Oracal 951 already, practicing cutting this logo, due to shift. 

Today, I tried on the SW900 material and got so close to perfection but the last two to three cuts, the vinyl shifted. Can anyone offer me some insight? This machine is advertised as being able to cut up to 144", right? I've attached our logo file for reference. I'm using the free vinylmaster software on a windows 10 PC.

Here's my method after much trial and error. 

• I pre cut the length of vinyl so it is not feeding from the entire roll
• I used masking tape on the machine to note the edge of the vinyl
• I have two plastic folding tables set up on either side of the cutting mechanism to hold the material
  • When the material exits the machine, I fold it over itself to reduce the amount of material being moved in half. While working, the vinyl sheet resembles a belt. 

Noting my file, the cutter successfully cut the letters in the center, then it started cutting the ovals starting from the inside out. After about two or three ovals, there was a slight shift, maybe 1 mm. Nothing that would be noticeable. Before cutting the last oval, it cut the weed line which is the rectangle surrounding the entire design, added by the software, itself. (not part of my design). From here, I noticed a significant shift. Then it cut the last oval and it started to overlap some other parts of the design so I had to pause the machine and give up the cut. It was probably 1/2" or more off from the masking tape. 

The only thing I can think of is my pinch rollers need adjustment. I can run the material through without cutting and during the cut, the material is fine, with minimal shift. Not sure where the issue occurs. The screws on my pinch rollers are about in the middle of the thumb nut. I marked them and turned them all the same amount of times starting from the top of the screw flush with the nut. 

*trademarked vector deleted per forum rules***

 

[MZ SKEETER 4,708]

Make sure your blade depth is correct, too much blade exposed, will shift the vinyl.  Here is the correct way.   Also I measure the pinch roller to vinyl edge.  They should be equal distance. Prefeed the vinyl and watch it. 

To start with, you should set your blade depth correctly, by taking the blade holder out of the machine, and firmly cut across a piece of scrap vinyl, you will be cutting. You should only be cutting the vinyl and barely a mark on wax paper backing, Adjust blade to get there, Then put the blade holder back in machine, and use the force of the machine to get there, same results, only cutting the vinyl and barely a mark in wax paper backing. You should barely see and feel the blade out of the blade holder. Regular sign vinyl is only 2-3 mil thick. You only cut with the very tip of the blade. 

https://support.uscutter.com/hc/en-us/articles/360037895391-Tracking-vinyl-as-it-feeds-Vinyl-Skewing-when-cutting-

 

  Cutter memory is determined by the amount of nodes in the design. 144"  could just be a simple file. 

 

[taisho 0]

I'm sure the blade depth is correct. I cut a few sample pieces and there was no marking on the backing at all. Granted, I'm using SW900 so the backing is textured but there is no noticeable marking, once the vinyl has been removed.

So 144" is more a function of memory than ability to accurately track? That seems misleading. If I wanted to cut out a single line that was 288", I'm sure the machine would have the memory for it but if it can't keep the line straight past 60" then what's the point? 

The most frustrating thing, for me, is how the machine was accurate up until the end. Is there a way for me to reverse the order of cuts so the large pieces are done first? That way, if it screws up, It's not wasting time cutting out the inside of the logo, and I can at least save that uncut portion inside to use for smaller cuts. 

[Dakotagrafx 7,297]

5 minutes ago, taisho said:

I'm sure the blade depth is correct. I cut a few sample pieces and there was no marking on the backing at all. Granted, I'm using SW900 so the backing is textured but there is no noticeable marking, once the vinyl has been removed.

So 144" is more a function of memory than ability to accurately track? That seems misleading. If I wanted to cut out a single line that was 288", I'm sure the machine would have the memory for it but if it can't keep the line straight past 60" then what's the point? 

The most frustrating thing, for me, is how the machine was accurate up until the end. Is there a way for me to reverse the order of cuts so the large pieces are done first? That way, if it screws up, It's not wasting time cutting out the inside of the logo, and I can at least save that uncut portion inside to use for smaller cuts. 

have you messed with the pressure rollers from the way it was shipped?  we have seen several people reduce pressure trying to eliminate the roller marks that is totally normal - that and too much blade exposure causing drag causes drift.

[taisho 0]

I did adjust the pinch rollers. I backed them all the way out, marked the thumb nuts, then adjusted them all the same number of turns. The nut is about halfway down on the screw and I am getting roller marks. It's not as defined as they were on Oracal 751/951 where the texture of the roller was really evident but I figured that was because the Avery SW900 is thicker and already has its own texture. 

[Dakotagrafx 7,297]

you created your own problem.  marks are normal and disappear once applied 

[taisho 0]

I understand that but your comment is not helpful.  I attached a photo of the pinch rollers' current settings to my post above. I've attached a photo of the vinyl after cutting using those settings. 

Do I need to tighten the pinch rollers more?

[darcshadow 1,626]

I believe you can set VM to only cut a certain length at a time to help account for bad tracking. I don' thave access to the software right now, maybe someone that does can look up that setting and tell you how to activate it. Basically it cuts everything in the design in say the first 5 inches, then advances and cuts th×e next 5 inches. 

[Dakotagrafx 7,297]

personally I believe your hypothesis of backing the nuts off and turning the same amount of turns might be flawed in the value cutters inherent variables - thinner metal parts, difference in the pinch roller assemblies might not be equal force when doing this - now it appears from the picture you added the pinch rollers might be too tight - it is a fine line 
darcshadow makes a good suggestion too.
I don't mean to come off as non helpful but over the past 12+ years have seen more people create tracking problems changing the pinch rollers than those that left them alone.  it is an observation based on years of watching this happen.

[taisho 0]

@Dakotagrafx I sincerely appreciate you helping at all. Unfortunately, "don't adjust the pinch rollers in the first place" is about the only advice I can find anywhere on the internet in regards to adjusting them and it doesn't do much after they've already been adjusted.

You say it's a fine line. Do you have any expertise beyond that? What am I supposed to be looking for? If a roller is tighter than another will that push the vinyl or will one that's too loose push the vinyl? What metric is used to set them from the factory? 

[Dakotagrafx 7,297]

not exactly sure what they use - I would start in the middle and adjust one side (only using 2 rollers to start) until I got it tracking straight.  another problem people run into is using some mark on the plotter to adjust vinyl in the first place.  put the vinyl on the rollers - pull it tight and even before locking the rollers down - then if it drifts adjust as necessary to get it tracking straight - I even do this on a $5K graphtec.   this week I had the pleasure of testing a NIB uscutter SC that I bought in a lost shipment auction - used the same procedure and got it running well before boxing it back up to sell.   
You are in that learning stage that will teach you a lot you will use for years to come about what changes affect what actions - you will get there but will require more fiddling now that the pressure rollers have been played with - wish I had the magic formula they use at the factory but it is really just a matter of adjust and try now till you hit the magic spot.  heck even the newest graphtec ce7000 is having a problem with that, which is almost unheard of in a graphtec - no amount of adjusting fixed it on that model but with the sc2 we know it can work when adjusted properly and is not an inherent design flaw like the 7000.

 

[kainth.c.s 53]

4 hours ago, taisho said:

@Dakotagrafx I sincerely appreciate you helping at all. Unfortunately, "don't adjust the pinch rollers in the first place" is about the only advice I can find anywhere on the internet in regards to adjusting them and it doesn't do much after they've already been adjusted.

You say it's a fine line. Do you have any expertise beyond that? What am I supposed to be looking for? If a roller is tighter than another will that push the vinyl or will one that's too loose push the vinyl? What metric is used to set them from the factory?