MDF question

[Alan Turner]

Guys --
I have recently made a crosscut sled, which I love. It is dead square, and easy to use. I used MDF for the base, and was wondering if I could rub a couple of coats of shellac on it to seal both sides? MDF is not something that I oft work with, but my stock of BB was not quite flat, so thought I would igve the MDF a try.
Any comments, or shared experiences, would be appreciated. Thanks.
Alan

[Mark Singer]

Alan,
I usuall seal it with a penetrating oil like Tried and True or Daly's. I have a sled I made also years ago and it works great... ths trick is to leave the second runner(only 1 screw) loose until both of them are in the miter slots and then set the second screw ...so the alignment is dead on.
Try the oil on a scrap ...2 coats and your good , but of course both sides.
Mark

[Tyler Howell]

Gents, :confused:

If I could dip this well of knowledge for a quick scoop? Is there Low DF, and High DF as well?? Haven't heard them mentionerd before.
Thanks

TJH

[Alan Turner]

I actually place the runners in the slot, with glue, and shoot them from the top with a nail gun. Then, flip it over and screw it. The cross pieces, front and back, go on later, squared to the blade.
If the oil/varnish is OK, then I think the shellac would be OK also. This way I can put two coats on in about 5 minutes with a rubber, and wax it up. I have not waxed it yet, not knowing what finish I could use. I will do both sides, of course. Shellac is my default finish, all things being equal. In Pa, varnish drying is like grass growing, but with more dust.
Alan

[Mark Singer]

Alan,
I am sure that will be fine...MDF takes everything pretty well.
Mark

[Mark Singer]

Tyler,
MDF is "medium density fiberboard" it is a laminayed paper product.. "High density board" is an overlayed plywood ...it has a "skin" and is used for signs and forming high grade concrete. MDF now comes in a lightweight version as well much better for the back...the other stuff is heavy,
Mark

[Tyler Howell]

Thanks Mark.
Now MDO (medium density oberlay) is the paper overlay for signs??? Can't tell the players with out a program. Getting in deeper here!

[Mark Singer]

MDO
Thats right! You've got it;
Mark

[Cliff Newton]

I use spray poly on my jigs made out of MDF. Then if your want to make it slick, rub a little wax on it. The poly will outlast shellac I think.