Made at 173
A scrap of hardwood, a pencil, and a few stolen minutes become one more useful workshop tool.
With no major projects being accomplished at 173 this year, and work continuing on its all-consuming course, I've enjoyed a year of stealing. That's right - stealing. For, you see, I have found a nice pattern of stealing time in the workshop - 5 minutes here, 10 there, a day here, another a week or two later. In those stolen moments I find myself making small tools, goofy, but useful little baubles.
What Is a Beam Compass?
Before we get any further, here's a fun little explanation of a beam compass:
A beam compass is used for drawing larger circles or curves larger than what would be possible with small compass sets. A scaled beam is required to carry two trammels found inside small casement. The beam can be of either wood or steel, depending on the workshop where the beam compass is being used.To operate, the central trammel pivot pin is fastened to one end of the beam, with outer scribing trammel point connected where required along the beam to suit the desired radius being drawn. The trammels can be adjusted by sliding along the beam, making it simple to draw a whole series of different sized circles. The trammels are locked to the beam by side-mounted set screws, and it is important to ensure that the trammels are securely locked to prevent sliding while drawing the circles. - Ernest Amor
And that's cool, I mean really nice! I suppose if I was making circles every day for a living, or if I was an architect or engineer or something, I'd probably invest in something like this. But, alas, I am none of these - nay nay. What I had in mind for 173 is much, much simpler!
The Inspiration
Right before Christmas I made a little bird feeder, that needed a plate-like base. I didn't have a compass big enough to properly draw a circle on the board, so I ended up getting a circle cutting jig for my router - and all turned out perfect:
I got the design from a book by John Perkins uniquely titled, Build Your Own Birdhouses. While looking through the book, I noticed this little callout box at the bottom of a page...
Making the Beam Compass
Pretty fancy subtitle for making what has to be almost the simplest possible beam compass, but here we go. Because it's such a thing for me, I searched through some scraps and found the perfect piece!
I started by scribing the center line using - you guessed it - the center line scribe I made from scraps back in November of 2019. Weren't they heady days!
I just locked the scribe into my vise and ran it over the scribe point a few times.
Then laid out points at 1 inch intervals.
From there, I got set up and drilled holes at the 1" intervals. These are the holes where the panel nail will go, and form the pivot point.
Having more than one spot for the nail panel makes the compass adjustable for varying radius lengths. Then I drilled a hole at the other end just slighter smaller than a standard pencil circumference to help the pencil stay firmly in place.
Esthetics
With that done, that could simply be the end of the project. But I thought I'd give it at least a little bit of a finished look. I started by using a washer to mark out a radius on the ends of the beam.
After that, I cut of the bulk of the waste, then took the beam to my benchtop belt/disc sander and rounded the ends.
Finishing
Somehow, pretty much since I first started making homemade tools (which isn't really that long ago), I've been drawn to Minwax Gunstock stain for the "signature" color.
Maybe because it works so well with amber shellac, which I also like. Either way, that's what went on the beam. Here's a first shot at the completed beam compass:
A little more of an overhead view...
The first thing I did was exactly what you'd expect, I drew a few circles simply because I finally could. The panel nail became the pivot, the pencil slipped neatly into its hole, and around it went. Nothing complicated, nothing especially precise by machinist standards, but perfectly accurate for the kinds of woodworking projects that happen around House 173. Sometimes that's all a homemade tool needs to be: simple, dependable, and ready whenever inspiration shows up.
And one last beauty shot.
A few of the hand tools made right here at 173!
∙ The small center line scribe
∙ The wide center line scribe
∙ The large marking gauge
∙ The 45 degree marking tool
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You might also like some articles about the 173 workshop!
Another Homemade Tool for the Collection
And with that, the beam compass is added to the collection of tools made right here at 173! Once again, writing this post took waaay more time to write than it took to make the tool!
Stay safe out there!
I smiled at the beam compass.
Not because of the beam compass itself, though I suspect I'll make one, but because it represents something you've been quietly documenting for years.
House 173 is not really a collection of finished projects.
It's a collection of small reclaimed moments.
Five stolen minutes become a centerline scribe.
Ten more become a beam compass.
A discarded drawer becomes oak for another homemade tool.
An afternoon becomes a workshop memory.
By the end of the post, I wasn't thinking about circles anymore. I was thinking about time, how most of us wait for a free weekend that never comes, while you seem content to build a workshop five minutes at a time.That may be the most useful tool in the whole post. Not the beam compass.
The habit. - The Writer
Frequently Asked Questions
What is a beam compass used for?
A beam compass is simply a tool for drawing circles that are larger than an ordinary drafting compass can reach. Instead of two hinged legs, it uses a long beam with a pivot at one end and a pencil or scribing point at the other.
Woodworkers often use beam compasses when laying out tabletops, bird feeder bases, arches, clock faces, circular shelves, or other projects where accuracy matters but the radius exceeds the capacity of a standard compass.
Why make a homemade beam compass instead of buying trammel points?
Commercial trammel-point sets are excellent tools, particularly for furniture makers, cabinet shops, architects, and anyone who regularly lays out large circles with precision.
For the occasional project, however, a simple wooden beam compass works surprisingly well. It costs almost nothing, stores easily, and can be built from scrap wood in less time than it takes to drive to the hardware store.
How does this design adjust for different circle sizes?
Each drilled hole becomes a different pivot location. By moving the panel nail from one hole to another, the distance between the pivot and pencil changes, creating different radii.
While not infinitely adjustable like commercial trammel points, one-inch spacing is more than adequate for most general woodworking and home-shop projects.
Why drill the pencil hole slightly undersized?
A slightly undersized hole grips the pencil firmly through friction. That keeps it from wobbling while drawing and eliminates the need for thumbscrews, clamps, or other hardware.
The result is a cleaner line and a tool that remains wonderfully simple.
Does a homemade beam compass have to be hardwood?
Not necessarily.
Softwood would work perfectly well for light use. I chose hardwood because I already had suitable scrap available and wanted something that would better resist wear around the pivot holes and pencil opening.
Like many projects at House 173, the decision was driven more by what was already in the workshop than by any strict rule.
Keywords
homemade beam compass, DIY beam compass, wooden beam compass, drawing large circles, woodworking layout tools, homemade woodworking tools, trammel alternative, scrap wood projects, workshop hand tools, House 173 workshop, beam compass plans