Materials in the Home Shop - Gym Weights

[PurpLev]

So I acquired a few weights from a gym pulley machine:



I am assuming this is cast iron - so first question of the day, does anyone with experience working/getting those know if they are indeed using cast-iron for those weights or might it be other materials (cast iron seems to make the most sense to me as it's the cheapest to produce but I could be mistaken)?

Second question is- are there any points to keep in mind (other than it's freaking messy) when using this for projects around the shop due to it's nature to chip/crack or are those marginal (I know backplates are sometimes using cast iron?)?

Thanks in advance!

 

[8ntsane]

Hi Sharon

I know that many people like to work with cast iron, because it cuts easy. You probably have exactly that, but myself, I avoid that stuff big time. I like the ease of machining the stuff, but not only the mess it makes, the grit it throws all over your machines. I usually find another material if possible, and cast iron is the last choice.

Any time I do machine cast iron, I cover as much of the machine as I can. I will allso aviod moving the saddle ,or crosslide untill the machine is wiped down, and the shop vac has been used to pick up as much grit as possible. Then as a final step, remove the wipers, and wash the grit out of them as well. The a good dose of oil to re lube the machine.

Cast iron is just one of those materials that Id rather not work with, and Im sure my machines would thank me for it. Though, I certain others will have a different veiw on the subject. I will admit, I do have a brush to clear the chips at my machines. I also have the shop vac at arms reach too. What the brush doesn,t clear off, the shop vac does.

Just me , I guess
I just feel as im sprinkling sand all over my machine when machining cast iron.

 

[jumps4]

sharon
they should be cast iron
on thing i have noticed using poor grade cast iron is sand in the metal
I was using window weights and the cast had so much sand it destroyed my bandsaw blade in minutes
but other pieces i have used were fine I guess it is a hit and miss
the window weights had a porous look to them if your metal looks tight and no pores your probably good to go
as far as what i have read the only advantage and reason cast is used in mills and lathes is cost
you can mold cast iron instead of forging it saving on machining costs and the material cost a lot less to manufacture
the cast being more ridged and able to maintain it's shape than steel is a myth from what i have read.
it is just heavy mass at lower cost
right now it is being replaced by high strength concrete and resin based materials in large machines and heavy equipment bases and mounts
this is not new in world war 1 due to a lack of large lathes in this country they build lathes out of concrete to turn 14" battle ship shells and barrels ect.
I know "way too much info" but i'm bored waiting on parts and stuck in the house due to health lol
steve

 

[george wilson]

Cast iron is the standard material for sliding surfaces because it is full of graphite for abrasion resistance. For example,I think it was Oliver machinery who tried making woodworking jointers with steel tables rather than cast iron. The steel tables soon got grooves in them from running wood on edge over them,so they went back to cast iron.

The graphite is what makes the cast iron so messy to machine. If you are making model engines,you have to have cast iron for the cylinders,piston rings,etc.,or it won't last long.

 

[bcall2043]

So I acquired a few weights from a gym pulley machine:

I am assuming this is cast iron - so first question of the day, does anyone with experience working/getting those know if they are indeed using cast-iron for those weights or might it be other materials (cast iron seems to make the most sense to me as it's the cheapest to produce but I could be mistaken)?

Second question is- are there any points to keep in mind (other than it's freaking messy) when using this for projects around the shop due to it's nature to chip/crack or are those marginal (I know backplates are sometimes using cast iron?)?

Thanks in advance!

I am no expert but also have collected some gym weights and other cast iron pieces as you have. I have been looking into the problems and the guys above have covered most of them. One thing that I have read is that the manufacturers of cheaper cast parts are not concerned with the mechanical properties of the iron. Gym weights or window weights are not normally machined or stressed in use so they may be made fast and cheap. If the iron casting are cooled quickly they can be very hard or have hard spots. Some of this can be corrected by heat treating.

I have taken a piece with about a 1 1/4" cross section by 6" square that I got from the scrap yard and squared it up on my shaper using HSS. The surface was a little hard but seemed to get better as I got deeper. I have not made any thing from it yet but would think twice about a critical part. If I were going to make a backplate or gear I would consider getting something like Durabar which is cast with known mechanical properties. You would not want to have a chuck come at you or have the gear you made take out the rest of your gear train. Of course I would probably use an unkown cast material for practice or applications where there was no risk of it failing and causing damage.

Keep us informed on how it goes. I still have my gym weights over in the corner waiting for a project.

Benny

 

[Tom Griffin]

The best way to find out what you have to to just try machining it. Chances are you'll be disappointed because what you probably have is low cost white cast iron which is likely quite hard and probably has quite a few flaws (sand, old tool bits and pieces of 57 Chevy's). The best stuff for machining is grey cast iron which, due to the addition of graphite, machines very well.

Tom

 

[stevecmo]

Some in a different thread (different forum?) said these weights were like bed frame rails - they threw everything, including the kitchen sink, into the furnace when they made these. You never knew what materials went into them. Just don't be surprised if you find some really hard spots.

Steve

 

[Metalmann]

Cast iron is the standard material for sliding surfaces because it is full of graphite for abrasion resistance. For example,I think it was Oliver machinery who tried making woodworking jointers with steel tables rather than cast iron. The steel tables soon got grooves in them from running wood on edge over them,so they went back to cast iron.

The graphite is what makes the cast iron so messy to machine. If you are making model engines,you have to have cast iron for the cylinders,piston rings,etc.,or it won't last long.

One of my Grandsons scrapped one of those fancy weight machines, and I used the cast iron for some small shop projects. Seemed to me the quality was just as good as a lot of CI valves I've rebuilt over the years. They were fairly medium grade cast iron.
The tubing has been used on several projects also.

 

[george wilson]

I don't see how your post relates to my post. Apparently,from what other's experiences have related,you were lucky to get good results out of using gym parts. I have noticed the rectangular weights when at the gym,and they did seem o.k. Never tried cutting one up,though. I had a bunch of window weights after replacing my windows in this 1949 house. They really were full of little holes,and seemed very soft. I never used them for anything. Might have given them to the Williamsburg Geddy foundry. They are sometimes looking for scrap cast iron for casting decorative objects that won't be machined.

 

[ScubaSteve]

Worst case scenario, you've got weights to weigh stuff down If you're gluing things and need pressure overnight you can use these. Or, some awesome anodes for electrolysis. Or, machine them down and use as spacers for a headstock. Or.....or.....