Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length.

[boatmadman]

Has anyone used oilite bushes for propshafts?

They are oil impregnated bronze bushes, used in the food industry amongst others.

Website here, no prices though:

http://www.oilitebearings.com/stock

Ian

[DavieTait]

Standard bushes for use in model submarines Ian , Subtech / D&E / etc all sell prop shaft seals with an Oilite bush built into it for their WTC's ( Water tight Containers for holding all the electronics ).

[Capt. Spaulding]

I have used flanged oilites on three scratch-built models and one kit, and never had a problem. They can be soldered to the prop tube, or fixed with epoxy (I prefer the latter method). 

[boatmadman]

Great stuff.

Next, is oilite easy to machine? What cutting speed does it need? What type of tool is required? Does it work harden?

where did you get your bushes from Capn?

Ian

[DavieTait]

Ian you can buy a fully assembled water-tight seal/ oilite bearing from D&E ( Dave Merriman ) or Subtech direct and you can drill out your stern post just big enough and bong it into the hull that gives you a full seal with a bearing without needing a long conventional shaft

[Circlip]

Oilite bushes are made by the Sintering process. that means they take a charge of powder or"beads" of the base material, squeeze it into a mould, compress it and then stick it into a furnace which fuses it together. In the case of "Oilites" the size of the particles used means that a PORUS "casting" is produced, which is heated and immersed in oil to absorb this as a pre-lubricated bearing. Wow, good stuff eh! Now to get back to your question. Yes you can machine it, similar to any of the bronzes, but don't go daft, as one of the problems is smearing the surface which seals the "holes" in the structure. Allow the tool to cut and not rub, and after machining,RELOAD the bearing with oil by heating in an oil bath (a tin can with the bearing immersed in oil) and allow to cool BEFORE removing, the bush sucks up some oil. For max temp, heating should NOT get to the flash point of the oil, - below smoking. I would think that if you solder the bearings in you will have burned off some of the lubricant, and they should be difficult to solder unless they are old stock. the oil can dry out in long/hot storage.

[boatmadman]

Thanks for that circlip, what kind of oil is used?

Ian

[Circlip]

I found light machine type oils best.

    Tother Ian.

[Subculture]

You can use DU-B bearings instead, which are bronze bearings impregnated with PTFE. They don't require any lubrication at all, in fact water lubricates them very well.

http://www.ahrinternational.com/Glacier_DU_DU-B_DP4_summary.htm

Andy

[Capt. Spaulding]

I usually get oilite bearings from hobby shops/suppliers that carry parts for slot cars -- they are a good source for small quantities at not-unreasonable prices.

re fixing the bearings to the prop tube: I have had excellent results with epoxy (soldering and I generally do not get along -- it is one of the black arts, in my opinion, along with alchemy, entrail-reading, and politics).

Here's my procedure; few things could be easier.

-- lightly scuff the inner portion of the tube and the outer portion of the bearing with 200-grit sandpaper. Use the tip of a cloth to wipe the sanded areas.

-- use the end of a toothpick to apply a small amount of epoxy to the inner portion of the tube. The "ring" of epoxy should begin just below the top of the tube, and extend for roughly half the length of the bearing.

-- push the bearing into the tube, make sure that it is seated properly in the opening, and wait until the epoxy cures (I always wait at least 24 hours before getting the assembly wet.)

That's it.

A word of advice:  Do not over-do it. If you use too much expoy, you risk building up a "wave" on the inner walls of the tube as you push the bearing into position; the wave could foul the hole in the bearing.