Bench top questions

[pelligrini]

I'm finishing up the assembly on a real bench and I'd like to get some input on a couple items on the top. The material is SYP and the top will end up being ~30x73

1. Large panel glueups: There's about 24 SYP pieces I've ripped for the top. ~1-3/8 x 2-5/8 x 76. I've never really done such a large glueup before. I ended up gluing 6 strips at a time (only two sets done yesterday). I wanted to do 3 sets of 8, but I couldn't move fast enough during a trial run. I also ended up rolling TB-III glue on just one side instead of both. I had all of my bar clamps in play; 14 going across and 10 more on the 5 cauls. I probably should have done 4 at a time, but I really didn't want to add days to the glueup staging. How do you all handle big panels like this?

2. Bench top fastening: Each of the front two legs has a tenon on top that will fit into mortises in the underside of the benchtop. I cut off the tenons that were going to do the same thing on the back legs. The wood isn't as dry as it should be, and I figured there's be some problems with future movement. I could have made the back mortices wider, but that idea came after the saw was put away. I need a rigid connection at the front of the base to the top as there are no stretchers. I don't have the room to not be able to put my fliptop planer cart underneath. I'm thinking about doing lag bolts near the front legs, probably going up into the top from below through blocking attached to the sides of the 2x6 top stretchers. I'm not sure about doing the same for the rear. I probably ought to allow for wood movement, So I was thinking of elongating the holes through the blocking for the back fasteners, if I even do them. The top will be able to move, but the front edge should stay flush with the front legs (especially needed for the leg vise). I'd like to not use too many metal fasteners, can't really say why though. Anyone with a better idea?

3. Bench Ends: I've seen many benches with boards attached to the ends covering the endgrain of the top, like a breadboard end. Some have splines, bolts etc. How do these work with the movement of the wood?

I might just be overthinking the movement I'll get from the top, but while I was doing some final crosscutting & the mortices for one piece I had them sitting out in the sun. The edges that got baked did shrink slightly more. The wood probably isn't as dry as it should be. Most of it was bought only about a month ago from the borg. (you can fit two and a half 16' 2x12s inside a 2003 Ford Taurus)

Here's a few photos of the construction. I had originally designed it with a couple 50" 2x12s spanning the top on the inside of the leg tenons. That was before I abandoned using a 2'x4' slab of maple in the top. The left legs are 5x5, rights are 5x7, I don't think the single 2x12 back stretcher was a good idea.

[Tom Miller]

First of all, that looks awesome!

1. I don't really have much to add on the glue-up -- sounds like you already had your clamps laid out, and your process thought out.

2. I think you're right about the tenons on the back legs as shown being problematic. However, I think you might still want, and can have, tenons there. I'm no expert, but it seems like if the tenons on the back legs were rotated 90 degrees (i.e. narrow in the side-to-side direction, and long in the front-to-back direction), they could work, and would be helpful. You could make them as loose tenons, gluing them into the legs. Then, the mortises on the top should have front-to-back clearance for movement, but not side-to-side (w.r.t. the bench top).

Then, I'd be inclined to just let gravity hold things together.

3. Bench ends -- everything I've seen allows the top to move w.r.t. the end caps, just like breadboard ends. Even the ones with dovetails allow the pins (usually on the backside of the top) to slip in and out of the tails.

What don't you like about the back stretcher?

Regards,
Tom
p.s. You might want to think of a better way to attach the vise. (You didn't think we'd let that go, did you?)

[LarryG]

+1 on Tom's "awesome!" comment. That's going to be a really nice addition to your workshop.

Regarding wide glue-ups ... what you did.

Regarding wood movement in the top, benchmeister Chris Schwarz deals with the problem by not worrying about it. In one of his articles he did mention that the mortises for the rear legs could be cut 1/8" wider to allow for movement across the top, but he didn't think it was really necessary.

Which wood is the wettest in the bench? Shrinkage in the top is actually beneficial since it will tighten up the mortises around the tenons. OTOH wet legs and stretchers are not so good: as they dry, their tenons will shrink within the mortises.

It's too late now, but IMO cutting off those back-leg tenons was a mistake. Your objections to them aside, you're going to need some kind of mechanical fasteners, methinks, in order to properly transfer the racking forces to all four legs rather than just the front two. It might still be possible to use loose tenons and drawbore them. Also, I think you're also going to want to add a front stretcher, and park the planer cart elsewhere, although I'm not sure how you'll accomplish that if the base is already glued up (is it? I can't tell). Or possibly a removable stretcher, so you can still park the planer cart underneath...?

And oh yeah ... leg vise! Way cool ... you are REALLY going to like that!

[dbhost]

So far I like it... Not real sure I would have picked the mortise / tenon arrangement for connecting the top, but I certainly understand it... Not that mortise and tenon is bad. I just stink at it still... Wanna show me how to do that?

You can breadboard the end, might not be a bad idea... I see a lot of these things done with I think it's called a sliding dovetail joint. Pretty sure the idea is to keep the end grain from walking all over the place on you...

Just curious, how does that fit into the scheme of working in a shed / shop? I mean space use wise... Maybe I am overthinking my pending layout, but I keep working on sketchups for both 10x12 and 12x16 just in case the HOA won't go for the bigger one. Pretty moot until we get some debt gone, and the funds saved to build the shed outright... No more debt...

[pelligrini]

I have much to learn about cutting mortises too. Should be a lot better learning with a solid bench now. Most of the construction for the base was with half lap joints and mortise holes made from the glued up pieces. Drilling the mortise hole for the bottom spacer for the leg vise was fun. I didn't even consider the 3" quill travel of my drill press when trying to go through the 5" thick leg.

The top is the wettest of the wood, and it'll probably shrink down quite a bit. One of the reasons I cut off the back tenons was that I could get the mortises lined up now, but they'd probably pull the top apart when it shrank. I could have made it a really loose fit, but that seemed pointless.

Instead of lag bolts at the front, I just had a thought of driving a couple dowels into the tenons going through the 1-1/4" piece that makes the face of the top. Those can be pulled out later if I ever need to take the top off. I probably ought to see how the bench works once the top slab is on. Still not sure how to do the back yet. It would probably be best to see how it all works when the top is on.

That single back stretcher will twist a little, even being a 2x12. After I had the base all glued up I was pushing and pulling to see how it worked. The front legs would lift slightly. This was also done without the top or anything between the front legs. It's probably more of a function of not having a front stretcher. If I just clamped something to the end stretchers going across the front legs the twisting would be greatly reduced. The main reason for the single oversized stretcher on the back was so that it wouldn't interfere with the height handle of that planer, and to add a little more mass. If I don't do some sort of fasteners for the top at the rear legs I probably ought to add one though. About the only way to add another stretcher now would be with loose tenons and a two piece stretcher that would clamp around them. It's all glued up.

I've been thinking about some sort of removable stretcher for the front for a while. Maybe using some bedframe hardware. Probably using another 2x12 and bore it for hold downs too.

Yea, those angles holding up the vises probably ought to be replaced with actual fasteners. That vise will drop down really fast and barely miss your foot if you play with the handle. They were mainly on there to see how it all fit in the shop. When I was first mocking up the top on the base I was excited to be able to fit a 9' top along that one side. Then I found that I couldn't even fit the other vise on the end much less open it. There's an 18" Drill press cart in the corner, and another 18" used by the POS jointer on the other end. A bench over 7 1/2 feet gets too tight on the ends.

[JR]

How about this idea for the front stretcher problem: install two braces. They could be embedded in lap joints on the legs and mortised into the top. Hopefully you'd still be able to get the planer in there.


JR

[cabinetman]

That's a great looking bench. Your glue up came out great, and if there is any movement it will likely be minimal. Since movement is a tangential issue, your orientation with edge grain up and not face grain will be in your favor.

I don't think I would glue down the top. Gluing it to the tenons might be problematic if there is some slight overall movement even if the mortises are elongated. I would like it replaceable. You could make mounting cleats on the side stretchers (and they already look stout enough to prevent racking front to back). You could make a back cleat if you like.

To keep the front open, you could just make gussets to tie the legs to the top. They would defer the racking in the length. From the side stretchers, and the gussets, you could lag/screw the top down. Once the top is mechanically fastened, torsional forces would be pretty much eliminated. FWIW.
.

[pelligrini]

Too much thought about nothing.

I just dry fit the 4 top slab parts I have glued up with a couple clamps across them. Nothing but gravity & the two front tenons holding it together. It took a whole lot of effort to get it to even budge. The movement I did get was from it sliding on the two 1/2 MDF blocks under the back legs keeping it level (the shop floor has problems).

I do wish I sprang for some maple for the top though. The grain pattern of the SYP was starting to giving me a headache. Might be all the Guinness.

[pelligrini]

Getting closer to the finish line. I got the top all glued up and flattened a little. There are a couple of low spots that I need to bring the top down to. They're less than .020". I think I'll wait a while to see what else happens to the top as it dries and moves before making it totally flat. I do want to bore some dog holes, but I'll wait till I'm finished with flattening it.

The thing is totally stable with just the top sitting on the two leg tenons. There's a shot of the underside while I was flipping it over to finish squaring the ends. I found that my 7 1/4" circular saw doesn't have enough depth for the top and none of my router bits could do it either. That top is really heavy. I probably should have glued it up in groups of 3 or 4 too. I found that the glue joints were tighter on that section of the top.

I've got the vises mounted and a prototype leg vise in place. I still need to make some jaw liners and figure out how to deal with the slight angle in the Wiltons. The back face is not parallel with the front plane of the top & legs. I’m not too sure if I like the placement of the front vise. I surprisingly and suddenly found that the big protruding part of the handle lines directly up with the bottom two buttons of my fly. No serious damage was done but it was an eye opening experience.

I also realized that the parallel guide for the leg vise doesn’t just keep the vise face parallel to the leg face when clamping, it keeps it from spinning around too. I was concerned with the spacing of the peg holes in Schwartz’s designs; ½” increments. I was about to make one with a bunch more holes at a 3/16” increments. I decided to try the ½” spacing using some stacks of MDF scraps. The ½” spacing works fine.

[chopnhack]

that looks awesome dude! Some serious woodworking and more can now be done on the new bench! beautiful

[jhart]

That's an awesome bench. Nice job.

[LarryG]

The bench is looking great. Seeing your pictures is making me antsy to continue work on my partly-finished Roubo, now languishing in the mini-warehouse along with the rest of my stuff.

Re: the slight angle on the Wilton ... how pronounced is it, and which way is it angled? The jaws on some vises are deliberately set out-of-parallel, with the tops of the jaws touching first, so they will come true as they tighten down on a workpiece.

Re: the parallel adjuster on the leg vise ... yes, the adjustment doesn't have to be all that close for the mechanism to work just fine. With mine (which uses an ACME threaded rod and jamb nut, rather than a movable pin) I found that with the vise adjusted for a 3/4" thick piece, a workpiece anywhere from 1/4" up to about 1-1/4" could be clamped without having to touch the parallel adjuster. And BTW, the surprise you had with the Wilton is one of the reasons I really like a leg vise. Having the screw down lower than on a normal vise gets it more out of the way of one's hips and, uh, other important parts.

[pelligrini]

Re: the slight angle on the Wilton ... how pronounced is it, and which way is it angled? The jaws on some vises are deliberately set out-of-parallel, with the tops of the jaws touching first, so they will come true as they tighten down on a workpiece.

Right now the top edge of the back face against the cutout in the bench is about 3/32 closer to the bench than the bottom. It may even up once I get some lag bolts into the bottom. I didn't have any the right size. They're only on there with a couple machine screws through the back face into brass threaded inserts in the bench. I'm not sure if it will even up with the lag bolts though. There wasn't much change in the angle when I had the vise fully extended.

Someone ought to design a quick release handle & face that could be removed easily from a bench. I think it would be a good safety feature for protecting private parts.

Thanks for the compliments everyone. I've learned a lot in this build.