Advice about "clock oil" for an engine

[mmagliaro]

The big wheel IS an electrical pickup, and on such a tiny engine with such little weight, I absolutely cannot give up any contact points.
I have finally gotten enough weight into it where, with all 8 wheels (4 tender and 4 engine), a stall is extremely rare, and that's how I want to keep it.

I did consider WD40, but as you point out, Pete, it does leave a residue and it's a little sticky. 
I polished the parts with 2000 grit sandpaper already, by the way.

The thing is, it mostly works.  It's just an occasional hang-up of the wheel I'm dealing with.  But I worry that in practice on a layout,
with grades, uneven track, etc, I'll see this problem more than just in its "experimental mode" on a flat test track on my work bench.

I am also going to press on and see if I can get any more weight into that locomotive part.   More weight would alleviate the need for a lot of this.

Silicon lube spray... Okay.  That's one thing I have not tried.  So I will investigate.

[wazzou]

I recently saw someone use a “non-caloric, silicon-based kitchen lubricant” with good result. 

[MK]

The big box stores like Home Depot has different kinds of silicone spray.

I have used this one on everything from windows (sliding) to R/C helicopter drive belts.  I figured because it's Food Grade that it would be "cleaner" and more "pure".  I can confirm that once dried you don't feel any residue other than the slipperiness.

https://www.amazon.com/Grade-Silicone-Aerosol-CRC-03040/dp/B07QN8RY8M

[peteski]

Silicone warning:

Don't get it near any surfaces which will be painted at a later time.  Even slight silicone residue will result in "fish eyes" in the paint.  It will likely also be a barrier to any metal blackening solutions.

[muktown128]

I'll second Peteski's warning about silicone and paint.  They don't play well together.  Silicone can significantly reduce surface energy, which will cause paint to pull or flow away from the spot where it is present resulting in a defect known as craters or fisheyes. 

Other sources of craters, fisheyes or de-wetting - silicone wristbands, certain deodorants, oil, grease, WD40...basically any contaminant that can lower the surface energy below the paint or coating's ability to wet out the surface.

[MK]

I believe the term is increased surface tension. 

[Sokramiketes]

If I'm going a step or two lighter than the Labelle line, I go to Singer sewing machine oil.  It's almost clear, compared to the yellow Labelle.

https://smile.amazon.com/Singer-Purpose-Sewing-Machine-3-38-Fluid/dp/B08DN2FHDY/ref=sr_1_1_sspa

[up1950s]

I was never able to get the snot to be un-noticeably concentric .

[mmagliaro]

Well, maybe somebody suggested this and I missed it... but I tries just rubbing a plain ol' pencil over the plastic surfaces that the crosshead sometimes lightly touchs.  It really helps!  Not only does it make the white styrene surface become a nice graphitey gray-black, but it creates a super slippery dry finish that also stains the plastic so it won't rub off.  I can definitely see an improvement because the motion is better, the current draw dropped a hair, and there hasn't been one catch or drag since I did this.  (When the whole mechanism only draws 30 mA, it's a little hard to definitively say that 1 or 2 mA is an "improvement"... but not having any drag occurrances in 5 minutes of running, when there would always be 5-10 before, is definitely better).
It worked better than the MT Grease-em graphite powder, I think because the pencil pressure can burnish the graphite into the plastic.  Rubbing the graphite powder on with a brush just doesn't do it.

[nkalanaga]

Most pencils have a binder in the graphite, which doesn't seem to matter, since it worked for you.  An art supply store should have pure graphite pencils, if you want to try them

[peteski]

I find it interesting that pencil lead (whci is likely graphite with some binders, like Max mentioned earlier) worked so well.  Maybe the burnishing did make the difference.

But after you tried pencil lead, I'm surprised you didn't try using the your famous NeoLube. 

[mmagliaro]

Pete,
I did try NeoLube, early on in this exercise.  But when it dries, it leaves the surface a little sticky - enough so that it makes things worse.
I think being able to rub with some pressure (i.e. the pencil) is key.   It makes the graphite penetrate into the surface of the styrene.  It does in fact stain it, which is a good thing because I don't want it "bright white" anyway, and I certainly don't want to paint it.
In a commercial steam loco, these parts would be made of Delrin.  But for a scratchbuilt model, that isn't so easy to work with because you can't really glue it with anything.    I was thinking about finding some thin Delrin strips or a sheet and putting a strip of it on the rubbing surface with a little Walthers Goo.  But the pencil lead worked so well I think I will leave it at that for now.

[woodone]

Liquid Bearing oil? I would polish the surface with jewelers rouge with a  hard felt polish wheel. Leave no scratches.
There is another oil  called Nano-Lube.

[Lemosteam]

Max,  did you ream the piston rod holes?  Could be that there is still some residual wax in there from the print (FUD or FXD).  The wax is kinda sticky.  I fond that the FUD resin is VERY slippery when smooth and resistant to create friction, so long as the wax is completely gone. Recall as well the FUX is quite porous so filling that with pencil graphite may be the trick anyway.

[mmagliaro]

Max,  did you ream the piston rod holes?  Could be that there is still some residual wax in there from the print (FUD or FXD).  The wax is kinda sticky.  I fond that the FUD resin is VERY slippery when smooth and resistant to create friction, so long as the wax is completely gone. Recall as well the FUX is quite porous so filling that with pencil graphite may be the trick anyway.

Good thought.... but... I drilled out those holes slightly and then lined them with thin-wall stainless tubing.  The main friction point is that I've got some styrene rails that the crosshead lightly touches.  Usually, it just oscillates back and forth into the cylinder completely on the crosshead rod itself, so it's just a phosphor bronze rod going in and out of a stainless tube.  But when the crosshead leans or wiggle a little and rubs on the guide rails, that's where the friction is.