Workbench top (plywood-hardboard, MDF, other?)

[Eric Roberts]

Hi everyone...I've been reading some great advice and info on this site...so I signed up!

I recently built a Murphy Bed as my first project and borrowed everything from a circular saw, router, saw horses, makeshift table and saw guides from my father in law...and now I have gotten bit by the bug. The Murphy Bed is awesome and albeit has quite a few imperfections...it works and works good. When the weather warms up I'll be coming back for some advice on how to finish it...but for now I have bigger fish to fry.

I used a free plan and am building a workbench/workarea...using the following plan:

http://woodworking.about.com/od/shopequipmentsupplies/ss/portableTable.htm

It has been very inexpensive and easy to build (maybe 130 bucks in materials and 4-5 hours of time so far). Besides being low cost I really like the concept of the collapsible casters so I can push it to the wall when not in use. Sorry...I'm rambling...to my question:

The plan calls for the top to be 1/2 in. plywood and 1/4 in masonite. Will this configuration allow me to create bench dog holes? I know it's a lightweight design...but should I consider topping it with a couple sheets of mdf or something - thicker plywood?? Will it then be too heavy for the caster concept? It's more important to me for now that it be mobile vs. heavy duty...but if I could have both that'd be nice. But I do like the idea of the bench dogs...any ideas?

Thank you for your time.

ER

[Travis Gauger]

Welcome to SMC. I don't think that 1/2" ply is going to be sturdy enough for a bench top even with the Hardboard top. I'd go at least a single layer of 3/4 sheet goods with 1/4" hardboard top and bottom. If you want to do bench dogs, I would reccomend steppng up to a 2 layer thick top. 2 layers at 3/4" each and then top with hardboard. You could also do a torsion box for your top.

[Eric Roberts]

Few questions:

1. Is hardboard the same thing as masonite?

2. Why is there a layer of hardboard on the bottom?

3. How would the connection process go to attach the layers to the bench and each other?

4. What is a torsion box? (I'll search the site...but if it's quickly explained...)

Thank you so much for the quick response!!

ER

[Louis Rucci]

I built a bench for my garage using 3/4" MDF for the top. Mine has 3 layers. First two were attached together using Contact Cement. The third layer was only used around the perimeter to give me the added bulk to install a vise in the future.

Trimed with wood to protect the edges and topped with a piece of harboard that protects the MDF and allows it to be replaced when necessary

If you get one 4'x8'x3/4" MDF and rip it in half, glue them together, the top will be sturdy and very heavy.

[JayStPeter]

Half inch won't work well with "benchdogs". To keep it cheap, you can use a single layer of MDF or 3/4" ply. These kind of bench dogs work well in those cases http://www.rockler.com/product.cfm?page=10510&filter=bench%20dogs . Or use the ones from your workmate if you have one. Combine with a veritas wonder dog, which works fine in a single thickness, and you'll be good to go. I've had a couple work tables built this way (including Festool MFT) and am planning on building another. To reasonably use more traditional bench dogs (veritas bench pups for example) takes at least 2 layers. They'll work in a single layer, but you have to hold them in place while you tighten and they fall through when you touch them.
If you use MDF, I'll caution that you probably want to edge it with some sort of hardwood. A raw MDF edge will eventually chip apart as you bang things into it. If you chamfer or round it over it will survive better, but it's eventually going to get messed up. Decent playwood with a roundover or chamfer will do OK by itself.

[glenn bradley]

Few questions:

1. Is hardboard the same thing as Masonite?

2. Why is there a layer of hardboard on the bottom?

3. How would the connection process go to attach the layers to the bench and each other?

4. What is a torsion box? (I'll search the site...but if it's quickly explained...)

Thank you so much for the quick response!!

ER

First an opinion; 3" minimum for bench dogs unless your top is hard maple or similar, then 1-1/2 would probably be OK. Mine's here: http://www.sawmillcreek.org/showthread.php?t=57879

Now my answers to your questions which is of course, still just my opinion ;-)

1. Is hardboard the same thing as Masonite?

There are tempered hardboards and other versions but mostly, yes.

2. Why is there a layer of hardboard on the bottom?

When you laminate only one side it can promote warping, even in plywood.

3. How would the connection process go to attach the layers to the bench and each other?

I would laminate the layers and attach to the stand from underneath with screws. If you go with a thin top and need to move your bench, lift by the legs, not the top (there's not much holding it on).

4. What is a torsion box? (I'll search the site...but if it's quickly explained...)

Two thin layers acting as skins over a grid. this design pretty much excludes dogs unless you build in a supporting structure for them.

[Ben Cadotte]

What I have done is use my scrap sheet goods to make 2 lower layers. I have used MDF, particle board, regular ply. I use only pieces sized correctly that they fall on a support structure member. The top sheet is the only one I use a full sheet on. I used 3/4 mdf for that. I believe the top came out to 2 1/16" thick. It is very solid! Also very heavy. I only put in 6 bench dog holes. And so far they have not shown any signs of wallowing out. The only thing I might do next time is put a sheet of Masonite on top of the MDF if thats what I use next time (use as a sacrificial top, replace when it gets worn out). I actually have enough cut off's right now I could probably do another 36" x 72" bench top with scraps. And just have to buy 1 sheet for solid top.

Would love to do a torsion box, flat assembly table. Might try that next.