Instructables
Picture of Make Your Own Precision Angle Finder
I always thought I wanted a precision angle finder. I finally decided to make my own. The photo shows it in use to check the angle of a rafter in my attic. This is a very easy project, but some precautions need to be followed to guarantee the accuracy of the tool when finished.
 
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Step 1: Tools and materials

Picture of Tools and materials
Materials
  • A plastic protractor
  • A piece of wood
  • Some screws
  • A piece of wire or a long finish nail and a hex nut
  • Magnetic cabinet door catches (optional)
Tools
  • A table or radial arm saw
  • A rule (and a square)
  • An electric drill or drill press and bits
  • A countersink bit
  • Screwdrivers
  • Clamps
  • A file
  • A pair of pliers to bend wire, or a welder to weld a hex nut to a finish nail
  • A level
  • A grinder

The photo shows a commercially available angle finder. It reads 360 degrees. A protractor has readings for 180 degrees, but that will be no problem for a reason explained later. While the commercial version is not expensive, it is more fun to make your own.

(The photo is from Lowes.com.)

Step 2: Cut a piece of wood

Picture of Cut a piece of wood
I used a piece of 1 x 4 clear pine I had from another project. The two long sides must be exactly parallel to one another. I used a caliper to check. If you have a good table saw accurately calibrated, you should have no trouble. 

Saw your piece off to be a little longer than the base of the protractor, and so the corners are exactly square. Check with a good square and by measuring the diagonals. These things really need to be very accurately done, or the whole tool will be compromised.

The square is a larger tri-square I have long wanted. See this Instructable for how I made it.
grgbpm2 years ago
genius
Phil B (author)  grgbpm1 year ago
Thanks.
I've just started doing 'angly' things and this is perfect for what I need - thanks!
Phil B (author)  bricabracwizard2 years ago
Thank you for your comment and thank you for looking. I am glad you can use this. I hope it works well for you.
veryken2 years ago
Nice job! I made something like this about 25 years ago. Much longer though. Now (for several years) I use the SmartTool Smart Level — practically every week to measure roof pitch at various job sites.
Phil B (author)  veryken2 years ago
I knew I could not be the first to think of this. It is only my version. Thank you for your comment.
caarntedd2 years ago
I'm making one of these.
Phil B (author)  caarntedd2 years ago
Thanks. I hope you enjoy it. I am finding uses I did not expect. You will, too.
bobzjr2 years ago
Phil,

Beautifully done. Thanks for showing us. I've seen these before but never realized that the marker floats freely and points down automatically via gravity. I will have to make one of these!

Your work continues to add valuable insight. I look forward to checking more of your expansive body of work. I'm going to the center finder next...
Phil B (author)  bobzjr2 years ago
Thank you, Bob. I never thought much about how these angle finders work, but, my son-in-law has one several years old. The plastic for the body has shrunk more rapidly than the clear plastic for the dial cover and it continually falls off. Under the round label is a small steel axle pin. The red plastic pointer has a hole for the axle in the portion not visible. Then the pointer piece broadens into a pendulum of sorts. It works by gravity, too. About 5 minutes after I saw that I began to think about how I could make one. Thanks for looking at my stuff. I hope some of it is useful to you.
snideprime2 years ago
I also miss the days when PS and PM published DIY stuff and tips, instead of always which-is-a-better-buy articles. When I find a stash of old ones at a yard sale or thrift store, I buy them. I guess I'm just made for Instructables!
Phil B (author)  snideprime2 years ago
Popular Mechanics and Popular Science now have old issues archived on-line. It is fun to go back and read articles I remember. But, those articles are often dated. It would be great if a magazine today had the editorial philosophy of those magazines then and published DIY articles for today's needs and technology. One problem is that many things today are non-repairable throw-aways. Still, I learned how to use power tools and do various aspects of woodworking through those magazines. Thank you for the comment.
Popular Mechanics! My dad used to bring those from the library! I loved those! Specially those projects that just used single board of ply! I wasn't allowed to use carpentry tools as I was around 8 then. I made miniatures of them using foam boards/paper. Please post the links to PDFs for old Popular Mechanics if possible!
Phil B (author)  artworker2 years ago
Popular Mechanics archives

P
opular Science archives

M
echanix Illustrated archives

T
he navigation procedures for each varies a little, but it is fairly intuitive.
Thanks a lot!
Phil B (author)  artworker2 years ago
You are welcome.
Bill WW2 years ago
Nice, VERY nice.

This comment from an engineer who has almost every imaginable angle measuring device.

Bill
Phil B (author)  Bill WW2 years ago
Thank you for the comment. I actually used this little device in a project yesterday. My wife wanted her bicycle hung on the garage wall. I was using a flip down hanger with two arms. Those are designed to support a level top tube on the frame. She has a lady's frame with a very angled top tube. The bike would look like it was racing downhill. I made a dry fit by hooking one arm where the seat stays connect to the seat tube and hooking the other under the top tube. I needed to know how much the rectangular mounting plate was angled. I held my angle finder on the top edge of the mounting plate with my other hand and read 11 degrees. Had I guessed, I would have thought the angle might have been 15 to 20 degrees. But, her bicycle now looks level on the wall.

At one time I wanted to be an electrical engineer. Although it is not electrical and although it is not a measuring device, the outcome of this project pleased me very much because it represented a precise outcome using very minimal and common tools. If you have not seen it, you might very much enjoy it.
Bill WW Phil B2 years ago
Phil, I imagine your wife has been enjoying bicycling lately with the surprising dry warm weather we have been having in the NW.

Read your instructable about enlarging the arbor hole in the saw blade. Wow, that is a difficult task, having to get it perfect. Especially with the tools we have, and none of the precision tools in a machine shop. I'm doing a similar task now, trying to find exact center on some small parts. So much easier if we can start start from a center punch mark and work outward from there!

Bill
Phil B (author)  Bill WW2 years ago
The weather has been nice. My doctor found something nasty growing on my skin and removed it, so now I get to be careful about sunlight. As much as I enjoy riding my bicycle moderately long distance, I have been limiting my cycling to hours of darkness, which has its own limitations. People who have had such things growing on them often slop on the sunscreen and go anyway, but I really do not like that stuff. Enlarging the hole in the sawblade was not bad after I used my head first. It took a while to decide exactly how I would do it. It might not help, but did you see my Instructable on making a center finder?
chobbs19572 years ago
I'll be putting this to use. Thanks, Phil. Keep 'em coming.
Phil B (author)  chobbs19572 years ago
Thank you. Each time I do an Instructable I am sure I have used all of my ideas and it is the last one I will ever do. I hope you enjoy it after you make it.
dimtick2 years ago
like this. very simple.
when i first saw this, is I wondered if you could incorporate a laser pointer that would project straight down so this could be used as laser plumb bob. would be really useful for framing. using this tool you would have the bottom & top points and the angle for the top cut. simple matter to measure the distance between the points to get the board length.
thinking out loud if you could reverse the laser so that it would project up, you could use this to locate points on the ceilings or rafters. let's say your framing a half wall. you locate the wall on the floor. place the angle finder on the floor and project it up, mark the point, then use the angle finder to measure the top cut.
commercial laser plumb bobs are $100 and up and way out of reach for your average weekend handyman so having a simple version could be really useful

thought you might like to see this:
i did a quick search on instructables to see if anyone had made a laser plumb bob and found this. another clever application of your little angle finder along with some geometry to measure heights.
http://www.instructables.com/id/How-to-make-a-tool-to-measure-angles/step5/How-its-done/

Phil B (author)  dimtick2 years ago
You have an interesting idea. For a lot less than $100 you can buy various laser levels. Either one of those could be mounted from a pivot, or the insides could be removed and repackaged to suit your needs. You would not even need to know the indicated angle, only where the laser beam falls.
rimar20002 years ago
Very good and interesting instructable, as always, Phil.

I did something like this when did my equatorially mounted solar cooker, unless instead of a hand, my pointer was a little steel ball inside of a soft clear PVC tube. The device was to set the parable's axis angle at local latitude.

Seeing the countersink with its note, I thought it would be useful for all we not anglophone a detailed "images and notes only" instructable with the tools and their names. Maybe somebody in the staff could do it. It could be a colaborative project, because surely some tools have different names depending the zone.
Phil B (author)  rimar20002 years ago
Thank you, Osvaldo. Many years ago Popular Science magazine had a feature called the "Wordless Workshop." Simple projects were described with a few cartoon drawings and no words.
blkhawk2 years ago
Very simple and practical idea. I remember doing something like this for elementary school, to determine the position of stars at certain times. Instead of the pointer it was a plumb. With some knowledge of trigonometry, you can even roughly determine the height of a building with this little contraption.
Phil B (author)  blkhawk2 years ago
Thank you for your comment. What you made in elementary school is almost identical to this and is called an astrolabe. I considered mentioning the astrolabe, but finally did not. A small weight on a string for an indicator would work here, too. I did search Instructables, but found nothing like this previously done as either an astrolabe or as an angle finder.
Nice Job Phil.....
Phil B (author)  coolbeansbaby682 years ago
Thank you, Jim.
Nice Job Phil.....
shazni2 years ago
Oh this is really good! I'm going to try it...thanks
Phil B (author)  shazni2 years ago
If you have a use for one of these, you will like it very much. Thank you for looking and for your comment, and for your rating, assuming you were the one to rate it.
shazni Phil B2 years ago
haha yes...only i rated 5 stars and it shows 4.2...in the stats..i guess it's the overall rating :-)
Phil B (author)  shazni2 years ago
Thank you, again, for the rating. The rating system is weighted somehow. Many "5" ratings are required before the rating number shown begins to approach "5." It is above my paygrade to understand this.