7mm twist mechanism quality

[vakmere]

I have run into a rash of 7mm transmissions that dont hold up after a short time. Complaints comming back that the top barrell spins and doesnt grab to extend or retract the refill. I am in agreement being the ones I make for myself are doing the same. Almost as if the tubes are too thin or the mechanisms are not milled correctly. The only fix to get it tight after a fail is to insert a piece of sewing thread into the top barrell and slide it over the trans. I can't expect my customers to have to put thread in the barrell whenever they have to replace the refill. Of note, I can recall last year the mechanisms were really tight. Anyone having this experience and what do you do to correct it? Are PSI, Woodcraft, Woodturningz, and others getting the mechanisms from the same place or is this a general quality control issue? I'm leary of doing any more 7mm pens in the meantime.

 

[robertkulp]

I ordered a bag of replacements from Wood-N-Whimsies and have been pleased. LeRoy also has some nice transmissions from Taiwan at Smitty's Pen Works

 

[KenV]

Not all 7 mm transmissions come from the same supply line -- and some are better than others.

While price is not an absolute indicator, those who get the lowest price components tend to have more (sometimes lots more) problems.

Have you gone back to the vendor you purchased the components from??

Most of the more reliable vendors do stand behind the products they sell, and they do cost a bit more from those sources.

You may be able to improved the grip on metal sheathed transmission with a light tapping with a sharp center punch -- raise small burrs that will increase grip. The trick does not work with the plastic surfaced transmissions.

Consider replacement of transmissions -- replacement will probably cost as much as a cheap component set though. But having one that works is important.

 

[Edgar]

Another way to improve the grip of the top barrel would be to wipe a little CA glue on the inside of the tube with a Q-tip. Be sure to let it completely cure - at least overnight - before pushing it down over the tranny. Depending on how loose it is, you might have to apply more than one coat of glue.

 

[vakmere]

I just ordered some from woodturningz. Not expensive. Removing a trans from a pen can be risky business and result in damage to the lower end. I have done it but with damage. Squeezing the trans with a pliers to widen it caused the twisting to be far less than smooth. All good suggestions above.

 

[Edgar]

I just ordered some from woodturningz. Not expensive. Removing a trans from a pen can be risky business and result in damage to the lower end. I have done it but with damage. Squeezing the trans with a pliers to widen it caused the twisting to be far less than smooth. All good suggestions above.

The way I do it is to first tap out the nib, then slip a spare tube down over the tranny all the way down until it meets up with the lower barrel tube. Then stand the pen on a hard surface (lathe bed, table saw top, anvil, etc) and use a transfer punch to tap the tranny down into the spare tube.

It only takes a few light taps to drive out the tranny and since the two tubes mate up perfectly, it avoids damage to the lower barrel.