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Forum topic by balsabob posted 03-09-2008 01:35 AM 804 views 0 times favorited 8 replies Add to Favorites Watch
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balsabob

4 posts in 2664 days


03-09-2008 01:35 AM

I am building the Norm Abrams Router Table and find that the top I built-and just tested with the assembled fence- is not flat.

I put the Fence on the top and find that the fence “rocks” lengthwise approximately 1/8” and when I turn the top over the fence remains flat.
I am leaning to laminating the bottom and using that surface for the final Table top.

Any suggestions would be appreciated.

Bob

-- Bob, Calif.


8 replies so far

View jcees's profile

jcees

953 posts in 2522 days


#1 posted 03-09-2008 02:13 AM

You should laminate both sides anyway. It helps equalize any stresses that the top comes under in use. Of course, I am assuming that you used either built up MDF or Baltic Birch ply. Also, how long has it been since you put the laminate on the topside? If it’s been awhile and the top has been in an air conditioned or heated space then that would explain why the top has distorted. The lack of opposing laminate is the culprit.

Now if that “bottom” side is truly flat, then I would get some laminate on it fast. And you might want to let it fettle and check it in a week or so and see if it is still flat. Other than that, you’re probably good to go with the flat side.

Have you already cut the hole for the router? Even if you have, you can still flip it and rout out the hole to the size of the plate then attach ledgers for the router plate to sit on. Good luck.

always,
J.C.

-- When one tugs at a single thing in nature, he finds it attached to the rest of the world. -- John Muir

View GaryK's profile

GaryK

10262 posts in 2711 days


#2 posted 03-09-2008 02:20 AM

I agree with jcees about laminating both sides. It balances it out.

If you don’t have too much work/materials into it already, it might be faster and more reliable
to just start over. I would be worried that when you add the second piece of laminate it might
just warp in some unexpected way.

I laminated both sides of my table. You can check out my workshop to see it.

-- Gary - Never pass up the opportunity to make a mistake look like you planned it that way - Tyler, TX

View DaveH's profile

DaveH

400 posts in 2501 days


#3 posted 03-09-2008 05:58 AM

I put the plastic laminated both side of my router table also. I used 3/4 mdf. 2 pieces glued together with contact cement. You need to make sure that the work table that you are using is really flat when laminating and that you apply enough pressure to make sure everything stays flat. I’ve got some project pics of my table.

-- DaveH - Boise, Idaho - “How hard can it be? It's only wood!”

View balsabob's profile

balsabob

4 posts in 2664 days


#4 posted 03-09-2008 03:10 PM

Thanks for the quick responses. The top is two pieces of MDF-1/2” and 3/4”. I have not cut the hole for the router plate and have cut the strip for the miter gauge. I guessing that when I clamped the two pieces I did not “hold” the middle sufficiently to bond as tight as the sides.

Very frustrating!

Gary, I might take your suggestion and just start over.

My weather conditions are southern California with minimal humidity. The glue up took place two weeks ago.

I could also place the top between two level boards and use the router as a “planer” and level the laminated surface.

I don’t have a sufficient amount of laminate for both sides and that stuff is expensive.

-- Bob, Calif.

View Dadoo's profile

Dadoo

1771 posts in 2713 days


#5 posted 03-09-2008 05:08 PM

Metal. Cast iron. 1” thick!

Or, speaking from experience, make it thicker. My first router table was a scrap piece of counter top 3/4” thick. Worked really great till I one day discovered it had sank 1/32” in the center! Try scrapeing 1/32” of hard maple off a 2” wide breadboard edge thats appx. 20’ long…and without marring the laminated top it’s securely glued to! Took weeks.

So another word of advice: Put a straight edge on it once in awhile. MDF sucks water right out of the atmosphere. It’ll swell and it’ll sag. Some of the guys here are getting good results with laminating 2 pieces of 3/4” MDF together. That makes a tabletop 1 1/2” thick bud. Should last as long as it don’t get within 30 miles of any lake or pond. LOL!

Good luck to ya!

-- Bob Vila would be so proud of you!

View jcees's profile

jcees

953 posts in 2522 days


#6 posted 03-10-2008 03:32 AM

Bob, ask your cab supply guy or the mgr of the big box cab dept for any cracked or broken sheets of laminate you can pick up on the cheap. You’ll be stuck with what you get but it will be much cheaper. Who cares if it’s lime green with pink polka dots… well… okay, maybe they’ll pay you to take that sheet away.

always,
J.C.

-- When one tugs at a single thing in nature, he finds it attached to the rest of the world. -- John Muir

View Woodchuck1957's profile

Woodchuck1957

944 posts in 2487 days


#7 posted 03-14-2008 06:53 AM

This seems to be a common problem with makeing your own router table. I had the same problem, and the top I used ( 1 1/4” thick, solid, not glued together ) was allready laminated on both sides. I eventually got it flat though. But your right, it is very frustrateing. I don’t know that I’d ever try makeing one again.

View SPalm's profile

SPalm

4904 posts in 2605 days


#8 posted 03-14-2008 02:34 PM

Just some thoughts. I went through this a lot with guys making CNC machines. We needed a substitute for aluminum plate. It is the same situation here. This is what we found as the best solution.

Put laminate on both sides. It will make the top extremely strong. This actually makes a torsion box (two skins tightly coupled to an inner core/structure). Torsion boxes have a natural resistance to twisting or warping or bending. I would recommend using regular wood glue and not contact cement. The contact cement will allow the laminate to flex as it itself stays flexible. When you glue it up, do both sides at once, and do it on top of your table saw and clamp it flat.

And as mentioned, if you use MDF (recommended), seal the edges with paint, glue, or varnish before you edge band. Two layers of MDF spread the two skins apart more, making the torsion box effect more dramatic. When this glue-up is flexed, one laminate skin tries to compress, the other will have to stretch. Laminate does not stretch very much.

Steve

-- -- I'm no rocket surgeon

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