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Glue Type For Preamp Knob Repair

denniswilson

denniswilson

Well-Known Member
Hi Folks.....Its been a while,

I picked up a Carver C-16 preamp. The Selector knob plastic insert broke. Somehow it was missing the tiny flat spring that supports the knob insert to the flat part of the shaft. It's a D shaft...not knurled. So when turning the knob, it broke apart. I have no idea how this could have happened, and the previous owner has no clue.

I'm getting a Carver replacement knob for a Carver C-1 preamp and want to swap out the insert to the C-16 outer knob so it matches the C-16. I already removed the broken insert following a thread on here using heat and steam from a clothes iron to loosen the glue. The outer knob is aluminum. What kind of glue do the stereo manufactures use to secure those inserts to the knobs? It came off pretty easily once I heated up the knob.

What glue do I use to secure the plastic insert to the outer aluminum knob. I will need a few minutes to set while I line up the index dot to the faceplate nomenclature.

Thank you !!
 
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If its just a crack I use super glue in the crack, clamp it and let it dry. I did this with a couple temp and blower knobs in my 2002 Jeep Wrangler several years go and its worked just fine. With broken ones I've used epoxy. Same thing, put in on the broken edges and carefully clamp it in a vice or use small vice gripps making sure no excess epoxy gets on the vice jaws, or small vice grips. I used a tooth pick to apply the epoxy.
 
+1 superglue. If the crack doesn't sit closed tightly you may need to work out some means of pushing it shut until it cures. Wads of paper or something inside the knob maybe, depending on the particulars.

If it does sit closed tightly, figure some way of spreading it just enough to get the glue in the gap first before letting it sit.


the original glue for the insert usually isn't very strong. Not sure what it is, but its probably the same thing used to glue in capacitors, whatever that is.
 
Lavane said:
If its just a crack I use super glue in the crack, clamp it and let it dry. I did this with a couple temp and blower knobs in my 2002 Jeep Wrangler several years go and its worked just fine. With broken ones I've used epoxy. Same thing, put in on the broken edges and carefully clamp it in a vice or use small vice gripps making sure no excess epoxy gets on the vice jaws, or small vice grips. I used a tooth pick to apply the epoxy.
Click to expand...

Thanks @Lavane
In my project, The plastic insert inside the knob has broken apart. And the insert was missing the tiny flat spring that supports the insert to the D shaft.
So, I got a complete replacement knob from a different Carver model and the knobs are almost identical except for the outer color (black vs grey) and index dot alignment.
I'm swapping out the inserts and wonder what glue to use to secure the outer aluminum knob to the plastic insert.
c16 knob.jpg C1 knob.jpg
 
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@gadget73
Thanks....I'm swapping out the plastic inserts I have already unglued and removed them from the knobs....so just simply use Superglue to secure the plastic insert to the inside of the knob? Super glue is strong enough to withstand turning the clicks on the selector knob?
Thank you
 
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With that black knob, if you can find something to wrap around the outside for extra support it should hold up better. Kind of looks like it had something originally, but some is missing. Does the C shaped outer piece just slide out? If it does maybe find a piece of tubing to sub for it that goes all the way around or rotate it so the repaired section is surrounded by the plastic and put some heat shrink tubing in there to help keep it all together.


and if you can swap that into a position that doesn't get used very much or is easier to turn, so much the better.
 
denniswilson said:
Thanks @Lavane
In my project, The plastic insert inside the knob has broken apart. And the insert was missing the tiny flat spring that supports the insert to the D shaft.
So, I got a complete replacement knob from a different Carver model and the knobs are almost identical except for the outer color (black vs grey) and index dot alignment.
I'm swapping out the inserts and wonder what glue to use to secure the outer aluminum knob to the plastic insert.
View attachment 2711551 View attachment 2711552
Click to expand...
I've had very little luck with glue lasting in this application if the switch needs any torque to turn over. I don't know what they're called (sort of a collett?), but some manufactures used spring metal collars on knobs where torquing the switch would inevitably break the plastic alone. Revox comes to mind in particular, they used them on the A77 power switches. Has to be a source for these out there, somewhere -- if only AliExpress had a search engine that worked.
Anyhow, pic related is what I'm talking about, glue works well with one of these on.

switch.jpg
 
titanstats said:
I've had very little luck with glue lasting in this application if the switch needs any torque to turn over. I don't know what they're called (sort of a collett?), but some manufactures used spring metal collars on knobs where torquing the switch would inevitably break the plastic alone. Revox comes to mind in particular, they used them on the A77 power switches. Has to be a source for these out there, somewhere -- if only AliExpress had a search engine that worked.
Anyhow, pic related is what I'm talking about, glue works well with one of these on.

View attachment 2711746
Click to expand...
I have not looked for those spring collars, or by another name? Maybe industrial supply houses for a source, like these:
Mc Master-Carr
MSC Industrial Supply
Field Fastner
 
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I would smear contact cement in there and stick the insert in. You would have enough time to set the outer knob so the indicator lines up and when the glue sets, it will be permanent.

I believe a similar type cement is what many manufacturers use.

Doug
 
Doug G. said:
I would smear contact cement in there and stick the insert in. You would have enough time to set the outer knob so the indicator lines up and when the glue sets, it will be permanent.

I believe a similar type cement is what many manufacturers use.

Doug
Click to expand...

Thats what a fellow said on "The Carver Site" Thanks !
 
I second the use of contact cement, it will give you the necessary adjustment time for you to adjust for correct pointer alignment..
Give the cement at least 24hrs dry time afterwards.
FWIW, I`ve had excellent success repairing various knob`s insert internals in this type of repair over the yrs.
 
I repaired a power button on a Braun A2 Atelier integrated with epoxy fill. The stem was broken apart internally in three separate pieces. I was able to mock everything back up as it was originally and glue everything in place. It's still holding tight / strong and "looks" perfect from the outside, but knobs are all different I suppose. If you can "fill" the empty surrounding space with epoxy to strengthen the repair while holding everything in place I would recommend that (if possible). Good luck with whatever works for your particular situation.

A2 power button.jpg
 
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