Router Table Top Build Questions

[Greg Stamm]

Hi all,

Just signed up or this website and this is my first post.

I will be laminating two 3/4" MDF panels together to create the table top using Titebond II. I will use a hacksaw blade to spread the glue, which will act like a micro trowel. My question comes in the clamping of the panels. I was thinking of making some curved cauls..........I saw an excellent method on this site where they were cut under tension. The table will be 36" x 27".

- In which orientation should I align the cauls and how many do I need (I was thinking 4)?

- Is it OK to sandwich the panel between sets of cauls or should I clamp the panel to a table using only cauls on top? If I clamp between the cauls do I risk having a potato-chipped top?

- How should the clamps be tightened? Should I clamp the center clamps down all the way before going on to the outside clamps or should I uniformly clamp the entire panel moving from area to area in a circle tightening a little each time (sort of like tightening the lug nuts on a car)?

Thanks,
Greg

[Jamie Buxton]

Another way to clamp the panels together is to use screws. The good thing about screws is that you can place them in the middle of the panels. The edges you can reach with conventional wood clamps. You can leave the screws in after the glue cures, or take them out. Be sure to bore clearance holes through the panel where the heads will be, so the screws pull the panels together.

[Michael Mayo]

I just finished a new router table top. I got an Incra LS Positioner for Christmas and needed a bigger table on my router cabinet to make the LS Positioner fit. I used 3/4" MDF two layers and I used Wilsonart contact cement to glue them together. It is so much faster than using regular glue. I have found that MDF really sucks up any type of liquid you put on it so it took two applications of contact cement to get them to adhere to each other solidly. Once I had two coats of glue on both sheets I lined them up to each other and laid them on top of each other. Then I used a laminate roller to squeeze them together and make them one piece. It worked beautifully and wasn't too messy. I then used the contact cement to glue a layer of formica laminate on top of the MDF layers and used the same procedure as I did with the MDF base layers. I checked it with my Woodpeckers straight edge and it is as flat as I can get it with my abilities in the home shop. It came out awesome and I am very happy with it. I don't think you need to go to all the trouble of using messy Titebond and clamps with cauls. Just get some contact cement and a laminate roller and you will be done in less time and using that table quicker than if you mess around with regular glue and clamps/cauls. As soon as I was done rolling the MDF layers and applying the laminate I was able to rout out the router lift hole and install it soon there after.

[Kevin McCluney]

I made my router table top using MDF and Titebond II as well. The attached picture shows my less than elegant clamping solution - clamps + scrap piece of granite countertop + paint cans + power tools. In retrospect I could have rough cut the router plate opening and clamped from the middle as well. My top ended up flat.

282550

[Art Mann]

I agree with Jamie. 1-1/4" drywall screws are a much more effective means of clamping than using cauls. I just built my second router table using that method. With such a vast surface area for the glue, clamping pressure and bond strength isn't an issue anyway. The more important issue is to force the two pieces to be flat while the glue cures. I used my tablesaw top as a flat reference surface and a couple of 75 lb RV batteries and a heavy tool box to force the MDF to conform to the flat surface.

[Shane Copps]

I have a question. What are you referring to as a "clamps with cauls"? I think I know what is being referred to but would like some clarification.

Thanks

[Myk Rian]

When you put the MDF together, put the convex sides together. )(
That cancels out any cupping, and makes the table flat.
I used Titebond III and just a few screws to keep it from sliding apart. Remember to countersink any screw holes between the panels, as MDF has a tendency to pull up in those spots.

[Ed McEowen]

Based on my experiences building two router tables with laminated MDF tops, just because your table comes out flat doesn't mean it will stay that way. If I had it to do over I'd place both convex sides up to make a slight crown. I should have used extra support directly under the edges of the router lift and seen that the outer edges of the table were well secured. I didn't use formica, so recently sanded the varnished MDF tops back to level.

[glenn bradley]

I am also with Jamie, especially on a panel that I know I will cut a section out of. Clamp around the outer edge and drive screws in the area that you will cutout for the router lift. You could alos use screws all around if you made you panel a little oversized. Then remove the screws, cut out the screw holes in the area of the lift and around the edges as you bring the panel to final size. Lots of options. I do use shop made curved cauls so don't get the idea that having some of these around isn't a good idea.

[Andrew Fleck]

I just finished a new router table top. I got an Incra LS Positioner for Christmas and needed a bigger table on my router cabinet to make the LS Positioner fit. I used 3/4" MDF two layers and I used Wilsonart contact cement to glue them together. It is so much faster than using regular glue.

+1 that's what I did too. It's been holding strong for over two years now and it was simple to put together. Just apply the contact cement to both sides with a paintbrush, roller, or whatever, let it dry about 45 minutes and put them together and apply pressure all over it to achieve a good bond. You can use a 2x4 or something to achieve this if you don't have the special J roller. I just cut one sheet a bit oversize so I could trim it all flush on the tablesaw once it was glued up.

[Roy Turbett]

You could also try the solution "Mr. Sawdust" came up with for a radial arm saw top. He cut !/8 wide dados in each piece and glued a piece of steel bar between the two to keep the table from sagging. I'd also go with screws over cawls but predrill pilot holes with the panels clamped together to eliminate tearout and dimples.

[John Coloccia]

I made my router table top using MDF and Titebond II as well. The attached picture shows my less than elegant clamping solution - clamps + scrap piece of granite countertop + paint cans + power tools. In retrospect I could have rough cut the router plate opening and clamped from the middle as well. My top ended up flat.

282550

For a while, i didn't have enough clamps to glue on guitar tops. I just made a caul and put my bench sander on one side and clamped up the other side :)

[Greg Stamm]

Thanks everyone for the advice.........so many good ideas!

Now, I have to decide between Titebond II or contact cement??

If I choose glue then I will use screws to clamp it.

Do you sand the mating surfaces of the MDF to give the glue some mechanical bonding advantage?


I have a question. What are you referring to as a "clamps with cauls"? I think I know what is being referred to but would like some clarification.

Thanks

Shane,

A caul is basically a tapered or curved length of wood or other material that is clamped across a panel with the thick part at the center of the panel........there is a gap at each end. When you clamp the ends the caul applies equal pressure (ideally) across the panel. Cauls are used in edge glue-ups for table tops and edge banding, as well, and probably for a host of other tasks.

Thanks again,
Greg

[Michael Mayo]

Thanks everyone for the advice.........so many good ideas!

Now, I have to decide between Titebond II or contact cement??

If I choose glue then I will use screws to clamp it.

Do you sand the mating surfaces of the MDF to give the glue some mechanical bonding advantage?



Shane,

A caul is basically a tapered or curved length of wood or other material that is clamped across a panel with the thick part at the center of the panel........there is a gap at each end. When you clamp the ends the caul applies equal pressure (ideally) across the panel. Cauls are used in edge glue-ups for table tops and edge banding, as well, and probably for a host of other tasks.

Thanks again,
Greg

I did not sand the MDF before applying the contact cement. But like I stated the MDF is very porous and soaks up the contact cement really fast so knowing this from previous failures I applied two coats of contact cement before putting the two layers together. I only waited maybe 15 min. between coats before gluing everything together. Just test the surface with your finger after waiting 10 min. or so. If you can press your finger down onto the surface and not get stringy glue to come with your finger it is ready.

[Art Mann]

Here is another tip to help prevent the table from warping. Laminate both the top and the bottom of the table. This will prevent moisture from being absorbed differentially during rapid humidity changes and the plastic laminate acts somewhat like the skins of a torsion box to keep the material flat.

[Shane Copps]

Greg,
That is what I thought so thank you for clarifying.

Next question for you guys (gals). What are the pro/con of mating 2 MDF boards vs. 2 plywood boards. I am assuming that the sizes (thickness) would be equal in the comparison.

Thank you for all the help and enduring the questions
Shane

[Myk Rian]

Greg,
That is what I thought so thank you for clarifying.

Next question for you guys (gals). What are the pro/con of mating 2 MDF boards vs. 2 plywood boards. I am assuming that the sizes (thickness) would be equal in the comparison.

Thank you for all the help and enduring the questions
Shane
Not much. My RT is MDF, the RAS is ply.

[Tom M King]

Single sheet of solid phenolic bowling alley flooring. The only downside is the fake woodgrain top.

[Kevin McCluney]

Here is another tip to help prevent the table from warping. Laminate both the top and the bottom of the table. This will prevent moisture from being absorbed differentially during rapid humidity changes and the plastic laminate acts somewhat like the skins of a torsion box to keep the material flat.

+1 on laminating both sides. I didn't do that with my first table (laminated one side only and painted the back side; warped as expected over time), but did do both sides on the current one. I also banded the edges with 3/4" maple (outer and the inner ones where the router hangs, and polyurethaned) - that prevents moisture intrusion at the edges of the MDF and looks a whole lot better.

[Pat Barry]

I am also with Jamie, especially on a panel that I know I will cut a section out of. Clamp around the outer edge and drive screws in the area that you will cutout for the router lift. You could alos use screws all around if you made you panel a little oversized. Then remove the screws, cut out the screw holes in the area of the lift and around the edges as you bring the panel to final size. Lots of options. I do use shop made curved cauls so don't get the idea that having some of these around isn't a good idea.
This is excellent advice. I also agree with the thought of putting the convex sides together as Myk described because that way you know the center comes together. Putting the convex outward will make it difficult to know for sure. Anything goes for clamping including the weight idea or cauls. Be sure to work from the center outward as you clamp / screw it together. I would use the Titebond for the glue up also.

[Greg Stamm]

Here is another tip to help prevent the table from warping. Laminate both the top and the bottom of the table. This will prevent moisture from being absorbed differentially during rapid humidity changes and the plastic laminate acts somewhat like the skins of a torsion box to keep the material flat.

I too, will be laminating both sides with some type of plastic laminate (Formica or similar). I will also seal all other edges, such as the router plate rabbet and any holes with varnish or something.


+1 on laminating both sides. I didn't do that with my first table (laminated one side only and painted the back side; warped as expected over time), but did do both sides on the current one. I also banded the edges with 3/4" maple (outer and the inner ones where the router hangs, and polyurethaned) - that prevents moisture intrusion at the edges of the MDF and looks a whole lot better.

I am planning on edge banding the table edge with a hardwood. I am thinking of rabbeting the top and bottom of the table to provide a tongue and routing a mating groove in the edge banding to provide a stronger bond. I am planning on adding a T-track to the router table for clamping one end of the pivot fence. I'm thinking of two options:
- putting the T-track in the table top itself or
- putting it in the edge banding

The potential problem that I see with putting it in the edge banding is that the edge banding will have to be wider to accommodate the track (because of the tongue and groove) and this, coupled with the clamping force may weaken the bond of the banding to the table.

Any thoughts on this?

I haven't thought about edge banding the cutout for the router plate, but I have thought about gluing on plastic laminate to the horizontal face of the rabbet, so that the router plate leveling screws don't dig into the MDF.

[Michael Mahan]

i use 2 sheets of 1/2" mdf & core of 3/4 oak ply , titebond II & screws I pull the screws after set-up & fill the holes
then laminate both sides with formica
then edge band with 3/4 red oak after the formica with dominos to hold fast the 3/4" thick banding
then trim the oak with a straight bearing bit
solid & stable
the ply adds opposing layers that stop the mdf from sagging

[Phillip Gregory]

I did the exact same thing you did with my Norm Abram router table with laminating together two pieces of 3/4" MDF, although I used Titebond I and an el cheapo olefin paintbrush to spread the glue. I applied pressure by putting a 3/4" piece of plywood down on my concrete floor, then put the two panels down, then put every heavy piece of metal in the basement on top of the two pieces of MDF. I put about 400 pounds of plate weights, dumbbells, a toolbox full of socket wrenches, and a few 25# bags of shotgun shot on there. It turned out beautifully. The weights avoid the issue of bowing and uneven pressure with clamps.

[Kevin McCluney]

I too, will be laminating both sides with some type of plastic laminate (Formica or similar). I will also seal all other edges, such as the router plate rabbet and any holes with varnish or something.



I am planning on edge banding the table edge with a hardwood. I am thinking of rabbeting the top and bottom of the table to provide a tongue and routing a mating groove in the edge banding to provide a stronger bond. I am planning on adding a T-track to the router table for clamping one end of the pivot fence. I'm thinking of two options:
- putting the T-track in the table top itself or
- putting it in the edge banding

The potential problem that I see with putting it in the edge banding is that the edge banding will have to be wider to accommodate the track (because of the tongue and groove) and this, coupled with the clamping force may weaken the bond of the banding to the table.

Any thoughts on this?

I haven't thought about edge banding the cutout for the router plate, but I have thought about gluing on plastic laminate to the horizontal face of the rabbet, so that the router plate leveling screws don't dig into the MDF.

To accommodate an aluminum miter slot and T-tracks for the fence I embedded maple in the MDF.
283011 283012

[Roy Turbett]

Greg,
That is what I thought so thank you for clarifying.

Next question for you guys (gals). What are the pro/con of mating 2 MDF boards vs. 2 plywood boards. I am assuming that the sizes (thickness) would be equal in the comparison.

Thank you for all the help and enduring the questions
Shane

I've found that the MDF is flatter but plywood is probably stronger.