Over-the-door Travel Pull-up Handles

I’m amazed how many hotel gyms don’t have a pull-up bar. I decided to build some lightweight, possibly dangerous, over-the-door pull-up handles. If you don’t hear from me for a while, it’s because I died with the Do Not Disturb sign hanging from the doorknob.

Gymnastics Rings Are Being Sanded (part 2)


As previously posted in part 1 I’m making wooden gymnastics rings from 1/8″ layers of laser cut baltic birch plywood. Of many possible methods my friends have suggested for sanding them, while keeping their circular profile, I’m starting off the first one with the most low-tech solution. I’m hand sanding them.



It is a lot of work. So far, the 60 grit paper is working great at removing the stepped profile and getting a nice, consistent curve.

I joked yesterday that sanding the rings is a better workout than using the rings.

BuEMjkDCEAA5yL2.jpg-largeI’ll move down to finer grits on this one, and then may take a shot at using a power sander and jig or some other higher-tech method for the second ring.


SPLixel Sweeper

Sometimes its fun to build and code a little project to test new hardware, as well as just for the heck of it. I built this demo thing with a Spikenzie Labs SPLixel board and LED strip, Arduino, and ScrewShield. I read one knob to control the position (which LED is lit), the other controls the green component of the color mix.

In order to keep the knobs from moving around too much, I screwed some small c-clamps onto them.

It’s fun to play with. A little bit.

3D Printer Build Surface

I bought a couple of sheets of this 3D printer build surface material from BuildTak when I was at Bay Area Maker Faire 2014. It works much better than the blue painters tape we were using on our 1st gen. Ultimaker at work, printing PLA plastic. The trick is in finding a material to which the printed plastic will adhere well enough for stable printing, but not so well that it is too difficult to remove the object when finished.

Note: As seen in the bottom-right photo, I wasn’t very careful laying down the sheet, and managed to trap a few air bubbles. Oops. Hopefully that won’t create any terrible problems with critical prints.

Get some here at BuildTak. This sheet was around $10 and should last for many, many prints. How many? I’ll let you know.buildTak.jpeg

Rings Are Being Lasered (part 1)

Today, I began making 1.25″ wooden gymnastics rings. I had designed them in Rhino when I wrote this post for Make: and since then I received a box of 1/8″ baltic birch plywood. I cut the cross sections and guides.




Next, I glued and clamped them. These were the easy parts — stay tuned for the sanding. Not sure exactly how I’m going to approach that yet. PART 2


Human Flag progress


Back in May I posted the below “selfie” (in quotes because how could I have possibly taken it?):


It’s a party trick I learned back in high school. I think Dan Jaffe showed me how. It’s called a “clutch flag” by some, because you clutch a pole (with elbow jammed into abs for support) and pretend you’re a human flag. You may even choose to get inside the mind of a flag and “be” the character if you like. It’s quite peaceful.

After I’d posted it, some people (it was me) egged me on to achieve the “real” human flag, wherein you don’t use the elbow for support, but instead grip with two hands, overhead, arms straight. I tried it once, collapsed, laughed at the absurdity, had one friend remark “Is this even possible?”. Turns out, it requires a heck of a lot more shoulder, chest, lats, abdominals, and oblique strength than I had on tap. So, I asked my awesome Pilates trainer, Jaime Rutt, to help me put together a training plan in order to achieve the fully laid-out, arms-only, human flag by September 1st. She came up with “JP’s ‘Super Selfie’ Workout”, which I’ll share in another post.

I’ve been doing a decent amount of conditioning toward this goal, but I haven’t actually done any training on a proper pole yet (the one from the my clutch flag photo is much too wide to grip properly) I’m very excited however to have tried a pike to flag position on the ladder rungs at the fitness trail the other day and not completely bitten it:

My goal is to hold the flat position horizontal to the ground for a few seconds. So I’m not even close. This is my first attempt at starting from a vertical pike position and lowering to horizontal. My dog is unimpressed. Incidentally, the world record is 1 minute 5 seconds — not something I’ll be challenging any time soon. Even that leaves my dog nonplussed, so. But check back on September 1st to see if I hit the three second mark.


Laser Cut Wood Gymnastics Rings


Gymnastic rings are excellent equipment for bodyweight fitness training. Anything from push-ups, dips, and pull-ups to advanced moves such as muscle-ups and the fabled Iron Cross can be done on a pair of gymnastic rings to improve core and upper-body strength and stability. Plus, as my kids can attest, it’s really fun to swing from them. Here is a great guide to getting started with the rings, and a fundamental rings workout routine.

You can purchase good, commercially made rings, such as these. But how about making your own rings instead? There are several examples online of DIY rings made from either plywood or PVC pipe.



You can create these wooden rings by laminating two pieces of 3/4″ plywood, cutting with a jigsaw, and then sanding.


These rings are made by filling PVC pipe with a length of rope and sand and then heating them in the oven to soften the plastic, and then form.

I have a set of commercial wooden rings (wood is the preferred material as it absorbs sweat, helping with your grip), but I’ve decided I’d like to make a second set with a slightly larger grip diameter (my current set is the 1.1” international size). I’d rather not use the jigsaw-cut cylinder method and the ensuing difficulty of sanding down straight walls to a perfect circle. My plan is to begin by laser cutting ten thin, stepped layers out of baltic birch, so that when stacked they are closer to the final profile. This approach should make it easier to sand them down to the proper circular profile after gluing.

Starting from from standard dimensions (1-1/4” diameter profile, 7” inside diameter) I drafted the design in Rhinocerous, a NURBS modeling tool I use for precise 3D modeling and laser cutter CAD drafting. (You could do the same in most any CAD or 3D modeling package.)


I then sliced my final design model into 1/8” cuts with a stepped square profile to mimic the laser cut materials I’d be assembling. This gave me ten circular slices to laser cut and assemble.

Since I’ll be stacking and gluing ten rings of varying size together, I replicated the profile curve of my stacked pieces and used this as a guide to create a laser-cut stacking/gluing jig. I’ll cut four of these into which to lay my ring slices for gluing and clamping.


I’ve ordered the baltic birch plywood, and am gearing up for laser cutting — and lots of sanding. If all goes well, I’ll get them super smooth, like my current set. (Because, otherwise, splinters. Which is bad.)


Also, a note on safety: make sure you rig your rings carefully from something that can support the load. You may buy buckled straps online made for rings, or, do as I have and use rock climbing web straps and carabiners to attach them to the backyard swing set.


If you’d like to get going and build your own gymnastics rings, you can download my design files here, on Thingiverse. Have fun, and please share your results.