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Discussion Starter #1
Can the contact cement be used to glue two large sheets of MDF together?

I just wasted two days preparing, clamping two nice sheets of ¾” MDF using Gorilla glue and the lack of clamp pressure for the middle of boards let the glue in the middle expand
So even though the edges were clamped nice and tight the middle curved. So much for the new router tabletop. I always use Gorilla glue but what a mess..
Any way I’m going to try again and I’m thinking contact cement because of fast contact bond. The weight of the boards should do the trick?
Any advice would be appreciated.
 

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Doug
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I've had great luck with titebond II glue when gluing up 2 sheets of MDF. I've used this approach on one of my earlier router tables, as well as my current work bench.

The technique I use is to clamp around the edges, and drive drywall screws in the center of the field (from the underside) to act as "clamps". If you're worried about having screws or screw holes in the bottom of your router table, just drive them in the area you are going to be cutting out for your insert plate.

When drilling holes like this in MDF, it is important to not only drill a pilot hole, but just slightly oversize the hole in the upper piece of stock. Otherwise, as the screw cuts into the lower piece, it could push material up and create the same void you were having using gorilla glue.

As for contact cement, I guess it would work, but just make sure that you leave one of your pieces OVERSIZED. In case you don't get your line up just perfect, you can chuck up a flush trim bit and no one will be the wiser.

Hope this helps,
 

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You can use any of the normal woodworking glues;white,yellow,brown etc. I agree that your problem may have been the polyurethane glue. If you use screws either do as kp91 suggested or else run a counter sink bit into top and bottom of the top board. A lot of tops there.

Regards

Jerry
 

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Just my 2 cents

Contract cement would be a hard one to do because you will have a hard time with the air pockets.
This is would I would do if you are going to use Gorilla glue, like Doug said screw it down but I would clamp the center and I would use carr.bolts or all thread rod with 2" x 4" from side to side 2ea.
Just premark for the base plate and move in by 2" and then drill two holes drop in the carr.bolts or rod and put on the glue and clamp away.
Also use 2" x 4" on the outside edge when you clamp it up.

Screws in MDF will pull the stock up at that point.(lift the stock up at the screw hole, will not be flat without taking the screw out and sand the hole a bit)

You can use T-Bond glue also and clamp it the same way.

Bj :)
 

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You could always park your car tire on the middle of the boards.. Put 2x10 or 12s on the top and bottom.. That way you can clamp the edges..
 

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Discussion Starter #8
Well, thanks for the advice. I made a second attempt using Gorilla again but spread thin
and light pressure from clamps on sides and about 60 pounds of weights in the middle. Turned out ok. Onward to part two. Cutting the miter track and plate opening. Pictures will follow when completed.
 

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Contact cement works great for glueing up MDF or hardboard. Just be ready with a rolling pin to get the air out.
 

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Router is still my name said:
Can the contact cement be used to glue two large sheets of MDF together?

I just wasted two days preparing, clamping two nice sheets of ¾” MDF using Gorilla glue and the lack of clamp pressure for the middle of boards let the glue in the middle expand
So even though the edges were clamped nice and tight the middle curved. So much for the new router tabletop. I always use Gorilla glue but what a mess..
Any way I’m going to try again and I’m thinking contact cement because of fast contact bond. The weight of the boards should do the trick?
Any advice would be appreciated.
I have ran a Taylor glue reel at work for about 15 years and all we ever use is woodbond or titebond they work real good.
 

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You can get around some of the expansion problem of Gorilla glue by "pre-foaming" it. I've used this method on joining flute halves and never had one split. No scientific test of teh glue joint, but flutes are subjected to many changes in temp/humidity when being played.

Keep in mind I don't squeeze gorilla glue right from the bottle onto the flute. I use a small mixing cup. After adding the gorilla glue to the cup I add a couple DROPS of water. Seriously.... DROPS and usually no more than 2. Stir it up REAL GOOD to mix in the water. Leave it sit about 1 minute. Depends on ambient temperature so time to leave it sit could very well be relative to that, but once it doubles in volume, it's ready. I then take it and spread a thin layer on my flute halves and clamp them up tight.

We do this on flutes when using gorilla glue because otherwise it will expand right into the bore of the flute and the squeeze-out needs to be removed. Titebond II doesn't do this.

And all of this being said, and while I find it to be a neat trick for using gorilla glue, it's probably best to use a non-expanding glue on a big area that's hard to clamp.

I used yellow carpenter's glue when sticking my 2 pieces of 3/4" MDF together and it has held amazingly. My wife even ran into my table with the lawn tractor and knocked it over and the lamination didn't separate anywhere. Chipped the surface of the table at the back though... so now I am going to build another one. :)
 

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Hi reikimaster

That's a Great TIP, on the drops of water in a cup with the gorilla glue , I like gorilla glue but it's so hard to clean up after it sets up. (scrap and sand) :)

Bj :)
 

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Discussion Starter #14
LIke the new Avatar Bj :)
Been using Gorilla glue since it came out and nothing since then.
One reason is the long work time which makes it ideal for large box joint projects. And it’s not effected by heat and humidity.
But the sanding and scraping is very time consuming.
Adding few drops of water is a good trick if you don’t need the long work time and small projects because it reduces the work time.
I have found that little extra work prior to clueing saves me a lot of sanding time later.
I tape up as much of the work as I can.
Also one of the things I learned about Gorilla glue is don’t bother wiping it off, when you wipe it off it gets into the wood. Just let it foam and dry. it is lot easier to remove then without leaving any shinny impregnated woods spots.
 

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i have been using Gorilla glue every sence it came out I have a letter from the company on how to use it they didn't say anything about water Probly didn't know about water than thanks for the tip Gorilla glue is all i use 90 Percent of the time Also i use gloves The glue leves a nice stain on the skin for a few if you don't use gloves
 

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Yeah, using the water trick is probably not something you are going to see suggested by the manufacturer. And the working time, while not as long as it NORMALLY is..is still pretty long. Gorilla glue....and possibly urethane glues in general... seem to react with the presence of moisture. It's just a little trick I learned while making flutes. Working with a small, shot glass sized mixing cup, if you put about an eigth inch of gorilla glue in the bottom add 1 drop of water and stir it in real well and then get a phone call that lasts about an hour, you will come out to find it has expanded over the rim of the mixing cup (but does not run down the side) and looks like a tiny muffin. :)

Don't ask me how I know that.... heheheh
 

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silvercreek said:
I have ran a Taylor glue reel at work for about 15 years and all we ever use is wood bond or Tiebold they work real good.

I use a caul for this situation .
It aligns several board if necessary and it also applies pressure to the sheets to evenly squeeze them during glue ups.

It's just a couple of 2 x 2 " posts with wedges for each caul.
1. Glue up the job.
2. Slip it in between the cauls .
3. Tap the wedges tight.
You can use as many of these home made cauls as necessary to keep thing dead flat.
I rarely use Gorilla glue or similar unless the project is going out side.
I find I get better penetration ( subjectively) from the PVC types of bonds like Tite-bond or the Lee Valley tinted stuff.

Bob
 

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