My old Macson uses a floating gearbox arrangement that sits on the power-feed shaft and is moved horizontally in the apron to select carriage feed or cross-feed and lifted slightly to lock on the appropriate gears to drive each feed.
It has always been tricky to engage and I eventually worked up the enthusiasm to look into some excessive up and down play in the bushes that support the gearbox on the feed-shaft.

Not a minor undertaking as the easy way was stymied by what appears to be a major burr from a tapered pin so rather than risk damage to the cross-feed shaft I removed the quick change gearbox, banjo etc in order to slide the power-feed shaft out that way with the gear installed.

I removed the two bronze bushes from the gearbox today and these are worn soooo close to damaging the housing on the gearbox it isn't funny but as luck would have I have escaped that misery.

These are the long suffering bushes (an impressive 0.122" out of round) - not sure if they are originals but I suspect they are so not bad service for 76 years.

IMG_1815.jpgIMG_1816.jpg

Remaking these would require a spendy piece of bearing bronze given they are each almost 2" in Diameter, 1.6" long with 1.25" bore so I am contemplating making the replacements from Delrin given the application that might be OK.
The bushes could be made 1/2" longer on the thicker section without clearance issues so that would allow a bit more support.

Does anyone have experience using Delrin as a plain bronze replacement to suggest it would be worth a try?

Ray
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