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2236 Push-On Knobs


 

Well, I did a stupid and broke one of the trigger level knobs on my 2236 trying to pull it off (at least both trigger level knobs match, now). I should have searched the group before I did this, as I would have found out that plenty of other folks have had a similar problem. The unfortunate knob has Tek part # 366-2049-01 (though it looks like 366-2041-03 might be a compatible replacement) and I see that they are basically unobtanium except as part of an existing scope (where removal will still be a problem).

My question is three-fold:

First, does anybody have any advice on how to remove the push-on knobs without breaking the tabs in the top of the knob that hold it on the extension shaft? I've considered heating the knob to soften the plastic, but am scared of deforming the printed faceplate which is also plastic. I've also considered WD-40, but I'm not sure it would work, and not sure that it wouldn't attack the plastic on continued contact.

Second, how to reattach the damaged knob? My best plan is to use silicone gasket compound, which cures to a pretty hard state, but I'm worried that the knob will no longer be removable. I've also considered trying to reattach the broken clips using a strong solvent, but I don't think I could reliably position them, nor that I could trust the resulting joint (though these won't be under significant stress, so, assuming the joint survives reinsertion, that should not be an issue).

Third, I am considering trying to cast replacement knobs using silicone casting compound and epoxy resin (and affixing the resulting knob to the extension shaft using silicone sealant, as above). Has anybody tried this? I assume that the epoxy resit doesn't have the same mechanical properties as the injection molded plastic, but, again, these parts are not under significant stress, so that might not matter much.

-- Jeff Dutky


 

Use a little bit of heat. Use a hair drier with a paper cone to direct the heat to the top of the knob.

Regards

On 12/5/2020 9:29 PM, Jeff Dutky wrote:
Well, I did a stupid and broke one of the trigger level knobs on my 2236 trying to pull it off (at least both trigger level knobs match, now). I should have searched the group before I did this, as I would have found out that plenty of other folks have had a similar problem. The unfortunate knob has Tek part # 366-2049-01 (though it looks like 366-2041-03 might be a compatible replacement) and I see that they are basically unobtanium except as part of an existing scope (where removal will still be a problem).

My question is three-fold:

First, does anybody have any advice on how to remove the push-on knobs without breaking the tabs in the top of the knob that hold it on the extension shaft? I've considered heating the knob to soften the plastic, but am scared of deforming the printed faceplate which is also plastic. I've also considered WD-40, but I'm not sure it would work, and not sure that it wouldn't attack the plastic on continued contact.

Second, how to reattach the damaged knob? My best plan is to use silicone gasket compound, which cures to a pretty hard state, but I'm worried that the knob will no longer be removable. I've also considered trying to reattach the broken clips using a strong solvent, but I don't think I could reliably position them, nor that I could trust the resulting joint (though these won't be under significant stress, so, assuming the joint survives reinsertion, that should not be an issue).

Third, I am considering trying to cast replacement knobs using silicone casting compound and epoxy resin (and affixing the resulting knob to the extension shaft using silicone sealant, as above). Has anybody tried this? I assume that the epoxy resit doesn't have the same mechanical properties as the injection molded plastic, but, again, these parts are not under significant stress, so that might not matter much.

-- Jeff Dutky



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greenboxmaven
 

I think those knobs were meant to be a one-time fit, push them on forever. They had all been pulled off on my scope and the internal clips shattered. I reattached them with silicon caulk, the pointers even lined up when they seated fully on the extension shafts. If you need to remove the front panel, the plastic control label sheet has to be peeled off, with the help of mild heat, to expose screws holding the front panel on. The sheet will come off over the extensions and knobs. The extension shafts look to be permanently assembled, so you will have to get each one started on it's individual control shaft as you re-install the front panel. Others may have different experiences and knowledge.

Bruce Gentry, KA2IVY

On 12/5/20 21:29, Jeff Dutky wrote:
Well, I did a stupid and broke one of the trigger level knobs on my 2236 trying to pull it off (at least both trigger level knobs match, now). I should have searched the group before I did this, as I would have found out that plenty of other folks have had a similar problem. The unfortunate knob has Tek part # 366-2049-01 (though it looks like 366-2041-03 might be a compatible replacement) and I see that they are basically unobtanium except as part of an existing scope (where removal will still be a problem).

My question is three-fold:

First, does anybody have any advice on how to remove the push-on knobs without breaking the tabs in the top of the knob that hold it on the extension shaft? I've considered heating the knob to soften the plastic, but am scared of deforming the printed faceplate which is also plastic. I've also considered WD-40, but I'm not sure it would work, and not sure that it wouldn't attack the plastic on continued contact.

Second, how to reattach the damaged knob? My best plan is to use silicone gasket compound, which cures to a pretty hard state, but I'm worried that the knob will no longer be removable. I've also considered trying to reattach the broken clips using a strong solvent, but I don't think I could reliably position them, nor that I could trust the resulting joint (though these won't be under significant stress, so, assuming the joint survives reinsertion, that should not be an issue).

Third, I am considering trying to cast replacement knobs using silicone casting compound and epoxy resin (and affixing the resulting knob to the extension shaft using silicone sealant, as above). Has anybody tried this? I assume that the epoxy resit doesn't have the same mechanical properties as the injection molded plastic, but, again, these parts are not under significant stress, so that might not matter much.

-- Jeff Dutky





adesilva_1999@...
 

If they do not have the "ring" around them like the Vertical knob, you can wrap a string around the shaft (just 1 round) and pull it out. That way, you exert the force diametrically on the knob and also the force is on the bottom of the knob. as long as the shaft is not fragile, it should come out.