Bench Design Question

[Lucas Evans]

I am planning on building an outside work bench out of SYP. I have attached a sketchup file of the design, the top as planned is 2x6 and the legs 4x4. I plan on a leg vise and an endvise for bench dogs.

My first question is do I need to take any special design considerations when attaching the top to the bench or will doweled M&T joints suffice (if so how deep should i make them) and allow sufficient movement due to weather (I live in Atlanta).

My second question is what should I finish it with?

I should also note that this will be done mostly by hand because I only have access to hand tools and a drill.

Any tips would be appreciated. This is my first bench and coincidentally my first SMC post.

Bench.skp

[Steve Baumgartner]

I am planning on building an outside work bench out of SYP. I have attached a sketchup file of the design, the top as planned is 2x6 and the legs 4x4. I plan on a leg vise and an endvise for bench dogs.

My first question is do I need to take any special design considerations when attaching the top to the bench or will doweled M&T joints suffice (if so how deep should i make them) and allow sufficient movement due to weather (I live in Atlanta).

My second question is what should I finish it with?

I should also note that this will be done mostly by hand because I only have access to hand tools and a drill.

Any tips would be appreciated. This is my first bench and coincidentally my first SMC post.

Bench.skp

Your Sketchup plan doesn't show any aprons at the top of the legs. For starters, I'd add them to keep the base from wracking.

The top is going to expand and contract maybe 1/4 inch during the year in your area. You need to choose the method of attaching it to the base to allow for that movement or the bench will tear itself apart. My preference would be to fasten it solidly at the front (so that your leg vise and dogs can bear against something immovable) and to let the back float with something like traditional table top buttons. That is, L-shaped blocks that screw to the underside of the top and the tongue fits into a slot in the apron. Almost all the forces on a bench top are down or lateral, not usually lifting, so holding it down isn't all that crucial.

You say "outside". Will it be under shelter, or exposed? If exposed to the weather, it is going to take a beating no matter what you use for finish. It will be hard to prevent cupping, regardless of the finish, because water and sun will cause the upper side to expand and contract more than the underside. I'd use something that is easy to restore, such as BLO, and reapply it frequently.

[Lucas Evans]

I plan on keeping it covered and out of puddles when not in use but it will have to be outside year round. As for the apron, would adding another 4x4 rail around the top solve the racking problem?

[Peter Kelly]

I'd hold the upper and lower aprons in a bit from the legs as well. Visually awkward with the stretchers and apron the same dimensions as the legs. The aprons and stretchers carrying the deadman on the "front" should remain in relatively the same plane as the edge of the top.

Screen-Shot-2014-07-16-at-44631-PM.jpg

[Lucas Evans]

I think this would address the apron problem and I made the apron thinner so its not the same width as the legs. It should be more stable now. As for adding buttons to the back and securely fastening the front I'm not sure how that would work. Would I M&T the front two legs and run buttons around the sides and back? wouldn't that allow the top to twist front to back when I'm planing especially if I give my buttons a 1/4" play?



Bench2.jpgBench1.jpg
Bench.skp

[Steve Baumgartner]

I think this would address the apron problem and I made the apron thinner so its not the same width as the legs. It should be more stable now. As for adding buttons to the back and securely fastening the front I'm not sure how that would work. Would I M&T the front two legs and run buttons around the sides and back? wouldn't that allow the top to twist front to back when I'm planing especially if I give my buttons a 1/4" play?

Bench2.jpgBench1.jpg
Bench.skp

Better and better!

Yes, if the top is only attached at certain points they will have to provide all the resistance to twisting. If the front M&T are substantial, that is probably less of a problem than you fear. You could also glue or tongue and groove the entire front apron to the top. But if it still makes you nervous, you could do M&T at the rear legs as well, just with extra front-to-back allowance in the mortises so that the top can float that direction. Don't glue these back joints or you will defeat the purpose. The buttons serve to hold the top flat to the base while allowing it to move. Yes, put them on both the sides and back.

[Prashun Patel]

I am not a fan of front aprons. I think it impedes clamping ability. But this depends on how you work.

I prefer a single, center stretcher under the top that runs between the top rails of the side leg assemblies.

This also provides attachment points for the top (being in the center you can bolt it tight if you wish). Then you just loosely attach the top at the top rails of the side assemblies to allow for movement.

If you are very concerned with racking beyond this, then you can put some breadboards on the ends.

[Lucas Evans]

I am not a fan of front aprons. I think it impedes clamping ability. But this depends on how you work.

I prefer a single, center stretcher under the top that runs between the top rails of the side leg assemblies.

This also provides attachment points for the top (being in the center you can bolt it tight if you wish). Then you just loosely attach the top at the top rails of the side assemblies to allow for movement.

If you are very concerned with racking beyond this, then you can put some breadboards on the ends.

If I don't put an apron on the front wouldn't the hinder the holding power and stability of my leg vise especially if I'm planing the edge of a longer board? Also does and extra say 4 inches that the apron adds really prevent you from clamping a piece flat to the benchtop?

[Prashun Patel]

If the apron is positioned far away back from the front edge or if you have long enough clamps, the apron won't hinder clamping. Make sure any front-row dog holes are not hindered by the apron.

Regarding the support of longer items when edge planing, I'm in the 'use a board jack' camp. But then again, my bench is so short (60") that I just support it with dog holes or a clamp on the far front leg.

Again, this is an issue of how you work. I find that edge planing is the easiest operation. Working a narrow edge where tearout isn't always an issue, I don't find I need much clamping power or stability.

Face-jointing, flattening, and smoothing, however, is much trickier and critical for me. I spend at least 10x more time on the face than the edges. So, my bench is over time being (re)designed to handle those tasks better. Stops and holding are becoming more important to me.

[John Sanford]

Build a simple Roubo. If you're really concerned about racking, rather than mucking the top up with any sort of apron (aprons are the devil!!), you can either put a panel in the back, or a single diagonal brace in the back.