fshanno said:
Tell me about some of the materials you've cut. Have you made long bevel cuts in sheet goods that weren't perfectly flat? If so how did you handle that?
Back in the late 1930's, when my grandfather Charles "Apa" Adams started me working with wood, he never used any sheet material. I did see plywood being used to repair airplanes and for building scenery. Compared to modern sheet material that 1930's plywood was crude. By 1946 I started to buy my own power tools. Eventually material shortages from WWII were forgotten. I noticed that plywood had become more sophisticated. Sheets 4' x 8' x 3/4" were available and sometimes nearly flat. I do not remember when particle board and MDF came along.
Long before I bought my first Festool TS55 I would snap a chalk line before making cuts on sheet goods. I took pride in following those lines without using any sort of straight edge. Often the material was less than flat, sometimes in both directions. My experience was that the results were better manually following the chalk line. Even when I intended to use a cabinet-size table saw to break down sheets, I still preferred to make the first long clean-up rip with a circular saw following the chalk line.
By the time I did buy my first Festool TS55 I was long past making-do with warped sheet material. There is some flexibility in 18mm thick plywood, but that is well within the ability of a Festool guide rail to follow, so long as the rail is appropriately clamped at both ends. Of course the design of pressure beam saws is like using 4 Festool guide rails top and bottom on both sides of the sheet. At least while the saw blade is making the cut the sheet is absolutely flat.
Prior to having my large shop I used two approaches to breaking down sheet goods.
When space and help was limited, I would work on a stack of sheets. I would lift the top sheet using wooden wedges so that I could slide pieces of 6mm Luan below it as a sacrificial surface. The Luan is far more supple than any cabinet-grade plywood. I would clamp that top sheet to several lower sheets, then use the long Festool screw clamps cat 489 571 to hold the rail in place. For practical purposes by the time I put my TS55 on the guide rail the sheet material was flat because of all those clamps.
I also had a sacrificial sheet of 18mm plywood supported by a frame on saw horses. If I was working with sheets I could lift easily I did the break down on the saw horses. With heavier material as the parts from the top sheet got lighter I would move them to the sacrificial surface. On that sacrificial surface if I needed a hole for a clamp, I simply drilled that using a hole saw. The supporting frame was inside the sacrificial sheet by a few inches all around. Again, if the sheet was not very flat, I would clamp its outside edges to the sacrificial sheet and then clamp the guide rail to both the sacrificial sheet and the goods being cut.
These days even if the bulk of the cuts will be made using a TS55 and guide rails, the clean-up long cut is usually made on the pressure beam saw. I still find that a Festool clamp at either end of a guide rail is a good investment in time.