Atlas 540104 Universal Cracked

[John]

User sooo-much-stuff on ebay has a lot of random parts .. he has various universals that you might be able to modify

[rrjim1]

Does Locktite hold on Delrin?!

It doesn't really glue it expands and holds very well. The slot car guys have been using 680 for a long time to hold plastic and metal gears on motor shafts. The trick is for the gear/part to be a little loose on the shaft so the 680 will flow under the gear/part. It expands and holds very well. It also works well with the original part I repaired a friends Alco 628 by drilling out a new joint and retained it with 680.  This way it won't crack.

[johnh35]

I've ordered a few universals from different manufacturers so I'll see what works. Atlas advises it will be at least 2 months before they have stock but it seems like they have been out forever. I may make a jig to line up the flywheel to drill for pins but that's going to be a fallback.

[johnh35]

Here is the website of the gentleman who has the universals on Shapeways. I will be ordering some from there to try as well. https://jamesmodelrailwayco.com/2020/05/26/replacement-atlas-n-scale-motor-universal-connectors/

[peteski]

It doesn't really glue it expands and holds very well. The slot car guys have been using 680 for a long time to hold plastic and metal gears on motor shafts. The trick is for the gear/part to be a little loose on the shaft so the 680 will flow under the gear/part. It expands and holds very well. It also works well with the original part I repaired a friends Alco 628 by drilling out a new joint and retained it with 680.  This way it won't crack.

Um, if it expands then that creates even more stress on the plastic donuts, making it even more prone to cracking. That makes no sense  to me.
  Excessive pressure was the reason those donuts cracked in the first place.

[rrjim1]

Um, if it expands then that creates even more stress on the plastic donuts, making it even more prone to cracking. That makes no sense  to me.
  Excessive pressure was the reason those donuts cracked in the first place.

If one know what there doing it causes less stress. It doesn't expand very much and to repeat some of what I stated earlier you drill out the joint for a slip fit.     

[MK]

Um, if it expands then that creates even more stress on the plastic donuts, making it even more prone to cracking. That makes no sense  to me.
  Excessive pressure was the reason those donuts cracked in the first place.

Maybe the Shapeway part is a hair bigger than the Atlas part and allows for the Loctite 680 expansion?

[robert3985]

Maybe the Shapeway part is a hair bigger than the Atlas part and allows for the Loctite 680 expansion?

No.  They're not bigger.  But, you could easily drill them out to make a slightly loose fit, like it slips on with the push of your finger, but doesn't rock and tilt...then use the Loctite 680 solution.

I think it's worth a try, but I'm really not sure if the FUD Shapeways part is any more durable than the original Atlas part, since the FUD part is more brittle than the plastic Atlas uses.

Cheerio!
Bob Gilmore

[C855B]

1) I found the little pill bottle of universal donuts, so while I was messing with them I fixed one of two SD24s with cracked donuts.

2) On taking measurements, I have artwork for 3D printing. Tomorrow I'll print-up a batch in plain-ol' gray resin and see how it works.

[C855B]

My crack (pun intended) at a 3D-printed replacement was successful. Thread about it including link to the STL is here.