Router Table Top Issues

[steve-norrell]

I want to build a new router table top that will be attached to the extended rails of my BT3100. I am considering two materials for the top -- 3/4 inch baltic birch and 3/4 phenolic. In both cases, the top will be supported by an equal-sized sheet of 3/4 inch of MDF.

Birch: I know I can glue this to the MDF so that is not an issue. I am concerned about:

1) the possibility of voids (I know there are not supposed to be any.) under the router plate edges, and,

2) whether or not the plies of the baltic birch are solid enough to hold the leveling screws in the router plate edge.

Phenolic: I can purchase a phenolic top pre-cut for the JessEm plate, but my concerns are:

1) can the phenolic be glued down to the MDF, or can I just rely on its weight to hold it steady, and,

2) how does the phenolic machine? I will have to cut it down to fit my application and I want to route out two grooves for t-tracks.

As usual, the help from forum members will be much appreciated.

Thanks and regards, Steve

[Workman]

Woodcraft sells a 3/4" phenolic faced baltic birch plywood (both faces) that is fantastic for router table uses. Stuff easily slides on the phenolic and it is already attached to the plywood. You can screw into the plywood as always. Only color is green - didn't matter for my router table extension.

[Tom Slick]

I would add a threaded insert into BB for leveling the plate.

phenolic can be glued to MDF.
phenolic machines very nicely but stinks really really bad in the process,

[LarryG]

Although the two-material sandwich you propose has been done successfully, I personally would use two layers of Baltic birch plywood, resulting in a balanced assembly that will minimize the chances of one layer reacting differently to temperature and humidity changes and causing the assembly to warp.

Voids in BB ply happen but are rare, and small. In the somewhat unlikely event you do hit one right where the router cutout goes, you can fill it with a miniscule amount of wood filler.

Wear under the leveling screws is a legitimate concern. You can coat the area with epoxy; or better yet, drive home a flat-head wood screw under each leveling point to give the leveling screw a metal bearing surface. Or use Tom's idea of a threaded insert, replacing the levelers that come with the insert plate with longer ones.

[JR]

My router plate came with four small magnets, meant to be embedded in the table under the levelling screws. Seems to work fine.

JR

[LCHIEN]

Although the two-material sandwich you propose has been done successfully, I personally would use two layers of Baltic birch plywood, resulting in a balanced assembly that will minimize the chances of one layer reacting differently to temperature and humidity changes and causing the assembly to warp.

Voids in BB ply happen but are rare, and small. In the somewhat unlikely event you do hit one right where the router cutout goes, you can fill it with a miniscule amount of wood filler.

Wear under the leveling screws is a legitimate concern. You can coat the area with epoxy; or better yet, drive home a flat-head wood screw under each leveling point to give the leveling screw a metal bearing surface. Or use Tom's idea of a threaded insert, replacing the levelers that come with the insert plate with longer ones.

Larry hit upon my concern, while two materials may work OK together, you may have in the worst case a severe problem with mismatched coeffificients of expansion resulting in bowed or warped table tops. I feel the best idea would be to use a sandwich of the same material top and bottom.

[steve-norrell]

Hmmmm! Hadn't thought of the different coefficients of expansion (but should have). So, it would seem that the best solution would be a sandwich of either MDF or baltic birch, either of which is reasonable. Threaded inserts or flat-head screws would be used under ther plate edges.

I would like to float one more idea . . . The open span that the router table will cover is 21 inches square, with aluminum 'angle iron' supports on two sides (mounted on the rails). Would a 3/4 inch thick piece of phenolic be stiff enough so it won't sag over that distance? Alternately, cross beams could be built to support the phenolic table top.

Thanks again for the help, regards, Steve

[Slik Geek]

I would like to float one more idea . . . The open span that the router table will cover is 21 inches square, with aluminum 'angle iron' supports on two sides (mounted on the rails). Would a 3/4 inch thick piece of phenolic be stiff enough so it won't sag over that distance? Alternately, cross beams could be built to support the phenolic table top.

Phenolic is like plywood, except that its laminations are made of fiber and resin instead of wood and glue. I would expect that it would be rather stiff for your application if it is 3/4" thick. A 2' x 2' - 3/4" piece is probably going cost you at least $75. I would still build a support structure to insure that it is dead flat.

Be sure to use carbide-based cutting tools and wear a very good dust mask. Don't use your best carbide blade on it either - you'll likely put quite a few "miles" on the blade in the process.

[JimD]

My extension table which also will serve as a router table (when I do not use my dedicated table or in addition to the dedicated router table) has a top of 3/4 melamine plywood with stiffening ribs of 3/4 plywood across the width and along the edges. I put a piece of 1/8 flat stock into the inside grooves of the rails and have knobs with studs that clamp the vertical outside stiffening plywood to the rails. Sounds more difficult than it was.

Melamine particle board is cheap, stable, and the top surface is both durable and slick (when waxed). You could put a router plate in it but I do not see the purpose of plates. I just routed the back side of the melamine to reduce the thickness of the melamine to about 3/8 (on the back side and only the side of the router base), cut an opening for the bit, and screwed the base directly to the melamine.

Mine is several years old and still working fine.

Jim

[steve-norrell]

Thanks to everyone for the suggestions,

I neglected to note that I am using a JessEm lift and cannot bolt the router directly to the underside of the table surface. I have to cut an appropriate opening for the lift plate. Sometime in the future I want to look at building a router table where the router is bolted directly to the top, producing a perfectly flat surface with no router plate to contend with.

After reviewing the input, I will most likely use two layers of baltic birch, although there is still a chance that I would use MDF. If I can find some melamine or phenolic impregnated plywood or MDF here in Anchorage I would consider using that.

This is not a rush project as I do already have router table attached to the BT3100 and I have plenty of time to ruminate about it. (I know -- why fix something that isn't broken? Answer: Woodworkers are natural-born tinkerers.)

Thanks again for the advice. Regards, Steve

[Scottydont]

I would remiss without sharing that I used 3/4 MDF and laminate flooring for mine. I like the combo because it is dead flat and extremely durable. Here is a pic of how I did mine.