Friday, March 27, 2015

Simple and Easy Box Joint Jig

This is my box joint jig based off Woodfather's design which is used with a single rip blade. It has a pin that matches your blade's kerf and a set of spacers in a 1:1 ratio to the fingers of the box joint. You can easily change the size and spacing of the box joints by changing the width of the spacers. Want 3/8" fingers? Use 3/8" spacers. Want 8 mm fingers ... you know the drill. For simplicity I used 1/4" plywood for my spacers which lets me cut each finger in two passes using my 1/8" blade.

Mine follows the original plan closely with a couple of minor modifications. I added a tab to the back of the fence so it clips over the jig and stays in place on it's own. The tape acts as a spacer allowing the fence to slide freely.

I added edge banding to the fence where it rides along the jig. The mating face of the jig also has edge banding and both are waxed. The fence travels smoothly left and right.

The pin (pic above) is a screw 3.17 mm in diameter with the head removed. The kerf of my Freud rip blade is 3.19 mm. The resulting joints are snug but allow room for glue.

The block on the far right is glued in place and never changes. I used cyanoacrylate in case I ever need to remove it. Below you can see the edge banding along the top of the jig.

The spacers are held in place by a scrap of wood approximately the right length, then a small wedge is inserted to keep everything snug.

Mine is a wee bit taller and the sides come farther back. This allowed me to attach a handle. I tried first without a handle but my left hand kept searching for a hold. I find it more comfortable with a handle.

The strip of ply along the front of the fence (red arrow below) is only 3/4", not sure what I was thinking, but it will have to be replaced with a deeper version that will accommodate more than a couple pieces.

An unplanned change which didn't work out, are the runners being short in front (see above). The wood took a funny bow and were binding so I had to cut them down but now the jig wants to tip forward. Definitely leave them long in front. Adding the handle stopped the tipping so I'm not sure if I will bother replacing the runners.

Thursday, March 26, 2015

Speed Square Miter Sled for Table Saw

A quick and easy sled modification for cutting 45° miters on the table saw. I trimmed a plastic speed square so it will lay flat and screwed it in place with the widest side toward the blade. The screws go through a scrap of wood which acts like a washer allowing the square to slide left and right. Very easy and very handy.

Monday, March 23, 2015

Dovetail Ratios

Dovetail Angles

Playing around with dovetail ratios. Three are common, plus phi (1:1.618) and pi (1:314) which I've never heard of anyone using but thought I would toss them in for fun.

If you are interested in the relative strength between dovetail angles, search the web for:  THE RELATIONSHIP BETWEEN DOVETAIL ANGLE AND JOINT STRENGTH - Notes from The Forest Products Research Laboratory tests (KS Walker) reported in Woodworker Magazine, January 1958.

To save you some reading I'll summarize the conclusions. In glued dovetail joints the angle made no significant difference. In unglued dovetails wider angles were stronger. The article claims that unglued dovetails were stronger because the joints could slip whereas glued dovetails the wood fibers separated. They tested hardwood and softwood, each from the same board. The softwood failed sooner in unglued joints because it more easily compressed and slipped free.

Wednesday, March 18, 2015

Making a Wood Carving or Marking Knife with Disposable Blade

Swann Morton scalpel blades have become popular for marking knives. They are a high quality, carbon steel, disposable blade available from the U.K. David Barron, among many others, uses them in his marking knives, epoxied solidly into the handle. The carbon steel blades are easy to sharpen and take a keen edge. I ordered some last fall and have considered several ways of making the blades replaceable.

Swann Morton 01 Scalpel

I started with a scrap of Spanish cedar. Cut a slot through the end deep enough for the blade. Drilled and countersunk a screw hole to retain the blade. Then sketched and cut out the handle shape. Full details are in the build video. My apologies for the lack of pictures but this was spontaneous and slotting, drilling, and sketching the handle blank was a less than a five minute minute job.

The blade is secured with pieces of walnut veneer that fit like splines in the kerf above and below the blade. As seen in the video, I did not adequately glue the veneer or didn't allow enough drying time (probably both), and the spline failed. On the second try I used cyanoacrylate glue which is holding up fine so far. There are stronger ways to secure the blade but I wanted to try this first as it's the easiest. If it fails again I will insert a brass pin above the blade. An alternative is an inner frame of metal with a cut out for the blade, then attached wood scales. I might do that in a future video.

I am not a carver and did not make this knife with carving in mind but wanted to see how well it might work for chip carving. The blade is very thin and sharp, and had no issues slicing through poplar. My skills are obviously non-existent and it would be interesting to have an experienced carver's opinion.

Most prefer single bevel blades for marking knives as you can hold the flat of the blade against a straight edge. These are double bevel blades but by holding them at a slight angle you can achieve the same accuracy.


Blades are available from:
I have no affiliation with either seller.

Monday, March 2, 2015

More pictures of shop made lathe tools

I get more questions about my carbide lathe tools than anything else, mostly about grinding, so here are more pictures of the business end.

The diamond tip is ground with a taper then flattens for the cutter. Nothing holds the carbide in place except friction and it hasn't budged. A few folks expressed concern because it isn't form fit like Easy Wood Tools but that isn't necessary for holding it in place.

I've had less success with the radius cutter and will eventually replace it with a round carbide. Radius cutters don't do anything the other shapes don't do better. I suggest that you use square bar for square, radius, and diamond cutters otherwise the tool tends to spin when using the corners. This cutter has several chips where catches have flung it against the tool rest.

The tapped hole goes completely through.

The grinding doesn't have to be pretty to be functional. Leave steel under the cutter for support then grind a relief matching the angle on the carbide.

Soon I will be making a new one with a square bar. I purchase my carbides from AZ Carbide, excellent prices and customer service along with fast shipping. I have no financial interest in the company and receive no compensation for recommending them.

Monday, February 9, 2015

Soldering Iron Stand

Took a break from tuning up my table saw to make a holder for my soldering iron. Nothing special, just some 10 gauge copper wire and scrap of ipe. This will come in handy on my upcoming WiFi antenna project.

Tuesday, January 20, 2015

How to wire an HVAC fan motor for 3 speeds

Disclaimer, I am not an electrician or in any way qualified to give electric advice. Following my instructions may result in a fantastically painful death and/or total loss of property and innocence,  but probably not

It's man's nature that if you have a motor capable of three speeds you will want to use all of them. Such was the case when I was looking for a motor for a small shop project. My choices were between a 1/4 HP single speed motor or a 1/4 HP three speed HVAC fan motor. The fan motor was designed so that you pick one speed, wire it, and that would be your speed forever. But does it have to be that way?

Probably not but then I had to figure out how to wire it. Simple, I found a rotary switch on Grainger: off/on/on/on. Not simple, I was advised by the internet this switch would cause my untimely death or at best, burn out in short order. OR, it was perfectly okay and would only last 100,000 cycles instead of 200,000. Back and forth came the advice with lots of technical mumbo jumbo about snapping that was over my head. I had 3 people telling me it was a bad idea and 3 telling me it was fine. And all of them seemed credible. One fellow had an engineering background and had worked for a switch manufacturer so I gave his advice more credence. The only thing all 6 could agree on was that toggle switches would be safer. So I called Grainger, ’We don’t sell switches rated for ac motors. Don’t use any of our switches!’ You think I’m kidding but that’s almost word for word what they told me. It’s also a bald face lie, they do sell switches rated for ac motors. So I threw in the towel and bought toggles rated for AC motors from Home Depot. They had no problem with me buying their switches and even walked me directly to them in a rare display of eptitude. In the end, of the 6 people actively giving me advice, only one was happy I went with toggles, the other 5 were disappointed in the lack of apocalyptic outcomes.

So you want to know how to wire a 3 speed HVAC direct drive AC motor? Here’s how I did it.

1 each – SPST (on/off) Gardner Bender toggle switch
2 each – SPDT (on/off/on) Gardner Bender toggle switch
wire, motor, and appropriate electrical housing w/ cover

You should turn off the first switch before changing speeds with the other switches. If you know of a more elegant way, feel free to post it in the comments below. If you believe my way will be my doom, well I'm here writing about aren't I?