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Ferret Bevel Box vent repair.
   (Ver 1)

 

From Ian in Seattle USA come the following info:

I found that two of the three vents in my bevel boxes had been painted shut, hence the leakage (minor but messy).

If you disassemble the vents, be very careful. The plug into which the vent is placed can be removed, then the vent assembly from the plug (or do it backwards as it's easier to remove the vent). Be very careful about the possibility of breaking the vent off inside the plug; remember that it's hollow and not solid like a bolt you can really torque on.

The vent is nothing more that a little poppet valve. There's a small spring that keeps the vent closed (down) and under pressure, allows the poppet to lift off the outside of the vent body which vents pressure. In one of my vents the spring had obviously rusted through and was not working. They can be repaired but only with very delicate work. The "inside" end of the poppet is peened over to retain a very small "washer" that in turn retains the spring. If you are VERY CAREFUL you can remove the washer to replace the spring. I used some flat bladed pliers, and very carefully "squashed' the peened over part so that the washer would slip off the end of the poppet. This must be done very carefully as the poppet is soft and the material you squeeze can break off leaving you nothing to keep the washer in place.

Then what about the spring replacement? After looking around in my parts boxes I came to the conclusion the spring from an ordinary ball point pen would work (right diameter and could be cut for the right tension). I used a guess as the the tension (pressure?) gauged from the other poppet that worked. I cut the ball point spring and put it on the poppet, slipped on the washer, and then again VERY CAREFULLY peened the end of the poppet over to hold the washer/spring. IT WORKED!

Now the only problem is overfilling the bevel box, so that the Hot 90 WT cheerfully emerges from the now working vent onto my pants...
Of course it would be a lot easier to find "new" poppet vent valves. It would be very easy with someone with the proper machinists equipment to make a new poppet shaft and put the parts back on without having to worry about disassembly.

A caution - if you don't get this repair right there is the very real risk that parts may fall off into your bevel box and this could result in mechanical failure of your bevel box. Undertake this repair only if you are satisfied you can do so safely.

My thanks to Ian.

 

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