Nylatron for bearings

[Bill Shields]

the color pattern you are describing is classical nylatron

[gwrdriver]

The first Nylatron I saw (late 1960's) was dark charcoal gray, almost black.

[Bill Shields]

reason for color is molybdenum disulfide which is mixed with the polymer.

ever seen the stuff in its native form?

swirls / changes in color indicate incomplete mixing. I am not sure if this is really a problem or not, but some batches are a uniform dark color, others look like one of our cats...

[dnevil]

Thanks to everyone for your input. VERY helpful.

I've collected information about Nylatron from your comments and from other sources and combined them on the following page for your convenience (and mine!)

http://ibls.org/mediawiki/index.php?title=Nylatron

Regards,
Daris

[Pontiacguy1]

I have used Oil Impregnated Cast Nylon as well as Nylatrol. The problem with the OICN is that it tends to be green in color, which won't look very good on your locomotive if the bushings are not hidden. I also think the Nylatrol is a better material to use, in addition to the color, but there is more than one that will work acceptably. I always machined them with a running fit clearance (3 to 4 thou) and they've always worked very well for me. I do actually oil mine, but only once per day just to wet them a little bit. Haven't had any problems with it. Just a few drops of oil on the rods in the morning when I fire it up, and then I leave it alone.

As far as using only materials that the prototype locomotives used... We weld our boilers, and most of the prototype boilers were riveted. We also don't use adjustment shims in the axle boxes or take-up bushings in the rods. A lot of builders use axle pumps and prototype locomotives didn't have those. We have to make allowances for locomotives that have to be picked up and re-railed on occasion. We also have to make allowances for stuff that doesn't scale down such as soot and cinders, water bubbles, and our own hands and bodies. The whole hobby is an exercise in compromises that have to be made. I am one that is willing to sacrifice a little bit of the originality of the locomotive to gain better reliability and performance.

[blff cty lcmtv wrks]

i don't know whether or not someone has already mentioned it, but i think the guys in florida were first to start using this material. they were looking for a bushing material that they could use without having to add any lubrication and they come up with the nylatron material. being as it is uber sandy where they are located, they didn't like the sand and dirt sticking to the oiled bushings and acting like grinding compound on their brass and, or bronze bushings. from what i gathered in later written articles, the dry material has worked out real well.

respectfully submitted

big c

[Fred_V]

the color pattern you are describing is classical nylatron

Thanks, now I finally know what I have.

[kapullen]

I built a Case Half Scale Traction engine about 30 years ago.
The valve gear is similar to a Hackworth gear.

I made the sliding block out of Nylatron as well as the
main crank pin. The engine would tighten up at times.

It took a while to find the sliding blocks were
tightening up while running.

I made a brass block and all was well.
The crank, don't recall a problem with.

Also made a light 3# cannon with nylatron wheel bearings.
The tapered stub axles got a bit of rust and chewed up the Nylatron
really well.

I recommend lubrication at least when not running!

Kap

[applejak_2000]

....
Today, I think that Delrin AF is a better choice and have used it in the Tom Thumb on the crankshaft throw bearings where lubrication is really annoying (gets thrown all around the loco)
The bearings should not get that hot...just do not BORE the holes...DRILL them and be sure that the stuff is COLD when you drill it...after all -> a slightly oversize drilled hole will not CLANK as with a metal bearing.
The concern is keeping the bearing from rotating in the rod instead of the pin rotating in the bearing.
SQUISHING the bearing (as you would with bronze) is not a option since you will close up the ID.
Pinning the bearing is necessary....

Bill,
how do you get precise ID if you should not bore the material? It might not CLANK, but suppose one wanted a close sliding fit on something they were building?

Should one lubricate these Delrin AF bearings in normal running?

[Bill Shields]

You can bore the material but keep in mind that it will grow away from you as you work....both from pressure and heat. The same occurs with drilling, but I find that often the drill is good to also stabilize the material and keep it from wobbling.

On occasions when need to bore the stuff, I find it helpful to contain it on the OD while boring the ID.

Bore intentionally under-size - wait for cool - measure - bore again...sneak up on it and don't trust your dial / dro to tell you what you actually have.

Several of my clients work with the stuff and to bore a straight (cylindrical) hole, the actually bore on a TAPER so that when they are done and the material has cooled...it is a cylinder.

Working with this stuff is an art as well as a science.

Even the rake angles on tools should be different

[applejak_2000]

Does anyone know where you can get off-the-shelf Delrin AF bearings or bushings?

[Bill Shields]

McMaster carr

I purchased thin wall bushings and used them in my valve gear up under where I cannot get at them without pulling the boiler (ugh).