King PDM30 - head counterbalance lift assist.

Canuck75

Canuck75

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Was looking at all the different power lift ideas for round column mills that have been posted but got the bug to try a counterbalance weight instead. As you might know this is an idea commonly incorporated into heavy machinery. Except for the ball bearings in the pulleys everything else was at hand so was worth giving it a try. Routing of the 1/8" cable was not difficult but necessitated the 5 pulleys The counterweight is more or less out of sight behind the cabinet and I'm using the snatch block idea to to give the weight more pulling power, but at 2:1 this means the weight needs 20" of movement for the 10" max that the head needs to move. This also means there is no room to have a greater pulling ratio. Am currently looking for weight material that is more compact and heavier than the scrap I'm using. There is 40 lbs on the cable now which makes for much lighter cranking but think 60 might be better, if not ideal. But, that much weight in a compact size is not cheap, at MetalPros probably $150 (1"x6"x12" HRS bars), an exercise weight probably the same but is not a usable shape (room again), even looked at anvils on Kijiji but want $7 a pound! When I get that sorted I think this will be a viable mod.

Canuck75
 

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Yeah the old style cast iron barbell weights would be perfect for that. They can usually be found for cheap or even free.

20 some yeas ago, I built a counterbalanced pot rack for my kitchen. I cast lead weights in empty soup cans and had to make a hole through centers for a threaded rod. It was one of the trickiest materials I ever worked, it grabs and snaps drills like crazy, yeah even dulled ones.
 
That's right! Lead is surprisingly difficult to machine- I'd forgotten that
Best to just cast the rod in
 
60 lbs of lead is 2.4 liters, or 0.53 gallons. That's doable with commercial food cans, or maybe stack two quart cans.

Last time I saw depleted uranium in stock at Wal-Mart, they also had rimfire on the shelves year-round. I wonder what happened.
 
pontiac428 said:
60 lbs of lead is 2.4 liters, or 0.53 gallons. That's doable with commercial food cans, or maybe stack two quart cans.

Last time I saw depleted uranium in stock at Wal-Mart, they also had rimfire on the shelves year-round. I wonder what happened.
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That sounds about right, I needed 45 pounds, I cast 4 cans + a partial cans worth.
 
I used lead wheel weights melted into cans for my drill press take counterweight. Before pouring I drill a hole in the bottom of each and pushed in a piece of scrap metal tube. Little bit of leakage but not much. The counterweight has made raising and lowering the table a great deal easier
 
mattthemuppet2 said:
I used lead wheel weights melted into cans for my drill press take counterweight. Before pouring I drill a hole in the bottom of each and pushed in a piece of scrap metal tube. Little bit of leakage but not much. The counterweight has made raising and lowering the table a great deal easier
Click to expand...
Thats what I will do if I ever have to make them again, I also thought of doing it that way at first but figured drilling would be easier... Wrong!
 
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