Summa D160R - Weird cuts...

[MikeyG]

Hi all
I posted previously about how my 3-month old Summa D160R started cutting circles with 'flat spots', making them look more like ovals.

Now it has started making some very odd cuts when cutting small lettering.
Have a look at the attached pictures I took of a test-cut.
This was a test line of A-Z text, 32pt sans-serif lettering (which is around about 8mm - or 5/16th of an inch high).
I printed a block of colour using an HP latex L26500 onto Hexis VL3000 100mic monomeric self adhesive vinyl, which I then laminated using Hexis V650 80mic gloss laminate.
The Summa cutter has a brand new Summa drag knife blade, which is adjusted to just showing from the holder. It is rotating freely in the holder.
The speed I generally use is 200m/s at a pressure of 185 for this heavy laminated material.
However, I have run multiple tests - cutting at different speeds and pressures. All seem to reproduce the same problem - even pressures that don't cut completely through the vinyl! All display the same sort of random 'mis-cutting'.

I had three Summa engineers looking at it last week. One diagnosed a new blade (now fitted) and replacing the X/Y motors because of a repetitive 'XY' error.
The second engineer came to fit the motors, but only managed one before the end of the day.
The third engineer traced the XY error to how the media was being loaded (I'd turned the 'Autoload' off due to too much media being fed through before cutting), and decided that the motors weren't at fault, so replaced the original motor.

If you look at the two images below, you can see that the cutter is beginning (or possibly ending) cuts in odd places. Look at the letter 'M'. You can see the cut stops halfway along the inside of the 'right leg'. Also the top of the 'L' is not straight or level with the other letters, and the bottom corner of the 'N' also doesn't meet up and wobbles off in what looks almost like a serif!
In the second picture, you can see that the centre cut of the 'O' does not meet up, and in fact begins at a point within the letter itself. The outer edge of the 'O' is also 'wobbly'.



I had assumed that possibly it was an Offset problem - but adjusting the Offset either up or down only makes the problem worse. And the Offset test cuts and weeds perfectly when set to the default (which is .45mm).

Does anyone out there have ANY idea what's going on?
Is it my own inexperience? Is there something I'm missing? Is it a machine problem? Is it a media problem?

Any suggestions are welcome!
Thanks!

 

[chester215]

I would still call Call Summa Tech support at 800.323.9766 (toll-free from US and Canada).

They are the most helpful tech support people I have ever dealt with.

Looks Like you have already dealt with them extensively, maybe you will speak to someone different with more knowledge of your specific problem.

 

[XtremeXccessories]

To me it looks very much like an offset issue. The only time I've seen a dragknife cutter leave those little tabs on corners and not finish cuts like on that O is when the offset is incorrect for the blade. What degree blade did you replace it with? The latest Summa Cutter Blade Guide says the dragknife offsets are .43 for the 36°, .50 for the 50°, and .90 for the 60° with an overcut of 0.1, 0.5, 0.1 respectively.

Edit: Attached the Summa Blade Guide for you and anyone who is interested. It gives you offsets, overcuts, maximum thickness for each blade, etc. for both tangential and dragknife cutters.

 

[AF]

Some ideas for you:

1. I can see a faint line leading to the "O" which is from the blade scraping the material as it relocated to the O. Too much blade exposed can cause this. Alternatively, the material was not held down flat enough. To hold it down flatter, make sure several feet of material are hanging off the spool. Also, per Summa tech, cover any exposed vacuum holes to increase vacuum under the material (this is something you should do for further debugging the material)

2. Turn on tangential simulation. This should reduce the rounding off of the tiny letters.

3. Use all the pinch rollers.

4. Test plot the same design but twice as big, it could be that the letters are simply too small. If the larger design cuts properly then you know what the minimal practical size is for that material.

5. Turn off paneling for this. Paneling can cause odd cuts at the panel line with difficult materials.

6. Make sure the leading and trailing edge of the material is not hitting part of the machine during cutting. Any impacts will mis-align the material and cause cuts to not close properly. If the leading edge is hitting the take up assembly, tape a piece of material to the front of the machine to guide the leading edge over the take up roller.

7. Slow down the media advance speed. This setting is only available from the service menu, so call Summa tech and have them walk you through it. Even though you can change the cutting speed speed for the job on the front panel, the media advance speed remains at a default value. Slick or stiff materials that are difficult for the pinch rollers to grip will need the media advance speed reduced to lower the torque and subsequent slippage.

8. Do a length calibration with the exact media you are trying to cut. This will waste 3 feet of material but will ensure you are properly calibrated.

9. Recalibrate all settings.

 

[MikeyG]

Weird cuts - partial resolution...

Hi all
Just wanted to let you know what's happened with the problem of the 'weird cuts' I was getting on the Summa D160R...

It was suggested by the people who installed the machine that I try a new blade holder. They thought that as I cut a lot of laminated monomeric vinyl, the extra pressure needed could have worn the original holder faster than it should have.
They also suggested I use a 'sandblast' holder and blade instead, as it is designed to cut thicker material with less wear.

So, I bought a new 'standard' holder and 36° blades, plus a new sandblast holder and blades.

The new 'standard' holder and blades seem to have solved the issue I was having with the cuts starting in the wrong places and not finishing. In fact, I've just cut some text in a printed polymeric vinyl that was less than 1mm thick. It was a bugger to weed, mind you, but it at least cut cleanly!

However, the sandblast blade is another matter.
I found a Summa document online that says the sandblast blades need an offset of .90.
If I set the machine to this, the cuts are pretty ropey - don't meet up and don't finish cleanly.
I tried upping the offset by .1 at a time all the way up to the maximum of 1.0mm. The best cut was at 1.0, but I'd still say it could be cleaner!

Anyone got any further suggestions as to how I can adjust the machine to cut cleanly with the sandblast knife?

Thanks for the help!

 

[MikeyG]

Sandblast knife

Hi all
So... an update on my situation.
A new 'standard' blade holder and blades gave me nice clean cuts for about a week.
Since then, the cuts are getting progressively worse using this holder, even though I've changed the blade again!

I have also had a bit of time (finally!!) to have a proper test with the sandblast knife.
I have calibrated XY using this material. Cutting speed is only 200mm/s.

Cutting Hexis V3000 monomeric vinyl that has been laminated with Hexis V650B monomeric laminate, I find I can get just about acceptable cuts using a pressure of 190gm and an offset of .95.
(More or less offset gives me worse cuts and the pressure is OK for letting me weed text fairly easily.)

However, I am still getting some places in the lettering where the blade starts and stops out of alignment.
Have a look at the picture...


On the inside of the letter, on the right hand side, you can see a little 'step', where the cut didn't meet up properly.
This doesn't happen on all letters, though, but is consistent on this particular letter from my test logo I have been using.

Does anyone have ANY ideas as to what I can do to get clean cuts?
Is the blade out too far? Or in too far?
Am I using too much pressure?

I really don't know where to go from here, so any help or suggestions are gratefully received!

Thanks!

 

[timstudio]

I've had similar problems and what happened was that the blade was pushed a little out of the holder by the thicker material (laminated prints.) Whenever I cut normal vinyl I make sure the blade is pushed in properly ( just sticker out a little bit) and everything is spot on. Too much pushed out and it doesn't cut as nice as it should.