Rounded corners cut deeper than straight lines

[Goatshaver]

I don't quite understand this issue. This happens on almost every rounded corner job. 90 deg cuts don't act this way and I'm trying to figure out why rounded corners cut deeper then the rest of the cuts. Often it's ruin the sheet simply because one or two corners are cut deeper and you catch the liner when peeling the label. This seems like the dumbest question but this haunts me all the time and I just don't understand why.

 

[Boudica]

It happens to me sometimes with our Summa. Like a giant circle, and half of it cuts through the liner. Or it will cut through in (some cuts) about the middle, but on the sides it's fine. I mentioned this second scenario to a tech once, and he suggested that sometimes the force is different in the middle than on the edges, and I do test cuts all the way across to find a median. That takes a long time... so now I just test it in the middle. Sorry, that probably isn't helpful to your issue.
Maybe it has something to do with the blade... is it a tangential?

 

[Smoke_Jaguar]

Acceleration runs through curves, 90 degree cuts are basically 2 cuts with a short stop between.

 

[Broome Signs]

you need to set the cutter nose correctly , basically the knife is sticking to fare out.
PB

 

[netsol]

if it only shows up on rounded corners, doesn't it sort of sound like a condition similar to tramming being out of adjustment?

 

[bob]

As previously noted, the blade may be a bit too long. That and it also appears that your tool carriage may be a little slow on the uptake which can be dealt with by removing any dust cover on the tool carriage and blowing out any and all accumulated dust and crud with a bit of air. Pay special attention to the tool up/down mechanism. It only takes a tiny amount of contamination to screw up the various timings involved in tool movement.

I've written about the blowing out any carriage contamination countless times and I'm tired of doing so. So read it, learn it, know it, be it.

 

[Solventinkjet]

I'm tired of doing so. So read it, learn it, know it, be it.

If I have to say change your dampers and cap top one more time!

I've run into a few times and it's always been a hard one pin down. I agree with bob, clean out the blade holder for sure. Check your cut strip for major divots or non flat surfaces and replace if necessary. Try slowing down the speed to see if that helps. If it does, your media may be buckling causing the issue.

 

[Goatshaver]

I don't think it's any crud in my cut head. It happens on by my Mimaki UCJV330 and my FC9000. I do have my blade out further on my Mimaki simply because I do a lot of embossing with cutting and I need the blade out if I want to cut through any embossed areas. My FC9000 that's a few years old so maybe it some build up but if it's happening on this shouldn't it effect every cut not just round corners? Cause as soon as it clears the radius the cut goes back to just scratching the backer and not cutting through. I'm going to try slowing it down on radius cuts to see if that improves it any.

 

[Smoke_Jaguar]

I found that excess drag in the blade holder can do similar, the blade is resisting the turn and digging in. A few drops of PTFE lubricant on the bearings can usually help. Cheap solution to try over a new holder. Also make sure the blade isn't rocking in the holder, be very careful to not cut the f*** out of yourself when doing this.

 

[unclebun]

The cutter goes slower on curves that on straight lines.

 

[Smoke_Jaguar]

Correct, as acceleration and all that means as a curve or direction change is initiated, speed tends to drop. The more significant the turn, the more velocity is lost. That said, a blade that can't pivot well can tend to dig in, the machine is going to be applying significant force under the assumption that the blade can pivot and skim along the cut as intended. If a blade is too deep, that can also cause the issue, but on thicker backing materials, I find blade depth to be quite forgiving.

 

[unclebun]

My point is that when the blade is going fast, it won't cut as deep.

 

[Smoke_Jaguar]

Yup, but the effect is exaggerated, hence something is up.