Cutting plywood on the BT3x00

[cwsmith]

I never have help in either getting the plywood or handling it during the project. So, I generally have it delivered and then use my circular saw and a "straight board" for a cutting-edge guide.

I use my computer and a graphics program to layout the panels on a 4 x 8 template and thus get the optimum use of the material. I then cut the sheet down to a 1/4 inch or so of the final size that I need and then do the final cut on stationary saw, using roller stands as necessary.

Yes there is some scrap this way, but having to handle the smaller pieces on the saw makes for better accuracy (for me) and less chance of error attempting to man-handle a full sheet of 3/4 through the saw. It's also a lot safer, IMO.

CWS

[JimD]

I have extension rails and a bigger table surface on my BT3100 but I still break down full sheets with my circular saw most of the time. If you want to cut full sheets, you need infeed and outfeed support and lots of room in the shop for clearance. The latter is my biggest issue a good bit of the time.

Full sheets weigh around 75lbs, more if its mdf, particle board or melamine. I handle them by myself but it is not totally easy. I use a trailer these days but have loaded lots of sheets on top of my previous SUV. It's a lot easier with a trailer than lifting full sheets overhead.

The best stuff at the big boxes last time I looked was the BCX. I would use it for shop cabinets (and have). I bought 3/4 BB from my hardwoods dealer. $44 for a 5x5 sheet was not too bad. It's heavy but much better plywood. I've made stuff from the cheap chinese 3/4 (around $30 for a 4x8 sheet) and they turned out OK but it is not any fun to work with. It is light but the inner plys wander all over. I had no stability issues with it. I kind of like the "handiply" Home Depot sells but I don't care for the outer surface. It is soft and fuzzes so it's kind of hard to paint. The inner plys are pretty good, however. If you get lucky, I have seen big box plywood that was pretty good but they didn't have any last time I looked.

1/2 is probably strong enough with face frames but will be significantly more difficult to work with than 3/4. Your shelf pin holes need to be near 1/2 deep, for instance, and holding the depth to a consistent 3/8 or a little more and getting all the dust out of the hole so you can use 1/2 is tougher than just drilling them 1/2 or a little deeper in 3/4. Dados in 1/2 can't be very deep. Lots of little things like that. Norm uses 3/4 for the backs but that is definitely overkill IMHO.

If I could tune and use the panel saw at the big boxes I might break down things there but I can't so I don't. If I knew a 1 inch tolerance would not cost me material, I might let them try. I don't think you can depend on them being much better than an inch.

Jim

[Schleeper]

I have extension rails and a bigger table surface on my BT3100 but I still break down full sheets with my circular saw most of the time. If you want to cut full sheets, you need infeed and outfeed support and lots of room in the shop for clearance. The latter is my biggest issue a good bit of the time.

Full sheets weigh around 75lbs, more if its mdf, particle board or melamine. I handle them by myself but it is not totally easy. I use a trailer these days but have loaded lots of sheets on top of my previous SUV. It's a lot easier with a trailer than lifting full sheets overhead.

The best stuff at the big boxes last time I looked was the BCX. I would use it for shop cabinets (and have). I bought 3/4 BB from my hardwoods dealer. $44 for a 5x5 sheet was not too bad. It's heavy but much better plywood. I've made stuff from the cheap chinese 3/4 (around $30 for a 4x8 sheet) and they turned out OK but it is not any fun to work with. It is light but the inner plys wander all over. I had no stability issues with it. I kind of like the "handiply" Home Depot sells but I don't care for the outer surface. It is soft and fuzzes so it's kind of hard to paint. The inner plys are pretty good, however. If you get lucky, I have seen big box plywood that was pretty good but they didn't have any last time I looked.

1/2 is probably strong enough with face frames but will be significantly more difficult to work with than 3/4. Your shelf pin holes need to be near 1/2 deep, for instance, and holding the depth to a consistent 3/8 or a little more and getting all the dust out of the hole so you can use 1/2 is tougher than just drilling them 1/2 or a little deeper in 3/4. Dados in 1/2 can't be very deep. Lots of little things like that. Norm uses 3/4 for the backs but that is definitely overkill IMHO.

If I could tune and use the panel saw at the big boxes I might break down things there but I can't so I don't. If I knew a 1 inch tolerance would not cost me material, I might let them try. I don't think you can depend on them being much better than an inch.

Jim

Good stuff, Jim (and everybody else who has contributed.)

As for the choice of 1/2 or 3/4 ply, I was thinking the same thing about the dado depth. However, today I just received my copy of Bill Hylton's highly respected Illustrated Cabinetmaking, How to Design and Construct Furniture That Works, in which he states, "The dado does not have to be deep to create a strong through dado joint. One-eighth inch [!] is deep enough in solid wood, 1/4 inch in plywood, MDF, or particleboard." (That was news to me!) The shelf support pins, as you pointed out, are another story.

The recommendation for using 1/2 ply came from one of my brothers, who has volunteered to help me install the cabs once they're finished. Perhaps weight (of the cabinets, NOT my brother) had something to do with that. He also recommended melamine interiors (except for the cabinets that will have glazed doors,) the rationale being that the surface is easier to clean, and it won't require staining.

[JimD]

John,

I used 3/4 melamine for cabinets in my basement with full overlay doors. It is durable and inexpensive. The issue is what to do with the edges and also how to cut it. With a good blade and a new ZCTP you can get low chip out but it is not hard to get more than I like to see. I caulked the intersections of the sheets inside the cabinets and the cauld tend to collect dirt. I may use it again but prefer plywood. It is more work because you must finish it but I like the end result better. You can also either get pre-finished plywood (that's what Norm uses) or finish the sheets yourself before cutting (I saw that in FWW) to give a finished interior.

I use shallow dados mainly to help locate pieces during glue-up. I'm not confident the strength is the same but it has always been enough.

Jim