Author Topic: Fixing a metal screw-in handle where the thread on the fitting has eroded away  (Read 789 times)

It's on our kitchen tap, which is only about two years old. 

It's not this model but the key bit looks like this:



The little stick that screws into the barrel to turn it on and off has fallen out.  On inspection the stick has a short screw thread just beyond the bit that is visible in the picture, about 5mm worth.  The barrel is then hollow.

The problem appears to be that the metal of the barrel has eroded away to the extent that the stick bit no longer stays in.  I thought of PTFE tape to make a better connection, but not sure it would be strong enough (and can't find it in the garage or I'd have just tried it). 

I think it would be beyond my soldering skills to do that.  Of course a different stick would do, doesn't have to be that one, but the chances of finding the exact size might not be too good.

Any better ideas? 

TimC

  • Old blerk sometimes onabike.
Before you weld it in, just check that the screw to allow dismantling of the valve isn't at the bottom of that hole!

Before you weld it in, just check that the screw to allow dismantling of the valve isn't at the bottom of that hole!

Well done! I've just peered in with a torch and there is a screw in there.
Thanks for the tip off!

fruitcake

  • some kind of fruitcake
    • Bailey
The corroded hole could be drilled and the thread recut with a larger thread. This should be possible with an engineer's tap and die set. You'd then insert a bolt of corresponding thread to secure a suitable 'stick'.

Perhaps you could replace the metal stick with hardwood. A piece of dowel with a coating of wax could look attractive, and should be easy to remove when the time comes to service the tap.

Wombat

  • Is it supposed to hurt this much?
I think the idea of recutting the thread to a slightly larger size and making a new handle with a threaded end is what I'd do.  However, I do have taps, dies, lathe and milling machine.  (double however, I also have a broken shoulder which means I can't really use any of that!)   I'm assuming the thing is stainless steel, so I'm puzzled as to why its corroded.  Of course it may just be plated brass of marginal quality.

Is it a known make? Could you ask the manufacturers for a new knob end (considering that term is what I'd call anyone who made a tap that frangible).
Wombat

robgul

  • Cycle:End-to-End webmaster
  • cyclist, Cytech accredited mechanic & woodworker
    • Cycle:End-to-End
If you know what make/model the tap is the manufacturer probably has an exploded diagram that shows the whole works - which may help to see what needs fixing.

Epoxy is often your friend  :thumbsup:
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I think the idea of recutting the thread to a slightly larger size and making a new handle with a threaded end is what I'd do.  However, I do have taps, dies, lathe and milling machine.  (double however, I also have a broken shoulder which means I can't really use any of that!)   I'm assuming the thing is stainless steel, so I'm puzzled as to why its corroded.  Of course it may just be plated brass of marginal quality.

Is it a known make? Could you ask the manufacturers for a new knob end (considering that term is what I'd call anyone who made a tap that frangible).

Chromed, not SS. And it may just have been a poor fit initially allowing relative movement that’s got worse. Tapping larger will only result in a bigger thread with less engagement (in terms of threads, which should be at least 0.5D). Personally I’d epoxy it, and then, come the time I need to dismantle to replace a leaking cartridge, scrap it for normal tap. Maybe replace the cartridge now to increase that interval.
We are making a New World (Paul Nash, 1918)

If the corroded thread hasn't gone completely, maybe use something much thicker than ptfe tape, like from a plastic bag or packaging.

If there's any thread engagement left, you could try putting it in with the addition of Loctite bearing retainer - not the same as threadlock - it resists rotational forces.

Thanks for comments everyone - some good options to consider.

Kim

  • Timelord
Bah!  This forum's slacking.  Nobody's suggested the Reasonable Adjustment[1] Mole Grips™ yet.


[1] In the Equality Act sense.
Careful, Kim. Your sarcasm's showing...

gibbo

  • Riding for fun, cake and beer.
    • Boxford Bike Club
Helicoil it.

My pragmatic approach would be: can you get a replacement cartridge easily and what percentage of a new  tap is the cost? If the tap cost £££'s and the cartridge is £ and easy to get / fit then consider engineering solutions. Otherwise, if the tap is ££'s  and the cartridge £'s buy a replacement fit it and epoxy in the actuator. Will be a good few years before you need a new tap. If the tap is ££'s and cartridge same or unobtainium then just glue in the actuator. I actally don't think helicoils will work as the cartridge cover is thin and hollow, plus the actuator thread will.most likely be damaged as well.

Time for replacement taps.
Methinks.
It has to be the easiest solution.







Nah, time for a new bike

Nah, time for a new bike
Always the best solution.

I think the verdict is that you need to buy a tap to tap your tap to ensure your tap remains functional.





Tap.
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Mr Larrington

  • A bit ov a lyv wyr by slof standirds
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I think the verdict is that you need to buy a tap to tap your tap to ensure your tap remains functional.





Tap.

Top tip :thumbsup:
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Tim Hall

  • Victoria is my queen
I think the verdict is that you need to buy a tap to tap your tap to ensure your tap remains functional.





Tap.

Top tip :thumbsup:
In the olden days you could buy a kit to renovate taps, yclept "Tip Top Tap Tops".
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"overhaul" it, or you can ride it.  (Jerome K Jerome)

andytheflyer

  • Andytheex-flyer.....
Helicoil it.
What he ^^ said. helicoil kit readily available. Comes with the correct size drill, the helicoil insert and insertion tool.  Drill out barrel to new size, insert helicoil, screw in the old stick - assuming you know what the thread on the stick bit is.  Metric presumably.  You buy the helicoil kit for that size.

Helicoil it.
What he ^^ said. helicoil kit readily available. Comes with the correct size drill, the helicoil insert and insertion tool.  Drill out barrel to new size, insert helicoil, screw in the old stick - assuming you know what the thread on the stick bit is.  Metric presumably.  You buy the helicoil kit for that size.

Given that the wall thickness of the barrel is likely to be 1.5-2mm I don't fancy the chances of getting a helicoil to work.

Wombat

  • Is it supposed to hurt this much?
Loctite 638, and if you do ever need to replace the cartridge, then the tap is then scrap. Fairly silly design, to leave such a thin wall for a threaded lever.
Wombat

Helicoil is an interesting idea.  There is about 5mm so it might work, and the thread on the little stick still looks good.  I'd not heard of them before so it would require some new tools but would be a learning opportunity. 

I'm not sure green Loctite would do it as there isn't enough thread on the barrel to hold it in.  It will come out with a bit of jiggling without turning now - althogh the bearing retainer stuff sounds more promising.   

New tap would clearly be the best solution.  It would be annoying though: I can't find out the make of the tap.  But what I can remember is that I got one that was a well-known brand as the previous one had to be replaced fairly early in life when we couldn't get spares for it.  Unfortunately I didn't buy it online so the answer is not to be found by searching my emails.

robgul

  • Cycle:End-to-End webmaster
  • cyclist, Cytech accredited mechanic & woodworker
    • Cycle:End-to-End
Helicoil is an interesting idea.  There is about 5mm so it might work, and the thread on the little stick still looks good.  I'd not heard of them before so it would require some new tools but would be a learning opportunity. 

I'm not sure green Loctite would do it as there isn't enough thread on the barrel to hold it in.  It will come out with a bit of jiggling without turning now - althogh the bearing retainer stuff sounds more promising.   

New tap would clearly be the best solution.  It would be annoying though: I can't find out the make of the tap.  But what I can remember is that I got one that was a well-known brand as the previous one had to be replaced fairly early in life when we couldn't get spares for it.  Unfortunately I didn't buy it online so the answer is not to be found by searching my emails.

If you take a couple of pix of the tap there are several "what's that tap" identification things online - or take a look at the website for Sterling the distributor (at Tewkesbury) of a number of brands and you may find it.

 . . . and I think you'll find the tools and effort for helicoil (or even using a a helicoiling service) will not be viable cost-wise - especially as it's a pretty small diamter thread.  I'd just epoxy it in and see how long it lasts!
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