Best Way of Making a Router Table Stay Flat?

[Michael Lutz]

I know there is another thread ongoing about a similar issue Rick had with his router table. His issue was with a standalone router table with a swing up top. I am going to be building my router table in my right TS extension table. I already have the lift and the router for the table. I was not going to build a cabinet underneath the table at this time, only the table.

This router table will replace the current extension table. I am looking for a more durable surface than the melamine surface of the table board (which already has a few gouges in it). The table will need to span 28" between the front and back rails. I would prefer to use BB plywood vs. MDF, since I don't like working with MDF. I would also like to use a laminate surface on the top. I had been thinking of adding aluminum miter tracks to the table, but I am reconsidering due to comments from others due to their usefullness and possible cause of warping the top.

Here are some options I am looking at:

a. torsion box - 3" thick, 1/2" top and bottom skins, reinforced in the area of the plate. Do you laminate the top and bottom skins or just the top skin, then how do you get glue to stick?

b. Thick top - 2.25" thick layer of 3 pieces of 3/4". Laminate the top and the bottom.

c. Similar to the extension table - 3/4" top with 2 1/4" support frame. I would reinforce it in the area of the router openning. Do you just laminate the top and the bottom of the top? How do you attach the frame to the laminate covered top.

Letter c. would be the easiest to set the table flat to the top of the TS, since there is access to the machine screws beneath the table. a. and b. would require installation of threaded inserts to use the machine screws or small lag bolts/large screws which may or may not work well.

What have others done mounting their router in the TS extension?

Thanks,

Mike

[Jim Becker]

Primary best practice is to provide good support for the top such that only small areas are left with nothing under them. It almost doesn't matter what the top construction is in that respect and within reason. I never had a problem with sagging on the two router tables I built...both used a double layer of MDF surfaced both sides with plastic laminate. The cabinet, particularly on the second one, left maybe only 12" "exposed" directly over the router compartment.

The same principles would hold for a table saw extension if built "traditionally". A "foot" directly under any dust control cabinet would provide additional anti-sag support, too. You could do a modified torsion box with a few inches "open" on the bottom right at the saw for easier mounting to cope with the issue you describe with fasteners.

[Bruce Benjamin]

I made mine out of 2 pieces of 3/4" mdf sandwiched together and laminated with "Formica". I used 1.5" angle iron set in a tic-tac-toe pattern under the top. Well, sort of. Maybe you could describe it as more of a capitol, "H" with 2 cross bars instead of just one. Using shims and small hex head lag bolts I was able to pull or push it dead flat without too much trouble and it's stayed that way for several years between the rails of my table saw. I see no way that it will ever change but if it does I'll have to reach under there with a socket wrench and maybe some shims and do some adjustments. That won't be easy considering the drawers and dividers I have under there but it will be possible. But as I said, I don't think it will ever move since it hasn't moved in over 4 years and it's had a heavy Freud router in it the whole time.

Bruce

[David DeCristoforo]

I have only built one router table and I used a 24"X48" chunk of 1 1/2" thick maple "butcher block" (commonly sold for use as counter top) for the top. It was not very expensive and it has never been anything but flat.

[Jim Becker]

I made mine out of 2 pieces of 3/4" mdf sandwiched together and laminated with "Formica". I used 1.5" angle iron set in a tic-tac-toe pattern under the top. Well, sort of. Maybe you could describe it as more of a capitol, "H" with 2 cross bars instead of just one. Using shims and small hex head lag bolts I was able to pull or push it dead flat without too much trouble and it's stayed that way for several years between the rails of my table saw. I see no way that it will ever change but if it does I'll have to reach under there with a socket wrench and maybe some shims and do some adjustments.

That's a really great idea, Bruce...kinda the same principle as strengthening shelving, but adjustable. Kewel!

[Bruce Benjamin]

That's a really great idea, Bruce...kinda the same principle as strengthening shelving, but adjustable. Kewel!

Thanks. I would try to take a picture but now it's pretty much invisible and only reachable by feel because of the drawers and dividers.

Bruce

[Nancy Laird]

Michael,

Find a local countertop shop that makes laminate counters and beg for a free or cheap top that has been declined for some reason. All such shops have them stashed back in the corner and you can get them for cheap or free just to get them out of the shops. You probably won't have much of a choice of laminate color, but you can make a pretty darned solid top out of it. After all, how many times have you seen a laminate countertop sag??

We have our Unisaw outfeed table and the 50" extension table both made of recycled countertops. They've been in place for 13 years with no sag - just edged with hard maple. One of those, with perhaps a grid beneath it, should last for years.

Just MHO.

Nancy (95 days)


Nancy (95 days)

[Chris Parks]

Some of those options are really heavy, make sure the table won't tip with the added weight.

[glenn bradley]

As Jim stated. The pattern of 2 1/2" x 1 1/2" ribs I posted in Rick's OP has worked for me and my top is only 3/4" w/ laminate on both sides. The trick seems to be not leaving enough of a span to allow the sag.

[Jules Dominguez]

In my opinion, you don't need a double layer of MDF or any other material that's at least 3/4" thick. Just glue some straight (must be straight) boards on edge to the bottom in one or both directions. I use oak for things like that, because I have a stock of it, but 3/4x1x4 pine, or boards cut from a scrap of decent plywood would probably work as well.

[Bruce Benjamin]

After all, how many times have you seen a laminate countertop sag??
Just MHO.
Nancy (95 days)

While getting a left over countertop at a good price is a great idea, I'm not sure I agree with your logic regarding not seeing a sagging countertop. How many times have you put a straight edge on a countertop? I expect my router table to be dead flat and I've checked it with a straight edge. When I first made the table it looked flat but when I checked it with a straight edge it wasn't. So I adjusted it using my method of shims and bolt tightening on the angle iron. It looks the same to the naked eye and now it looks flat when I use a straight edge too. My point being, check a countertop before you assume it's flat.

Bruce

[Michael Lutz]

Chris, there are legs on the end of the TS extension table. The extension table is approximately 36" long.

Bruce, I am intrigued by your idea, but I have a few questions. How did you attach the top to the support rails? 1.5" depth would not be deep enough to reach my rail attachment bolts. Is the steel angle iron also attached to the rails?

Thanks,

Mike

[Bruce Benjamin]

Bruce, I am intrigued by your idea, but I have a few questions. How did you attach the top to the support rails? 1.5" depth would not be deep enough to reach my rail attachment bolts. Is the steel angle iron also attached to the rails?

Thanks,

Mike

Mike, I don't know what kind of table saw or fence setup you have. Mine is on a General International 50-185 contractor saw with the GI clone of a Biesemeyer home version fence. The fence rails are angle iron. the front rail is 2"x2" angle and the rear is 1.5"x1.5" angle and it's attached all along the front and back of the cast iron table top of the saw and extends about 34" to the right of the cast iron table top. These are the stock fence rails. The front rail also has the rectangular tubing attached to it for the fence to clamp to but that part isn't relevant to the router table. So the router table is framed with some 1x3. It's bolted to the end of the cast iron extension wing using the stock holes. It's also bolted to the fence rails using stock holes in the angle iron rails. Then, because I built an entire TS and router table on a large and sturdy cabinet I bolted the end of the router table to the end wall of the cabinet. The 1x3 was necessary so that the fence rail holes could be used to attach the table. But it was very close. Really, it's a very simple setup. Here's a link to the GI website showing the saw in stock form with the short rails. Mine is the long version. http://www.general.ca/pagemach/machines/50175185a.html

The angle iron that I used to level the bottom of the table isn't attached to anything else but the table. If the table sags in the middle, (concave) the bolts in the middle of the angle iron, (which ever one is closest to the sag) are kept loose and playing card shims are placed between the angle iron and the table top. The bolts at the end of the table are then tightened until the shims push up the sagging table. The opposite procedure if the table is convex. Shim the ends, tighten the middle bolts. I didn't rely much on the cast iron extension wing, the fence rails, or the end cabinet wall to keep the table flat. Only level with the table saw table. Clear as mud?

Bruce

[Michael Lutz]

Bruce, I have a PM66 with a biesmeyer clone fence similar to yours. So did you attach the angle iron to the table with threaded inserts? I now have a better picture of what you did to keep it flat. Thanks.

Thanks,

Mike

[Bruce Benjamin]

Bruce, I have a PM66 with a biesmeyer clone fence similar to yours. So did you attach the angle iron to the table with threaded inserts? I now have a better picture of what you did to keep it flat. Thanks.

Thanks,

Mike

Hi Mike. No, I didn't use threaded inserts although it wouldn't hurt to do so. I used some 1/4" lag bolts, (I think that was the size, maybe 5/16") and they got a good bite into the MDF. If I was going to be adjusting the table a lot I think it might be a good idea but as it is I've never had to adjust it again after the initial setup. If I were using screws with smaller threads I think the threaded inserts would be a good idea. The lag bolts aren't going to pull out, or at least they've shown no sign of it in several years. This is assuming that the angle iron you're referring to is the angle that keeps the table flat. If you're talking about the fence rail angle iron then I used wood screws and I didn't use threaded inserts there either.

Bruce