What steel should I use?

[Razzle]

I picked up a non functioning walker ceramax chuck on fleabay for a decent price. Figured I could rebuild it per the posts I have read here. Getting it open was a process but, sure enough, the cam piece was broken. So I need to make a new cam lever. (As well as some other parts).
I was thinking about using 4140 for the new parts for better wear ability, but then it occurred to me that maybe the cam is supposed to wear. Since it slides AND lifts the magnet, using 4140 might wear a hole in the top plate of the chuck instead of wearing the cam.
The chuck won't be seeing production use as I am just a hobbiest.
Any opinions? I would guess that mild steel (A36) would be off the list. But I have 4140, 4130,1018, and 12L14 in stock. I also have some O-1 but it would be alot of work to make the cam from that. Or I could buy something more appropriate.

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[DavidR8]

I can’t offer any help on the material choice but can pass along some information I got from Walker when I was rebuilding my 6x18 mag chuck.
First they said to not separate the plates because it is very easy to damage them or injure yourself due to the forces involved.
Second thing was to put .25” of 90 gear oil in the bottom of the chuck before reassembling the two parts.
Third was to use a sealant such as Permatex on the mating surface.

When I took mine apart, in one corner of the bottom I discovered a small drilled hole that angled slightly down. I drilled and tapped it for a set screw so that the oil wouldn’t leak out.

 

[markba633csi]

I think 12L14 would be a great choice because of the lead content it might slide better?
-Mark

 

[benmychree]

I would go with the 4140 HT

 

[Razzle]

@DavidR8 Thanks for the heads up. My chuck is also a 6x18. Do you recall the shaft size for the cam shaft? Also the pin diameter on the cam end itself? Both are pretty worn on mine so I want a check on my measurements. Did you buy the kit from walker, or did you make your own parts? I may have to bore out the shaft hole and put in a bushing. So I want to make the correct bushing choice.

I also have one cracked spring out of the three flat springs. I need to find a replacement for that as I can't make one.


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[DavidR8]

I didn't measure anything as it all worked. I do have to pull the chuck and take it apart again though as the other day I noticed that the gear oil was leaking out.
I can measure the for you. One thing to note is that my surface grinder is from 1963 and Walker could not identify it so definitely no parts available.
I was working with Carl at Walker. Really helpful fellow.
Did you see the pics of my chuck in my grinder thread?

Parker Majestic #2 surface grinder

The Parker has landed. Took some effort to move it with my 2-ton engine hoist but it went smoothly. Sent from my iPhone using Tapatalk

www.hobby-machinist.com

 

[Razzle]

Hmm, yours is different from mine. I have the actuator on the right side, not in the middle. I also didn't get the nameplate. The seller lost it. So I don't have much to go on in identifying it's age. The insides look like it was run dry for a loooong time. So I have alot of cleaning up to do prior to reassembly.

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[DavidR8]

I found a number stamped on the end of the magnet that actually produced a result when I googled it. Alas Walker still didn’t have any information for me.
Look for a number and I will pm you the contact at Walker.

 

[Razzle]

The only number I found was on the bottom. AXMY-874


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[DavidR8]

Ok that's basically the same format as mine which is: