Angle Set Up Gauges for Grinders and Belt Sanders

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Introduction: Angle Set Up Gauges for Grinders and Belt Sanders

OBTUSE ANGLE SET UP GAUGE


When you sharpen your own chisels and wood turning knives, you’ll find it necessary to set your grinder or sander support table to different angles for different tools. Of course, you’ll find it necessary to repeat the previously set angle, to avoid removing valuable steel from the tools, and to get consistent cuts.

Setting up a tool rest of a grinder or belt sander to grind a specific angle presents a challenge because you can't use triangle templates (see first photo), angle gauges like I use in the steps of this ible, or similar set up tools.

You can use a bevel gauge. To do so, you’ll have to set it to the angle you need for the tool you’re sharpening. You can do this using a protractor to set the bevel gauge, then use the gauge to set the tool rest of the belt sander or grinder. This requires two steps, two tools and trying to set an angle twice.

Another quicker and more simple method is, use an obtuse angle template with the angle you need.

Unfortunately, obtuse angle templates aren’t easy to come by. Even on line. If you do find them, you may not be able to buy an angle template with the angle you want or need. Or you may not like the material its made from or even the size of the template. Your best bet may be to make your own gauges, since they are easy to fabricate.

To make your own set up angle gauges, you'll need the following:

[TOOLS]

1) Safety glasses.

2) Hearing protection.

3) An adjustable angle protractor.

or

3a) A protractor

and

3b) An adjustable bevel gauge.

4) Something to mark the material for cutting:

- An awl, knife or other sharp, pointed tool can scribe lines into plastic and aluminum surfaces.

or

- A fine tipped, felt pen.

or

- A sharp or mechanical pencil

NOTE: Choose the means of marking the material which works best for you. For example, the sharp point of an awl or knife works well for marking plastics that have had the paper removed. A fine felt tip pen may also work. A pen, fine point felt tip or a pencil works well for plastics with the protective paper still on. Any of the above may work for, or for marking wood, Masonite, aluminum or other material.

5) A tool which can cut the plastic, aluminum, wood, Masonite, or medium density fiberboard [MDF] you’ve chosen for your templates:

a) For long cuts in aluminum, plastics, wood and things like Masonite, I use my table saw with a fine tooth blade (e.g., 60 or more teeth on a 10" blade).

NOTE: If you are cutting aluminum, you can cut it with a table or miter saw, but will need a fine toothed, carbide blade. Specialty blades designed for this, with specialty tooth settings, are commonly sold where blades are for sale. You may find it handy to have around for other aluminum projects, like cutting your own miter slot guide rails for jigs.

b) If the pieces are not so short they pose a danger holding them by hand or with a clamp, I’ll use my motorized miter box.

NOTE: The smaller the pieces being cut, the more dangerous saws become. When cutting small pieces with a motorized miter or table saw, it becomes even more important to use clamps and, in the case of the table saw, to use a sled to carry the pieces.

c) For cutting smaller pieces of material, I prefer the band saw, which may be the safest and easiest to use.

NOTE: In the course of cutting some plastics, melted plastic will build up under the cut and catch on the saw blade opening (throat). You can clamp a piece of Masonite or other thin material on the side of the blade you are holding the material from, to raise the plastic enough so the melted plastic won’t catch. The raised be should be about 1/8" away from the blade, so the melted plastic doesn’t catch on it either.

d) If you have a hand held scroll saw, it can work just fine for these cuts. You will need a metal cutting blade and you will need a means of holding the material, if the pieces are small.

6) A method for smoothing the edges and fine tuning the angle:

a) A drum disk sander or edge sander, which is my go to method of smoothing the edges and adjusting the angles.

or

b) A belt sander

or

c) A course flat file at least 12" long.

7) If the sandpaper or file you used to smooth the edges and adjust the angle was very coarse, you’ll need a pad sander to knock off some or all the roughness.

8) If you want a polished edge, you’ll need a method of buffing them:

a) A buff pad you can mount on your drill press.

or

b) A buff pad you can mount on your lathe

or

c) A buff pad you can mount on a grinder (it MUST be able to spin at the RPM of your grinder;

or

d) An actual buffer, similar to your grinder and dedicated to buffing.

or

e) A hand held tool you can use to buff, like a die grinder, a Porter Cable random orbit [RO], variable speed sander-polisher with polishing head, or a Festool ROS with a polishing head.

MATERIALS:

1) Plexiglass, acrylic, Masonite or thin (approx. 1/8") aluminum.

2) 150 grit sandpaper

3) Polishing compound (I have very good luck with the red jewelers rouge).

Step 1: Setup Gauge Layout

1) Determine what size you want to make your gauges. For example, I chose five inch sides for mine and stayed in that ballpark size.

2) You can cut your material to the width you are going to make your gauges (e.g., five inches, as noted above) at this time, or you can move to the next step and make these cuts at the same time you are cutting the angles of your gauges.

3) Set your adjustable protractor [or bevel gauge] for the angle you want to transfer to your material (e.g., 30º, 35º, 40º, 45º, 50º, 55º, 60º, 65º, or 70º).

4) Lay your adjustable protractor [or bevel] on the material with the square plate of the protractor against a flat edge.

5) Mark your line in whatever fashion works best for you and the material you are using (e.g., scribe, knife, pencil, or felt tip marker).

6) If, instead of parallelograms you are going to do a different angle on each end, such as 30º and 35º, set the adjustable protractor up for the next angle and mark it opposite from the one you just marked. NOTE: If you, like me, used colored Plexiglass or Lexon, drag a pencil (carpenter’s pencils work good) across any scribed lines to make them stand out.

Step 2: Cutting the Gauges

1) The short, sweet and simple of it is, cut near the lines and as straight as you can. Any roughness of the cut will be touched up on the next step (sanding)

Step 3: Final Shaping, Sanding and Smoothing

1) Once you've made all your cuts, clean them up using a drum-disk, edge or belt sander.

2) After the edges are smoothed to the grit of the sander, check the angles of one or the other side, then, lightly, touch up the front or the back of the straight light until the angle of your gauge matches your adjustable protractor.

3) If you are doing a different angle on the opposite side, flip the gauge around, so you are dealing with the other two edges. Then, again, lightly touch up the front or the back of the shortest run until that side matches your adjustable protractor setting.

4) Once your angles are correct, if you are using plastic, and if you want to smooth or polish the edges, sand them using 150 grit paper. You can go finer sandpaper if you desire. Doing so will make polishing easier, but it may not be necessary to use a finer paper, if you have a good buffing system.

5) Once your edges are smooth and again, if you’re using plastic, buff them using a fairly hard wheel and the red rouge. Polish at about 1,500 RPM for quick results.

Step 4: Label the Angles

Whether you made parallelograms or gauges with a different angle on each end, labeling each angle would be a good investment of time, so you can tell, at a glance, what angle a given gauge is.

In addition to labeling each angle, I make a partial circle joining the two parts of each angle to make it clear which parts of the gauge I or anyone in my shop has to work off of to set something to the angle indicated.

The partial circles [drawn using a circle template, jar or whatever] are large enough I was able to scribe the angle inside the circles.

SIDE NOTE: Monitors and televisions can be salvaged to provide some nice, thick acrylic for projects like this.

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    12 Discussions

    When my son and I built his CNC plasma table, I thought things like this would be a good use. Draw up something, and cut it out. BOOM, DONE. Works great.

    1 reply

    A couple were throwing away a pickup load (literally) of plastics. I rescued the plastic before it ever hit the dumpster and am using some for this project, as well as a variation which incorporates at least six angles on one piece of plastic.

    Since I was into making a few, I figured I'd make several sets for friends and an associate or two. THAT is where a CNC, with a trim router, would REALLY shine. It could even label each one with it's angle(s).

    My tip about trig was really two things:

    First for fixturing: If you lay out a line parallel to the intended edge and drill a couple 1/4" holes along the line, you could temporarily put a couple 1/4" pins in the holes and run them against a straight edge or fence to cut or finish sand the edge.

    Second, if you can find a trig table of 'Tan' versus angle, you could multiply tan(angle) * length between holes to get rise between holes. For example, tan(70 degrees) = 2.747477, so you could make an 8" wide 70 degree angle by making a mark, going over 8" and going up 21.98" Or you could do it backwards and divide-- with a 24" carpenter's square, 24"/2.747477 = 8.735" out on the outside of the short leg would be 70 degrees. See https://www.instructables.com/id/Get-accurate-angles-without-a-protractor/ for some tangent trig ratios on a carpenter's square.

    Taken together, if you can work out the trig, and measure over and up, you could drill some fixturing holes in from your corners a bit and be able to cut, check and re-finish your angles very accurately.

    2 replies

    David, you might clarify, if my take is correct. You are proposing a method of laying out the lines that does not require buying or owning a protractor and bevel gauge, or an adjustable angle gauge?

    If so, you REALLY should do an ible, because it would be helpful to many.

    If you go that route, an explanation of why that approach is useful would be helpful too.

    Making angled gauges is a great idea.

    I think bringing trigonometry into the workshop is more hassle than it's worth. I know how to do trigonometry and no way I want to make my world that complicated to make sawdust. Just buy a protractor if you need to know an angle. If you are going to use trig, use a calculator or computer. If you are using a 3-4-5 triangle to check square you are using trig, beyond that it is more trouble than it's worth.

    Yep.

    Shows to go you, you should always have your mind fully on whatever you're doing. I suspect I was thinking about bandsaw cuts at the same time I was tossing in a tid bit about taking advantage of your table saw for some of the cuts. Of course, they don't use sixty teeth per inch, but do rely on TPI for various thicknesses of wood, and for smoothness of cuts.

    You wouldn't have to torch the cuts. They'd already be melted [and probably welded back together].

    I think that would be pretty much an abrasive cutoff disk...

    Thanks for the catch, dwieland. That was a bit obvious to be left hanging out there. I can only imagine what a 60 TIP, 10" miter blade would look like and cost. At least you'd never have to sand anything it cut.

    Try some trig to lay out a couple holes at the proper angle, and you can use pins/drill rod through the holes to fixture the part for cutting, trimming and re-finishing extremely accurately.

    With trig, you can lay out accurate angles with large baselines without even a protractor at hand.

    1 reply

    David, many of us barely know what trig is. For example, I never graduated from high school, and I avoided classes on "complicated" things like chemistry, geometry and so on. As such, a bit more information to help those of us not familiar with such things would be helpful. Maybe an instructible using your, more simple approach?

    Brilliantly simple but oh so useful, thanks for sharing. This falls into the "why didn't I think of that" category.