Need suggestions for an alternate way of attaching workbench legs

[Jeff Skory]

Me again with another workbench question. Based on my feedback to my previous post regarding leg vises I have decided to build a Schwarz-Roubo bench using a fifth leg so that I can angle the leg vise.

My question however regards attaching the leg to the top. The method outlined in the book uses mortise and tenon. I am thinking that I might be moving within the next 5-10 years and of course I would like to be able to take the workbench with me.

However, my workshop is in the basement and I know the bench would never make it up the steps. Reworking the base so that the top is screwed on would probably not work well in combination with a leg vise.

So any ideas for alternative construction?

And in lieu of that, when I eventually move should I
A) leave the bench behind and build another one
B) chop the legs off halfway and rebuild them at the new house

[Jim Koepke]

Why not attach the legs mortice and tenon style so the bench can be taken apart when you move?

jim

[Jeff Skory]

Why not attach the legs mortice and tenon style so the bench can be taken apart when you move?

jim

In other words just don't glue the tenons in or put any dowels through it?

[Jeff Skory]

Jim, you're right. I wasn't thinking straight. Having the heavy bench top sitting on top of those tenons is going to be way more holding power than the screws that are used for some bases.

[Sean Kinn]

You could always use the mortise and tenons in combination with a bed-bolt like setup to hold it tight in lieu of glue.

[Jim Koepke]

Also think of removable pins and wedges.

jim

[Jon van der Linden]

Since you're looking at Roubo, you might want to consider large dovetails for the leg/top joint like you see in Roubo. I believe that your book has copies of Roubo's illustrations. One of the illustrations shows the leg: it is a twin tenon with the tenon at the front of the bench being a through dovetail. The weight of the top should be enough to keep it from lifting.

[Dave Matson]

St. Roy has an two part episode on the woodwright's shop about this entitled "the french workbench" where he details how to make the "rising dovetail" joint used in attaching the legs to the bench. It might be available online to watch but the PBS site appears to be down for me at the moment :P

There are plans for a knock-down Holtzapffel Bench at the woodworking magazine blog:
http://blog.woodworking-magazine.com/blog/Free+Drawing+The+Knockdown+Holtzapffel+Workbench.a spx

[harry strasil]

Sliding dovetails in the outside edges, similar to a mortise and tenon but exposed and flush with the outside edge.

[Wilbur Pan]

Chris Schwarz's article on making the Roubo calls for drawbored mortise and tenon joints to attach the top to the base, but without glue:


I drawbored the top to the base without glue. If I ever need to remove the top, I can drill out the pegs to dismantle the assembly.

[Todd Trebuna]

I built the simple bench featured on Fine woodworking. I used 3/8 inch threaded steel rod with 2x4 strechers. The stretchers have a Dado cut for the threaded rod to ride in. 4x4 on the ends. Very solid. Appears to be heavy enough and you can tighten the nuts on the end of the rod to compress everything together. It's definitely not my dream bench, but it will certainly do for my first woodworking bench. ( I have a 2x4 workbench that I built years ago, that is pretty beat up).

scroll down and click workbench (http://www.taunton.com/finewoodworking/getting-started/season-two.asp)

link to free plan (http://images.taunton.com/downloads/GSIW_workbench.pdf)

[Daniel Kennedy]

Jeff,
I asked myself many of the same questions as I was building my bench. I decided to do through mortises. I did not glue them, the weight of the bench and the base make it extremely rigid. I used 1/2"X12"bolts and mortise and tennon to hold the base together. In theory I could take the top off of my bench and then disassemble the legs and stretchers. After all the work I put into this bench If I ever have to leave, there is no way I am leaving my bench behind.

[mike holden]

Jeff,
One of the traditional methods of attaching the top was simply to lay the top onto two large tapered pins. Look kind of like 50mm artillery bullets on the base, and matching mortice in the top.
It is a method that has worked for years (centuries) so I would not hesitate to use it.
Mike

[David Keller NC]

Jeff - What Mike H's suggesting is a good method, and a related way is to use lag screws (the way I did it on my most recent bench).

Making this work effectively requires a modification to the Roubo design. In Schwarz' plans, the Roubo has a stretcher between each pair of legs 12" or so above the floor, but no stretcher at the top of the legs, as it's M&T to a solid benchtop and so that stretcher would be unnecessary.

However, for a rapid take-apart bench, one makes the pairs of legs at each end of the bench into a "ladder" assembly, where there's a stretcher between the pairs of legs 12" above the floor, and one stretcher at the very top of the legs. One then either through-bolts the top to that top stretcher with counter-sunk bolts through the benchtop, or either blind lag-screws from underneath, or the dowel pins as Mike H suggests.

This is a lot easier to visualize than it is to explain in words. If you've Chris' bench book, have you downloaded the free "extra" chapter on knock-down benches? It's worth having and you can get it at the Woodworking Magazine blog.

It is, by the way, not necessary to have a fifth leg to make an angled leg vise - one simply angles the legs as well as the leg vise chop. Angling one pair of legs does make the construction more complex, but it gets an extra leg out of your way when you're using the bench.

Finally, you might consider giving up the angled leg vise altogether and including a sliding board jack with an auxillary leg-type vise built into it. With that set-up, you can clamp a board of just about any width to your bench for dovetailing.

[Richard Francis]

Here is a current and working link

http://www.pbs.org/woodwrightsshop/schedule/27season_video.html

Also, Scott Landis shows the double tenon joint in his chapter on Roubo

[Circa Bellum]

Sliding dovetails in the outside edges, similar to a mortise and tenon but exposed and flush with the outside edge.

that's kind of the way I did mine. I don't think it would be as difficult as the rising dovetail that St Roi did...
http://4.bp.blogspot.com/_wkdvV7sXBmw/SGhF2qUT8rI/AAAAAAAAAaI/iKsWwY_YfrU/s1600-h/june29c.jpg

http://2.bp.blogspot.com/_wkdvV7sXBmw/R9iF-sXVlxI/AAAAAAAAAW4/jegxwl67AWE/s1600-h/benchdone.bmp

[Jeff Skory]

Wow! I thought this thread was dead after I replied back to Jim in post #3. Great responses with a huge variety of options.

I think I will end up going with what in my mind is one of the simpler methods that should give me great strength which is the original mortise and tenon with drawbore dowels but without glue. Drilling those out if/when needed is a great idea. Thanks for pointing that out Wilbur.

[Jeff Skory]

Jeff -

Finally, you might consider giving up the angled leg vise altogether and including a sliding board jack with an auxillary leg-type vise built into it. With that set-up, you can clamp a board of just about any width to your bench for dovetailing.

David, I'm curious about your sliding board jack with a leg vise built into it. I would think that this board would not be strong enough to withstand the forces that the vise might put on it. Do you have a picture of this?

[Casey Gooding]

I would build it with standard mortise and tenons. Instead of glue, use bed bolts. Let the top just sit on the tenons on the legs. It should be plenty heavy enough to stay put.

[David Keller NC]

"David, I'm curious about your sliding board jack with a leg vise built into it. I would think that this board would not be strong enough to withstand the forces that the vise might put on it. Do you have a picture of this?"

Jeff - I don't have a pic handy, but Chris Schwarz has had a picture of this arrangement in one or more of his blog entries. I think (but am not certain) that Jameel Abraham's workshop bench (not his travel bench, which has extensive blog construction entries in the last few months) has this setup.

[Daniel Kennedy]

I built the sliding leg vise on my bench. I got the idea from Chris Schrwarz's blog. With the blog and the links there there is penty of information available on how to do it. The vise is plenty strong. It is extemely useful when you can slide it back and forth in the deadman spot. I used angle iron to reinforce the slot. I also set the slot back 3.5" from the edge so the edge of my bench wouldn't blow out.

[Daniel Kennedy]

You can see the picture of the sliding leg vise here: http://www.sawmillcreek.org/showthread.php?t=105734

It's the second picture down.

[John Schreiber]

I used 1" stub tenons and 3/8" lag bolts to attach the top to an upper stretcher on the leg assy. The stub tenons totally prevent any lateral movement and the lag bolts allow me to lift the bench 1/4" to pivot it around the shop one side at a time. You might want to go with higher quality lag bolts. I used the ones from the bin at my hardware store and broke one off screwing it in with a ratchet wrench.

I just had some friends and family over last weekend. I showed some of the guys how to disassemble the bench without any damage should they need to do it when I'm not around. I expect this bench to last longer than I do and I'm good for at least another 50 years.

[Jeff Skory]

I built the sliding leg vise on my bench. I got the idea from Chris Schrwarz's blog. With the blog and the links there there is penty of information available on how to do it. The vise is plenty strong. It is extemely useful when you can slide it back and forth in the deadman spot. I used angle iron to reinforce the slot. I also set the slot back 3.5" from the edge so the edge of my bench wouldn't blow out.

Daniel, Thanks for the pics and the info about setting the slot back. Looks like quite the beefy sliding leg vise!!

David, (and Daniel) I'll search Schwarz's blogs to see what other info he has on it.

[David Keller NC]

Jeff - After reading Chris Schwarz' blog entry about the sliding leg vise in place of the board jack some time ago, I had an idea that might be pertinent if you choose to build one.

Chris mentions that cutting out a 3/4" deep X 1/2" track in the underside of the front of the bench may well weaken it substantially, with the vise screw on the sliding leg vise providing the force that might distort/crack it. Several readers mentioned the "U channel" steel reinforcement as a potential solution, but I've a potentially better idea:

Instead of routing a groove on the underside of the bench for the leg vise to slide in, cut a groove in the end-grain of the sliding portion of the leg vise. For the track, cut a strip of hard, dense tropical wood. Purpleheart comes to mind, but a scrap of cocobolo or honduran rosewood might provide an advantage - the natural oils in the wood would self-lubricate the track. Fix this track to the underside of the bench with stainless steel, countersunk deck screws about every 4 inches. The stainless screws are a bit stronger than normal, and the deck threads on these that are commonly sold in the big box stores are a bit deeper than normal threads.

The potential advantage of doing something like this is that it doesn't weaken the front of the bench, there's no interfering track if you want to drill dog holes on the front, and the track is totally and easily replaceable should that be required down the road. One additional thought is to make one section of the track non-continuous for about 8" or so. That way, the sliding leg vise can be made to fit the top and bottom tracks closely so there's less slop, and if necessary that small section of track can be removed to remove the vise and backing plate.

I haven't built one of these yet, but I'm thinking about it.

[Wilbur Pan]

Dave -- that's an excellent idea. The only thing that I can see is you're transferring the weakness from the bench to the sliding vise, but it would be far easier to rebuild the vise than to rebuild the benchtop.

[David Keller NC]

"The only thing that I can see is you're transferring the weakness from the bench to the sliding vise, but it would be far easier to rebuild the vise than to rebuild the benchtop."

Yep, that's the idea. My guess is that what would actually fail over time would be the strip of hardwood that comprises the two rails (top and bottom), which should be cake to replace. The only thing I wonder about is how many screws, and what size and spacing, should go into mounting the rail. It might be possible to actually calculate what's needed from this paper:

http://www.ssina.com/view_a_file/fasteners.pdf

But I'll have to admit I'm too lazy to do it (despite and engineering background). Instead, I'd probably space them on an evenly-distributed pattern, so if it turned out that more were needed, they could just be inserted in the space between the existing screws.

[Jeff Skory]

Good idea Dave.