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A Reason to NOT Epoxy Knobs

elcoholic, I'm not opposed to trying that idea, either! Same problem as stated earlier----getting to the exact site of the epoxy.

Tago Mago, I'd like to work on that repair person's car ---- turn-about is fair play, right??!!!! Maybe the gas cap needs epoxy, too.
 
An R-1050 cadaver found that has all knobs. NOW, how about this: I drill through the center of the epoxied knobs, thereby drilling through the epoxy in the split shaft of the different pots/switches. Those existing pots/switches (save the speaker selecter rotary switch --- it's destroyed) all work. With the unit that is going to be delivered next week with ALL the knobs, I could use those to replace the knobs I will be removing. That would be the best at this point. As I've written before, this unit works well! The power is there, the FM circuit as particularly good, and the pre-amp and all switches are very good. Hope this works (drilling out the epoxy, replacing the knobs).
 
HTHMAN said:
Heat is the only solution.

I work on golf clubs and the heads are epoxied on. To remove them, you heat the bond with a heat gun or torch. The epoxy usually fails at a lower temperature than the plastic ferrule or the paint on the heads. Failure temp depends on the epoxy used, so it may not work on yours. Try heating it with a hair drier while you pry on it from under the knob.
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Heat worked for me, but it was an aluminum knob. I used the tip of my soldering iron and let it sit for a few moments, then the shards from the broken shaft came right out. This was after clamping, drilling, solvents, pounding, plus an application of intense verbal abuse failed to dislodge it.

Might not work for your plastic knobs, but who knows what application epoxy was used? A little heat might be worth a try.
 
ZeroG, thanks for your story about removing knobs. I'm way up on verbal abuse category, but I haven't tried using heat. I believe this epoxy was applied a long time ago -- it may be susceptible to heat. I'll give it a try, knowing it has about 3/16" of plastic to go through before it gets to the epoxy. As I wrote, I have more knobs coming -- what have I got to lose? Thanks again!
 
Can't say I didn't try. I used a Conair 1500 hair dryer at full force, directed at the function knob. I held the dryer less than 3 inches away for several minutes, going around the knob. When I turned off the dryer I used a rag and pulled on the knob -- sure enough, the outer shell came off almost immediately -- the inner shell, the thicker part with the knurled inner part holding the shaft, was still holding onto the shaft and pulling away from the rotary switch. Uh-oh. Using an awl, I drove through the hole at the inner part of the knob, trying to scrap away whatever epoxy I could. I could see epoxy at the end of the inner part (chassis side) just as I had seen on the first switch (that I destroyed by pulling on it). I applied more heat for several more minutes, but no luck.
 
that's damn strong epoxy seems stronger than a rusted bolt in a hole .. keep at it .my theory is it went on there and will come off again . i have at times spent over an hour removing a rusty bolt . i just keep it moving one way and back then another way and back and convince myself its on the move but tiny movements . all the time being careful not to break anything . it can be a total test of patience .sometimes walking away for a while can be beneficial .
i know this involves plastic ..oh do i hate plastic .
 
Here I am, sitting, drinking coffee (alas, no brandy), thinking, 'I've gotten this far, I've made just a little progress, maybe I can make a little more with the dryer." I know the hair dryer got something of that knob so hot that I now have a blister on my forefinger. Patience. Good word; I practice it often. Here's another challenge for me. You are right about it being stronger than a rusted bolt--- I've used penetrating oil and, over time and more applications, the bolt finally did give way (like exhaust manifold bolts). I will take another run at it, petehall345.....after my coffee. Thanks!
 
MyHeresyIsMe said:
Here I am, sitting, drinking coffee (alas, no brandy), thinking, 'I've gotten this far, I've made just a little progress, maybe I can make a little more with the dryer." I know the hair dryer got something of that knob so hot that I now have a blister on my forefinger. Patience. Good word; I practice it often. Here's another challenge for me. You are right about it being stronger than a rusted bolt--- I've used penetrating oil and, over time and more applications, the bolt finally did give way (like exhaust manifold bolts). I will take another run at it, petehall345.....after my coffee. Thanks!
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elcoholic said:
In the wireless industry when we build a cell site on a municipal watertank we normally have to epoxy the antenna mounts to the the tank as they don't allow welding. When the occasionally fail, it's almost always on a cold morning.
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Now that you have it more exposed, it might be a good time to hit it with the cold. A compressed air can turned sideways or upside down will spray the cold liquid out directly.
 
mech986, I'm new as using compressed air to shoot cold air --- I tilt the can sideways or upside down and hit the shaft or the epoxy? and then tap the remaining shell of the knob off? Hate to be dense about this but this is my first travel 'off the main road.' Believe me, NOTHING I can do will hurt it any more than the shape it's in now. It's almost like going to the junkyard and stripping parts, althought the receiver passes a signal and fills the room nicely with sound----just the selector switch has been hotwired and the switch is no longer a switch; just crumbled up wafers, electrical contacts, and a lot of isolating tape to keep the hot wires from crossing.
 
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My thought was to hit the shaft and cause it to contract. Then the shock of a rap with a hammer on the knob might break the bond. It's a crap-shoot, but worth a shot.
 
Here's what I'll do, elcoholic: I'll spray some (liquid) compress air on the shaft as close as I can get to the knob and then hit the knob with my 'persuader' hammer and see what happens. I'm beginning to build up a parts bin (like a did with all of my 70's Mercury Capri's) and I'll scrounge around for another knob, another shaft; plus, I got another C- R-1050 coming in this week that I ordered. I'll do my best to assemble a 'Luxmanstein' out of all these parts. Thanks for the tips!! I should have gone with your suggestion first, BTW. When I use the hair dryer on high heat, I blistered my thumb and forefinger when I tried to pull the knob off. All I did was loosend the rotary selector switch and blistered myself. Glad I don't have blow torch.
 
It sounds like you have a problem and I have a solution, maybe. Have you tried any of the adhesive remover on the epoxy? If you let it soak for an hour or two then use the hair dryer and get any remaining epoxy softened up it should come off with a bit of patient pulling. Another thing you might try clamping the knob in something with the amp facing up and hanging the receiver by the knobs, one side at a time and half an inch off the table then using the hair dryer and letting it sit there for a bit. Hope this helps.
 
MyHeresyIsMe said:
mech986, I'm new as using compressed air to shoot cold air --- I tilt the can sideways or upside down and hit the shaft or the epoxy? and then tap the remaining shell of the knob off? Hate to be dense about this but this is my first travel 'off the main road.' Believe me, NOTHING I can do will hurt it any more than the shape it's in now. It's almost like going to the junkyard and stripping parts, althought the receiver passes a signal and fills the room nicely with sound----just the selector switch has been hotwired and the switch is no longer a switch; just crumbled up wafers, electrical contacts, and a lot of isolating tape to keep the hot wires from crossing.
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Yup, the liquid evaporates super quick, leading to extreme cold (down to probably -20F), then the rap with the hammer. I would place something hard underneath it to take the blow rather than have the shaft possibly bend or break (course too late now!).

elcoholic said:
My thought was to hit the shaft and cause it to contract. Then the shock of a rap with a hammer on the knob might break the bond. It's a crap-shoot, but worth a shot.
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Yup!

MyHeresyIsMe said:
Here's what I'll do, elcoholic: I'll spray some (liquid) compress air on the shaft as close as I can get to the knob and then hit the knob with my 'persuader' hammer and see what happens. I'm beginning to build up a parts bin (like a did with all of my 70's Mercury Capri's) and I'll scrounge around for another knob, another shaft; plus, I got another C- R-1050 coming in this week that I ordered. I'll do my best to assemble a 'Luxmanstein' out of all these parts. Thanks for the tips!! I should have gone with your suggestion first, BTW. When I use the hair dryer on high heat, I blistered my thumb and forefinger when I tried to pull the knob off. All I did was loosened the rotary selector switch and blistered myself. Glad I don't have blow torch.
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Hot stuff is tuff to control. Maybe the cold method will be preferred now.

MyHeresyIsMe said:
Off like a prom dress....
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So, you got it off?? :thmbsp: Like your analogies!
 
Rockyhill said:
I have a 2235B with a push button switch that was sheared off. Thanks to the generosity of a fellow AK member I have a replacement knob to attach. I've been mulling over how to attach it! Due to the design of the face plate using epoxy is not an issue - the through hole for the switch is large enough to remove the plate. This may be a situation where using epoxy isn't a bad thing.

Thoughts?
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Solved: I used contact cement to marry the push button to the shaft. Since the switch is the Dolby circuit it will never be used and now the receiver looks good.
 
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