Well that didn't work as I expected

[Anthony Whitesell]

I building a workbench top. My first, so I used 2x8-12' cut and ripped in half (making a whole bunch of 2x4-6'). I jointed, edged, and planed each one. Grouped and glued them in bundles of 4, then jointed, edged, and planed those. Each bundle looks great, nice and square, flat and smooth. Now I'm ready to glue the bundles together and have a flat top. Or so I thought. Close but not close enough, darn it. Each bundle is jsut a little off from the other.

There's too many knots in the wood to attempt to hand plane the top flat. So it looks like I'll need to build some sort of bridge and use the router. The most cost effective large bit I can find is a 1 1/4" dish cutter bit. Now I'm looking for the materials to build the bridge. Suggestions are welcome here.

I have a few options, keeping mind that cheaper is always better.

For the rails, I could use aluminum angle, jointed 1x or 2x pine, or 1 1/2 black pipe (nevermind why 1 1/2 in particular, let's just say it will have a future use and I have to buy it anyway).

For the bridge, I could use aluminum angle, 1/2" pipe (from the pipe clamps), or pine.

The most expensive option would be the aluminum angle for both. I was thinking the pine rails and the 1/2" pipe bridge would be the most cost effective. How well do you think it would work?

[Jamie Buxton]

I've done the bridge trick a lot. (For instance http://www.sawmillcreek.org/showthread.php?t=97018&highlight=bridge) For the rails, your pine idea will work, as long as you fasten it to the slab so that it can't flex while you're leaning on it. The bridge should be sturdier than your 1/2" pipe. The issue is that the pipe will bend a bit as you slide the router back and forth; you can't help but lean on it with different weight at different times. Make a wooden bridge with a U-shaped cross section. The router runs on the floor of the bridge, and the sides of the U extend upward as high as you want. Higher is stiffer.

[tyler mckee]

I read an article in fine woodworking not long ago about working with large slabs, they used a simple plywood jig. As long as everything is fl, and the bridge is sturdy, should work fine.

Have you thought about finding a local woodwoorking/cabinet/boat building shop that could flatten it out on a large drum sander? Local shop charges ~$70 an hour for machine work and it wouldn't take long for them to make a few passes.

[Anthony Whitesell]

I had thought of a wooden bridge, but I wasn't sure if I could keep the lower face (the board the router rides on) flat enough while glueing it together, especially if I use pine. I figured maple would be better/best. How do would think yellow poplar would work (compared to pine and maple at either end of the spectrum)?

[Jamie Buxton]

I had thought of a wooden bridge, but I wasn't sure if I could keep the lower face (the board the router rides on) flat enough while glueing it together, especially if I use pine. I figured maple would be better/best. How do would think yellow poplar would work (compared to pine and maple at either end of the spectrum)?

Do you have a jointer and planer? If so, you can make the bottom board very flat and uniformly thick. If you don't have a jointer and planer, I'd use plywood for the bottom board. A sheet of plywood will have almost the same thickness throughout -- typically within .01" or so. The walls of the U-channel ensure the plywood is not cupped -- presuming you have the facilities to cut the bottom edge of the wall straight, before you glue it to the bottom board. If you don't have that capability, you can probably rely on the factory edge of the plywood sheet. It is often quite straight. Of course, I'd check it before I relied on it.

[Anthony Whitesell]

U Shaped? I was thinking L-shaped. Which direction would the opening be pointing?

I have both a jointed and planer, but haven't had much luck lately (obivously) getting my glue-ups to come out flat or straight.

[Jamie Buxton]

U Shaped? I was thinking L-shaped. Which direction would the opening be pointing?

I have both a jointed and planer, but haven't had much luck lately (obivously) getting my glue-ups to come out flat or straight.

Look at the pics in that thread I referenced.

[Anthony Whitesell]

Doh! I missed the link in the post. I get it now. Is that a plywood bottom in the U of the bridge? How thick?

P.S. I was re-reading the thread and found all the same informaion I'm using now.

[Ken Shoemaker]

See if you can get a cabinet shop to run it thru a wide belt sander. I'd think they would do it just for something to do these days.

I had a wide pice of cherry that was way to wide for my machines. They did it for nothing.

Good luck.

[Anthony Whitesell]

I haven't found a "wood" cabinet shop with anything larger than we typically have (around 20-22" wide). They say they don't have a need for anything larger than that. Most are specializing in granite countertops and having the "custom" order stuff shipped in.

[Ken Shoemaker]

I belive the shop I went to had a 58" B-sander. Just a thought. Is there a mill by you that could remove the top 1/2" to level it for you???

[Peter Quinn]

The shop I'm at in CT has a 37" wide belt and sells time a bit over $1/minute to individuals and other shops. Perhaps look for a shop that does passage doors and or wooden counter tops. We have rented time from a bigger local manufacturer that has a 52" wide belt for things we couldn't handle in house.

Fact is though that a wide belt is no more going to flatten your top than a planer will. It will sand it flush, and can help improve flatness across its width if the passes are light, but it WILL NOT flatten it over its length or take out much twist if that is a problem. I think the router rails or bridge is a better small shop option. I have seen cold rolled steel rails used on David Marks show. I don't think any pipe is going to be straight or rigid enough to give you the degree of flatness you are probably seeking.

We also have a 20" jointer with a nearly 9' bed that can go a long way towards flattening large projects when necessary. Perhaps a local shop might have a jointer big enough to flatten your blanks before glue up to final width? Or if you have glued up you can always rip and reglue after flattening.

[Anthony Whitesell]

Although I do think the strength of the pipe would be a problem in its own right, I was thinking it could be supported along its length. I questioned the straightness of the the pipe. That is one of the reasons I suggested it, to see if there was a nay-say to the idea.

As you might recall, I did have it in pieces jointed 6" at a time and that piece by piece idea didn't work out so well. So I doubt if it would work any better on someone else's equipment. Unfortunately, there was so many boardfeet involved I just could afford or (for my first bench) justify anything as pricey as hardwood. I believe most of my problem comes from the spruce 2x material I used.

I was wondering how a wide belt sander was going to work without the bottom being jointed first. I guess it doesn't.

On that note though...I saw a trick a while back about jointing board wider than your machine. The trick was to joint a wide rabbet and support that surface on a piece of MDF or melamine (or any board with two flat and parallel sides) as it is sent through the planer. Flatten the top first, then remove the board and flip over to flatten the rabbetted bottom. I wonder if I could rabbet the center of the bench top. Then support the center on a piece of 1/2" MDF and send it through my own drum sander in two passes. I have a Grizzly G0490 and a Jet 16-32. If I removed the fence and the guard, could I joint the middle of the board? The bench top is 24" wide, if the center 8" were jointed that would put just over 4" of the MDF on the belt. Would that be enough area to support the piece or would it tip too much?