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Split Top Roubo Bench Build #7: Fixing mistakes

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Blog entry by ic3ss posted 03-15-2015 04:42 PM 1733 reads 1 time favorited 6 comments Add to Favorites Watch
« Part 6: Flattening and starting on the tail vise Part 7 of Split Top Roubo Bench Build series Part 8: Install the tail vise, done with the top »

I forgot to update last week. I didn’t get much done because I was busy fixing a mistake. In episode 6 I showed a picture of the end tenon and the lead screw channel cut out. The weird thing is that the huge mortise cut into the end of the tenon. The mortise was too wide and I didn’t notice until last week I was thinking about it when I was in bed. That’s when I do my best thinking. I got up in the morning and checked the drawing and I was right. The drawing says the mortise should be 2 – 5/16” from the edge of the top. When I was preparing for the mortise, I looked at that dimension probably 5 or 6 times before I cut into it and I saw 2 – 15/16” every time. The old saying of measure twice and cut once, well, I don’t know what to say here. I didn’t think I was in a hurry or anything like that, I just saw the wrong number and convinced myself that it was the same each time I looked at it I guess.

Oh, well. I was able to chisel the bottom very flat but I just took the high spots off of the side. I wanted to leave it a bit more open at the top and then cut a scrap piece to fit. I didn’t want to use glue with this kind of thing because it will have a huge gap on the side and it serves as the mounting surface for one of the tail vise rails so it has to be rock solid and not move at all. I’d never worked with epoxy in woodworking before so I did some reading. I see that West Systems is pretty common for woodworkers but for this job I can’t afford what they want for the smallest setup. Maybe later I can get set up with it, but for now I just need a single small job’s worth.

I went down to the big box and picked up a couple of Gorilla Glue epoxy syringe packages. I figured one should do it but if not I’ll have a second one.

So I got it all taped off and mixed the first one, and I tilted the filler piece out so I could get the epoxy in the bottom, spread it on the sides and then tilted it back up and poured it in the gap. Good thing I got the second one because I used all of that too.

While it was curing, I went back to the lumber yard and got a board for the front face of the top, and another walnut piece for the end cap. I still need another board for the gap stop, but that’s later I guess. The lumber selection is getting pretty thin, lots of defects.

So I spent the rest of last weekend marking and drilling out holes in the end cap. This is a fairly dark picture of it but I’ll show it again. More to come shortly so thanks for reading.

Wayne

-- "I am endeavoring, ma'am, to construct a mnemonic memory circuit using stone knives and bear skins."



6 comments so far

View LJackson's profile

LJackson

295 posts in 1061 days


#1 posted 03-16-2015 04:30 PM

I’ve been wondering where you’ve been.

I agree, West Systems is very expensive. And, I think it has a very low viscosity.

I have been trying to complete my own workbench, and have been thwarted at every turn. I need a bunch of bar clamps for obvious reasons, and so I decided to make Izzy Swan’s version with wedges, but unfortunately they did not work for me. I’ve got four 2×4s glued up, and I want to then glue a couple of those together. The problem is they’re so warped that I can’t get enough clamping pressure to secure them while the glue dries.

I think I’m going to just run a couple of rails along the bottom, screw them into the tops, and fill the gaps from the top some how.

View ic3ss's profile

ic3ss

387 posts in 2244 days


#2 posted 03-17-2015 12:22 AM

I just looked at the video, that’s a pretty sweet design for a bar clamp. Making a bunch of those would be pretty easy, and cheap. Let me know how it works for you.

Wayne

-- "I am endeavoring, ma'am, to construct a mnemonic memory circuit using stone knives and bear skins."

View LJackson's profile

LJackson

295 posts in 1061 days


#3 posted 03-17-2015 03:57 PM

They were very easy to make. I made 16 in one weekend. Unfortunately, they are not appropriate for what I need. You see, the wooden planks (two sets of four 2×4s glued up) are warped with respect to each other. Too much warpage that a wedge can’t close.

My plan was to use my only pipe clamp to wrench the two planks together, and then secure them while the glue dries with the home made bar clamps. Then, move the pipe clamp to the next location that needs tightening and continue down the 8 foot line.

The problems were that the screws weren’t sufficient on the heads of some of the clamps. This is probably due to incorrect grain orientation (something I rarely look at and do not know what is the right orientation). Also, on some of the tails, I did not drive the wedges in far enough to prevent them from sliding back. Finally, as I would hammer in one wedge, the shock would shake loose another clamp’s wedge and then I would have to start all over again.
All of this is happening while I’m frantically trying to get everything together before the glue dries.

Really these two planks are just too warped to make this any kind of feasible. I bent my 1/2” pipe clamp and the handle, and I twisted right around the handle on my 8” C-clamp which I was using to try to get the two boards roughly flat. I purchased a 3/4” pipe clamp, but the handle does not lend itself to increased leverage necessary to pull the planks together fully.

As Izzy Swan states, you really want boards that are jointed and ready to go for this type of bar clamp.

View ic3ss's profile

ic3ss

387 posts in 2244 days


#4 posted 03-17-2015 05:27 PM

Man, sounds like a real pain in the neck. If you have a warping problem, maybe you could try face jointing one side flat and then plane the other side. Do this on two boards and laminate them to get your thickness.

Sounds like the clamps only work with moderate pressures. Nice try though.

Wayne

-- "I am endeavoring, ma'am, to construct a mnemonic memory circuit using stone knives and bear skins."

View LJackson's profile

LJackson

295 posts in 1061 days


#5 posted 03-23-2015 04:27 PM

Thanks for the tip. I can’t see myself trying to pass an eight foot by about six inch plank across my jointer and get it any kind of flat. Maybe if I had infeed and outfeed supports. But, it seems to me with a hunk of wood that size, you take the tool to the wood, not the wood to the tool.

I did purchase a 22” jointer hand plane, but I have absolutely no experience planing. Instead, I’m throwing the bench together, warps and all, and I’ll use The Wood Whisperer’s method for flattening the top. I know it’ll end up with voids, but I think I may be able to route a straight channel through the voids and insert additional wood to fix it up. Then I might be able to use my jointer or my jack plane to level the extra wood to the rest of the top.

View ic3ss's profile

ic3ss

387 posts in 2244 days


#6 posted 03-23-2015 05:30 PM

I was thinking the same thing for my tops. I’ve already got it all worked out, I just need a couple of 2×6 boards and a new flat bottom large diameter bit. Rockler has a 1 – 3/4” for less than $30.

Are you blogging your build here?

Wayne

-- "I am endeavoring, ma'am, to construct a mnemonic memory circuit using stone knives and bear skins."

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