Hello All,
After trying to source replacements for cracked axles and worm gear couplers on several diesel locomotives- -both in and out of production, without success I began thinking…
…Yes, I know that can be dangerous!
My question to fellow forum members:
Do you think these parts could be 3D printed?
Thoughts?
Recommendations on 3D printing services?
Thank you in advance for your comments.
Hope this helps.
I don’t know anything about the printing, but you said you had cracked worm gears as well?
Would you mind sharing with us wjat locos you need parts for?
What printed things I have bought, I searched for a dealer on Shapeway’s web site.
Mike.
Hello All,
The failed part(s) is/are not the brass worm gears.
It’s the plastic coupler, press fit on the metal worm gear shafts to the dogbone, that fails.
They are all Bachmann diesels: GP40s & GP30s.
Bachmann doesn’t sell the worm gear assembly with the plastic coupler- -the failed part- -as a separate item.
This part is included in the larger assembly of the Truck Gearbox (HO GP40/GP50/Universal).
At $6.50 each, to harvest the replacement worm gear and coupler, adds up.
I have four GP40s and three GP30s that have had at least one of these worm gear couplers cracked and needed replacement.
Now I have eight of these Truck Gearbox assemblies, minus the worm gear couplers that I have no use for.
I contacted Bachmann to see if the worm gear coupler assembly was available in bulk.
The response was that just buying the singular part was not an option and directed me to the entire Truck Gearbox assembly, which is currently sold out.
I also have an Athearn Blue Box SW 1500 with cracked plastic axles (Part #40023- -discontinued).
The wheels press into the plastic axles but the diameter of the O.E.M. axles are larger than anything currently available from Athearn.
I ordered what I thought would be a substitute from them but they don’t fit.
That’s why I’m considering 3D printing of these specific parts.
Again, thank you for your question, and…
Hope this helps.
The Athearn site says preorder, Due late May, 2021. ATH60024
Mel
My Model Railroad
http://melvineperry.blogspot.com/
Bakersfield, California
I’m beginning to realize that aging is not for wimps.
Have you looked at the A-Line drive shaft parts?
https://ppw-aline.com/collections/miscellaneous-re-powering-parts
Scroll down.
Athearn SW universals:
Good Luck, Ed
Model aircraft and model car/trucks also use universal joints.
And gears for that matter.
The main problem for train manufacturers is packaging, shipping and handling if spare parts. Even car manufacturers have this issue. Computer repairs are subject to the same out if proportion costs of stocking repair parts.
As labour costs in our market continue to rise relative to capital costs of manufacturing stuff this problem can only get worse.
You might also want to consider NWSL. Given the volume, it justifies a phone call (I assume they still answer the phone - the previous owner did).
In all cases, it will not be cheap.
Simon
Hello All,
Thank you for all your great responses.
As I posted…
Unfortunately, the current replacement parts from Athearn are not a viable option.
Yes, I have three sets of them and nothing is compatible.
I apologize if I didn’t make it clear that I have two separate problems from two manufacturers:
The first is with Bachmann.
It’s the plastic coupler from the worm gear shaft(s) to the dog bone drive shaft(s) that has cracked.
This coupler is not available as a separate O.E.M. part.
Bachmann only sells this part in a larger sub-assembly, which is currently out of stock.
I only need this specific press-fit coupler, not the entire sub-assembly that I have harvested this specific part from, and have a surplus of un-needed gear towers.
The second is with Athearn.
Which is the plastic axel.
The older 42-inch wheels have a larger diameter spindle, that presses into the geared axel, than any currently available replacement parts, is cracked.
I have purchased several replacement wheelsets from Athearn and none of them fit- -adding to the useless parts bin, and lost monies.
This is why I am exploring the options of 3D printing these specific parts.
Thank you for this suggestion and I will look into this option.
[quote user=“snjroy”]
You might also want to consider NWSL. Given th
I found some Model Power axle gears on Shapeways (about 5 yrs ago) and one cracked as I attempted to install it the other only ran a few hours (over a weeks time) and cracked. I finally got some that worked (still OK) I think from NWSL.
I read on another forum to drill out the Shapeways gears and use super glue (CA) on the shaft, haven’t tried that myself.
Mel
My Model Railroad
http://melvineperry.blogspot.com/
Bakersfield, California
I’m beginning to realize that aging is not for wimps.
Hello All,
Thank you for your suggestion.
I’m thinking, even with 3D printed parts, there will be some hand tooling to get them to fit.
Again, keep the great comments/suggestions coming.
Hope this helps.
If the older axles are larger in diameter than the 60024 gear you might tri drilling it out and using CA.
CA is amazing, I glued a axle gear on my Bachmann 2-6-0 G gauge locomotive back in 2005 and it still works like new. The locomotive was under warranty and Bachmann sent me a replacement wheel set with the gear but since it’s still working OK it is still in the package.
Mel
My Model Railroad
http://melvineperry.blogspot.com/
Bakersfield, California
I’m beginning to realize that aging is not for wimps.
Hello All,
I just want to begin by thanking all of you for your great suggestions and invoking all of your knowledge.
I considered this but the amount of material on the newer axels won’t allow me to bore out the needed clearance for the older axel shafts without failure of the thinner walls after “machining”.
This is why I’m considering, despite the initial price of tooling, 3D printing options.
Thank you for all your input and…
Hope this helps.
With all of the dog bone types of connectors that NWSL has you can build your own dog bone- the sets are not that expensive. Just measure you shaft size and go from there.
I think that I keep 5 or 6 sizes in my parts bin for re-motoring jobs.
Swap the wheels out with the smaller 40" wheels, since it’s a switcher and shouldn’t have 42" wheels anyway? Can use Athearn parts, I did an Athearn switcher years ago with NWSL’s replacement wheels, which I’m not sure they make any more. Though these were sized to press fit the stock Athearn axle gears.
–Randy
Being a printing process rather than a forming process, would 3D printed gears and axels actually be strong enough?
Hello All,
Yes, you’d think that would be true.
As I’ve previously posted, the current NWSL webpage only has written descriptions…
But…
Shapeways seems to be the folks to reach out to and see if this is possible.
Great point!
That’s why I’m reaching out to see if a material in 3D printing will be sufficient.
Thank you for all your input and keep the suggestions rolling in.
Hope this helps.
Yes they can be made strong enough. At a price. Right now, to get a 3D part. You have to hope somebody did the engineering cad work already or you have to do. Then send that over to shapeways or others to print it. Then you have to check refine and reprint for corrections. Gets pricey if you don’t plan to set up a sales run with one of these print houses Could you upgrade the whole drive line, not just the universals? No luck on sites like auction of hoswap? Shane
Hello Railfans!
Heres my experience with this very subject and 3d printing…
Can it be done? Yes. I have made for myself a replacement set of 3d printed axles for the Bachmann 2-8-0.
Did they work? Yes, to a degree. While the new parts served their function, the inherent bad design of this type is still a problem. Slippage will eventually reoccur even if it doesnt crack the new parts. Even replacement axles of commercial grade with eventually experience the original problem. Its plainly a bad design.
Are 3d axle replacements durable enough? Yes. They can take the load just as the originals do. But again, up to a point. the flaws of the design still overcome the advantages of replacement. Do know you can select the hardness of plastic you print.
Pro vs Con: Unless you are set up yourself to 3d print, it is more practical to search out and aquire commercial versions. If not found or not available, then someone like Shapeways ( i hear) or other company may be able to help. These are such small parts they might not be cheap for a company to make just one set. Its time intensive to design, populate, print, then test a part.
Only if you are able to print these up yourself would this be an economical process. Once you have the original you can reproduce as needed because but again, the flaw will always exist in this type of design. Youll likely print a few during the lifetime of the loco.
Lastly, consider a straight axle to an axle with a gear (or teeth rather), its a bit more complex part to produce at such a small scale, even for 3d printing. Though it can be done. To produce a commercial quality gear, you would have to print below ‘normal’ print sizes.
Best of luck!
PMR
For split gears on half axles would filling the gear with epoxy, crack included, and drilling an interference fit hole down the centre be feasible? Model sized drill press accurate enough? Maybe stick an axle in before the epoxy sets instead of trying to line bore the gear shaft?
Reason I ask is one video I watched about these gears suggested that even new plastic cast gears might be too tight an interference fit and suggested very slightly reaming out the axle hole to reduce the pressure inducing the splitting in the first place.
The problem with interference fit with dissimilar materials is the forces change with temperature. Our mint ran into this issue when first making our toonie ($2 coin) which is a concentric interference fit between a smaller coin and a larger doughnut hole coin. They separated under some conditions and no the two halves were not worth $1 each (evokes the real meaning of two bits).
Hose can work as a universal joint. You need to find the right ID and stiffness. Rubber tubing might be quite suitable if the wall thickness is enough.
Rubber has been used as a CV type driveshaft coupling (it bisects the angle so operates at constant velocity unlike a single Hooke’s type) in Rotoflex joints found in the axle shafts of the Triumph GT6 and Alfa Romeo GTV6.
You cut a short piece and jam it onto the two halves of the split driveshaft. If not possible to interference fit perhaps an adhesive would work to secure the tube.
Im pretty sure those model universal joints are double Hooke’s joints to give constant velocity rotation. In essence they include a very short connecting shaft between two Hooke’s joints which absorbs and rectifies the uneven rotation speed induced by the crosses.
There are other methods including a tripod type “cross” which results in CV operation. I note the universal joints I’ve seen in the standard Athearn type drive seem to allow the pins on the ends of the cross to slide laterally inside the external housing which also gives CV rotation.