Best Lubricant for Rudder post

Maybe, if you have the room, you can wrap the shaft with teflon tape, such as that used on pipes. They have some extra thick stuff I use on old pipes, which is easily 3 times the thickness of the regular tape. If wrapped tight enough and it's inserted without bunching up, a nice cushion and self lubricating thing, that easily renewed.

 

In my case the only way to get any insulation between the two now is with a lubricant. The bushings are actually more like sleeves 6-8 inches long. There is no room at all for tape. Perhaps a teflon based liquid lubricant? Lithium grease? or the moly stuff mentioned earlier?

 

In my case that would defeat the whole purpose of mixing graphite powder into the resin at the contact surface, to act as a lubricant. This practice was outlined in the building plans. Perhaps it is not so nifty an idea after all.

I sure would like to hear from any builders/boaters who have used this method and compare notes, especially re galvanic problems.

 

Charlie,

Just check the bearing/stock surfaces in a year or two.... & chill on it till then, we used to do just plain glass bearings but would use a graphite/colloidal silica epoxy mix then 6oz glass cloth on a spare peice of stock, we'd cut then slip back on to the stock with some masking tape to give clearance then fill the slot & lay some more glass- the top hat for the top would be done against a donut of melamine sheet on the tube- both sides so two made at once.
If you want to lube the stocks just a squirt of wd40 or baby oil or singer sewing oil every time you go out, just dont spill on the steps Baby oil works in the heads too, I used on a recomendation & just a couple of drops a day kept good for years.

Jeff.

 

LOL.
That is so funny. That is exactly what i was about to do the other day. Then I hesitated and thought... no, first I'd better vet this with the experts over at bd.net. So now Ive come full circle. I am still glad i did though, I have learned a lot from this thread. Thanks to all for the input.

 

Your problem is most likely because the shaft is not perfectly round such as a machined shaft would be and you laid up the bearing with a too close a tolerance to allow for this. It would have been worthwhile to have had a machine shop just skim it in a lathe to make it round. No big deal though, your options are to just squirt some lube in there and be patient and wait for it to wear in with use or, since they are not too difficult to remove, take them out, use a caliper to find the high spots and dress them with a file or emery cloth, lube them up with a thick waterproof grease and reinstall them.
Ive made bearings the same way and they work fine. When using engineered plastics you need to be careful in your selection as some common bearing plastics such as nylon that work well above the water, absorb water and are not so suitable if immersed if you want close tolerances.

Steve.

 

It depends on the type of Nylon. The more common 6 and 6/6 do absorb water - in fact the proprties of the material rely partly on some moisture take up. try a fresh injection moulded part and it will snap pretty easily, 24 hours later after leaving in warm water and it will flex well. Whether this is a problem depends on how much water can be absorbed and consequent dimensional change.
However other Nylons such as 12 do not take up much if any water, an example of this material may be found in some oil level windows on engines.

Agree about lapping the shaft to get a better fit. Working fairly evenly with a fine wet and dry (wet) should be adequate to remove light high spots. It was good enough on a crankshaft, for me to remove 0.007 mm.....to get the fit into a mains roller bearing..... many years ago.