Idonno
Member
That may be true but, if that's the case the term "self-lubricating" is at best a very poor choice of words and regardless most plastics tend to leach a small amount when exposed to extreme stresses. Even the freezing of water bottles is thought by many to be unhealthy because of the proven leaching of plasticides into the water. Anyway it is at least my preference at this time to stay away from any type of plastic lining due to the high stress of the environment coupled with it's immediate contact to a consumable product, my tobacco.You're pretty much right. Usually you don't need a cutting fluid on it except to remove heat (making deep holes), for surfaces you just need to get the "chips" away, most of the heat is in them. The material itself accounts for the low friction, not many things can stick to it. If the surface is smooth, then there's not much for anything to mechanically get a grip on either.
Now this is probably the ticket. Thanks for the detailed explanation "leverhead". I always knew that bronze made a good bushing but, I wasn't sure how it would apply to this application and what you said makes sense.There's allot of different kinds of bronze, some are pretty soft, some are pretty hard, but they are very tough. Until ball screws came along, tin bronze (softer) nuts and steel lead screws moved heavy loads on machinery with a long life. For plain bearings (not roller), you mate up hard against soft for fit (break in). The soft part moves to even out the pressure, then most of the wear is on the hard part. Acme or Stub Acme threads are a very robust thread form/shape, closer to a square thread, but easier to make than a square thread.