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Fibonacci gauge

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Project by Dave Polaschek posted 03-17-2019 05:15 PM 722 views 3 times favorited 31 comments Add to Favorites Watch

After wrapping up the spring swap, my workbench was a mess, and one of the things in the way was a box of shorts I had received from EarlS. Rather than actually clean anything, I decided to dig through that box and see what I could find. There were a bunch of smaller strips of wood that were about a foot long, and most of them were 3/4 wide or more (and down to 1/4 thick).

I decided to make a Fibonacci (or golden ratio) gauge, but the plan I found online called for long legs that were 340 mm long (which is more than a foot). But none of my scraps were more than a foot long (they had all fit in a square large flat-rate USPS box, which is 12×12, so that wasn’t surprising). Rather than trying to stretch the wood (I’m told that doesn’t work real well), I decided to do some math.

My first attempt was to multiply everything by 0.8, which gave me all sorts of measurements that were in 64ths. Nothing that lined up with an eighth anywhere in sight. Scratch that plan.

OK. Let’s back up and think a little. The plan online has pieces that are in the ratio of 1:1.618. If I whack that in half, I get 0.5 : 0.809. Multiply that by 10 and I’ve got 5 inches and 8 3/32 inches almost exactly. That’s something I can work with!

So I drew up the plan that’s picture 5 above. My drafting skills are pretty awesome, aren’t they?

The long pieces are 8 3/32 from the pivot to the tip. The short leg is 5 inches from the pivot to the tip. And the connecting piece is 3 3/32 between the holes. In fact, the holes on all the pieces are 3 3/32 between the holes.

So I put a 5/32 drill bit in the post drill (because that’s the size of the brass rivets I have) and drilled a hole through about an inch from one of the ends of a stack of four pieces. I dropped a rivet through to keep everything aligned and drilled another hole 3 3/32 from the first (measuring from the centers, as best I could), then cut out the pieces and shaped them on the belt-sander. I even avoided sanding me this time!

With the pieces more or less the right shape, I riveted them together, not being especially careful in cutting the rivets to the right length. After peening them enough that they’d hold together I headed back to the belt sander to “trim” the rivets to length. And discovered that I had put one in backwards. Oops! Sand them down a little, then peen them over again, and things are looking good. The gauge is a little stiff, but it’ll loosen up with use.

Throw on a coat of BLO and call it done. And the shop is STILL a mess!

Note, there’s a good writeup on Fibonacci gauges here for the curious.

-- Dave - Minneapolis





31 comments so far

View Bill Berklich's profile

Bill Berklich

742 posts in 722 days


#1 posted 03-17-2019 05:29 PM

Looks great. I really need to make one – though I don’t know what I’d actually use if for :-)

-- Bill - Rochester MI

View Dave Polaschek's profile

Dave Polaschek

3575 posts in 916 days


#2 posted 03-17-2019 05:34 PM

I plan to use it (or its big brother that I haven’t built yet) when making boxes that aren’t designed to fit a specific item. Check to make sure the sides are in a pleasing to the eye ratio. Will probably find other uses too. Mostly I was looking for something to do with some scraps that would keep me from having to clean.

-- Dave - Minneapolis

View ralbuck's profile

ralbuck

5910 posts in 2600 days


#3 posted 03-17-2019 06:57 PM

Sometimes we make something; just because we want too!

ABSOLUTELY A GOOD IDEA!

If it never gets used it is still a neat tool(TOY)!

-- Wood rescue is good for the environment and me! just rjR

View oldrivers's profile

oldrivers

1644 posts in 1900 days


#4 posted 03-17-2019 07:00 PM

That is a great looking instrument. Did use a pencil CAD to do the drawing? Just kidding you should some of my scratches yet we know how to read them great job well done.
PS I have to build one of these tools I have used this rule for years but always did it with a calculator it really works. Thanks for sharing.

-- Soli Deo gloria!

View Oldtool's profile

Oldtool

2762 posts in 2524 days


#5 posted 03-17-2019 07:32 PM

Nice work, handsome home made tool.

-- "I am a firm believer in the people. If given the truth, they can be depended upon to meet any national crisis. The point is to bring them the real facts." - Abraham Lincoln

View Dave Polaschek's profile

Dave Polaschek

3575 posts in 916 days


#6 posted 03-17-2019 07:33 PM

Thanks, guys. I had the plan from online printed out too, so the important thing on my sketch was the math, but I managed remember “5 and 3-3/32” on the walk to the shop, too.

-- Dave - Minneapolis

View robscastle's profile

robscastle

5830 posts in 2538 days


#7 posted 03-17-2019 07:51 PM

Interesting build Dave,

I have made a few and given them to friends, one I use for myself occasionally as I have found when building boxes in particular I have found if it does not “look right” and adjust the dimensions and then whip out the gauge it usually reflects very close to the golden ratio dimension.
Then if your really keen walking round the house checking “stuff” its interesting what you find that complies.
The humble light switch plate for example ….anyway enough rabble

Nice work

-- Regards Rob

View Tom Regnier's profile

Tom Regnier

372 posts in 2881 days


#8 posted 03-17-2019 08:11 PM

I always seem to be doing research after reading one of your posts. Thanks Dave for posting projects that make us think a little…I need to go clean my shop!

View JohnMcClure's profile

JohnMcClure

601 posts in 974 days


#9 posted 03-17-2019 08:35 PM

Looks great Dave! I like the brass rivets. Are those the leatherworking type?

-- I'd rather be a hammer than a nail

View LittleBlackDuck's profile

LittleBlackDuck

2384 posts in 1154 days


#10 posted 03-17-2019 08:44 PM

Neat little build DP and thanks for the maths lesson… I always thought that fibonacci was a sneezing lie to the cops.


..... My first attempt was to multiply everything by 0.8, which gave me all sorts of measurements that were in 64ths. Nothing that lined up with an eighth anywhere in sight. Scratch that plan…..
- Dave Polaschek

Wouldn’t it be easier to convince The Donald into changing from imperial to metric?

PS. You’ve also educated me on the use of a peen hammer.

-- If your first cut is too short... Take the second cut from the longer end... LBD

View jeffswildwood's profile

jeffswildwood

3892 posts in 2311 days


#11 posted 03-17-2019 08:49 PM

Nice looking set Dave. You have really been busy lately!

-- We all make mistakes, the trick is to fix it in a way that says "I meant to do that".

View Dave Polaschek's profile

Dave Polaschek

3575 posts in 916 days


#12 posted 03-17-2019 09:24 PM

Thanks, Rob. Yeah, there’s a lot about that matches the ratio. Had a maths teacher in… a long time ago… who told me all about it, and I’ve seen the ratio in many places. Took me three and a half decades to get around to building a tool for it.

Tom, glad to help! I’ll do what I can to keep stretching your brain. ;-)

John, yes, they’re the leatherworking type with a collar, but they work great for attaching wood, too. And they’re dirt cheap on eBay. That was another bit of high school learning. We hand-riveted some metal bits in shop class, and my brain hung onto it.

Ducky, even if the Donald changed things, all my rulers are still in 64ths, so I’d be stuck. Old dog, etc…

Thanks, Jeff. Just knocked out another this afternoon (also walnut), so they definitely go together easier once I’ve got the hang of it. Next up I get into some of the more exotic things from Earl’s shorts. :-0

-- Dave - Minneapolis

View LittleBlackDuck's profile

LittleBlackDuck

2384 posts in 1154 days


#13 posted 03-17-2019 09:34 PM



..... Next up I get into some of the more exotic things from Earl s shorts. :-0
- Dave Polaschek

Is that a smile on your face?

-- If your first cut is too short... Take the second cut from the longer end... LBD

View Dave Polaschek's profile

Dave Polaschek

3575 posts in 916 days


#14 posted 03-17-2019 09:39 PM

We’re wholesome midwestern boys, Ducky. We smile because we’re friendly. ;-)

-- Dave - Minneapolis

View Kelster58's profile

Kelster58

722 posts in 874 days


#15 posted 03-18-2019 12:48 AM

Pretty cool project Dave…...You come up with unique projects and ways to make projects all the time. I wish I was that creative….....VERY Nicely done !!!

-- K. Stone “Tell me and I forget, teach me and I may remember, involve me and I learn.” ― Benjamin Franklin

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