Troubleshooting Curved Rips in Melamine

Cuts coming out curved when you rip melamine? It's probably due to stresses in the material, not a problem with the table saw. August 14, 2007

When I rip with my 1265, it cuts at a slight arc (crown). If I ripped a 4x8 sheet in half and just let the pieces come back together just as they were before I ripped it, they touch at each end of the sheet but have about a 1/16 gap in the middle. I have had about 6 months with no problem, then an employee ripped 4" stock and I noticed the stock was all arched, and it seemed like the more rips, the worse the arch. I checked for tightness on bolts that attach it to floor. I put string at very top that arm rides on to check for straightness and I trimmed off 1/16 on all pieces on bottom that sheets set on, but still cuts in arch. Even if it didn't cut in arch, why would end of boards touch and be 1/16 gap in between?

Forum Responses
(Cabinetmaking Forum)
From contributor L:
Stress in the panel stock? Variations in moisture content? I know that melamine will do that sometimes. Our saw has an automatic program that we use when we encounter a unit of board that has excessive stress. The controller will pick a rip near the center of the sheet and make a cut that starts 4" in from the end and ends 4" short of the other end. It then adjusts the rest of the cuts automatically so it has an 1/8 of an inch or so to cut on both sides of the first cut when it gets back to that point. The process is totally automatic on our saw but it seems the same could be done on other saws manually. The process may work best on saws that cut with the sheets laying flat.

From contributor E:
I've had the same problems on my 1265. On some panels, the only solution is to cut the piece oversized and then recut. I don't see how the saw could be the cause. If it were cutting on an arc, I'd think one would hear/smell it!

From contributor O:
Are you using wedges? And are you ripping form the same point the 4" stock was done at? Did you buy this used? If so, check the rail and see if the seller used epoxy to fill wear spot. I've ripped wide and re-ripped for a smoke free edge on some of the multiple verts I've worked with at various shops.

From contributor T:
Don't worry, it's not your saw - trust me! Welcome to the world of melamine. You will notice this condition (stress in the board) vary greatly with the time of the year, humidity, age of the board (in your shop or at your distributor). Just think of the six months without this problem as the good ole days!

From the original questioner:
Thanks. I had to cut some freshly brought in MDF 12' and it cut it perfectly, then it did dawn on me that this was the bottom of the pile and usually gets restocked before we use it and we have had lots of rain. Just never ran across the problem on 4x8 sheets of material, usually because we go through it quickly.

From contributor R:
It's the material, from your description. Inner tensions! Cut oversized as suggested.