Cutting MDF Compared to Plywood
Both MDF and Plywood can be very tough on the cutting tools. This is why it is important to use saw blades that are specifically designed for cutting MDF and Plywood. Below is a link to some tools specially designed for cutting MDF and Plywood along with some helpful tips on how to choose a saw blade for cutting MDF and Plywood. The rest of this article explains why MDF and Plywood have such a high wear on cutting tools and the differences bewteen the two materials.
MDF is much harder on tools than plywood is for a variety of reasons.
The density – especially the varying density (see below)
The mechanism of separation. Plywood shears while MDF ruptures.
The amount and kinds of fiber
The amount of glue and additives used to stretch it.
MDF is harder on cutting tools for several reasons.
There is just more material being cut. Typically MDF is heavier than plywood because MDF uses wood fibers and then compresses them. (See below)
Plywood uses peeled wood while MDF can use a variety of fibers some much more abrasive.
Plywood and MDF can both use the same woods. However in plywood the cells are open or hollow. In MDF the cells have been compressed flat. Cutting hollow a straw is easier than cutting a solid piece of plastic because you can cut the straw one wall at a time.
The binder is distributed differently in the two materials. In plywood the binder is largely in the overlapping sheets. MDF can be considered binder with particles in it.
In analysis of worn tools we see several things.
Just the amount of material being cut.
MDF is more abrasive because it denser. When cutting the fibers are severed but the cut material rubs on the side of the tooth causing wear similar to the effect of a stiff bush versus a soft brush.
MDF seems to trap more heat in the cut and heat affects the saw tips. Again this is a natural property of the density and the glue distribution.
Suppositions
It is widely believed that MDF is “grabbier” on cutting tools and tests with ammeters have seemed to confirm this. MDF draws more power than wood or plywood.
It is widely believed that the glue in MDF is stretched with a clay like binder much as clay is used in paper. This binder is much more abrasive than wood as clay is technically fine sand.
MDF is made of wood fibers and any source can be used. Although the fibers are broken down into cells they retain many of their base properties. Bamboo cells have different properties than fir cells.
Tips for choosing a saw blade for cutting MDF, Plywood, and particle board:
Buy a triple chip blade or an ATB blade with a 10 or 15 degree hook.
A higher tip count will give you better cuts in MDF, Plywood, and Particle board.
Make sure the board is completely supported during the whole cut - absolutely no overhang without support.
Feed the material absolutely straight and steady against a guide. 2 x 4’s are not really good guides. You can greatly affect cut quality, both good or bad, by how you feed. Experiment with scrap material to make sure you are feeding correctly.
Keep the blade sharp. Plywood and MDF are glued together. The glue uses clay as a filler. Clay is very small rocks so it really wears saw blades.
Yes, I'm going to do that but the cut can still turn out rough according to the blade you're using. Yes, low tooth blades will rip it good and not smooth is my experience with harder, natural woods and fiberboard.if you clamp a straight piece of 1/4"-3/8" plywood or MDF to to your work and follow it with the edge of the saw base it will cut smooth as glass
spent 5$ at harbor freight on a 142 tooth plywood blade. worked great. However, I only use my circ saw 5 or so times a year, and it's only for cutting mdf for enclosures.What type circular saw blade is best for cleanest mdf cuts (60 tooth, 80 tooth, 140, etc.)?