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Combination of BB Plywood and MDF for Router Table Top

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Forum topic by PresidentsDad posted 11-27-2018 08:53 PM 1101 views 0 times favorited 12 replies Add to Favorites Watch
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PresidentsDad

38 posts in 668 days


11-27-2018 08:53 PM

Hey all,
I’ve seen a number of arguments against Plywood for a router table top and a number of arguments for an MDF/HPL covered top. Typically, it seems that most folks double up on pieces of 3/4” MDF to make a 1-1/2” thick top and then cover in HPL. I’ve a a couple of reports that even the 1-1/2” solution would sag over time if a 3-1/2 HP (aka heavy) router motor is used.

My question is this…has anyone done a combination of 3/4” BB Plywood on the bottom and 3/4” MDF on the top (still covered with HPL) to create a more stable (but still flat) router table top? If so, pros and cons to that idea?

Thanks in advance for the assistance.


12 replies so far

View jonah's profile

jonah

2075 posts in 3719 days


#1 posted 11-28-2018 12:56 AM

Why wouldn’t you use plywood? My router table extension is made of plywood and it’s perfectly fine. It’s two layers of 3/4 baltic birch laminated together. I have a hard time believing MDF is going to be in any way better.

View Mike_D_S's profile

Mike_D_S

595 posts in 2635 days


#2 posted 11-28-2018 02:36 AM

Like any project, you simply need to reinforce where you expect the loads to be highest. You can check out my blog linked below for my DIY router table wing I built for my table saw.

I used 3/4 phenolic faced ply and simply reinforced across the bottom with a couple of strips of 3/4×1 1/2” oak strips. No sag after 3 years with the big PC router motor and a fairly heavy Jessem lift. The strips made a convenient place to attache the home built dust shroud that goes around the router motor.

Mike

My blog post

-- No honey, that's not new, I've had that forever......

View ksSlim's profile

ksSlim

1301 posts in 3310 days


#3 posted 11-28-2018 03:46 AM

I used 3/4 Melamine over plywood. 8 years with WoodPecker lift and 3 HP porter Cable router and no sag.

-- Sawdust and shavings are therapeutic

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PresidentsDad

38 posts in 668 days


#4 posted 11-28-2018 07:36 AM

Mainly I’ve heard that plywood is not really flat and MDF sags over time. I was thinking a sandwich of 3/4 BB plywood on the bottom and 3/4 MDF on the top with HPL on top of that would be stiff and flat. Thoughts?

View WoodenDreams's profile

WoodenDreams

623 posts in 331 days


#5 posted 11-28-2018 07:50 AM

I would not use plywood for a table top. But would consider plywood as a under layer. My router table is 1” melamine. You want a surface that allows you to slide the board smoothly, across on each pass, with no possibility of snagging on each pass. MDF top would be alright. Have you considered a formica laminate or formica countertop. My next router table I’m planning on using a formica countertop.

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PresidentsDad

38 posts in 668 days


#6 posted 11-28-2018 07:53 AM

Wooden Dreams…re-read my last comment. :) My thoughts are to make a top that has BB Plywood on the bottom layer, MDF in the middle layer and HPL (aka Formica) on the top layer. My thinking is that Plywood is strong, MDF is flat and HPL is durable.

View Fred Hargis's profile

Fred Hargis

5591 posts in 2913 days


#7 posted 11-28-2018 11:40 AM

I have not used a laminated top like you describe, but I do think that those who have sag simply have not supported the top adequately. (BTW, some inserts will also sag under heavy weight, suggest you stay with a thick aluminum one). My table is a version for the one Norm built and has support underneath it near the center, both sides of the insert. It’s over 15 years old and still has no sag. I used 1/2 of a 1 3/8” solid core door to make mine, but I think the results would have been the same with any of the materials mentioned.

-- Our village hasn't lost it's idiot, he was elected to congress.

View HokieKen's profile

HokieKen

9950 posts in 1558 days


#8 posted 11-28-2018 11:56 AM

My router table top is 2 layers of 3/4” MDF with Formica laminated on top and oak edging. I built it over 2 years ago and it’s had my 3.5hp PC router hanging from it since with no sag. I may have to replace my Kreg plate soon because it’s starting to show some sag. But not the top. YMMV of course but I’m happy with the MDF. I don’t see any issue with using ply and MDF either. As pointed out above, the key is starting with something flat and supporting it properly.

-- Kenny, SW VA, Go Hokies!!!

View jonah's profile

jonah

2075 posts in 3719 days


#9 posted 11-28-2018 02:07 PM

With a decent finish on it, plywood is more than slick enough for a router table top. I put a few coats of arm-r-seal on it and then applied paste wax. It’s as slick as can be.

View Robert's profile

Robert

3436 posts in 1901 days


#10 posted 11-28-2018 04:48 PM

I just built my 3rd router table top. That’s because of new routers/new inserts, desire for larger table.

I built everyone the same way: 2×3/4 MDF + laminate.

When you glue the MDF put on a flat work bench and use screws as “clamps”. When glue is dry remove screws. Edge with hardwood and LAMINATE BOTH SIDES & it will not sag – I promise!!.

Be sure to use the thicker horizontal laminate for countertops.

If you build a cabinet will have a cross brace on either side of the insert anyway if you’re worried.

-- Everything is a prototype thats why its one of a kind!!

View MrRon's profile

MrRon

5571 posts in 3663 days


#11 posted 11-28-2018 08:16 PM

I have a 3-1/2 hp router with a router lift hanging from 3/4” MDO. The top has stayed flat for the past 5 years. It’s all a matter of how you support/brace the top. A piece of 3/4” plywood that has bracing 6” away from the router is plenty stiff, but if supporting structure is 24” or more apart, the top will sag.

View PresidentsDad's profile

PresidentsDad

38 posts in 668 days


#12 posted 11-28-2018 08:17 PM

Got it, thanks for the info gents!

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