I have one of those streamlined Bakelite zenith '30s radios (model 4-B-314) with small skirted plastic Z-knobs for volume control and tuning. These knobs were used on a lot of Zeniths during this period and they have a tendency to get stuck to the shafts. I need to remove both knobs so I can get the chassis out of the cabinet to repair it. Past attempts to pry off this kind of knob have usually resulted in breaking chips off the skirt or worse.

Has anyone found a reliable method for removing these knobs?

John

NO, they are brittle, buy a repro.

Yes. Get a piece of 1/16"x8"x1" mild steel. Cut a fork in one end 5/16 wide and about 3/4" deep. You can do that by drilling a 5/16 hole at the "bottom" of the fork, then using a hacksaw to cut down to it. Clean it up with a file, and smooth all the edges and faces. Then bend that end into an "L" shape about 1" from the end. If you want, make a handle out of wood (say, 5" long, an inch wide, and maybe 1/2" think, rounded off) and then epoxy and screw the handle to the "upright" of the L.

To use, slip the fork behind the knob, make sure it is flat up against the back of the knob, and pull. Once you get it off, if it was really tight, clean up the splines with a dremel tool and a tiny wire brush. If that makes it too loose, you can spread out the slot in the shaft.

Brett

Thats all well and good but not of any use on these knobs, the thin plastic skirts won't take any pressure. I've cut them off with the dremel and looked around for replacements. The shaft is splined.

What about heating or cooling either the knob or the shaft with hopes that one or the other will shrink or expand just enough to make getting 'em off easier? Thinking out loud...

I agree with Tom.
Lately, I've used a heat gun to remove a few stuck items. One was the phenolic strip that the '39 Zenith hook/push-buttons are stuck on. I wanted to remove the button intact to reproduce it and needed to see how deep the phenolic piece is imbedded in the knob. I first clamped the strip in a vise and put a steel forked tool under the push button and used all my force to try to pull the button off. It wouldn't budge. I then applied moderate heat, about 200 degrees to the button, and it pulled free.

Last night, I again used heat to pull a push-button from a splined shaft. Without heat, I don't think I could have gotten it off without breaking it.

Try warming the knob. Give it time to absorb the heat, then try pulling or prying. The heat may make it less brittle too.

Ed

My favorite method with stubborn knobs is to use an old T-shirt, slipping some of the fabric behind and then looping around behind the knob, and pulling.

If there is room between the back of the knob and the front of the cabinet to insert the straw from a can of WD40, shooting some lubricant in helps as well.

Yep,
its frustrating.
I broke both of the skirts on the knobs off of my 5-R-312.
I tried every way in the book and they would just not come off.
I finally tugged and tugged until I broke them.

now I have a very nicely restored radio with no knobs.
and no one makes replicas....I may have to cobble some together by cutting the long shafts off of my broken ones and glueing them to replicas for the ones that fit the other style of radios mentioned, like the 4-B-314

~jeff~

Buy repro knobs here.
http://www.renovatedradios.com/parts.html

None of those will work

the KZ9 is the correct knob except for the fact that the knobs I need have a long shaft on the back that reaches inside the bakelite case. Those knobs are flat on the back. So are the ones that Great Northern Reproductions (Alan Jasperson) makes and he doesn't make the correct ones either.....

~jeff~

I ran into one that had replacement knobs with set screws. Did some damage before I noticed, so always look for set screws !!

Ed

I have a restored 6D312 that has the same problem. Luckily it's been recapped and works fine, but I think I'd be out of luck if I ever had to remove the chassis. Some people have suggested trying to pull the chassis backward rather than the knob forward, the idea being that you gently and repeatedly shake the radio with the front up and the rear down and hope that the weight of the chassis eventually starts to separate it from the knob.

I tried to figure out a way to get penetrating oil on the metal shaft, but the long plastic section of the knob that covers the shaft pretty much prevents that. It's an incredibly stupid design.

The other choice, I guess, is to find a parter with an intact knob or knobs, and resell it after harvesting what you need from it.

Bob

I have bought them before for that set. Look here: (K47)

http://www.alanjesperson.com/gn_repro.htm#Zenith%20Reproduction%20Parts

None of those will work

the KZ9 is the correct knob except for the fact that the knobs I need have a long shaft on the back that reaches inside the bakelite case. Those knobs are flat on the back. So are the ones that Great Northern Reproductions (Alan Jasperson) makes and he doesn't make the correct ones either.....

If someone can send me a good original, I can probably reproduce them.
Ed