Looking for help designing a truck axle pocket wear test fixture

[peteski]

And as soon as you make one, some mfr will come out with one. 

Make what?    Axle pocket wear test fixture?  I highly doubt that.

[narrowminded]

@mmagliaro , Says the man who has just exhausted all resources for a valve handle.  Lol. 

Uh, not yet.

If you wanted to proceed with something like the drum with rail wrapped around it I could probably just machine a drum with proper rail spacing and very concentric with the axle.  PM if that's something you'd like to pursue.

My own thoughts would be, based on limited experience and as somebody already mentioned, that the wear with the hardness of the FUD would not be much of an issue but getting axles assembled without breaking the truck would be.

[Ed Kapuscinski]

Make what?    Axle pocket wear test fixture?  I highly doubt that.

No no, there is a RULE in play here!

[alhoop]

I got chastised mightly on the old Atlas forum for saying a lot of extra weight might
cause some measurable axle wear( I did show photos from Model Railroader showing some
such wear but to no avail). So there will be NO wear.
Al

[peteski]

No no, there is a RULE in play here!

I know the rule, but the device we are talking about is so far in the left field that there is a zero chance of a commercially made version.  It is not like it's some very oddball boxcar or a locomotive (where chances of a commercially-made version are at least somewhat probable).

[learmoia]

I know the rule, but the device we are talking about is so far in the left field that there is a zero chance of a commercially made version.  It is not like it's some very oddball boxcar or a locomotive (where chances of a commercially-made version are at least somewhat probable).

And I'm likening this quest to proving to flat earthers that the planet is round..

~Ian

[peteski]

And I'm likening this quest to proving to flat earthers that the planet is round..

~Ian

Even harder!    With Flat-earther you could shoot them up into Earth's orbit and put them out for a space walk.   I don't think they could have any doubts at that point.

[Lemosteam]

Guys this is for me and me alone.  I have always been curious and it's not as if I don't want to take your word for it.  I really like the way axles roll in these trucks, its nearly as nice as an MT truck, maybe damn near equal.

This fixture idea from @learmoia is inexpensive, simple and maybe somewhat fun!  I plan on allowing the motor to slide up and down to allow band adjustment prior to securing it. 

I don't want perfect- track isn't perfect, pockets aren't perfect, axles aren't perfect.  I want down force, axial forces, speed variation, all of the things a car's truck will experience.

And if i experience any durability issues with the material, I'll be the first to know.

[learmoia]

This fixture idea from @learmoia is inexpensive, simple and maybe somewhat fun!  I plan on allowing the motor to slide up and down to allow band adjustment prior to securing it. 

I have what may be a better idea involving a drill press and a dremmel bit..

.... OK..
So if you took a drill press - Add a dremmel bit (polishing disk, or 8215 or 85422 grinding stone)
Then make the jig to attach to the drill press..  (the axles would be vertical)

The jig would have a post with a slightly flexible extension to mount the truck where the axle is vertical.
 D
---IT==H
           H
           H
         ===

D is the Drill Press
'---' is the dremel disk (that 'drives' the wheel)
I is the wheel/Axle
T is the truck
== is the extension (flexible so it can put a bit of tension on the cone - and absorb shock of the dremel driver.)
H is the post
'===' is the base.

(If that makes sense)

Edit
Duhh Ian.. You could Omit the wheel - just use a rubber band between the axle and shaft and achieve the same effect..

~Ian

[narrowminded]

With Flat-earther you could shoot them up into Earth's orbit.

Nuff said.

[Alwyn Cutmore]

I do not think that what John is asking is an unreasonable question seeing it was I who started this off on a face book page. I have been manufacturing bogies (Trucks) for years in tooling resins and I stand by my product 100%. I can do that because of I have proof that my bogies will stand the test of time. I do this by offering a lifetime warranty which is genuine. In the last 14 years I have only ever replaced 3 bogies. Most bogies to-day produced by AR Kits how been around since 1980 so I gather the test of time has been my biggest truth teller. I also use high quality virgin delrin as opposed to medium quality with regrinds.

John I believe that the engineers at Shapeways should be able to answer your question as a comparison to delrin as in all reality both are composite plastics or in that family. They should be able to provide shore hardness values as well as other appropriate specs for the comparison.

Regards

Al

[robert3985]

Looking for some thoughts here.  As you know I design some FXD passenger trucks that use metal wheels inside.  Some folks have asked me about FXD wear in the axle pockets and I don't have a useful answer!...

...Whatcha think?

I'm of the opinion that although I can see someone being curious about just how many revolutions a particular truck sideframe will last until failure....in practice, I've NEVER had a plastic truck sideframe fail due to wear in the axle cups in the 35+ years I've been running trains.

For any testing of FXD to have any relevance, equal testing should be done on competing, common truck sideframes made from various materials to see where FXD truck sideframes stand compared to ones made from FUD, Styrene, high-impact Styrene, Delrin and brass.

Then, you're going to have to relate your results to the N-scale model railroading world, which I think is going to answer a question that almost nobody asks or worries about since we don't keep track of the revolutions of wheelsets in our model cars and engines. 

Well, at least I don't!  LOL!  Do you?? 

I did particularly like Ian's "flat earther" comment, which elicited a "Yup!" which scared my cat off my lap!


Cheerio!
Bob Gilmore

[Lemosteam]

As we all know by now, in a dynamic world full of variability, no single factor can determine the life expectancy of a material, process or function, Delrin or otherwise.

I never mentioned that I was going to solve all of the world's ills with this post or report the findings, more so I did mention that it was to satisfy my own curiosity and to provide an information driven response to any question that does arise rather than a "Meh, don't worry about it", to a potential or current customer.

I think the fixture design issue has resolved, and in fact it's my time to waste if I so choose.  Maybe I also want to know if there is a difference in reliability between FUD and FXD (denser printing matrix) in my offerings.

[learmoia]

This weekend (Wednesday).. I'm goin to try to get to the basement  and throw together a jig on the drill press and see if I can get this to work..

I will post results if I'm sucessful..

[peteski]

This weekend (Wednesday).. I'm goin to try to get to the basement  and throw together a jig on the drill press and see if I can get this to work..

I will post results if I'm successful..

While your latest idea is viable, why put all that wear and tear on a drill press when the same thing can be accomplished with a small hobby motor and some rubber bands?