PET Roll Processing
MakeIt Labs PET Roll handling lessons learned
Video of the first roll we processed.
Safety - These rolls are heavy. If your stand supporting the big roll isn't strong enough and well balanced you will drop a roll. We used an auto lift as our primary stand and we still dropped a roll off the lift four inches to the floor. It damaged the edge of the roll and reduced effective yield about 50% for several hundred feet of PET. Luckily it was a short drop and the only thing damaged was a C-clamp instead of toes or fingers.
Cleanliness - be sure your work area is CLEAN. Static will build up and attract dirt every time you handle these sheets. Any dirt will scratch the surface more and more as you handle the sheet. Try to reduce manual handling of PET as much as possible. We started cutting it into 4' lengths because that's what our laser cutter handles and quickly realized that making smaller rolls was more efficient for storage and transport. Our laser quickly got set up to feed directly off the rollers.
First thing - you need bushings for the center of the roll. We made ours out of delrin, with the outer diameter of the bushing an almost snug fit to the inner diameter of the cardboard tube. The center of the bushing was cut to the OD of the scrap steam pipe we had on hand to actually support the roll. We used 5 1" thick delrin bushings on the heavier rolls, with gorilla tape wrapped around the steam pipe to hold 1 bushing in the center and 2 at each edge of the cardboard tube. You need bushings in the center of the PET roll because it will not unroll if the cardboard tube just tries to spin on a much smaller pipe. A little play in the bushing is OK, but be sure the bushings don't allow the roll to walk off the edge of the bushing either.
You need a pallet jack or forklift to move the rolls around. To tip the rolls from vertical to horizontal we lifted one edge of the pallet up a few inches, inserted a pipe through the center of the cardboard roll and muscled it to horizontal. Use your bushings when you lever over the PET roll so you don't damage the inside cardboard edge. Don't tip it onto toes.
Find something to use as a roller stand. We used an auto lift for the big rolls, but two of these will work for all but the largest rolls we've dealt with. Right now we are using these to direct feed 800+ lb rolls into our laser cutter.
Be sure the roller stand is safe. If momentum builds up on that PET roll it will either run right over the lip of an auto lift's jack point plate or off the roller stand. We always had one person standing at the heavy roll managing it's speed as it unrolled while we processed it into smaller rolls. Having the roller stands not perfectly square with the PET roll is bad.
If you are processing a giant roll into smaller lengths we found it easiest to put a stand to roll the PET onto a fixed distance (10' for us) away and bolt that to the floor. Be sure the two rollers are parallel with each other or else the PET will spiral on the new roll. Every ten feet we marked the roll and called for the next mark when it reached the rolling station. Our rolling station was made out of part of a weight bench lag bolted to the floor. We then zip tied a PVC coupling to each arm and ran a 6' long PVC pipe through the PVC coupler.
On the PVC pipe we press fitted a handle and taped a shim to one side of where the PET would start rolling. At the start of the roll we would hand insert a shim at the opposite edge and try to tightly wrap the first wind around the PVC. Once we got the PET started we could just spin the PVC and generate rolls to length. We started with 50' rolls but found that 100' rolls were easier. At the 100' length we would use a hook knife (linoleum blade) to cut the sheet then wrap it with two wraps of pallet wrap.
Another one of our roll making teams found that putting a layer of pallet wrap on the PVC; rolling the PET onto it without using any shims at all, then spinning the PVC roller backwards at the end caused the core to loosen up enough for the PVC roller to slide out easily as well. When removing the PVC roller one person would hold up the 100' PET roll and the other person would pull the PVC roller out.
To remove the rolls we would slide out the shim that wasn't taped. The PVC pipe would then slide right out and we would label and stack the 100' rolls. The 100' foot rolls could be given out to smaller scale cutters to process as they could and didn't require any special vehicles for transport. Once the large rolls got to be under 300 pounds we hand carried the first few to our laser cutter to feed off the back. Eventually we moved full 1000 pound rolls into our laser room on a cart with the roll strapped to it.