How to Make a Cutting Gauge

Step 1: Materials

Supplies:

1" x 2" x 24" Red Oak Board (craft/hobby area) - $2.24
Knurled Screw - $0.92
Wood Insert Nut - $1.24
Junior Hacksaw Blades 5 pack - 2.88
1/4" Dowel rod (Optional if you have a Dowel plate)

Tools:

3/4" chisel
small files (I just had a set of cheap ones I bought at a cheap local tool store, pretty junky but they work ok)
Combination square (or try square)
Coping saw
Spoke Shave (optional)
Block plane
Rip saw
Crosscut saw or Dovetail saw
Flat head Screwdriver
Dremel 
metal cutting disk for Dremel
metal grinding cylinder for Dremel
Dowel Plate (Optional, if you don't have one just buy a 1/4" dowel)
Pencil
Permanent Marker
Drill (or hand drill)
Drill Bits (1/4" and 3/16")
3/4" Auger bit (or paddle bit if you have a electric drill)
Tape measure
Sharpening stone

Step 2: Cutting the Backstop

Taking your Dovetail saw cut a 3" long section of the Red Oak off.  Then take a Block plane and smooth off the cut lines carefully ( it's easy to tear out the corners).

Step 3: Chamfer the Corners

Make a mark at 1" and 2" on the top then another mark at 1 1/2 " on both sides then connect the dots.  This should be 1/2" down from the top edge.  Cut it out with a Coping Saw then smooth it out with a spoke shave.  This step isn't essential its just cosmetic but it does look nice.

Step 4: Cutting the Square Dowel

This step is optional if you decide to just buy a square dowel but it's really not too hard.  The wood is already 3/4" thick you just need to make a cut at 8" length then cut the height down to 3/4".  This will leave you with a 3/4" x 3/4" x 8" square dowel.  The last photo has a 3/4" Auger bit and a 3/4" chisel for proportion and because they are needed next.

Step 5: Cutting a Mortise in the Backstop

Measure 1 1/2" over and 1" up to mark the center of the face.  Next measure 3/8" to the left and 3/8" to the right, then 3/8" up and 3/8" down.  This should give you the rough outline of a 3/4" square.  Take the combination square and draw lines to form a square in the middle.  Repeat this process on the other side so you will have a square on both sides in exactly the same spot.  

Now take a piece of electrical tape or painters tape or duck tape and mark your auger bit at 3/8" from the cutting edge not the screw tip.  This will help you see when you have reached the halfway mark.  Now carefully drill halfway then flip over and repeat.  If you drill all the way through it will blow out on the other side (it happened to me).

Take your 3/4" chisel and remove the rest of the waste in the same manner as you cut the hole.  Only go about halfway down then flip over and repeat.  Clean up the waste with a chisel and then a file.  I used a 3 sided metal file.

Step 6: Check the Fit

Snug is good, loose is bad.  If it's too loose you might need to start over, otherwise keep filing till it fits pretty good.

Step 7: Installing the Knurled Screw

Remove the square dowel and mark off the center of the top.  Check the bit against the wood insert nut to make sure it's the same size (on mine it was 3/8") then drill a hole (check to make sure the drill is straight, I didn't do this and my knurled screw is leaning forward).  Next screw the wood insert nut into the hole to thread it.  Then remove it and cut it in half with a dremel and notch the top with a dremel so you can screw it back in.  This way there will be room for a dowel pad to protect the square dowel from the force of the knurled screw.  

Step 8: Making/Installing the Dowel

I decided to make my 3/8" dowel this way I wouldn't have to go to the store again and I guess I'm a bit of a cheapskate.  You can purchase a 3/8" dowel if you want from the store and just cut it down to about 1/16" height then install it if you want or you can do like I did and make your own.

To make a dowel you will need a dowel plate.  In my case that is a 1/4" thick steel plate with various sized holes from 1/16" to 1".  I work in metal fabrication so I had one cut at work on a CNC laser.  I then etched the hole sizes so I wouldn't have to check each time.  Making a dowel isn't too hard, cut a small piece of wood 3/8" x 3/8" x 1 - 2 " then the fun begins.

Remember how they used to scold you for trying to put a square peg in a round hole?   Now's your chance to prove them all wrong!  Drive that square peg down with a mallet.  Beat it till it fits!  If it really won't go at all just go up a size, knock some of the corners off and try again.  It does help to take a pocket knife and round off one end to help it start off.

After your dowel is complete carefully take a chisel and scribe all around it at about 1/16" height then push a little harder on the chisel and roll it around pushing a little harder each time till it breaks off.  Be gentle on this step because its really easy to destroy your dowel by smashing it too hard with the chisel.

Step 9: Making a Cutting Blade

Now I know you've been wondering 'Just what are the Junior hacksaw blades for?'   What a good question.  I couldn't find any cutting blades and those were only 2.88 for a 5 pack so I reasoned I would make my own.  Take your dremel and cut off about 1 inch worth of saw blade.  Remove the barb on the end you won't need that.  Next cut a rooftop shape by making two 45 degree cuts.  Change the cutting disk out for the grinding cylinder and grind off the teeth (you won't be needing them) and sharpen to a general blade shape by using the grinding cylinder to bevel the edge.

A word of caution here.  As with all power tools wear Safety glasses.  Cutting metal WILL cause sparks and grind dust to go flying.  Grind and cut away from your body so that the grind dust and sparks will preferably go to the ground.  Use pliers or a vise to hold the saw blade while you cut it, the metal will be very hot and will burn you if you try to hold it in your hands.  Gloves are good too.  Just use common sense when handling any and all power tools.

 After you have ground a rough bevel to the blade use the sharpening stone to put a better edge on it.  Remove any remaining burs and measure the width of your new cutting blade.  Mine is 1/4" so you will need a 1/4" drill bit for the next step.

Step 10: Mortise for the Blade

Make a mark about 1/2" inch down from the end and 3/8" from either side this should be center, repeat on the opposite side.  Drill a 1/4" hole halfway then flip it over and repeat to prevent tear out.  I don't have a 1/4" chisel so I cut it roughly square with a coping saw then took a small file and cleaned it up.  You want  to make sure the blade lays flat against the back side.

Step 11: Wedge for the Blade.

The wedge to hold the blade in needs to be about 1/16" - 1/8" shorter than the blade.  It should be 1/4" x 1/4" square.  chamfer the bottom with a file.  Then I would take a block plane and shave it down till it fits snugly with the blade in as well.  The blade and the wedge should be very snug.  On my gauge you have to tap it slightly with a mallet to set it.

Step 12: Enjoy!

Now you have the satisfaction of saying 'I made that tool!'  

Comments

[technofossil]

Nice project. Anyone who considers themselves a woodworker should have several marking gauges.

As a retired woodshop teacher, I have to comment.

In step 1, before you round off the top, mark the diagonals on the face. This will give you the center and account for any vagaries in size.

Also in step 1 you use a spoke shave to round the top. Someone less skilled may find it easier to use a file to shape the top. It will give more control. (You may like the result better yourself.)

Last. You spend a lot of effort converting a saw blade into a cutting edge and then cutting the mortise to fit it. If you drill a small hole instead, you can use a sharpened nail to do the job. Some sharpen the nail like a pencil, I prefer to grind the end of the nail at a 30 degree angle it gives a nice edge and is easy to keep sharp. Old drafting compasses were sharpened this way. (http://en.wikipedia.org/wiki/File:Cyrkiel_RB1.jpg) You said you were a bit of a cheapskate, so am I. I just saved you $2.88 :)

I like that you use a lot of hand tools. Less noise and more skill required.

Again, nice job.

[vincent7520]

I had also the idea of using a ball point stuck into the hole instead of a sharpened nail. Actually it is very practical for long markings and not too fine jobs in "crude" carpentry. This way you're sure to see the marking on wood that is barely planned. Of course this shouldn't be used for normal carpenter or cabinet making.

[technofossil]

Use a pencil not a pen. The ink may bleed and make the mark harder to follow. It may also stain the wood making finishing harder. The nail will give you a cleaner line to follow. I use both.

Get into good habits even if it is only for rough or practice work. As you start to do more intricate work, it will pay to have the right habits.

[vincent7520]

You're right !
Actually I used it to mark long pieces of wood to shape into a mast for a boat. Stains were not really a problem at this stage and the benefit was I didn't have to worry about the lead being used and not marking in the middle of the process.
For the rest you are perfectly right and it's a pleasure to talk to people like you.

Congratulations for you name too : I love technofossils ! …Although I have almost the whole paraphernalia of modern times (mac, ipod, ipad, etc…) I am quite one myself : some of my friends call me a luddite !…
My belief is that NASA technology is not as great as one may think as you can't plank a boat properly with it !!… LOL

[technofossil]

There is something about working with wood that can't be explained to an outsider. I've never meet another woodworker who wasn't eager to share. I tried to build a canoe once but never a boat.

I'm a Technofossil because I started as an electrical engineer in the early days of the computer explosion. I made a career change to teaching woodworking in high school. Never looked back.

Be well.

[cheekypaper]

Hi. You are so right. I am also a technofosil (1955 model). I have designed, built and flown aircraft using wood. (God's Composite) I think I'll build one of these just because I can cheat. I have a waterjet :~)
https://www.facebook.com/cutit.co.za

[technofossil]

It's not cheating,,,It's producing. The difference is what your goal is. When I start a project, I look at the reason. If the goal is to build a quick book case, out come the power tools. For a process like this one, working the wood by hand (minimal use of power tools) creates a bond between you and the final piece (IMHO). When I was teaching woodshop, the only power tools the my students would use were the lathe and the drill press. Everything else was done by hand. Power tools only allow you to make more sawdust faster. Be well.

[vincent7520]

thank you
you too

[pfred2]

OK you convinced me I'm going to have to make some. Although usually I just mark off with calipers.

[splazem]

Very cool!

[Cheiron]

Thank's for noticing the problem on step 3 baustin,I fixed it. It should have read 2" not 2 1/2".

BTW very nice work PS118 that looks great!

Thank you all for your comments and suggestions I especially liked the ones about preventing tear-out. It's so frustrating when you have put time in on a piece only to have it ruined by something so simple.

[PS118]

Thanks. :)

[Cheiron]

I double checked ... you were right 1 1/2" LOL Sorry it's been a long day.

[Cheiron]

Thanks!

You are definitely right about the layout. Marking the diagonals in step one would have been a better way to find the center on the top and the front and back face. Drilling the hole in the top for the knurled screw would also have been easier before rounding off the edges.

A nail would have been easier and cheaper than making a knife blade, however I wanted to challenge myself to make a wedge to hold the blade in tightly. I figured it would be good practice for making a wedge for a tusk tenon (which will be part of my next project building a workbench hehehe).

[MadBricoleur]

Oh, wow! I first saw this because it was featured on the front page... I had invented (or so I thought) something similar to aid in making my ukulele, marking an offset perimeter from a curved piece of wood. Never knew there was a name for it! I guess the idea wasn't original after all.

[espdp2]

Just think, all by yourself, out of necessity, you invented a tool for a job that has been successful for millennia. Congratulations on being a secret genius!

[MadBricoleur]

haha, true dat. thx!

[PS118]

Thanks!!! Reading your instructible gave me the ideas and inspiration to finally build my own! (see attached image)

I used a 1/2" oak dowel and a piece of 3/4 oak scrap. I also had the 1/4"thumb screw laying around, so I just tapped the oak and screwed it in. The pad underneath is just a piece of 1/4" pine dowel I cut off thin with a utility knife.

It is 7" long overall, and I should be able to mark up to 6" wide with it.

Since I had no tiny tot hacksaw blades, I originally intended to use an xacto blade for the marking point. Since I couldn't come up with a way to not have part of the blade sticking out the top, I reluctantly decided to spare the inevitable accident and went with a grabber screw.

Actually that gave a few advantages:
1) super easy to do -- just drill a pilot hole and screw it on in!
2) Easy depth adjustment -- screw it in or out.
3) Easy sharpening -- take it out, screw something together with it, put in a new one.

[Endante]

This is Awesome Cherion! Great tips on how and why you did what you did. I already have the parts in my shop and am going to make one.

I am building a celtic harp and had the same "blow-out" issue you mentioned earlier, when drilling for the tuning pins in the neck. Wated alot of good wood.

I looked around and found the answer as to why it happens and what to do about it. This wont work with the auger bits because the force themselves through is why i didn't mention this earlier.

-- this is what I found--

The WHY is that the drill bit creates a pressure cone in front of the cutting surface as it bites into the wood. as you near the far side that pressure cone can "explode" outward ripping the underside surface.

the WHAT to do is: slow way down as you near the far edge, pause and even back the drill up to let the drill clear the material it is removing out of the hole. and MOST importantly keep your drill bits extreemly sharp and ground the the proper cutting angle.

Hope this helps

[baustin]

You could also add a knurled screw to the end of the square dowel to make it easier to change/adjust the blade.