|Project by Brad||posted 12-02-2011 02:24 AM||3742 views||7 times favorited||8 comments|
Backsaws are like rabbits (the furry kind), they multiply fast. And when placed on a pegboard, they take up a lot of space. So I’ve been contemplating a saw till for a while. Rather than take on the whole, every-saw-I’ve-got saw till, I decided to get some till experience under my belt first with a backsaw till.
I’ve seen a lot of pictures people have for various saw tills. They are short on dimensions. Nor do blogs I’ve read go into detail about such tinsy details as, oh, say, a good width for the saw plate slot…or how far apart they should be spaced…or how far out the bottom saw handle (dowel or board) support should be from the carcass. So to answer these questions for myself, I built a prototype.
Working out good dimensions with a prototype
If you ever watched Norm Abram’s TV show, The New Yankee Workshop, you know that he always built a prototype before doing his project for the show. He never let on, but I highly suspect that he ironed out the “kinks” of his design with the prototype. In other words, he made all his mistakes on it and looked flawless when he built the one for the program.
As a beginner woodworker, I frequently build a prototype of my project out of cheap pine before trying it with the “good stuff”. Not only does that reduce the risk of destroying good wood beyond use (notice I didn’t say “eliminates the risk”) but it gives me repetitions doing skills I want to program into muscle and cerebral memory.
For the good-wood backsaw till I built, I had a few criteria.
1. It had to hold at least 6 saws. 2 x carcass saws, 1 x rip saw, 1 x dt saw, and 1 x dream saw. Yes, I left a slot to be filled by the Badaxe Toolworks sash saw I’ve been dreaming about. I’m going to go with the thin plate, 13 ppi…oh well. No sense boring you with the details.
2. It had to be compact, but not so much so that I would be bumping my hand into an adjacent saw when removing it for use.
3. It had to be the right height, so that my arm naturally extended to the right “place” when reaching for a saw.
4. And it had to hold the saws at a sufficient forward lean angle, so that they wouldn’t fall backwards out of their docks into my eye, or my workbench.
Truth be told, I had no idea what all these dimensions should be.
Dimensioning the till
In order to meet my criteria, I started doing some math.
The formula I used to determine the width of my till was:
(Carcass stock thickness to account for DT joinery x 2) + (end slot distances x 2) + (middle slot distances x 5) = top rail length
So, 1.5” + 4” + 12.5” = 18”
Here’s a diagram to clarify what I mean.
I built the good-wood till using my initial flawed design (18” width), which rendered two end slots unusable. I was able to save one slot by using it to dock my Dozoki saw, but that still leaves one obvious slot to mock me every time I look at it.
What was I thinking? 2” on the end slots? Jeez. They should have been 2 ½” as measured from the inside edge of the carcass don’t you think? Well you’d be wrong. I forgot to take the thickness of the dowel supports into account.
To increase the structural strength of the supports, I placed them on the inside bottoms of the carcass. So I should have accounted for their thickness too. The first slots on each end should have been measured 2 ½” from the edge of the dowel supports to give my hand enough clearance to retrieve a saw without touching them. Maybe this diagram will help you understand what I mean.
So correcting my formula would read:
(Carcass stock thickness to account for DT joinery x 2) + (thickness of dowel supports x 2) + (saw plate slot distances x 7slots-the spacing should all be same darn it!) = top rail length
So 1.5” + 1” + 17.5”= 20” rail length
I ballparked the till height by measuring the lengths of my backsaws. My crosscut Disston #4 and Noble #1 are about 15” from the top tip to the curved crook of the top of the handle. My S&J tenon saw is 16 ½” from tip to crook. Taking into account the approximate placement of the dowel (a few inches from the bottom of the carcass) and measuring from the place it would fit into the Disston handle crook gave me a height of about 16”. This was the dimension I used on the prototype and it worked well enough to carry over to the good-wood till design.
What should the top-rail spacing between the saw plate slots be? Make it too wide and I squander valuable space to hang fewer saws. Too narrow and my hand would bump into adjacent saws when removing one. To me, that would be a woodworker’s Chinese water torture. So to test what the best distance for my hand size would be, I designed the prototype with different slot spacings: 1 ½”, 2”, 2 ½”, 3”. Keep in mind that the spacing is measured from slot centerline to slot centerline. So the effective space when I reach for a saw will be two times that. For me, the Goldilocks spacing was 2 ½”. I could retrieve and replace saws without touching anything. The 3” spacing gave me agoraphobia.
The next variable is the slot width itself. What is the optimal dimension? Make it too thin, and I suffer frustration at having to line up the plate perfectly every time to seat it. It it’s too wide the saw would twist to one side or the other in the slot to infringe upon another saw’s personal space. The ¼” slot was too narrow—the saw back wouldn’t fit. The ¾” slot was too big. But the ½” slot was just right.
Finally, there was the lean angle, meaning, how far out does the dowel need to be from the stiles to ensure that a docked saw would not tip backward? I had no woodly clue.
So I designed a slot into the prototype’s dowel supports. This would allow me to extend them up to 2” and try different lengths to hash out this variable. In use, I found that the shallowest depth of 7” worked just fine, so I went with it to minimize the z axis (from the wall toward me) space.
That left the best placement of the ¾” oak dowel to support the saw handles to work out. On the prototype, I placed the ¾” hole center point 1” from the top edge and 1” in from the front edge. In use, my LN DT saw would catch on the top rail, so I lowered the dowel support y-axis center point by ½”. That’s 1.5” from the top edge and 1” from the front edge.
—Dovetail slot support width and location.
My LN DT saw is shorter than my other backsaws. It also sports a tool guard. This means I had to craft and affix a saw plate slot to support the shorter length. And I had to cut a ½”-wide slot to accommodate the girthy tooth guard. I wanted the top edge of the DT saw to sit a few inches above the top of the slot piece so that docking it would be easier—no lining the tip up. So I located the top edge 3” from the inside edge of the top rail.
I decided to use alder from the local big box store. This hardwood is relatively inexpensive, but also looks good when finished.
—After cutting the carcass pieces to rough length, I used a shooting board to trim them to exact length.
—Then I cut the dovetails. I started with the tails, laid them out, put both stiles in the vise and cut them at the same time.
—Then I cut the dowel supports to length and designed a profile to break up the blocky appearance of the ends. I tried tracing the top edge of my LN DT saw as a pattern but abandoned it in favor of the curvy design because it was too complicated.
I cut the pattern with a coping saw and shaped it with a hand-held belt sander, rasps, files and sandpaper.
—Then I cut the DT slot support to size and drilled pilot holes for screws to hold it in place.
—After that, I tried using a smoothing plane and card scraper prepare the surfaces for finishing but didn’t get good results. So I broke out my random orbit sander and went over everything with 150 and 220 grit papers.
—Then I chamfered almost every edge (not the lower edge of the upper rail—it needs to support the till on the pegboard).
—Then I made a mistake. I cut the saw plate slots. This was an error because when I glued up the carcass, I broke one end at a weakened slot point while pounding the DT joint together with a dead blow hammer. Instead, I should have glued up the carcass, and THEN cut the slots. After they were cut, I chamfered the edges with a file.
—The dowel supports were next. I drilled pilot holes for the brass screws and countersunk them. Then I glued and screwed them into place.
—To mount the till on my pegboard, I laid out the placement of the L-screws so they didn’t line up with any slots. Then drilled pilot holes and screwed them in with the aid of a wrench for leverage. I detailed this operation in my 1st pegboard post.
—Then I made another mistake by finishing the piece. The moment I applied polyurethanes finish, the glue smears from the carcass glue up light up like white under a black light. I should have heeded the Woodsmith tip that says to wipe down everything with mineral spirits first to locate glue smudges. The smears had to go so I sanded those using 150 and 220 grids then applied a 2nd coat.
—Lessons learned. Once you cut the top rail saw plate slots, the whole piece becomes very weak. That increases the risk of breaking it when you glue up the dovetails, or sand it, or chamfer edges…just about anything you do to it. Also, a little care when gluing up would have eliminated the additional time I spent sanding and finishing the project.
Here’s the final product. Yes, I do have many dovetails to go before I feel even remotely competent at this joinery skill.
The score card
After the finish dried the till found its new pegboard home. Here she is after loading up my backsaws.
So how did the final result compare to my initial requirements?
—Hold at least 6 saws.
No. Holds 5 comfortably after calling an audible and using one end slot for my Japanese DT saw. 5/6 = 83%
—Compact, no-bump access to saws.
Yes for 4 slots.
—Right height when arm naturally extended.
—And it had to hold the saws at a sufficient forward lean angle, so that they wouldn’t fall backwards out of their docks onto me or my workbench.
—Strict grading standard is 3 out of 4 =75%
—Cut-some slack standard = 3.83 out of 4 for 96%.
—My dovetails were functional, but not pretty. That earns me a “Needs improvement”.
-- "People's lives are their own rewards or punishments."