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Blog entry by BanjoBen posted 04-10-2017 03:20 PM 991 reads 5 times favorited 9 comments Add to Favorites Watch

I posted this project over the weekend and got several questions from people about it, so I thought I’d share some of the process in case anyone’s interested. You can find out more about where the object comes from here: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.314.4240
and here:
https://arxiv.org/abs/0811.0225
Be warned….there’s math in them thar links!

The process is pretty straightforward. To begin, I cut bars 1 inch x 1 inch, making sure they were long enough to get several of the final pieces out, without a lot of waste.

Then I took them over the router table to round over the corners with a 1/4 inch roundover bit.

The next step is to cut the miters. The pieces are needed in two lengths, 5 inches and 7 inches (tip of miter to tip of miter). As with any miters, absolute consistency is key. With 15 miter joints in this contraption, you can’t allow any variation in the lengths, or the angles. I used a stop block to ensure matching lengths

Because of the way the pieces end up having to be arranged, it’s very difficult to clamp this stuff up for gluing. Cutting the slots for the splines helps with this, and using a good thick glue does as well (Titebond No-Run No-Drip is a good choice). But that means the next stage is to match up mitered joints, and cut the slots. To keep track, I labeled all of my pieces from A to O, with an arrow to indicate the orientation. That way, I could match up the slots later.

The jig above is a simple, homemade version of a spline jig that many of you probably already have. Someday I’ll make a better one, but it got the job done.

At this point, the only thing left is to cut the splines themselves, and glue things up.

My process was to glue up pairs (matching corresponding letters in sequence. The Titebond No-Run glue works pretty well with hand pressure for 30 seconds or so, and then give it time to set. You can see the bottle of Titebond3 in this picture. I did use it for a couple of joints on this, and quickly learned my lesson…

Once you get pairs glued, up then match those up, until at the end you have two pieces that can be glued up to the final form. After trimming/sanding the splines, you can finish with your choice. I used Enduro-Var from General Finishes.



9 comments so far

View Derek Oliver's profile

Derek Oliver

205 posts in 1907 days


#1 posted 04-10-2017 09:26 PM

Thanks for info.

View Chris Cook's profile

Chris Cook

276 posts in 2037 days


#2 posted 04-10-2017 11:47 PM

Can you give up your lengths for your pieces A through O? I am sure I can work through and figure it out, but this would be a big shortcut.

Is yours basically 9 pieces at L1 and 6 pieces at L2?

-- Chris, "all we are is sawdust in the dust collector""

View Chris Cook's profile

Chris Cook

276 posts in 2037 days


#3 posted 04-11-2017 01:02 AM

So you peaked my curiosity and I had to work out some dimensions. While I may not match yours, I think I have the ratios inline.

The critical part is the direction of the 45’s and of course lengths. Here I have similar 45 degree cuts/lengths color matched.

CC

-- Chris, "all we are is sawdust in the dust collector""

View BanjoBen's profile

BanjoBen

79 posts in 656 days


#4 posted 04-11-2017 02:54 AM

Chris,
That’s basically right. You can make the pink green and white pieces all the same length though. And the orange and blue pieces can all be the same length. In mine, the short pieces are all 5 inches, and the long pieces are all 9 inches. Since the bars are 1 inch squares, this means you end up with a 9 inch knot, with 1 inch between each layer.

View ChuckV's profile

ChuckV

3008 posts in 3283 days


#5 posted 04-11-2017 01:30 PM

Thanks for the details Ben.

I think you mean 7 inches here:


... the long pieces are all 9 inches…

-- “Big man, pig man, ha ha, charade you are.” ― R. Waters

View BanjoBen's profile

BanjoBen

79 posts in 656 days


#6 posted 04-11-2017 01:34 PM

Yup, that’s exactly what I meant to say.


Thanks for the details Ben.

I think you mean 7 inches here:

... the long pieces are all 9 inches…

- ChuckV


View Chris Cook's profile

Chris Cook

276 posts in 2037 days


#7 posted 04-11-2017 11:24 PM

Ah! Very good! I was going for simple and you made it even easier.

So, 4 different pieces at 2 lengths. I had to break it down for myself so I shared it here:

I did not account for kerf in picture 3*

Thanks Ben!

-- Chris, "all we are is sawdust in the dust collector""

View BanjoBen's profile

BanjoBen

79 posts in 656 days


#8 posted 04-11-2017 11:44 PM

Very nice.

Is that drawn in Sketch-Up? I’ve been meaning to learn to use that software for a while, but haven’t gotten to it yet.

View Chris Cook's profile

Chris Cook

276 posts in 2037 days


#9 posted 04-12-2017 11:09 PM

It is sketchup. Fast and easy

-- Chris, "all we are is sawdust in the dust collector""

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