Split top bench downsides etc?

[ian maybury]

Some specific bench questions. The long planned Roubo style bench in beech is about to get started (tired of looking at the stack of timber), and I'm wondering if anybody has found that the popular split top has downsides? It'll be hefty - 4in plus thick top, with matching understructure. i.e on the heavy end of the spectrum. The thinking so far is to use a Benchcrafted style leg set up with cross rails under and blind tenons into the top, and bolt up stretchers - to enable future disassembly if needed.

The extra clamping ability and ease of handling during build and afterwards all sound like strong arguments for incorporating a split top - and it would make wood movement less of an issue too. Wary though of supporting the two half width/half weight top pieces off just cross rails between the legs - of effectively halving the mass of the top, and leaving it totally dependent on the rails for support. i.e. the solidity and ability of a bench like this to absorb impacts when chiselling and the like without bounce is the whole point in making it heavy - it'd be a pity to give that away. It may not be an issue given that even a half top wil be a very solid piece of timber - but right now a one piece top is the plan...

Another basic is adhesives. Something like Titebond 2 extend is attractive, but I'm wary about longevity. A thread a couple of years ago floated the thought that a structural adhesive like liquid polyurethane might be a better if less convenient choice, but in absence of hard data (as opposed to marketiung claims) didn't reach any firm conclusions. i.e. both seemed to work fine. Has anything popped up since to change this view?

The choice of vise has evolved, but seems to have settled on the now almost standard DIY leg vise and wagon type at the end. I've ordered a Benchcrafted criss cross for the leg vise. Are these (the criss cross) holding up well in use? Any downsides?

Thanks

[Dave Anderson NH]

Ian I highly recommend using Titebond Extend for laminating up a top. The extra open time makes life a lot easier when you are trying to spread the glue out reasonably evenly over a large amount of surface area. As far as I can see my latest bench done 5 years ago hasn't had any problems with the adhesive breaking down or losing strength. Do yourself a favor and DO NOT try to laminate the whole top at once. When I did mine I separately laminated the white ash in groups of 3 strips at a time. When all the groups of 3 were done I then laminated the 3s in pairs to make 6s. Each group of 6 was then jointed and planed and the 6s were then laminated together and so forth. It makes life a lot easier. By the way, you are going to need some extra muscle to move things around once you get 6 pieces laminated together. Another hint, build the base first so you can use it to work with the top as you are doing the laminating. Any extra time spent carefully aligning the pieces in each grouping as you laminate will pay big dividends in cutting down the amount of time you spend jointing and planning. Good luck and show us pictures as you progress.

[Chuck Nickerson]

Four years ago I built a split-top Roubo from the Benchcrafted plans. The only negative in my work is getting both top pieces level with each other after a move; it's also my assembly table. It takes an extra five minutes each time I move the bench, perhaps four times a year.

Having the split top means I can break it down by myself to take the bench to club meetings and for demos. I don't regret the decision.

[Jim Koepke]

My thought on a split top would be to have a ledge along the insides so pieces could be placed in it to bridge the top when needed/wanted.

ability of a bench like this to absorb impacts when chiselling and the like without bounce is the whole point in making it heavy - it'd be a pity to give that away.

Somewhere I learned to always chop out above the legs. My bench is too light weight to chop in the middle on some of the heavy stuff.

jtk

[Bob Lang]

My split top bench is coming up on its sixth birthday, and I haven't experienced any of the issues you're worrying about. Once you reach a certain mass the differences are minimal, probably not measurable without laboratory instruments and for me, not noticeable. I'm still happy with the decision I made as the open space makes the bench a lot more versatile. As far as the glue goes, titebond types of adhesives have been in use for about 100 years. We don't know for sure if they will last longer than that, but I don't think there will come a point in time when every PVA glue joint fails due to age.

Bob Lang

[Curt Putnam]

Ian, what follows is all IMO which means YMMV.

I'm going with a split top. I'm currently toying with the idea of making the working side 15" instead of 12". The base structure will be stronger than a true Roubo where the top is the support. As long as the transverse stretchers have at least a third sitting on top of a leg the result should be stronger than a Roubo. You will still have the tenons into the top as well as the stretchers. My top will be mixed maple - I want the front 3" to be hard maple. Tail vise(s) are not yet decided but I already have 2 7" QR units: a Wilton and a Rockler - one for each half of the top. Leg vise is Lake Erie screw with Jim Ritter's Chain Leg Vise instead of the criss-cross. Still dithering about length, I want 8' but really only have room for 6'. The only argument against a split top is the difficulty of keeping the two halves perfectly coplanar. It may be the only argument but it is mighty powerful and part of the reason that I'm thinking about a 15" front "half."

You don't have to worry about heat during glueup. If I do it in the summer even Titebond Extend will start curing before I can get it spread. I will probably go with something like Unibond 800 or Dap Weldwood to get a sufficiently long open time. Other than that Titebond !, II or III or LHG are just peachy.

[Adam Maxwell]

I'm wondering if anybody has found that the popular split top has downsides?

Can't speak to the Roubo, but I have a doubly split top on my Nicholson-ish bench, and it's been very useful; I mainly keep battens in the gaps to act as a planing stop and minimize the junk that falls through. It's only 2" thick, and bounce/solidity is a non-issue.

[ian maybury]

Thank you gentlemen. That sounds like a pretty unanimous vote for the split top and the PVA - which is nice to hear, because they bring some other benefits. That's a yes on both pending anything else coming up. The wide near half bears thinking about Curt.

One benefit of a leg vise is that it places the screw pretty low - which leaves scope for a pretty deep traverse rail/stretcher. It certainly makes sense to glue the top up in sections which can also be jointed and planed.

Bob's 21st century bench (took a look just now) with an end vise on a split top make possible sawing to the left or right of the vise - i guess that's the one that's given away in return for the planing and other capabilities of a wagon vise if that's the decision. The leg vise likewise seems to have a basic simplicity, holding ability and depth above the screw as above that's attractive, but gives away capability to a twin screw in terms of ability to carry clamping dogs in the moving jaw, sawing off the LH end, holding wide parts (a Moxon covers this), tapers etc.

I'm tight for space too. Looks like I can manage about 90in or a bit less length, but the back will be only about 7in from a wall and access to the ends is a tiny bit restricted. (about 30in to a wall one end and a bit more to a tool board the other) Additional width over the usual 24in would reduce badly needed space in the area in front. Height is an awkward choice - that most suited for planing is potentially too low for other work given my dodgy back. Thinking of making a narrow platform to move in and out from underneath as required to get the best of both worlds...

Benches generate interest like nothing else it seems - but then as a design problem there's so many angles to them. Especially the interaction between features. A case of making calls as best we can and then finding out over time how they work out… Will take some photos, but can't guarantee the schedule....

[Paul Saffold]

Ian,
I finished mine a little over 2 years ago and have no regrets with the split-top. I followed the plan you are describing - Benchcrafted style. I second Dave's advice about gluing up in stages. I used Titebond III for it's longer open time and put it on quickly with a 2" paint roller.
"Wary though of supporting the two half width/half weight top pieces off just cross rails between the legs - of effectively halving the mass of the top, and leaving it totally dependent on the rails for support." If the cross rails are flush with the top of the legs, then the top of the leg will be supporting much of the top. My legs are 5"x5". So 10" of the 24" top is on the leg. With a stout cross rail it isn't going anywhere.

[ken hatch]

Some specific bench questions. The long planned Roubo style bench in beech is about to get started (tired of looking at the stack of timber), and I'm wondering if anybody has found that the popular split top has downsides? It'll be hefty - 4in plus thick top, with matching understructure. i.e on the heavy end of the spectrum. The thinking so far is to use a Benchcrafted style leg set up with cross rails under and blind tenons into the top, and bolt up stretchers - to enable future disassembly if needed.

The extra clamping ability and ease of handling during build and afterwards all sound like strong arguments for incorporating a split top - and it would make wood movement less of an issue too. Wary though of supporting the two half width/half weight top pieces off just cross rails between the legs - of effectively halving the mass of the top, and leaving it totally dependent on the rails for support. i.e. the solidity and ability of a bench like this to absorb impacts when chiselling and the like without bounce is the whole point in making it heavy - it'd be a pity to give that away. It may not be an issue given that even a half top wil be a very solid piece of timber - but right now a one piece top is the plan...

Another basic is adhesives. Something like Titebond 2 extend is attractive, but I'm wary about longevity. A thread a couple of years ago floated the thought that a structural adhesive like liquid polyurethane might be a better if less convenient choice, but in absence of hard data (as opposed to marketiung claims) didn't reach any firm conclusions. i.e. both seemed to work fine. Has anything popped up since to change this view?

The choice of vise has evolved, but seems to have settled on the now almost standard DIY leg vise and wagon type at the end. I've ordered a Benchcrafted criss cross for the leg vise. Are these (the criss cross) holding up well in use? Any downsides?

Thanks

I've a split top, it has advantages....easier to handle during the build, gives a place to hold saws and chisels while you work. Ease of clamping, not so much, but the biggest problem and the reason my next bench will not be split is I use holdfasts and battens for most of my bench top holding and the split is often right where I need a hole for a holdfast. If you do not use holdfasts there is no real downside.

[Bob Lang]

Bob's 21st century bench (took a look just now) with an end vise on a split top make possible sawing to the left or right of the vise - i guess that's the one that's given away in return for the planing and other capabilities of a wagon vise if that's the decision.

When I designed that bench I came "this close" to putting in a wagon vise. In the end I went for the quick release because I can still capture stuff between dogs on the bench top and I have normal vise capabilities on the end. It also simplified the installation so I see it as a bonus. I use that vise a lot more than I thought I would going in.

Bob Lang

[Mike Brady]

I've found no real drawbacks with the split top. One puzzle solved was in flattening the two top sections. I now just loosen the rear section and slide it forward to meet the front one. After clamping them together, I run a 5-1/2 plane with a toothed blade over the whole thing. It is perfectly level then and has that nice grippy surface.

[ian maybury]

I hadn't thought of that angle Mike. Benches are the subject of never ending interest it seems Bob - it's always compromises. Many of us i suspect (me anyway) don't have the experience and/or consistency of the type of work we do to make a really tight choice - we end up running with something and finding ways to make it work for us.

I have a Record from the late 90s, and thought of using it too. Was put off a bit by the fact that it wasn't that well made/had it's limits in use. (e.g. it didn't like asymmetric loading) Plus there were some mutterings about regarding the possibility of droop. Likewise regarding the possibility of a twin screw on the face, although there are additional complicating factors to that too to do with layout of the bench legs. No doubt most of these issues can be headed off by choosing the right vise, and installing it properly - but my thought/hope with the leg and wagon vise and given our limited access to hardware over here (tends to be a case of ordering stuff you haven't seen before from a catalogue) was to keep it simple and reliable...

One option that's not much seen in a leg vise except in historic pictures is to extend the chop and the leg some distance above the top of the bench - it sounds like it should provide a nice solution for sawing from either side, and at a comfortable height. Seems like it could be a bit of an obstruction at times though. e.g. long pieces using the deadman or other support to the RH end as well would need to be raised quite high for planing...

ian

[Paul Saffold]

I've found no real drawbacks with the split top. One puzzle solved was in flattening the two top sections. I now just loosen the rear section and slide it forward to meet the front one. After clamping them together, I run a 5-1/2 plane with a toothed blade over the whole thing. It is perfectly level then and has that nice grippy surface.

Mike that sounded like a easy solution and I was wishing I'd thought of it a couple of months ago when I fattened it. But when I went downstairs and looked I need to slide the top 4 inches (tenons are 2 1/2" wide plus the tenons centered in the leg) but the gap is 2".

Ian, I have a Record 52 for my end vise and am happy with it. My bench is here http://www.sawmillcreek.org/showthre...t-top-finished. I have added a second row of dog holes in the front section and don't have a problem with the gap interfering with clamping.
Paul

[Joe A Faulkner]

I note that there is guy named Bill Shenher who has several uTube posts on his split top build. You might want to check that out. In episode 4 he covers how he flattened his top. I considered a split top, but in the end went the single slab route. If I were to do a split top, I would integrate a board in the middle that would sit flush, but could be flipped to act as a planing stop - maybe 3/8 inch to 7/16 proud. Good luck on your build.