Mr. Sawdust Table

[Tommy Squires]

I am considering this technique for a router table top but I am unclear about how the metal is embedded in the layers of MDF. I gather the metal strips are turned perpendicular to the flat surface of the top then epoxied in. Is that correct? I would also assume that the strips of metal are not quite as wide as the top is thick? Is angle sometimes used?

[Michael Prisbylla]

Funny you should ask this question. I've built a few radial saw tables this way and am currently building a router table this way, too. You've got it right. If you're using 3/4" thick stock, get 1/8" thick bar stock 3/4" wide cut a little shorter than your table is wide. Cut kerfs a little deeper than 3/8" deep and a little more than 1/8" wide into both pieces so that they line up when the halves are placed together. Epoxy the bars and yellow glue the rest. I just use heavy weights for clamping pressure on a flat floor. MDF works better than plywood for this. Oh, if you're using t-track or a miter gauge slot in the table top, the bottom kerfs will need to be deeper and the to ones shallower for clearance.

I'm putting angle iron screwed to the bottom of my table. This will be perpendicular to the bars so it's supported both ways. In my case, since this will be a portable table, they will also extend over the rear edge to provide a way to clamp the table top to my bench.

Let me know if this isn't clear.

[Roy Hill]

Do either of you have photos of this table. It sounds like something I might be interested in.

Thanks.

Roy

[Fred Hargis]

I just use heavy weights for clamping pressure on a flat floor. MDF works better than plywood for this.
Don't overlook the "flat floor" part of the above post. it has to be clamped perfectly flat once assembled. This is apparently where most folks have a problem putting it together. When I made mine (for an RAS)) I put the bar 1/2" deep into the lower panel to give me a little more clearance at the top...in case of a disaster. Ditto on the MDF also.

[Ben Martin]

Did you guys buy the Mr. Sawdust book to get instructions for the table, or is there a link that you have with directions? I have heard many people refer to the book and his table.

[Fred Hargis]

Did you guys buy the Mr. Sawdust book to get instructions for the table, or is there a link that you have with directions? I have heard many people refer to the book and his table.
I did not buy that book (yet), but after reading many posts on a couple of different forums garnered enough info to build mine. It's really not that hard, you sandwich two pieces of sheet stock, and cut grooves to accommodate the steel bars. The bars run the long dimension, and once they are epoxied in place it really makes the table solid. Here's a link to photo that shows the grooves quite clearly. http://www.owwm.com/photoindex/detail.aspx?id=555

[Ben Martin]

I did not buy that book (yet), but after reading many posts on a couple of different forums garnered enough info to build mine. It's really not that hard, you sandwich two pieces of sheet stock, and cut grooves to accommodate the steel bars. The bars run the long dimension, and once they are epoxied in place it really makes the table solid. Here's a link to photo that shows the grooves quite clearly. http://www.owwm.com/photoindex/detail.aspx?id=555

Hmm, interesting. The iron is supposed to reduce sag, right? Or am I completely missing something...

Seems to me that that would be overkill, I couldn't imagine two pieces of MDF glued together sagging.

[Tommy Squires]

Ben, they can and do sag. As we mount heavier and heavier routers this becomes more of a problem. I have a shaper so this will be a light duty router table but still I want to do all I can to make sure its flat.

Why is MDF better for this application?

[Andrew Joiner]

I like a router table to have a slight crown to the top. The stock will then contact the cutter and the table at the point of cut.

I will be making a router table top with hardwood bars slightly larger than the steel bars. When I glue it up I'll bend in a crown to the top. About 1/32" over the 3' foot length of the top.

I might make it adjustable with no embedded bars but one bar under the top. A screw will bend the top up a hair as needed, but it will never sag. Yes that's it simple, cheap and sag proof.

[glenn bradley]

I couldn't imagine two pieces of MDF glued together sagging.

Believe it. DAMHIKT. Proper support is critical for your router table or any other MDF (or double MDF) span of a foot or more that needs to remain reliably flat.

[Tommy Squires]

Michael, Fred, each of you seems to favor MDF for this metal / sheet goods sandwich. Can you tell me why? I would think that BB ply would do as well but maybe I am overlooking something.

[Michael Prisbylla]

Well, I've never worked with baltic birch, so I can't really talk much about that, but MDF is very flat and stays that way if supported. Ply sometimes tends to warp. I like to get my RAS and router table st up to .002" tolerance if possible. At least that's what I've read is a good idea for the RT, this is my first. I can vouch for it staying good and flat on the RAS, though. Sorry, I don;t have any pictures of it going together. About the Mr. Sawdust book, it is very DeWalt specific, it's of less use for other brands of RAS, though still helpful.

[Fred Hargis]

I have worked with BB (but not in this kind of top), and think in this application the MDF is much better, as much as I hate it. It's very stable and the stuff I buy is generally more flat. The weight is something of an advantage as well. But remember, mine is on an RAS...I haven't done this for a RT...though I will consider it if I ever rebuild mine.

[Randal Stevenson]

I am having shop time issues and at the rate it is going, it is going to be a while. Has anyone used the phenolic coated, baltic birch plywood, that Woodpeck has on sale now? I was wondering about using the 1" stuff, for a replacement top on the other RAS I picked up last year.


Otherwise, I will just have to let it sit until I have time to build the other.

[John Petsche]

Nice tips on mrsawdust table.

[Jerome Hanby]

he "Mr Sawdust" book is a great one to have in your collection even if you are never going to touch a RAS.

[Mort Stevens]

Do a search for "Wally Kunkel" (Mr. Sawdust) - he wrote an article about building a radial arm saw top strengthened with steel bars... basically you take 2 pieces of MDF mill some slots in what will be the middle core to receive the steel - being mindful of the openings and miter slots you need. When I made my router table (based on the New Yankee Workshop design) I used three 3/16" by 3/4" straight steel bars and poured epoxy into the slots and inserted the steel bars after spreading wood glue on the MDF. I used screws in a pattern like the NYW table to clamp the 2 layers of MDF together. Then I also put plastic laminate on both the top and bottom surfaces. I'm glad I took the extra time to put the steel in the MDF, because the top is rock solid, and that was done ~5 years ago and it's still nice and flat and I expect it will be for the life of the router table.

It took me a while to find it, but, because a pictures worth a thousand words, here's the drawing I made when I did my top; http://img10.imageshack.us/img10/7864/66162695.gif

[Bill Geibe]

<<Did you guys buy the Mr. Sawdust book to get instructions for the table, or is there a link that you have with directions? I have heard many people refer to the book and his table.>>

I finally got curious enough to buy the book. Michael B. in Post #2 gave a description that's pretty accurate to the way Wally Kunkel designed his table. Wally said to use two identical sheets of 3/4" marine grade or hardwood ply. Mort has a nice spin-off design above.

Bill

[John Coloccia]

Believe it. DAMHIKT. Proper support is critical for your router table or any other MDF (or double MDF) span of a foot or more that needs to remain reliably flat.

Yep...believe it. My MDF/Plywood lamination sagged over the course of a couple of years.