Flat Work Surface

[Jules Dominguez]

I'm considering using a flush door for a fast and cheap flat work surface for glue-up and assembly work.
I looked at a 36x80x1 3/4 flush hardwood door at Home Depot. It wasn't flat either lengthwise or across the width and I found it was constructed with only a one inch perimeter of solid wood and the interior filled with something like particle board.

Has anyone done this successfully and if so, what type of flush door is likely to be flat and stay flat?

[Bob Winkler]

What I used for the same application was one of those plastic resin fold-up tables they have at Staples, etc. You can get them in 4,5, or 6 foot lengths and they are light, strong, and cheap.

Plus, glue and stain wipe off very easily.

I've never worried about their flatness because I glue up on straight 2" think cauls, top and bottom.

Bob

[Joe Unni]

Jules,

Before I moved into my new shop, I did most of my work "on site" doing built-ins. I used an old hollow core door on two saw horses for all of my glue up and assembly - worked just fine.

Good luck,
-joe

[Jules Dominguez]

Bob, thanks for replying, but what are cauls and how do you use them? Does it provide surfaces that are in the same plane?

Joe, I went back to HD today and sighted down the edges of some hollow core interior doors and they're not visually perfectly flat, either.

Maybe I've become overly concerned about having a dead flat surface. I'm sure it would be nice, but not sure it's necessary for most work. I hadn't really worried about it until I read the "torsion box" threads and then went to the David Marks article and read it.

[Chris Barton]

I built a torsion box table. This is the table I use for putting together my projects. I made mine out of malamine coated particle board and 2x4s.

[Jules Dominguez]

Chris, I assume your table is pretty flat. How difficult was it to achieve that?

[Maurice Ungaro]

Jules,
You may want to look at using a solid core door, if you want someting quick and simple.

[Chris Barton]

Jules,

While its not brutally difficult, it does require the internal members of the torsion box be completely strait so, if you don't have a jointer it can be a difficult project. David Marks did a torsion box table project on his show "Woodworks" and you can find the step by step process and DIYnet.com.

[Jules Dominguez]

Maurice, the door I looked at at HD was a solid core, albeit something like particle board rather than lumber in the core. It was pretty flat, but not dead flat. You could see the bow in it both lengthwise and cross-wise it you sighted carefully down the edges.

Chris, I had looked at David Marks article some time ago and his method appeared difficult to me. Having a flat surface to build the torsion box is the first problem, and the second is the glue-up. I made a torsion box planer sled from the FWW article a while ago by using my old slate-bed pool table for a flat surface and bricks to weight the top down for gluing. It worked, but was a pita to do. Since then I gave the pool table to my SIL to free up more shop space, so it would be more of a pita now. I admit to being lazy, and was hoping for an easy way out.

[Jules Dominguez]

Bob, I've now learned what "cauls" are. I've used them before, but didn't have a name for them.

[Corey Hallagan]

My assembley bench is a 36" hollow coor door that I replaced in the house with a solid door. Works great! Throw down some of the resin saw horses and put them away when I am done. I built my shop cabs on top of this during the assembley stage. Will use them on my kitchen cabs as well.

Corey

[Jules Dominguez]

Thanks, all. SMC to the rescue once again.

[Jon Toebbe]

I'm using a solid-core door for my workbench top, and it's been great so far. Particle board core, so it's heavy and pretty uniform. I got it for something like $7 at a building supply salvage yard. Bud's Warehouse, for anyone in the Denver area.

I had to root through a pile of doors that was five feet tall, but it turned out to be worth it. :)

I imagine there are similar outfits in your neck of the woods.

[Jules Dominguez]

Based on your posts, and serious thought about it, I decided to go with a solid core door rather than try to build a big torsion box. Bought one of the ones I had looked at at the borg - 36x80x1 3/4 - hardwood skin and perimeter, particle board interior - weighs a ton. It's pretty flat but not perfectly so. Large work surface. I may put a 1/4" hardboard tabletop surface on it, haven't decided yet. Can always do that later. I bought four adjustable feet from Lee Valley and am in the process of building the support frame, with slotted adjustable legs that will allow tabletop heights from about 27"-37". As much as it weighs, I won't be moving it up and down like a yo-yo, but wanted the option.
I pigged out on the Bessey October clamp sale; this will provide a large surface to use them on without having to clear off of my workbench when I do an assembly. Will post pics if the adjustable legs prove to be practical, meaning I don't throw my back out doing it.

[Bob Noles]

Hi Jules,

Just saw your post and wanted to inject my experience with solid wood doors. Here is a link to my workbench that was built using 2 solid wood doors laminated together. Got a good flat surface out of the deal and one really soilid woorkbench. The thing weighs over 500 lbs.

http://www.sawmillcreek.org/showthread.php?t=17648

Drop by sometime if you want to see it in person :D

[Jules Dominguez]

Bob, thanks for the invite. I might do that if I get over on your side of town. Are the doors actually solid wood throughout, or do they have a particleboard core? Is the finished tabletop dead flat, or "pretty flat"? How did you join them together? Were they flat when received, or did you have to do something to make them flat? How did you join the doors together?

[Gary McKown]

If you want a flat surface and want to keep it that way, you may want to think about adding an "adjustable" torsion-box-type frame underneath to keep the door flat. I have used this on discarded conference table tops (thick plastic laminate over chip board), every one of which has sagged in the middle (which is the reason they were discarded) and is sensitive to humidity and temperature. Frame pieces are made from 3 laminations of 3/4" plywood, 2" wide, ripped straight on the TS. Cross members are dadoed into the rails. This provides a frame with stiffness much greater than the top. Lag bolt the frame to the top, and use shims to get the top perfectly flat. Re-shim as necessary to maintain flatness through all kinds of weather, etc.

For MDF or chipboard (where lag bolts do not hold very well), I bolt the frame to the top using the "blind T-nut" anchor method.

[Bob Noles]

Bob, thanks for the invite. I might do that if I get over on your side of town. Are the doors actually solid wood throughout, or do they have a particleboard core? Is the finished tabletop dead flat, or "pretty flat"? How did you join them together? Were they flat when received, or did you have to do something to make them flat? How did you join the doors together?

Jules,

The doors have the standard "termite poop" core, yet I got lucky and ended up "pretty close" to dead flat. I guess it was a rare borg day for sure :eek: I can run a long metal yard stick across the top and not see day light so I guess it is flat enough for my purposes anyhow :) The doors came off the rack that way so all I did was bring them home and laminate them. My lamination method was top secret and very complicated, but I will do my best to give you an explanation :D I simply smeared glue all over the 2 surfaces and put them together like a sandwich at which time I drilled long deck screws into what was going to be my bottom side of the top. After 2 days I removed the screws and could not believe it..... the darn thing stayed together without them :p

Just some fun Jules, but really it was really very simple and I most likey experienced some severe beginners luck. I know flat is important, but feel as though we can get carried away with the "dead" part of the term at times ;)

I really need to get over to highland one of these days..... sounds like it would be the treat of my life. If I can schedule it in anytime soon, I'll give you a shout and maybe we can hook up for coffee.

[Jules Dominguez]

Gary, your torsion box undercarriage sounds like a sounds like a simple and effective fix. This thing is already heavy as hell and I plan to use a simple 2x4 skirt under it, at least to start with. I'll remember your method if I have problems. As I said before, I want to be able to adjust the height and it's already almost too heavy, at least to do it the way I've designed it.

Bob, give me a call any time. I'm retired, so all days are the same to me. My only qualification is to avoid the heavy traffic hours.

[Jeff Booth]

I wish I noticed this thread when it was new, but I was too busy re-truing one of my solid core door benches :( I have a seemingly endless supply of these doors - about once a year some office in my officepark changes tenants and they ALWAYS have to move offices around I guess and the by-product inevitably are oak veneered particleboard/hardwood-edged doors in the dumpster. I have 2 in reserve.

The upside is the low expense and the damping mass when you hammer on the surface. The other upside is that because I paid nothing then I am not too remorseful to drill holes for new 'accomodations' however permanent they may be into/onto the bench surface. The downside is that the mass to strength ratio is such that even with a few vertical 2x4s with the crowns carefully chosen and then married to the underside, if loaded with say .... an old 150 lb drill press then these benches inevitably begin to sag (maybe I am a moron .... :eek: ). In my case I noticed this over the course of a few years. This reveals the next problem, the veneer is just that and below it is a mess, so there is no possibility to flatten the top by removing material. Once there is a sag in the bench, re-truing it is a real PITA. Therefore I recommend an overkill support system to begin with.

For me they are a good fast way to get a reasonable bench, but having used 2 of these for more than 7 years I would have to say that I see a better bench in my future. I use either my tablesaw or my concrete floor if I want something flat for gluing things together, my benches sag too much. If time were not the premium that it is (3 little kids and a wife building a new career) then I would be laminating my own hardwood benchtops.