Bench build top flattening (dumb) question...

[Harold Burrell]

I am building my roubo style workbench. It is actually fun. Mostly...

I have the top of ash @ about 3 1/2". The legs will be through mortised.

Here's my question(s)...

How flat do I need to make the underside of the bench? My first thought was to not worry about it too much...but then I realized that the bottom side would play a rather large part in the legs being equal/parallel/square, etc. Of course then I worry about how to make the bottom and top co-planer. I also want to retain as much thickness as possible!

Help me...please...

[Zach Dillinger]

Harold, my solution to this problem, when I built my Roubo, was to figure out where the legs meet the top, scribe a line from the top to establish the plane to insure that all four legs are even, then only flatten those areas, leaving the rest as glued without regard for flattening. No need to flatten all that and, like you said, its better to leave more thickness.

[Harold Burrell]

Harold, my solution to this problem, when I built my Roubo, was to figure out where the legs meet the top, scribe a line from the top to establish the plane to insure that all four legs are even, then only flatten those areas, leaving the rest as glued without regard for flattening. No need to flatten all that and, like you said, its better to leave more thickness.

So, you flattened the topside first? And then use that to reference the "leg contact" area?

[Adam Neat]

Im in the middle of doing a bench as well. I made my bottom flat, not necessarily smooth/flat but it is flat. I had some pretty rough stuff so I "practiced" on the bottom.

I had a bit of a panic when I put the top on a couple of saw horses and the top was rocking like a hobby horse, indicating about an inch of twist. Then I realized one of the sawhorses was propped up on one side.......

[Zach Dillinger]

So, you flattened the topside first? And then use that to reference the "leg contact" area?

Yup, that's what did. But I had another bench to work on while flattening the Roubo top. If you don't, you can throw it up on horses and do it that way.

[Harold Burrell]

Yup, that's what did. But I had another bench to work on while flattening the Roubo top. If you don't, you can throw it up on horses and do it that way.

Yep, it's on horses.

Once you got the top flat, what did you use to flatten the bottom areas? Did you have to flatten the entire front and back edges (the thickness of your legs)?

[Joey Chavez]

I made my bottom flat as well. I figured the entire bench build was filled with lessons towards more fine projects (I'm not as experienced as most) so I tried to cover every detail I could, secondly, I found that working the bottom helped me really understand the hi/low spots on the top so I was able to get the top really flat and faster. Plus it was just easier to rag on the finish to a smooth surface. One other thing it did was help identify some of the boards I inadvertantly ran the grain the wrong way. I'd rather have any tear out on the bottom than top.

[Trevor Walsh]

You might also consider housing the leg joints with the mortise exposed to the one side. Mark the "thickness" to the housing, and work it down in reference to a square front edge to a depth co-planar with the top. Cut joints in the leg as normal.

[Adam Cruea]

You could also just measure up from the floor, then when it's all said and done, flatten the top.

Or you could do as Trevor suggested (which, while not a Roubo type bench, I will be doing something similar on mine).

[Zach Dillinger]

Yep, it's on horses.

Once you got the top flat, what did you use to flatten the bottom areas? Did you have to flatten the entire front and back edges (the thickness of your legs)?

I basically just scribed the line and then planed down to it, creating almost like a large dado from front to back. It isn't very deep, since I only planed about a 1/4" off to get to a common maximum thickness. I was careful in my glue up. I used a Stanley #10 for the work.