Making Tools: Straight Edge

I fear that I may open up a kettle of worms with this one. In order to produce a truly perfectly precisely accurate straight edge most machinist manuals will tell you to make 3 straight edges, and there is a process to “prove” them against each other…

I’m not working in metal, I do not need to be accurate to 1/10,000″ over the span of 4 feet.

I need it to be OK over the length of the straight edge.

So I probably should have made this post before making the post about the winding sticks. Because making a straight edge is like making one winding stick. (But one winding stick by itself is useless 😉

I have been using the same straightedges for decades, one @ 2′ long made from a fall off of birds eye maple and one made from plane maple but @ 4′ long.

After planing to thickness use your longest plane to make the edges as straight as you can. Use the trick of sighting down along the edge to “see” if it is straight.

IMG_20200406_200159229

Occasionally the edge gets dinged and I just re-plane it.

Putting a hang hole in one or both ends is a good idea too.

And you could make it a “notchy stick” by making cyma and cyma reversa cuts in the end. (a reference to Christopher Schwarz’ notchy stick)

be well

Karl

Making tools: Compass

 

With all us stuck at home I thought that now would be a good time for me to start a series about making your own tools.

Thus thinking back… When rocks were soft etc. I’m asking myself what was the first tool I made.

It’s a large compass. Everyone in the shop had one. They were all very obviously made by the guys out of wood scraps and a few pieces of hardware.

You can get small compasses at lots of hardware and tool suppliers, and at stationary stores. (“Stationary stores” makes it sound like most stores are mobile???). And you can now get good big ones from some specialty tool suppliers. But back then you couldn’t. And trammel points are great for huge circles, and we can make them too. But not today.

Many that I saw at the time had bigger than 12″ legs. But since then I’ve seen smaller ones.

This build is very simple, it can be done with either hand tools or power tools.

Let’s look at mine to see where we wish to end up.

Select a scrap of nice wood. You can use crap wood but you will be using this for years so I suggest you go with something nice. You can make both legs out of one piece of wood all at once or make them separately… I’m going to use some crap to show you 3 different ways because I don’t need a new one right now.

The scrap needs to be as long as you want the compass legs, and as thick as you want them and twice as wide plus a little for the saw kerf, or not…

EASIEST AND FASTEST WAY!

The quickest way is to draw a centerline down the wide face, make a mark @ 3″ from the end (all the way around) that will be the pivot end.  Drill a hole for a small bolt @ 3/4″ from the same end on the centerline. Saw from the far end to the 3″ mark. Rotate 90 degrees. Draw a centerline on the edge of the pivot end. Saw on this line down to the 3″ mark.

cut on the 3″ line very carefully with a hand saw or a band saw. You need to cut from one edge to the center line and only half way down on both sides to make this work, look at the photos for clarification.

Set the legs in a bench vise so the ends are pointing up. drill a hole that is a tight fit for a pencil in one leg. there are lots of ways to mount the pencil. this is quick and easy. if the hole is a little too tight split the leg with a saw up a little past the bottom of the hole, if it’s too loose wrap it wit a piece of paper.

Pound a small nail half way into the middle of the other leg. cut off the nail so it’s sticking out at least 1/4″ and sharpen it to a point.

Take a pencil stub you have sitting around (we all have pencil stubs right?), sharpen it and push it into the other leg until the tip is even with the nail.

 

img_20200403_1312189816797112111901274648.jpg

 

You will need to take the corner off the legs where they collide. 

use a small bolt and a wingnut if you have one, or a regular nut if you don’t, and washers to unite and tighten the pivot point.

You are done.

 

 

 

LESS FAST (NOT MUCH) BUT MORE WOOD WASTE.

This makes a slightly nicer looking joint.

Same criteria for your material width and thickness, but you will need twice the length. So cut two lengths of your material the length you want your legs (pivot to point plus space above the pivot).

on Both parts: Draw a centerline the length of the face, come in from one end @ 3/4″ and drill a hole for the pivot bolt on the centerline. Make a mark on the centerline about 4″ from this end all the way around.

 

 

Set it (them) on edge and mark the centerline of the edge on the pivot end down to the 4″ mark and across the end and down the other side to the 4″ mark. you need another mark @ 2″ down on each end as well… then on both sides of each draw lines from the 2″ mark on the edge to the 4″ mark where it meets the centerline.

Here is a tricky thing now, both these pieces need to be identical (not opposite) when you are done. So you will be flipping one over.

So while you have them looking the same scribble on the waste area (see picture). I don’t care if you pick the left or the right just keep them both the same. it’s scribble down one side of the CL and on one face of the pivot area.

Saw up the waste side of the leg and out the side along the bevel line between the 2″ mark and 4″ mark.

 

img_20200403_1318284653950698511883721110.jpg

 

Flip it and put it in a vise or a bench hook to saw the diagonal on the other side. ONLY half way down!!

 

 

stand it up on edge to saw the rest of the waste in the pivot area away.

insert point and pencil as previously described. here this is with my old one opened up.

You can clean this up and pretty it up as much as you like.

FANCY SCHMANCY SLOWEST WAY, AND IF YOU TAKE YOUR TIME, PRETTIEST WAY.

Instead of using saws and chisels to make this joint we are going to use an auger bit of some sort to outline it. You can use a spade bit, a Forstner bit or an auger bit.

img_20200403_1321202054871994430196842863.jpg

Mark a line up the center face of your stock.

 

 

 

 

 

img_20200403_1327114278814168690471860406.jpg

 

Drill half way through with the boring utensil you chose.

 

 

 

 

 

img_20200403_132808068_mp94710147273848062.jpg

Very carefully saw from the side to the hole and not into the hole (top), and saw off the opposite leg as waste (bottom)

 

 

 

 

And very carefully whittle away around the hole with a very sharp chisel or knife, very very sharp… (yes I have used “very” too many times here)

img_20200403_133917601953090232748904421.jpg

As you can see the pivot will be the center mark from your Auger and this will make a very nice “rule joint” when you have cleaned it all up

clean up and insert points as desired.

 

 

 

Be Well, Stay Well

Karl