Wheel Static

I looked at your thread on the car build. Nice work. I can’t answer your question on the static in the plastic.
Not sure what size wheel is required. Other than your mention of smaller than a standard O gauge wheel.  You could look into S Gauge Flyer. I believe Lionel offers them. You would get wide rims and a deep flange. Still a smaller gauge but it might play well with your Ross track. I suppose you could cut the axles in half and maybe print up a spacer for a press fit to gauge them to O.

You could also use On30 wheels.  But would not the metal rails bleed off any static electricity if the rails are grounded?

Jan

@BillYo414 posted:

Does anybody know if PLA wheels will build up a damaging static charge?

The wheels in question are 3D printed and they're for a scale ingot buggy. They would ride on the outside rails and be connected to each other by a metal axle. I don't want to have wheels custom machined and I haven't found small enough wheels in O Scale so far. I think I have felt PLA holding a static charge before. I don't know how damaging static electricity is to our model trains. As usual and always, electricity is a little mysterious to me and when it comes to damaging myself or my toys, I'm concerned.

Would a conductive filament be the better option if static electricity is an issue?

I doubt you'll have enough static to cause any issues.  I use a little coal car with plastic wheels for a magnetic debris pickup car, never gave static electricity any notice.  The only thing metal on this car is the axles and that screw holding the coupler.

@BillYo414 How many buggies are we talking about; a few or a few dozen?

Static charge is caused by the transfer of electrons between two materials. Friction between these two materials seems to enhance this process. The types of materials is also important. Materials like wool fur and glass tend to lose electrons and materials like rubber ans plastics tend to gain electrons. PLA is considered to be a type of bio-based polymer plastic that functions like petroleum based plastics.

I have made many PLA parts to replace parts destroyed by zinc pest including wheels on pilot trucks and have not noticed and effects of static charge such as a shocks or sparks.

I have 3D printed drive wheels for a McCoy Steam engine that I am going to test. I will have to pick up a ground from the tender as the PLA is an insulator.

As a test I rubbed the PLA wheel on our cat and did not see any effects of static charge such as shocks, arcs or hair standing on end.

@BillYo414 they now make Electricly Conductive PLA filament.

I forgot to try the S Scale wheels. That might help. Does anybody have a diameter on them? The axle isn't a big deal. There are plenty of places to buy rod in a variety of sizes. The only issue I have found with scale flanges on scale wheels is just navigating anything besides regular track. The gaps in switches are huge for three rail wheels compared to the small two rail track.

I didn't think it would really build a big charge but it could be a sizable train of up to 20 cars, depending on the track plan. So that's 160 wheels total.

I figured a conductive filament would negate the potential issue since our outside rails are connected by normal wheels and axles. There can definitely be some static charge with PLA. I removed a large flat piece from the printer last night and it was enough to hear it and feel my arm hairs move. But that's removing PLA from a PEI sheet. I think that's different than PLA mostly rolling along steel rails.

It sounds like it will be safe based on what I'm hearing. I would just have a few hundred wheels made of metal if I knew with certainty I would be able to sell these cars. In the mean time, I think I'll throw a car on the rails and do a little testing.

I think the wheels are far too small to actually be a significant problem.  A static charge on a small object would be difficult to detect.  The reason you can experience them from your body is it's a bit larger than a small wheel and a lot more conductive.

I figured it had something to do with square inches. The piece I printed was roughly 50 square inches. The wheel isn't even 1 square inch on the biggest face and the area of the part in contact with the rail is very small.

Bill, these were the ones I came up with doing a search to see if anything is available that’s cost effective. Someone on the S Forum can probably get you a measurement.

I also saw some axle bushings offered that could be press fit into your printed sideframes.