Monthly Archives: November 2014

Chevy Update

I got the saw frame finished yesterday and glued up.  This was the last bit that I was worried about being able to make, mostly because of the  large finger joint between the arms and back.  The key was doing a careful layout, working from the reference face on all the parts and assembling them the same way.  Accurate sawing is important too of course, but the bandsaw fence took care of most of that.

Layout for the finger joint

Layout for the finger joint

On a related note, I have a practice project to get my hand sawing skills tuned up in this area.  I’m going to make a couple of wooden squares, but I didn’t want to make a mistake on this part.  I’d chosen the straightest quarter sawn Sapele for this part, rough dimensioned it and let it acclimate for several weeks…

Once the points were cut and fitting well I added in the details.  The arms taper in thickness from 1.125″ at the saw back to 0.5″ right before the wounded ends.  I also cut a step in the arms (in use this is where you hold the saw, not at the knob) and a curvy-swoopy thing in the back of the saw.  Is that an Astragal?  No, that’s not right.  Cyma Recta?  I think that’s it.  Or Curvy Swoopy Thing.

Dry fit of the detailed saw frame

Dry fit of the detailed saw frame

It will need the edges chamfered and a final sanding after gluing, but it’s sitting in the clamps right now.

Glued up.  I need some shorter clamps, these are a pain for small parts...

Glued up. I need some shorter clamps, these 5 footers are a pain for small parts…  The plywood in the center is to keep the arms parallel.

With the saw frame mostly done (I need to add the gimbal brackets on the back, but it’s already morticed for them), I moved on to preparing the stock for the next major subcomponent — the seat.  Once that is done I only need to make the clamp and clamp actuator and I’ll be done.

The seat parts are all 1.75″ thick.  I dimensioned the lumber, and laid out all the joinery from my drawings.  Next time I get to work in the shop I should be able to cut and fit all of this, it’s all straightforward (if large).

Parts for the seat assembly.  From the top: seat, front and rear legs, lower stretcher.

Parts for the seat assembly. From the top: seat, front and rear legs, lower stretcher.

The dovetail joint at the front of the seat / top of the front leg will easily be the biggest dovetail I’ve ever cut…

Mondo-Tails!

Mondo-Tails!

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Chevalet Plans Update

I’m pretty close to finishing the saw arm for the Chevalet, so I figured I’d better get the rest of the project modeled in CAD so I can sort out the joinery.  Things go much more smoothly in the shop when I can focus on doing rather than juggling dimensions in my head while I’m trying to saw of chisel.  At least for projects with this many parts.

So I pulled the major dimensions off of the blueprints from Patrick Edwards and modeled them in CAD — adjusted for the materials I’m using.

Chevalet3

CAD rendering of Chevalet — still missing the actuator for the clamp, but mostly all together.

The joinery for the “stool” portion is mortise and tenon for the stretcher and the rear leg, but the front leg connection to the seat is an odd recessed dovetail to make room for the spring arm for the rear clamp.

Dovetail joint at the front of the seat is recessed to make room for the spring arm that forms the rear of the clamp

Dovetail joint at the front of the seat is recessed to make room for the spring arm that forms the rear of the clamp

I’ll probably have another iteration of the plans later when I get to the clamp actuator, but this should keep me busy for a while.  This version of the plans can be downloaded from here.

Nearly-complete Chevalet plans.  The clamp actuator is the only significant piece missing.

Nearly-complete Chevalet plans. The clamp actuator is the only significant piece missing.

 

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Chevy Saw Frame

I got the joinery done on the saw frame for the Chevalet this morning.  I was worried about getting the giant finger joint to fit and be straight — it turned out to be pretty straightforward.  It’s not perfect — the shoulders could be a little tighter in a couple of spots — but it lays absolutely flat on the bench and the joint is nice and tight.

I need to do the rest of the details on it after lunch, the mortises for the brackets on the back, the mortises for the blade clamps and the shaping/tapering.

I started by laying out the joinery, and marking the waste.  I sawed the faces on the bandsaw with a fence.  It tried to be careful to account for the kerf and just remove the scribed line (from the correct side!).  Then it was chiseling out the waste and some tune up here and there.  I want to be able to do this with a hand saw, but this wasn’t the project to experiment on.

Joinery laid out

Joinery laid out

After sawing on the band saw, chopping out the waste and general clean up it all fits pretty well.

After sawing on the band saw, chopping out the waste and general clean up it all fits pretty well.

This is where I’m headed.  I need to do all of the details and glue the saw up next, that should feel pretty good.

The saw frame -- I rendered the CAD model using different materials for the arms and the back to show the joinery more clearly

The saw frame — I rendered the CAD model using different materials for the arms and the back to show the joinery more clearly

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Less Messy

My shop has been getting a little messy lately.  That tends to happen when I’m in the middle of a project, but also I’ve been accumulating the detritus from several completed projects.  The kicker was gluing up the blanks for the Chevalet, so I decided to get serious about improving the situation.

First I bribed my 14 year old with a new video game to do a super good dusting/sweeping.  Shameless, check.

Second I decided to make some racks for my clamps.  That took a little more doing, but not much.  Leftover scraps of plywood, metal L-brackets, and presto — no more booby traps on the floor or in the corners.  This should also make is easier to clean up.

Before.  This makes it tough to sweep up.

Before. This makes it tough to sweep up.

After

After

After

After

After

After

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The Saw Frame

So here is the little bit of joy that is next on my hit list: the saw frame for the Chevalet.

The saw frame -- I rendered the CAD model using different materials for the arms and the back to show the joinery more clearly

The saw frame — I rendered the CAD model using different materials for the arms and the back to show the joinery more clearly

It’s not really a tough piece, but I’m worried about getting the fit of the finger joints just right.  If they are too loose it won’t be strong enough, if they aren’t straight the arm will be crooked — and useless.  Or, as we say around here, “kindling”.

I’ve updated my working copy of the plans, you’re welcome to download and follow along.  I’m just making plans to sort out the details in my head, based on the materials I have on hand.  On the saw arm, I haven’t resolved the gimbal attachment mechanism.  In the plans it’s not shown clearly, although my understanding is that it’s a weird wedged mortise and tenon construction.  I’m not sold on the idea of cutting mortises into the back of the frame, so I’m still noodling on that detail.  And of course the seat assembly and front clamp are still to be done (virtually and actually).

(incomplete) Chevalet Plans

(incomplete) Chevalet Plans

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Hand Sawn Tenons

I’ve been working on my Chevalet, and making slow but steady progress on the support arm.  I wrapped up the joinery this past weekend and am in the process of gluing it up.  Basically there were two joints to cut here, a double tenon from the vertical post into the horizontal arm that holds the saw frame adjusters, and a bridle joint on the other end of the vertical post into the horizontal arm that connects to the main body of the Chevalet.

Before we move on to the point about hand-sawn tenons, here are the progress shots from the weekend.  Not as much progress as I’d hoped, but I had to go buy more wood, and it was my wife’s birthday and there were important preparations to be made!

Double tenon on the top of the vertical post.  The faces and shoulders were cut with a dado stack (the part horizontal on the table saw).  The faces between the tenons cut on the bandsaw, and the waste chiseled out.

Double tenon on the top of the vertical post. The faces and shoulders were cut with a dado stack (the part horizontal on the table saw). The faces between the tenons cut on the bandsaw, and the waste chiseled out.

I screwed up the bridal joint, I was trying to cut it to the exact size but ended up with a slightly loose joint.  Crud.  I cut a thin (~1/8″) slice and glued it to one face of the bridal joint, then used a hand plane to smooth both faces for a snug fit.

Repair shim glued in with Titebond II.  I've now used three different kinds of glue on this project...  Random Woodworking by Joe.

Repair shim glued in with Titebond II. I’ve now used three different kinds of glue on this project… Random Woodworking by Joe.

For reference, this is the dry-fit assembly that I’m working on:

Dry fit assembly of the saw support assembly.  This is from the perspective of the front of the Chevy.

Dry fit assembly of the saw support assembly. This is from the perspective of the front of the Chevy.

Hand Sawn Tenons

Now on to the main point of this post.  It’s been bugging me how much I’m doing with power tools.  Not that I have a religious objection to power tools, but really from the perspective of efficiency.

I’ve done tenons several different ways.  I always lay them out with a marking gauge or knife and square, but the way I cut them has varied.  I cut some by hand, including the ones on my workbench.  I’ve never been good at hand sawing tenons, and I’m very out of practice now.  Most commonly, I set up a dado stack on the table saw and chew away the waste from the face of the tenon.  I set the fence to control the length of the tenon, and raise the the blade to set the depth of the shoulder using a piece of scrap.  Then I can knock out a bunch of identical tenons, but it’s time consuming to switch the table saw over to do that, and then back again.  Just for completeness, I’ve also cut tenons on the table saw with the tenon vertically (I absolutely HATE that method, very scary!) and on the bandsaw.

If I need to do a batch to identical tenons, it’s probably worth setting up the table saw.  Like when I made the two Blacker house sconces, that was 32 tenons I had to cut.  But for something like this where I have one tenon to cut, it’s a real time sink to set up the table saw.  Maybe the bandsaw is a better method, but I think hand sawing might actually be nearly as fast to make the cut and perhaps more accurate.

In that vein, let me offer something I saw posted on Derek Cohen’s “In The Woodshop” website, a magnetic saw guide for cutting tenons.  This looks like it could make the setup very fast, and the results very consistent.  The recessed magnets hold the saw plate against the jig, just adjust the jig to your layout lines and saw away.

From inthewoodshop.com, a nifty tenon jig

From inthewoodshop.com, a nifty tenon jig

Part of why this is on my mind is that I need to make the saw frame for the Chevalet next (ish).  Once I finish the CAD model of the saw frame I’ll post it, but it’s essentially a large finger joint, with the fingers just under 1/4″ thick, two fingers on the arms and three and the back of the saw.  Any inaccuracy on that is going to be problematic, and it’s not something that can be easily done on the table saw (read: vertical orientation and a special jig).

Plan “A” is to make some test cuts on the bandsaw, plan “B” is to hand saw it, maybe with a jig like this.

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