Building a lever squat machine

Someone once asked how we design equipment and put it together. Here’s a rundown.

Chapter 1: What are we building?

A new lever based squat/push/pull unit that has two arms that articulate independently.

The brief

Two arms that move smoothly in both the X and Y axis. Ideally mounted on a rack.

Parts overview

• There’s the mounting point on the rack. I decided to integrate the pipe on which the Y axis bushing will move into the mounting point. So that’s two parts so far.

• For the X axis bushing to attach to the Y axis bushing, I am creating a housing out of square tubing.

• And to make the arms detachable, I am creating a small fixture on the X axis bushing to slot the pipe into.

It’s that simple! 🙂

The detailed parts list

1. Pipe (60mm × 50mm)

   • 36-inch long for the Y axis bushing to slot onto.
   • The pipe will fit on a 10mm thick fixture that can be bolted onto our squat rack.

2. Y axis bushing (75mm × 60mm)

   • We will increase the bore of this pipe by 1mm to slot onto Part 1.
   • This will weld into a square tube.

3. Housing to connect the Y axis and X axis bushings

   • This will be a 7-inch long square tube 100mm × 100mm on the sides.
   • We will mill two holes of 75mm and 48mm diameter on the perpendicular sides.

4. X axis bushing (60mm × 48mm)

   • A 60mm × 48mm pipe will slot over a 48mm × 38mm pipe.
   • These pipes are cut into 4-inch and 3.75-inch lengths.
   • The 48mm pipe is welded into the housing (Part 3).
   • This will be polished.

5. Pipe (48mm × 38mm)

   • A 48mm × 38mm pipe will be grooved and welded onto the 60mm × 48mm pipe.
   • This will allow to insert the working arms into the housing.
   • These arms are what we hold or load for using this unit.
   • These are grooved and chamfered.

6. 2 pipes (8-feet long)

   • These pipes have holes to lock into the pipe welded into the bushing.
   • And it will also have a hook that allows for the two units to be linked.
   • The pipes are chamfered and drilled.

7. Sleeves

   • Allow plates to be loaded onto the unit, and you can hook sandbags etc. onto the unit too.

So there you have it. 16 parts total. Not including the 4 nuts and bolts needed to secure it all together.

One of the things I do since I lack the capacity to draw, is describe and visualize in great detail what I am building and how we will use it!

Only the housing (Part 3) and the sleeves (Part 6) are fresh bits of steel. All the other parts are from the scrapyard.

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Chapter 2: The next face (literal and metaphorical)

We’ve sorted out the fixture, the arms that will move the unit up and down. Now onto the mechanism that will move the arms side to side.

You can see the two parts of the bushing and the one piece that the arms will slot into.

1 goes in 2. 1 won’t move. It is welded into a box. 2 will spin around one. 3 will be grooved to fit on 2 neatly.

All the parts have been faced. That basically means they’ve been made perfectly level. And some of these have also been milled to make the ends of the pipe more amenable to welding onto the housing. That’s called a welding chamfer.

And the tolerances are precise. 2 is 89mm long so it fits into a 100mm × 100mm box comfortably without getting jammed. And having a little room to apply lubricant. 1 is 101mm long. It is to precisely fit into the box and be welded in there neatly.. 3 is going to be grooved to fit flush on 2. These are fairly precise fits. There’s about 0.6mm of wiggle room. That’s enough to fit 4 healthy, thick strands of hair.

We don’t use bearing for a simple reason.

Bearings are fittings that are purpose built to spin freely when they are fit into components.

Having used bearings, I realized two things:

When they fail they are very very hard to replace. And they are not as durable as a heavily fabricated bushing.

I get all the spin and friction-free performance I need from the bushing design that we use.

If you can’t picture it. Don’t worry. You are not alone. The finished product should contexualise this stuff better. At least it does for my wife 🙂

The housing should be done on Monday. That will mean the welding happens on Tuesday. I’ll walk you through the housing first. And the finished bit right after!

The point of all this is to walk you through the stages of making things. As is evident, if you get the initial material choices and dimensions right, it comes together quite neatly like a straightforward jigsaw puzzle. The stuff you are watching me do is to make sure the jigsaw pieces fit neatly with no excess bits or weird lines.

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Chapter 3: Tolerances

Today’s focus is on something we have gotten better at with time: the tolerance of the things we make.

Basically how precisely can the different components fit with each other.

In the video below, you can see the mechanism that I’ve put together to move in the Y axis is cut and machined to an incredibly tight tolerance. The sleeve fits on the shaft and spins freely. The shaft has a diameter of 60.4mm. The sleeve has an inner diameter of 60.7mm.

And this is crucial. Being able to achieve such tolerances enables a fit between components that allows for free movement without the shake or vibration that a poor fit would cause. This is possibly thanks to incredibly talented machinist who patiently plug away and measure twice before etching away.

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Chapter 4: Bringing it all together

In today’s piece I focus on the main enclosure that is going to bring the two components that will move our lever squat mechanism in the X and Y axis.

The mechanism to move the unit in the X and Y axis are complete. So the gadget moves freely up and down. And side to side.

Now I am building a housing to link both those units. And an arm can be connected to it.

The housing is a 100mm × 100mm box. We mill in two holes through the tube. One to house the sleeve that will move the squat ladder in the Y axis. Another in the perpendicular side that will move the squat ladder in the X axis.

The two sleeves are welded into the box (yet to be done).

This should create a robust enclosure that is aesthetic and functional. It won’t weigh too much either.

One of the tricky parts of making these components is we have no real prototype program. Since I am making only one piece for our use, I plan it incredibly carefully, carefully pick the different parts and have to ensure the thing is beefy enough and engineered to endure punishment and plenty of use.

There’s a lot of time spent just thinking through the design and making sure it does what it is supposed to. Visualizing how we will use it for different moves and how folks of different sizes and proportions will use it. And I am now informed × experience and coaching. There is no substitute to watching people do thousands of repetitions.

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Chapter 5: Finishing up the enclosure

Today saw the enclosure being completed. Both the sleeves and shafts for the bushing fit perfectly into the enclosure. You can see Gokul holding the piece and showing me how the sleeves fit in there. I can sense the pride in his voice as he shows me how well the components come together. And the enclosure is one step away from being finished. And I really like how it looks. You can see this artistry and skill while watching a talented machinist work and create parts. It takes precision and great feel to make these parts happen.

I also picked up the 38mm pipes that will slot into the enclosure to be used as the lever arms for this unit.

The pipes are 90 inches long. The pipes will be faced and holes milled in to attach into the enclosure. This should be completed tomorrow. And to also hold the sleeves to load plates. Those will be welded on along with a couple of hooks.

Why does it take so long to make these things!

I juggle these projects alongside coaching between 6-9 hours a day in addition to family time. So I take my time to get things done. And as you see the parts come to fruition, you begin to realize how the final unit will look. And I learned a few years ago, to not rush machinists. I also learned to measure twice and pick parts carefully ensuring the fit was great and robust enough.

The enclosure had to be milled slowly to ensure the vibrations from the machine do not cause an uneven surface. The machinist spent close to a day prepping the enclosures for the bushings. And I consider myself pretty lucky to have access to the talent that can bring our really quirky and exacting ideas to life.

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Chapter 6: The final stretch

This is the sixth post of how are putting together the version 5 of the squat ladder machine.

Before we weld all the sleeves into the enclosure, we are doing all the basic checks. Will something not move as freely as we intended.

Will welding warp a part and mess up the fit?

Did drilling holes or grooving a pipe introduce deformities such as ovality in the pipes that messes with one pipe fitting in another?

We answer most of these questions today.

So far the enclosure is fine. We have a flush fit. The first welds should go down later today.

You can also see the shaft for the Y axis sleeve. It is a 10mm thick steel clamp. We took a single 4 inch wide and 22 inch long stainless steel plate. We folded it to hold the 60mm thick pipe. We welded this pipe in. Two holes were also milled to have this fixture attach with two 20mm bolts onto our pull up rack.

Some of the work got pushed by a day since our lathe is caught up with some deadlines for larger orders.

So the holes get milled on the arms for the connectors and caps only tomorrow. The connectors and caps need to be drilled too.

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Conclusion

The final bits of machining and prep concluded today. All the parts are ready. We kicked off the welding this morning. And the sleeve for the Y-axis got welded into the enclosure.

You can see the final components two steps away from their final form. They need a bit of cleaning and grinding before being welded.

What remains to be done:

• The sleeves to load and secure plates on the arm will be welded onto the 38mm arm.

• The sleeve for the 38mm arm will be welded on the 60mm pipe that will spin on the X axis.

• The 48mm shaft for the 60mm pipe to spin on the Y axis will be welded into the enclosure.

• All of the above will be completed in the next 16 hours. Once all of the above it done, the unit can be mounted on the rack and it is ready to go!

• I will make a custom cushion sleeve to be fitted on. But will manage with a decathlon piece for a few days.

• Stretch goal: a racking mechanism for the unit and the pads.

And here’s a summary of all the work done so far:

• We shaved the inside of two pipes. We drilled a total of 20 holes. We folded one 10mm sheet. We faced a total of 30 surfaces. We are laying down 14 welds. And are using 8 bolts to hold the entire thing together.

• 1 welder, 2 machinists and 1 impatient coach were involved in the making of this thing :D

• Pistol squatting with this will be the most comfortable way to load a single leg squat.

• We chose not to use bearings since the feel of bushing will trump bearings in this use case. Both in terms of responsiveness and how the unit will feel. Plus the bushings will be far more durable.

• Every part was selected carefully for the task. Every sleeve and bushing is built using 6 gauge or 11 gauge pipes. No compromise or hanky-panky to make do.

• And the welds are high-quality TIG welds using quality TIG filler wires.

Now here is something I want to make clear: nothing about this project is jugaad or DIY. I truly believe this unit will be the best landmine and single leg lever squat unit in the world.

I resent this idea that we are making things to save cash. At this point, we are designing and building equipment that is genuinely the best tool for the job. And using material that is best in class too. And you won’t find these really cool, thoughtfully built tools anywhere else.

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