2022 Kensington Derby

2022 Kensington Derby

I decided to go with a side-by-side tandem bicycle concept for this year’s Kensington Kinetic Sculpture Derby. To start we acquired 2 gently used bicycles at exceptional discounts from the Trenton Bike Exchange and two trailer bicycles as well. To attach the bicycles together we purchased 1” square tube stock from Finkles Hardware Store in Lambertville, NJ.

Bicycles acquired from the Trenton Bike Exchange
Weld preps to build a side by side tandem bicycle

The primary design constraint was to be able to fit everything in the back of my minivan for transportation so the cross members were spaced at 22” apart. This eventually turned out to be just sufficient room for my son and I to pedal shoulder to shoulder side by side. The side by side tandem bike was accomplished with two cross members welded between the bikes. The first steel member was placed directly between the fixed portion of the front steering joint and the second member was placed immediately below the seat. The rear cross member had to be carefully placed or it could potentially interfere with the pedaling motion.

Side by side tandem bike
Side by side tandem bike
Side by side tandem bikes with trailing bikes

For steering I welded one flange off of the front outer fork on each bike and then attached with 2 threaded Rod end joint bearings. The connecting steering member for the side by side tandem bike was fabricated from steel tube and two corresponding nuts welded onto each end. To finish off the quad bike setup we mounted the two rear trailer bikes onto the seat posts (as designed) of the two front bikes. Test drive revealed the bike was easy to steer and the whole concept worked. Success! I later experimented with a removable cross member for rear trailer bikes for better stability of the rear riders but it significantly negatively impacted the ability of the turn radius, so I scrapped that idea. The biggest lesson learned for the side by side tandem bike is you really have to get the alignment correct such that both bikes are perfect parallel to each other and perpendicular to the ground. The flex in the base can create some unnerving leaning or tilting while riding side by side and any mistake in welding up the two together will further amplify this challenge.

Kinetic Derby Float: Queen of Hearts
Vinyl cut decal
XL playing cards were zip tied to the wheels
Queen of Hearts decal cut on the vinyl cutter

Kinetic Derby Theme: Queen of Hearts

We chose the theme of Queen of Hearts for our kinetic derby bike. We used the vinyl cutter to cut a massive Queen of Hearts vinyl decal and then mounted it to a thin plywood base with XL playing cards glued down around it. This piece was conveniently cantilever mounted to the front welded cross member of the side by side tandem bike. We fabricated a heart out of leftover pink insulation foam (from the old rhombus body) and spray painted it red and then cantilever mounted it to the rear cross member. The whole thing amazingly was able to be broken down and shoe-horned into the back of my mini van as intended (just barely).

Derby Day

We got soaked! It rained off and on most of the day. I was dismayed to see a few floats break down after the first corner. Thankfully our bike assembly held up except for a blown tire in my rear bike about mid-race. Somehow we were able to finish the race on one flat tire and make it to the mud pit.

Kensington Derby
Kensington Derby
Kensington Derby
Kensington Derby
Kensington Derby
Kensington Derby
Kensington Derby

At the award ceremony we won the Media Choice Award which was a thrilling end to the day. Thank you Kensington!


2021 Power Racing Series Build

2021 Power Racing Series Build: Dodge Ram

My neighbor donated his child’s abandoned “Dodge Ram” power wheel toy to me. We used it as the outer shell for this year’s PRS build. The split plastic body of the Dodge Ram posed benefits and challenges to the design.

Power Wheels Dodge Ram
Power Wheels Dodge Ram
1” steel members for the frame
Cleaning up the edges for welding with the Bridgeport milling machine
Welding the frame
Spindle camber set to 5 degrees. For reference king pin inclination (KPI) was set to 12 degrees.
Final electric go kart frame
Electric go-kart motor mount
First test ride

Brushless motor ESC learning wire instructions

  • Turn off power to ESC
  • Connect the learning wires
  • Turn on the power to the ESC – the motor should spin
  • If motor spins in correct direction turn off power and disconnect learning wires. All set!
  • If motor spins in wrong direction tap the throttle for a few seconds and wait for motor to pause and turn the other direction. Turn off the power and disconnect the learning wire. All set.

Lathe Tailstock alignent

At the end of last season I noticed I was getting a measurable taper on some of my Grizzly G4003 lathe turnings. I put an Edge Technology tailstock alignment bar on my Christmas wish list and Santa was good to me! Now that the weather is nicer and there is actually some free space to work in the garage I decided to inspect my lathe tailstock with the edge technology tailstock alignment bar.

Edge Technology Tailstock Alignment Bar Review

The thing works like a charm and paired extremely well with my 3d printer dial indicator for my quick change tool post (QCTP). It’s almost too easy.

Edge technology tailstock alignment bar
G4003 with spindle exposed after chuck removed
Edge technology tailstock alignment bar
3d printed dial indicator for the QCTP installed and ready to measure the tailstock alignment.

I zeroed the dial indicator at the left hand side and then moved it to the right to find the distance out of tolerance if any. Surenough

Spindle side – zeroed out
Tailstock side – measurement shows .004 out of alignment

Sure enough the measurements revealed the tailstock was .004” out of alignment.

After a few more mods to the tailstock I was able to get it within .001” alignment in short order.

Final alignment with the edge technology tailstock alignment bar


The edge technology tailstock alignment bar is easy to set up, sturdy, and makes an accurate tailstock measurement quick and easy. I would recommend it.

3D printing a 5C collet Chuck base

I’m pivoting over to CAD modeling and 3d printing storage bases to store the chucks for my Grizzly G4003 lathe when not in use. the concept was something with holes to accept the dowel pins face down and side grips to easily grab and lift the lathe chuck into and out of the tool chest. Simple right?

5C Collet Chuck Base Concept modeled with Autodesk Fusion 360
Slicing up the 3d model with Prusa Slicer software
3D printing the 5C collet chuck base with the Prusia 3d printer
3D printed Collet Chuck Base – the finished print
5C Collet Chuck prototype – proof of concept

The first concept came out better than I had hoped but I see a few areas for improvement. The next interaction I am going to increase the diameter of the dowel holes to make landing the chuck ridiculously easy and to make the side grips wider and longer to it’s less tippy in your hands.

Flea Market Bell Refurbushment

I came across this tarnished bell at a local flea market. It was the perfect candidate to test out my new Grizzly Buffing Polisher! The final results greatly exceeded my expectations.

Tarnished flea market bell
Tarnished flea market bell
Polishing a tarnished bell
Polishing a tarnished bell with a Grizzly buffing wheel
Polishing a tarnished bell with a Grizzly buffing wheel G1061 at 3450 RPM

Polished Bell

Final Result: Bell polished to an amazing shine with the Grizzly G1061

3D Printing a Vernier Caliper Tool Wall Holder

Pittsburg Tools Vernier Caliper Tool Wall Holder

I recently upgraded my precision measuring instrument (PMI) toolbox with a lovely Mitutoyo vernier caliper and a Mitutoyo micrometer. They are sweet! Buttery smooth precision.

My new Mitutoyo Micrometer
My Mitutoyo Vernier Caliper

That being said, I still have an economy Pittsburg Tools vernier caliper acquired from Harbor Freight that has served me well in years past. Especially when you consider it retails for under $20.

I still like to keep the Pittsburg caliper on my tool wall for quick and dirty measurements that don’t require three decimal place precision. I decided to model up a bracket for 3d printing to mount it on the tool wall.

Pittsburg Vernier Caliper tool wall mounting bracket 3d model

It took me three iterations to get the model right. The first prototype my mouthing angle for the angled base was off by a few degrees and the upper mounting arms were to thin and aesthetically too flimsy in my opinion.

The second iteration I was able to both add and remove material in various locations to optimize the print time down to 40 minutes.

Pittsburg vernier caliper tool wall bracket
3d printed tool wall