So I was reading through the instructions for the Crisscross guide I ordered for my leg vise when I was struck with a sudden feeling of dread.
The mortise for the Crisscross mechanism needs to be 19.5″ long, 1.75″ wide and 1.4375″ deep. As I was staring at the diagram in the instructions I had that sinking feeling… Can you see it yet?
Crisscross Layout
Here is a hint. What is going to intersect the mortise (slot) for the Crisscross? Why, the tenon on my front stretcher of course.
If you look closely at the picture below you can see where I’ve drawn in the slot for the Crisscross and the mortise for the stretcher. Now, if I hadn’t already cut all of the mortises for the stretchers this would be relatively easy to avoid. Just move the tenons to the beck of the stretchers. However, I have already cut all the tenons and chopped all of the mortises. Dang.
The real life problem
Well, first, I can rout out the slot for the Crisscross until I’ve assembled the base because I’ll need to cut through the tenon. That also weakens the tenon, and if this bench is anything less than absolutely rock solid then it’s a fail. I can (and will) drawbore the joints, and that should help reinforce this joint. I could also drive some long lag bolts through the leg into the end of the stretcher (or use barrel nuts) to reinforce it, but that strikes me as sloppy.
Grumble, grumble.
What other options do I have? I could change directions and not use the Crisscross. But I don’t want to do that. I could re-make this one leg and the stretcher, but I don’t see that happening either.
Thinking out loud (so to speak) I expect I’ll follow these steps:
- Drill all the base parts for drawbore pins
- Drill the holes for the vise screw in the leg and chop
- Machine the slot for the Crisscross and test fit it
- Assemble the base and top, glue, wedge and drawbore everything
- After the glue has cured use a router to clear out the protruding tenon
- Assemble the leg vise and slather on a finish
If the bench loosens up in the future I’ll have to deal with it then. I can always screw on some plywood shear walls, because we all know that would e attractive.
Sorry about your current problem. I had the same problem when thinking about the Criss-Cross. I opted to use the linear bearing and hardened shaft. My fear was of weaking the stretcher tenon and vise leg itself with the crisscross mortise. I purchased the parts through Amazon (see below).
http://www.amazon.com/Amico-LMK30UU-Linear-Motion-Bearing/dp/B0081OU64W/ref=sr_1_16?ie=UTF8&qid=1376111709&sr=8-16&keywords=30mm+Linear+bearing
http://www.amazon.com/750mm-Steel-LinearRace-Shaft-Thomson/dp/B002HAX1X4/ref=sr_1_19?s=industrial&ie=UTF8&qid=1376112212&sr=1-19&keywords=Linear+motion+30+mm+shaft
This option isn’t cost prohibited.
I had to cut the shaft to length and had a 3/8 inch hole drilled about 3/4 from the end. I’m going to draw bore and glue this into the chop.
Unfortunately, I wasn’t able to get to my Chop this weekend. My air conditioner when out. That’s not good in August in South Louisiana.
No AC in August is a problem in most places, Louisiana especially. It was a problem where I grew up in Missouri for sure. Not so much in Northern California.
I *think* I’ll be OK with the Crisscross, but if I’d realized seen the interference problem earlier I might have gone in a different direction.
I’m eager to hear how your setup works out, the videos from Richard Maguire’s shop looked great.
How about patching up the mortises then reboring further back on the leg to achieve the required clearance?
I’d have to move the stretcher back (of course) and I wanted it flush with the front of the bench so I could clamp to it. Unfortunately, anything more than living with this may be more than I want to add to the project unless it’s just not going to work otherwise. I *think* the 2″ long tenon with drawbore pins will be sufficiently strong for this bench to be sturdy and last a good long time. If not, depending on when that turns out to be a bad assumption, I’ll deal with it then. If it’s the week after I finish the bench I’ll add a reinforcing bolt or a middle stretcher. If it’s in 10 years I’ll probably build a new bench.
Maybe after I sleep on it I’ll feel differently. I won’t have time to do much for a day or two anyway.