Friday, July 4, 2008
Bench #3 - Building the top
The top is going to be 4" thick. This is 8/4 Ash ripped to 4-1/2" wide.
After jointing and planing the stock flat I glued 4 boards each into 7" wide sections. Then I jointed these and planed them to thickness (just over 4"). Schwarz says you can build this bench with a 6" jointer. You definitely need some serious infeed and outfeed support (rollers) to joint planks of this size. Each of these sections weighs over 70 pounds. Not exactly the type of work I enjoy.
Then I glued the three sections together. I ended up with around 22". That's just a little shy of my final width of 25".
I was really diligent to get my edges at 90 degrees. With boards of this weight and size, that's not very easy. Anything less than 90 creates a valley or a hump, which will have to be planed out when the bench is flattened. I'd rather have a valley, and that's what I ended up with.
While the glue was curing I decided to partially assemble the base. These are the holes for the drawbored tenons.
And here's a finished joint.
After the top cured, I had a helper give me a hand and place the top on the base (the top alone weighs over 250 pounds). The bench is taking shape.
The next step was to make the dog hole strip. This quick jig works with a template collar on my plunge router.
I used a circular saw from both sides, followed by a router with a straightedge clamped to the top to cut the top to length and form the tenon for the end cap at the right end of the bench. The end cap is an integral part of the tail vise.
I laid out the area of the tail vise that needs to be removed to house the vise screw and sliding block components. This is a lot of wood, and in hindsight, I probably should have built this void into the laminations as I was making the top. I honestly didn't want to take the time to plan this out though. This method may be more work, but it's less prone to error.
I got rid of most of the material with some cuts from a circular saw.
Then I busted the waste out with a mallet. Yeah, felt pretty good to wail on the bench like this, especially after all the sore muscles this bench has given me!
To further excavate material I build up this quick jig for routing out the pocket. I used a straight bit to get close to the line.
Followed up with a round nose bit to get even closer. I finished up with a couple carving gouges followed by a curved scraper.
The finished pocket with the dog hole strip in position.
I made an end cap from some 12/4 Ash and drilled a couple holes for 1/2" bolts. The elongated hole allows the top to move.
I routed out the mortise for the tenon. Like a genius I figured I could just do this on the table saw lickety-split. But then I realized I didnt want a gaping hole in the front end of the end cap (that's the reject end cap on the right). Classy. ;-)
Once I got the end cap fit (it took me the better part of a day, and I have no idea why. It should have been a 20 minute job) I drilled for the captive nuts. I marked the holes with my custom rosewood-handled Czeck Edge bird cage awl. Fantastic tools that Bob Zajicek makes. Highly recommended.
I didn't want to get too fancy here so I drilled holes the same width as the nut, so I could just drop the nut in and tighten the bolt. My 3/4" auger bit is quite dull, and I didn't want to sharpen it, so I grabbed one of these new Speedbor bits and chucked it in a 10" brace. These bits are way more aggressive than a typical Jennings type auger bit. It cut cleanly and accurately, but it was a real bear to drive. These bits are really designed for heavy duty slow-speed drills and softwood boring. I put one in my 1/2" Dewalt drill (typical high speed drill) and it just stopped. Definitely a high-torque bit. I think it would have been easier to sharpen the bit after all.
Placing the nut in the hole with a magnetized bolt.
The end cap installed. This is the underside of the top. I considered using some beefier bolts, but figured the thread holding power is already way more than it needs to be with 1/2" bolts. And it's the threads that are doing the work here. Bolt diameter matters little in this application.
A shot of the end cap in position (it's purposely too long).
The end cap and front laminate strip in position.
Front view of the same. The front strip will be dovetailed into the end of the end cap.