slitting plastic roll

sigmatero · Dec 7, 2020

A bit different question from CNC work.

My son needs to laminate a lot of pages and we are getting 18" wide roll of 3 mil thick laminating plastic (they are out of 9" wide rolls). Want to slit it in two 9" long sections. Am I crazy to think I can mount it up on my manual lathe and use a sharp fillet knife to slit it either by holding the knife by hand (ala wood lathe) or mounting the blade in my tailstock? Anyone done something similar.

BTW, since it is laminating film I don't think I can heat it up much when slitting or it will probably stick together.

M.B. Naegle · Dec 7, 2020

We have a machine that works just as you describe for cutting rolls of Mylar foil to different lengths. Sorry I'd take a picture of it but it's in storage at the moment.

On ours, the roll spins (maybe 800 rpm?)while the operator manually feeds in a hinged arm with a razor blade on the end (one of the trapezoid shaped ones). The mandrel that the roll fits on has an internal driving clutch of sorts so you don't have to clamp and mar the material. Be sure the roll spins the opposite direction that the film is wrapped and that the film is wrapped tight and taped down. If doing it on a lathe, I'd run it in reverse with your razor cutting in from the top so if it bites, it doesn't throw it at you.

vmipacman · Dec 7, 2020

Is the roll is 18” wide and you want to part of in half right? What is the roll diameter though? What is your tolerance on the 9”, like 1/4”?
My first thought is that you won’t be able to get a sharp enough, narrow enough, long enough parting blade to do it.
I’d look at band sawing it in half. Truthfully, I can see a good sharp handsaw and a steady hand, following a snapped line, making a good straight cut quicker than any other option.
Edit: maybe I’m thinking too cave man. I had an idea this was a one off. I think you want a film respooler setup if you are doing a lot of this.

sfriedberg · Dec 7, 2020

I occasionally run a laminator. If your son has a batch of pages ready to go (i.e., not doing one at a time), then just feed two pages into the laminator at the same time, with a small gap between.

I have been running 12" rolls recently to laminate 8.5x11 pages, but my laminator takes up to 27" rolls which are plenty wide enough to do two pages at once. It is not necessary that the pages be synchronized going through the machine. In fact, it's a lot easier to manage if you get one started straight, and while it's feeding line up your 2nd page over on the other side and get it started straight.

Or maybe I misunderstood. Does your son's machine only accept 9" rolls?

sigmatero · Dec 7, 2020

Thanks for the ideas. I had thought about using the bandsaw to cut, and may try that, but was a bit worried that it would melt the cut and then not feed off the roll properly so hence the knife version.

Our laminator goes to 13" wide and we could feed our 8.5x11 sheets landscape format but we have this idea to feed directly from the printer we're using for his work and it spits out portrait format. The laminator has adjustable speed so we're hoping to be able to match the speed of the laminator with the printer (two-sided cardstock that takes about 20s to print). If not it might make a good project for him to work on with an Arduino or something to sync the two. That or keep it simple with a leaf switch but we haven't played with the laminator enough to see if it will cause problems for the sheet ahead if we turn it off to wait for the next sheet to feed. Pretty soon we'll have a CNC printing setup- doh

Phil in Montana · Dec 7, 2020

Use a bandsaw..Phil

9100 · Dec 7, 2020

A band saw is going to leave a rough edge and a lot of dust. Several people have described razor blade setups that they are using, apparently successfully, so what is the debate? I have often slit plastic with scissors half open and simply slid along the sheet.

Bill

jatt · Dec 8, 2020

Kinda just what the collective has already said. The fabric slitter a guy tried to sell me just had a gang of standard razor blades in custom made holders on a bar. Could adjust cutting widths to suit what you are after.

Also done the bandsaw thing on a 4mtr wide roll. Needed 2 x 2mtr wide with a bit of fudge. Bugger my machine can only handle 3.2 wide!

dian · Dec 8, 2020

like this:

DDoug · Dec 8, 2020

Maybe this:
https://www.homedepot.com/p/Makita-...rdless-Multi-Cutter-Tool-Only-PC01Z/303797633

Bill D · Dec 8, 2020

I think he wants to cut it in half on the bench before he puts one half into the machine.
Bill D

rbent · Dec 8, 2020

I've cut rolls of .005" mylar on a bandsaw before, worked OK. Wrapped it up tight on each side of the cut line and away we went but it was rolled tightly on a core. It left a little bit of a jagged edge but I wasn't using the edges anyway so it worked fine. I'd imagine laminating film would be softer so I don't know how much you can get away with.

DDoug · Dec 8, 2020

Bill D said:
I think he wants to cut it in half on the bench before he puts one half into the machine.
Bill D

You can't rig up a "unreel" and "reel back up" set-up with that cutter in between ?.... :toetap:

Scottl · Dec 8, 2020

How tightly is it wrapped?

I routinely cut tightly rolled material using a woodworking miter saw. I've cut everything from rubber shelf liner to paper auto body masking rolls and even once replacement plastic side curtains for an air conditioner. Those weren't rolled but came very tightly compressed in plastic shrink wrap packaging.

Illinoyance · Dec 8, 2020

Take a foot square piece of plywood. Tack a fence (3/4" sq.). Jam a utility knife in at 9". Pull the material through.

That is the real cave man way.

jermfab · Dec 8, 2020

Laminate sheet isn’t something I have any experience with, except as an end user, but I’ve seen plenty of rolls of shrink wrap ruined by guys trying to cut them down. Doesn’t matter what saw got used, 10-12” miter/chop saw definitely melts the cut together, but even the bandsaw leaves a ragged enough edge that the wrap never pulls evenly from the roll.

Proceed with caution.

boslab · Dec 9, 2020

Make sure you put the roll on the lathe the right way, if you don’t it’s like machining plastic with a 8” wide blade, it’s impressive to see a whole roll of film thrown out in seconds ( I did a spell in a plastic bag factory, yes it was me!)
Mark

wheels17 · Dec 9, 2020

I used to work at a film manufacturing facility. On some products we used carpet knife blades to slit off the uneven edge. They were in special holders that could be screw advanced. There was a routine where the screw got a quarter turn every couple of hours to move to a fresh edge. This would represent over 3000 feet slit between adjustments.

kb0thn · Dec 10, 2020

Scottl said:
I routinely cut tightly rolled material using a woodworking miter saw. I've cut everything from rubber shelf liner to paper auto body masking rolls and even once replacement plastic side curtains for an air conditioner. Those weren't rolled but came very tightly compressed in plastic shrink wrap packaging.

I second this notion. I've cut various rolls of plastic this way. Vinyl flooring is great. Take the roll from Menards and throw it in the chop saw and cut to the width of the room.

surplusjohn · Dec 10, 2020

Nada on a band saw, it will make a mess. Turning it on the lathe is exactly how a balony slicer slitter works. It important that the material can telecsope away from the cut. Ie is the roll. Loose enough to all one or both sides to slip. The baloney slicer style slitters use large hollow ground blades which are incredibly sharp. But i think a sharp straight blade will work here. Utica mill supply or firschings still make these and the new ones look exactly like the ones from the 30s

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