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Replacing Leather Pump Cups

Discussion in 'Fettlers Master Class' started by RonPH, May 2, 2012.

  1. RonPH

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    For someone who has not replaced a leather pump cup on a stove, sometimes would be a head scratching experience. Why? Well, it would seem that when these stoves were manufactured, the only way to ensure that the retaining nut on the shaft will not come off was the tip or end of the shaft had to be peened or flared whichever you prefer the term as seen here:

    1335943771-pic001.jpg

    Making removal a nightmare. Assuming that the stove you are working on has a brass knob and a steel shaft, it is with certainty that the knob can be removed by unscrewing it from the steel shaft. Having said that, there are some pump and knobs that are all brass and may have been soldered. But that is another tutorial. So let's go back to the one in this picture

    1335943944-pic002.jpg

    With a set of locking pliers and if you prefer something placed between the teeth of the pliers and the shaft so as not to marr the metal, you could place a leather or gasket material before locking it firmly to the shaft so it will not turn, try to turn the knob first by hand if this will work. Otherwise, you may need another set of pliers to help turn the knob. Once freed should look like this

    1335944116-pic003.jpg

    Next is to slide out the pump cover or collar.

    1335944167-pic004.jpg

    Assuming that the leather is really bad, you can probably rip it off the shaft exposing the brass ring at the bottom. For this demo, the leather is still solid. You can now place the locking pliers to grip the round brass nut as seen here

    1335944276-pic005.jpg

    1335945257-pic006.jpg

    With either a needle nose pliers or a small wrench, grip the (usually metal) threaded female nut and turn it clockwise until it separates from the brass bottom and the leather can now be removed as seen here



    1335944400-pic007.jpg

    You can now slide out the nut and leather cup and replace it with a new one. Note that the hole on the new leather cup's diameter may be smaller and may require enlarging the hole or coaxing it to go in with a bit of oil and a bit of twisting. In my case, I enlarge the hole by using a dremel tool with sandpaper which makes it easier for me rather than fighting the leather to fit into the collar. Once thats in, screw back the metal retaining nut and tighten. I really do not need to overtighten at this point. Slide in the brass pump cap and screw back the pump knob. If you have thread locker, it would be best since losing the knob in the field would make for a sore thumb pumping without it.

    There are other options in replacing the leather pump cup, but that will be another tutorial.

    Hope this short tutorial helps.

    Thanks for looking.

    Ron
     
    Last edited by a moderator: Jun 26, 2015
  2. yonadav

    yonadav Israel Subscriber

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    Hey Ron,

    You can consider this as chapter 1 for a book you can publish: Ron's illustrated guide to brass stove fettling.

    Excellent tutorial!

    Yonadav
     
  3. linux_author

    linux_author United States Subscriber

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    yep, it was a puzzler at first when i attempted to replace the cup on my Optimus #1

    willie
     
  4. Murph

    Murph United States Subscriber

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    Thing is, here in the US, the Coleman stoves have the leather cup acting as the piston seal AND the check valve to build up pressure.

    The European stoves have the piston float on the shaft, and the tapered junction between shaft and piston act as the valve.

    The last picture shows that extremely well!

    Murph
     
  5. RonPH

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    Murph, you are correct, the Coleman pumps differ and I have yet to replace one. I have owned only two colemans and have yet to replace any of their pump cups :-k

    Yonadav, when I have time, I will post one on the nut removal and options available.

    Ron
     
  6. Rick b

    Rick b United States Subscriber

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    Hi Ron, nice tutorial and photos.
     
  7. pshaw United States

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    Ron, Thanks much for that. As I said in the PT I'm not that handy and looked at a couple of these scratched my head, put them in the someday box and took down a working stove. Now I'm pumped to fix them with the leathers I got from Sefa!
     
  8. hikerduane

    hikerduane United States Subscriber

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    Ah, so I was thinking the nut stopped the assembly from rising too much and it is actually the brass part which has the smaller inside diameter. Never gave it a thought. The nut at the end of the shaft was there for a reason, it's gotta come off right. Still, this way has to be tough screwing the cup onto the brass piece as I have to use a screw driver to save my fingers the way I have been doing it.
    Duane
     
  9. RonPH

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    Duane, using the screwdriver to force the leather into the neck would risk damaging the brass thread and therefore you need to enlarge the leather as a safer method.

    Ron
     
  10. hikerduane

    hikerduane United States Subscriber

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    That's why I use my fingers to get it all started Ron. The screwdriver is used in the provided slot to screw the piece into the pump cup once everything is lined up.
    Duane
     
  11. RonPH

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    Duane, that is fine if the brass collar is out. In my tutorial, you can not put the flathead screwdriver. If you have removed the bottom nut and the collar comes out, yes, you can use the slotted portion with the screw driver. I have had too many chipped nails (among other things) and would rather have convenience of the correct sized leather hole diameter by enlarging it with a dremel. In your case I guess you just have to fight the leather to let it go in to where you can start turning the collar and the leather starts to go into the bottom as it follows the thread. To each his own way of doing it as I have done that in the past and includes profane words as I do it :mrgreen:

    Ron
     
  12. hikerduane

    hikerduane United States Subscriber

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    Except for my Campingo, I've managed to get the pump cup on, but I can see now why you enlarge the hole in the pump cup just enough. I had to do that with the cup for my Campingo, it required a much larger hole than Sefa's had, but I had gotten a number of his cups for other stoves as well.
    Duane
     
  13. HT Scheg United States

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    Awesome Tutorial! Thanks!
     
  14. gClark United States

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    Thank you for the tutorial. Only a 10 minute repair once I got the instructions from you. It all came apart simply, just like you outlined. Nothing was stuck, so the process was very straight forward. Optimus 111B. Fettlebox provided the replacement pump cup.
    Regards, gClark
     

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