Roubo benchtop issue

[Ken Peluso]

Hello all,

I've been lurking here for about a month now and just wanted to say thanks for the vast knowledge you all share. This place is great! Anyway, I've been "woodworking" for about 8 months now over a 3 year period (a newborn puts some things on hold) and recently began building my first bench which will be used mostly for handtool work.

For the top I'm using hard maple and a little purpleheart at the front and back. I milled everything to 1 1/4" x 3 1/4" and glued up 4 sections of maple, planed them then glued them up into 2 main sections each 80" x 3" x 10".

Here is where I may have run into a small problem. I believe that all of the clamping pressure has bowed one of the main sections as when I did a dry run last night, 1 of the 10" sections has a slight bow causing me to have to apply good clamping pressure to get the sections to joint flat. Its only a small section right in the middle, maybe less than 2' long and maybe around 3/32 wide.

If this were one of the smaller sections I wouldn't be concerned but with a piece this big, can I count on the glue and clamping to bring them together at glue-up sufficiently enough to keep them joined for the life of the bench or do i need to gbar my No 7/drag the 10" slab to my jointer and try to eliminate this bow altogether?

Sorry to ramble and thanks for your help!

[John Dykes]

While not necessarily the same issue you have, mine recently, was very similar. I also am building a bench and gluing up a hefty top - 24" x 90" x 3 1/2" thick. At the point to join both slabs, I dutifully used my powered jointer to do the work. Unfortunately, my 15 yr old son and I managed to mill a considerable hollow in the length of both sections. Rather than attempt it again on the jointer, and with some hand holding of those who frequent here, I took a handplane to the joint and was able to wholly perfect it - both straight along the length, and square to the face. The glue up was, to me, remarkable in that I had to do very little further flattening along that 8' length.

So in short, I'd take my time - shoot for perfection in length and squareness, and ensure a glue up that will outlast you. It worked wonderfully for me.

Cutting accurate tenons, however, is another issue....

- jbd in Denver

[Ken Peluso]

Thanks John. I found your post and plan on doing some hand work tonight!

[Greg Cole]

Ditto that idea to do it the unplugged way.
With a tailed jointer it gets difficult to edge joint big heavy boards never mind sub sections of a heavy bench top to be. Even with in & outfeed supports I'd rather just do it the ol'fashoined way and be sure.
I took the easy route and bought a premade top so I only need to do do a little flattening (about 1/16" over 72").

Cheers.
Greg

[Wallis Hampson]

Ken,

If you spend a few minutes to get your iron really sharp, wax the bottom of the sole, get the offending slab secured and make sure your planing with the grain, i bet it wont be but a few minutes and youll be happy that you took the time for the peace of mind of not having to overclamp. GOOD LUCK.

[Ken Peluso]

Thanks Wallis. Im about to try. Securing the slab, not that is going to be the biggest challenge i think. building a bench without a bench really stinks.

[Ken Peluso]

I got the slabs secured last night and worked them a bit with my No 7. I got them under 1/64th according to my feeler gauge. I was hesitant to do much more based on my feeble planing skills.

Glue-up went quite smoothly and I left them on until this morning; approx 8 hours.

[Greg Cole]

Good to hear Ken.
I know what you mean about the needing a bench to build a bench.... working holding is a PITA without a decent bench, something that I'm all to familiar with.
Toss up a pic or two when ya get a chance!

Greg

[Ken Peluso]

Will do on the pics Greg. I took a few this morning but didnt have time to download them from the camera.

I have to say that Im still worried that for some reason this thing may split at some point so I may modify the plans for my base to mechanically attach the top to the legs for now; just in case.

[Ken Peluso]

a bit delayed, but here are the images as promised. shot them with a fisheye lens so they may appear slightly distorted.

http://kpdg.com/images/workbench2008/benchtopShavings.jpg

http://kpdg.com/images/workbench2008/benchtopLength2.jpg

http://kpdg.com/images/workbench2008/benchtopSide1.jpg

http://kpdg.com/images/workbench2008/benchtopLength1.jpg

Good to hear Ken.
I know what you mean about the needing a bench to build a bench.... working holding is a PITA without a decent bench, something that I'm all to familiar with.
Toss up a pic or two when ya get a chance!

Greg

[Greg Cole]

Woof. Very cool!
Mine's underway fullspeed ahead right now as well. Take a peek....
http://www.sawmillcreek.org/showthread.php?t=95077
Skirting to go, vice installation and a handful of other "minor" details...:rolleyes:
Flattening the top... boring dog holes (using the mill seen in pics....shhhh I'm in the cave and don't wanna get tossed out:D)
The reference to Bob's #7 has come to reality. I revived it tonight and made a couple curlies too....

Cheers and nice bench top in the works Ken.

[Ken Peluso]

Thanks Greg. I've been following your thread and was waiting to see the top!
The knight coffin in my pics came from Bob as well. :D

Ive got the day off Friday and plan on starting on the base and cleaning up the wreck my small shop has turned into lately.

[michael osadchuk]

Ken,

That's a very solid and good looking benchtop.

I built a similar heavy laminated benchtop a decade ago and I've experienced no "delamination" whatsoever, so I wouldn't worry about splits.

Similarly, with the way the laminations on the benchtop are oriented, there should not be significant wood movement differeintial between the benchtop and any supports/legs of the benchtop..... and with the sheer mass/inertia of the benchtop, it isn't going be knocked out of position by you bumping against it - you likely can get away with a fairly light duty attachment method between the benchtop and supports, one that primarily "indexed' the benchtop in the correct position on the supports.....

... enjoy having a substantial, perfectly flat workbench that you can keep flat, if need by, with some touch up handplaning.

good luck

michael