Making the cheapest pkp truck known to man kind

So I love the feel of pkp trucks, my first version was made with aluminum and it was great other than one tiny detail, it costs too damn much!

So for my second version I’m going back in time and making a nosno inspired version out of 16mm steel rod that’s threaded on both sides, with a laser cut steel plate welded onto it. Here’s the design so far.

The main point of this truck is to be dirt cheap, the cheapest trucks man kind has ever built. So far the cost is about 50CNY or 7.86USD a pair without the motor mounts and bushings.

There’s the design so far.


Do you plan to weld motor mounts onto it?

Will the heat affect the strength properties or cycle fatigue resistance?

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Yes I’m planning on welding on the motor mounts, not sure about strength properties but it’ll be so cheap to make I can make rapid iterations if there’s a problem. First step is to make it and try it out.

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Are you planning to use regular (not hardened or heat treated low alloy) mild steel, or something stronger?


I’m not well versed in steel but I’m planning on using 35crmoA
US equivalent : ASTM A29/A29M 4135,4137
Standard : ISO 683 34CrMo4

Yes, that stuff will probably need to be heat treated after welding. Much stronger than regular (soft) mild steel after being heat treated though.

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you will need cross bracing. that steel is pretty alright but you gotta do a proper heat treatment on it, other wise it’s not much better then mild steel. steel is also not the best thing for trucks nor motor mounts it’ll tend to want to bend and during weld warping will happen.


@taz this guy wants to do stuff and things that you’re good at


That is a quenched and tempered steel

Here are its properties

and here is the heat treatment required to obtain them

As already said if you weld it and don’t heat treat it afterwards the mechanical properties will be very close to mild steel


What kind of heat treatment for it after welding though?

Theoratically the same. Heat treament is done for both the weld and the HAZ.
If you weld with low heat input and depending on the size of the axle and the throat thickness of the weld, you might get away without heat treatment and have minimal distortion.
Use TIG with a 312 rod and let it cool between passes.
Checking strength loss should be prety easy by putting the welded axle in a vice and measuring the bending moment required to bend it to around 30degrees and then comparing to an unwelded axle.

Definitely a sub optimal solution but since you are going for dirt cheap manufacturing cost, PWHT would increase the price considerably.


In that case I’ll just not do heat treatment at first and test it out, if it starts to deform I’ll make another set with heat treatment :sweat_smile:


my stalled project :sweat_smile:
made of 10mm fully threaded high tensile rod through 1/2" common steel pipe

The baseplate serves as the pivot point of the hanger. The problem of this design is that the roll axis is way up high which will result in hammocking.

Better have the pivot point in the hanger in-line with the axle.


ahhh,alright, should be easy enough to accomplish,

I just want to chip in and make sure there’s not confusion between rake and hammocking happening.

Hammocking is when the deck height is lower than the roll axis. Normally the roll axis of a truck doesn’t move all that much with different truck geometry, so its usually more about deck design and risers. How much drop there is, etc. But getting rid of the baseplate like the no-sno design gets rid of a lot of height, and make risers a more interesting topic.

With the diagrams it can look like you’re talking about rake, and the rake is changing, but that’s a different aspect.


You’re speaking my language…

What if you widen the hanger flange dealy-ma-bob- this will allow you to space the welds out and lessen the heat input into the axle?

With bushings in a more traditional PKP style base mount, it would look a little something like this

Screenshot 2022-02-23 222845

But then there’s the conundrum of bushing seats and/or how do you keep the axle flange from flopping around on the kingpins? I’ve used these Polyurethane Washers with success on some prior prototypes. Two of these stacked fit perfectly in a .625" OD hole (metal is laser cut from SendCutSend- .188" HRPO Steel) and keep a standard .375" diameter kingpin from hitting the metal- cheap bushing nipples so-to-speak:

Of course, I’ve also had some success with 3d printed bushing seats as well

Just some food for thought… I love projects like this, please keep the updates coming!


weld seating cups on


Man you were the inspiration for this project!


I’m planning on using those thane washer thingies. I’m planning on not having a baseplate, just use the deck as baseplate maybe with some washers.
I’m getting the pieces laser cut, now I’m looking around for a welder lol.