Changing a pulley to a cam on a machine

I searched on the forum for this but did not find anything.

Has anyone changed a round pulley (on a machine) to a cam on the same machine?

I have an old, generic prone leg curl machine (doesn’t even have a brand name on it) with a round pulley that a cable goes around and then to the weight stack. In view of the real benefits of a cam, I would like to change that pulley to a cam.

Anyone here do such a thing? I imagine that the cam would be very similar (if not identical) to one on a Nautilus prone leg curl machine equipped with a cam.

Any info appreciated - and thanks in advance.

Jesse Lee

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As i write this i don’t know what the right variable resistance is to the changing strength curve on a leg curl machine

If the resistance needs to be the heaviest at the contraction where the ankle pads touch your butt the solution is quite simple

Take a cue from powerlifters that use heavy chains…on exercises such as squats, deadlifts, bench press etc they will place heavy chains on end of bars where as they lift the weights upward they pick up more links of the chain gradually being heaviest at top of the movement

A low tech way of achieving variable resistance

Maybe hook a chain to the pin in the selectorized weight stack (?)

On a machine with a cam, the cable/belt/chain etc is attached to the cam. It doesn’t simply pass over the cam the way it does a pulley. Usually the cam is attached to the weight stack via the chain (or whatever) and then you lift the weight by moving the cam either directly, or remotely through another attachment point.

I found a few pictures that are not great. It looks like the pulley stays, and the cam is attached right under the path of the cable.



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Jesse Lee
Can you post a pic of the machine ?

Give me a day or so to move the clutter that’s all around the machines that I have so I can get room to take a picture of most of the machine - specifically the pulley area.

Thanks for asking.

Jesse Lee

Zonetrainer – I am still trying to get a presentable picture of that machine amongst all the clutter around it. I have my machines in an old, dilapidated tin-roof garage – onto which a recent storm blew a humongous tree fork. Rafters, timbers, wood bits, etc. fell all over the place inside the garage – and I’m still cleaning up. (Luckily I was not in that garage at the time the tree fork hit the roof)
Gladly, none of the machines were damaged – a testament to the solidly-built early generation Nautilus machines - and that generic prone leg curl machine that is also built like a bulldozer.

I have recently taken to training at a local YMCA because of the structural damage at my ‘gym’ - but I still want to modify that leg curl machine after I clean all the junk up.

Jesse Lee