Workbench HELP

[Jay Knoll]

Since no one gave the Vertias bench a hearty thumbs up, and after some somber assessment of the cost, I decided to build my own.

I'm using the Shopnotes 65 plan.

I laminated the MDF top last night. I didn't have anything that I thought was flat enough so I used a folding table kind of like one of those tables churches have for banquets except this one had a plastic top. It had a steel understructure so I thought it would be OK.

Anyway, this morning I realized that I hadn't checked it for flatness. Out to the garage, put my Festool guide rale on the top. I"ve got a 5/32" sag in the center of the glued up piece over a 75" length.

I'm not sure if I should keep going on the top or start over again. Is this sag too much to make the top usless as a flat reference? I've got a lot more to do on it, apron, vices etc, so I don't want to spend a lot more time and then end up with a pretty looking but usless top,

So help me out gang, what should I do?

And how would you suggest that I avoid the problem again considering that I don't have anything else to use as a table to glue up the next one (Unless I use the "bent one" but I'm afraid that another sheet of MDF will just sag to conform with the surface.

Thanks for your help

Jay

[Todd Burch]

What did you laminate the MDF to? Another piece of MDF? I would flip it over to put the crown up and if it's big enough, it's own weight should assist with it coming into flat. If that's where all your screw/nail holes are, laminate a piece of 1/8" or 1/4" hardboard to it. If you are going to use an apron underneath, your fasteners might pull it flat.

If you made your top out of home center MDF, and you only used 1 sheet, if you started over now you would only be out < $30. No big deal. How many thicknesses did you use?

Any why MDF? If I was making a workbench top, I would use veneer core plywood. It holds screws better long term, it's lighter to move around, damage from liquids aren't as traumatic, and it's just a bit prettier too!

[Jim Becker]

Todd's correct abot flipping it. The surface should flatten out, especially once it's on your understructure.

Todd, the MDF provides a huge amount of density and that's why a number of recent designs use it rather than plywood. Two or three layers laminated makes for a very heavy, massive benchtop. And most of these benches are capped with a replaceable tempered hardboard layer to deal with the surface durability issue. It's exactly the design technique I was going to use before I got the great deal on the Adjust-a-bench system I recently posted about.

[Jay Knoll]

Thanks for the advice guys, we'll see if it works, Since the glue is dry, I'm not sure how it will flatten without breaking the joint.

Any other thoughts concerning the amout of crown? (Now that it is "right side up")? Is that too much to make it useless as a reference surface?

Jay

[Jay Knoll]

I've been puttering and sputtering all morning, and thinking about all your good advice. I think that the work involved in the next steps is far more "expensive" than redoing the top.

SWMBO said, why not do it on the marble floor in the living room (glue up the bench top I mean!) We have a marble floor with big tiles, the guys who laid it spent a lot of time getting it smooth, so I'm going to give that a go.

Don't ususally bring projects "inside" but hey if she says so I'm up for it.

I'll let you know how it goes.

Jay

[Jim Becker]

Jay, that floor may not be flat, either...to many opportunities for it not to be flat!!! You may be better off with shimming sawhorses and some extra sheet goods flat, similar to what David Marks did for his assembly table project.

[Jay Knoll]

Jim

I've been over it with my level and it seems dead on, no wobble anywhere I can find it. I watched them put it in, every tile was leveled with the ones next to it. It took them a half hour just to set one tile.

I guess I could lay an extra piece of sheet goods down first and check that, if it isn't level then I could shim that just as easy as putting it on a sawhorse.

Jay

[Jim Becker]

I guess I could lay an extra piece of sheet goods down first and check that, if it isn't level then I could shim that just as easy as putting it on a sawhorse.
I think this is a good idea "just to be sure"...

[Lou Morrissette]

I had the same problem a while back looking for a suitable flat surface. I ran some lengths of 2X3 on the jointer and then ran them thru the thickness planer to create a set of "parallel bars" so to speak. I set these on sawhorses and made sure they were coplanar with a 6' level. With a sheet of MDF layed across, I had a perfectly flat work surface.

[Dan Schmidt]

Gents, I am building the same workbench from ShopNotes 65, but instead of the MDF top I am using a laminate maple top with the same dimensions. I am wrapping the top with a 1-3/4" thick x 3" high oak apron. The front and rear apron (along the length of the bench) is flush with the ends of the maple top. The side aprons (along the LH and RH sides of the bench) are the same width as the other aprons, but are cut to length so it's flush with the outside faces of the front/rear aprons.

MY QUESTION: Can I glue the side aprons to the top as I am with the front/rear, or will the seasonal expansion/contraction of the maple ruin my top? What would happen?

I see the new Powermatic saw has a maple side table which has an apron which is fixed in the way I'm describing.

[Brandon Shew]

Buy the thickest sheet of 4' x 8' melamine you can and lay it on the flattest surface you can find (sidewalk, garage floor, etc..). That should be a good start and you can shim as needed.