Does pot metal shrink

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Does pot metal shrink

Postby Walter Newton » Tue Feb 16, 2021 9:27 am

Hi,

I purchased a handle for my Columbia project, the hub at the base of the handle is in great looking shape, no cracks, no rot, really almost looks new.

Even the leaf spring and lock peg looks new.

But one problem.

Handle hub does not fit over the steel stub that is attached to the reel kicking mech.

About a 1-2 centimeters difference.

Before I do anything, just a simple question, does pot metal shrink?
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Re: Does pot metal shrink

Postby marsonion » Tue Feb 16, 2021 11:10 am

Walter Newton wrote:
About a 1-2 centimeters difference.



Not that much! :shock:

Could you post a picture of the situation there--?
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Re: Does pot metal shrink

Postby radiorich123 » Tue Feb 16, 2021 12:36 pm

I dont think it shrinks. The problem with pot metal is it is cast in a foundry and if there is any lead in the casting it crumbles over time.
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Re: Does pot metal shrink

Postby marsonion » Tue Feb 16, 2021 12:44 pm

The best guess I can take is that the gash in the steel stub has raised burrs stiff enough to keep the mating surface from sliding on all the way; I see some damage reamed into the inner diameter surface which also may have raised its own burrs, which can't help. If it were me, I'd take a calipers to both the OD and ID and check their respective measurements and circularity: warpage would be just as deadly as shrinkage per se. If the clearance between the diameters is irregular or less than zero, I'd file or sand them down to where they'd be able to mate. At any rate, I don't see 1-2cm of difference between these mating surfaces, but I do appreciate that they're not fitting right now... the handles are often snug, but I've never encountered one that wouldn't go on there with a little extra effort.

Thanks for the pictures!
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Re: Does pot metal shrink

Postby Walter Newton » Tue Feb 16, 2021 1:00 pm

My observations ...

Yes, it looks to me like someone, at some time, used vise-grips on the steel drive shaft, probably to try to cycle the machine. The original handle hub was pot metal trashed.

I took a file to the steel hub, trying to make sure I didn't have any raised "gouges," it seems smooth to me.

The scoring you see inside the handle hub was from me trying to fit the handle on the steel drive shaft.

I took inside diameter measurements on the handle hub, and outside diameter measurements on the steel drive shaft, and I found a 1-2 centimeter difference.

I suspect that I will have to "gently" bore out a tad of metal inside the handle hub.

But I wanted to make sure I wasn't missing anything.

Your comment confirms what I was seeing and what I suspected the answer is.

Thanks.
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Re: Does pot metal shrink

Postby marsonion » Tue Feb 16, 2021 1:30 pm

Walter Newton wrote:
I took inside diameter measurements on the handle hub, and outside diameter measurements on the steel drive shaft, and I found a 1-2 centimeter difference.

I suspect that I will have to "gently" bore out a tad of metal inside the handle hub.



"1-2 centimeter difference" would be a difference of something like 1/2"-3/4" and that's simply not possible. I think maybe you mean one or two millimeters, but even that sounds like a huge difference in this context, and would require a lot more than just a tad of reaming out the ID in the pot metal. In any event, creating/increasing the clearance all around the inner mating surface (by whatever means) is for sure your best approach. Good luck!
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Re: Does pot metal shrink

Postby Walter Newton » Tue Feb 16, 2021 2:18 pm

Yes, I did mean millimeters.

But that's the measurements I got.

Anyway, I think a very little removal of metal from the arm hub bore will do it.

But I gave away all my Dremel stuff to someone when I got rid of my rock cutting equipment, so I have a new Dremel coming in from Amazon on Thursday.

That should do the trick.
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Re: Does pot metal shrink

Postby Walter Newton » Wed Feb 17, 2021 4:38 pm

Thanks for all the help.

I hit the steel stub (drive shaft) with a Dremel and stone bit, it took out any surface imperfections that was stopping the handle from going on.

Now handle fits nice and secure.
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