Allen mogul siderod project
Allen mogul siderod project
One of the things I never liked about my Allen mogul were the aluminum siderods and main rods. I machined them a long, long time ago when I was first teaching myself machining and they were, well, not so great.
I drew up the new rods in DraftSight and sent the drawing over to a local shop and had them laser cut out of 1/2" HRS. Then a lot of face milling ...
I used a 3/8 ball end mill to machine the fillet around the bearing areas.
One of the design flaws was the way the front rod was connected to the rear rod: A steel pin, threaded at one end, that screwed into the aluminum casting. Over time the threads get beat to death by the rods and the pin will work its way out. This happened to me not once but twice at Mid-South ... on two different visits! The engineer's side at last year's fall meet and fireman's side at this year's spring meet.
So, I redesigned that pin (as many others have) and made it like this:
(more to come in next post... )
I drew up the new rods in DraftSight and sent the drawing over to a local shop and had them laser cut out of 1/2" HRS. Then a lot of face milling ...
I used a 3/8 ball end mill to machine the fillet around the bearing areas.
One of the design flaws was the way the front rod was connected to the rear rod: A steel pin, threaded at one end, that screwed into the aluminum casting. Over time the threads get beat to death by the rods and the pin will work its way out. This happened to me not once but twice at Mid-South ... on two different visits! The engineer's side at last year's fall meet and fireman's side at this year's spring meet.
So, I redesigned that pin (as many others have) and made it like this:
(more to come in next post... )
Re: Allen mogul siderod project
Closeup of the new final connecting pin: The one other major change from the original design is I'm using Delrin AF for all the bushings. The oilcups are for decoration only. I've heard mixed comments about Delrin AF, from "It's the best thing ever" to "It'll beat your crankpins to death."
We'll see how it does in a couple weeks when I take the loco out to run.
- LivingLegend
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Re: Allen mogul siderod project
How do you castrate a castle nut?
LL
LL
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I have no life. Therefore, I have a hobby
It's not that I'm apathetic, I just flat don't care
An Intellectual is nothing more than an Over-Educated IDIOT
Blogs: Where people with nothing to say..... Say it
Re: Allen mogul siderod project
Edit: I just realized Fred's mistake and your joke, heh!LivingLegend wrote:How do you castrate a castle nut?
LL
They're not too much to make on a rotary table or an indexer, but I went the easy route and ordered mine from McMaster-Carr.
Mine are all 3/8-24 thread, and I actually started to make them myself, but realized it was worth the couple of dollars to just order them.
- LivingLegend
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Re: Allen mogul siderod project
LOL.... I was making light of Fred calling them castrated nuts. I've made many castle nuts in my day from 5-40 up.... Some with non standard thread diameters and TPI single point threaded. Once worked as a prototype machinist/modelmaker/toolmaker.
LL
LL
Last edited by LivingLegend on Mon Oct 06, 2014 8:40 am, edited 1 time in total.
Do it right.... Or don't do it at all
I have no life. Therefore, I have a hobby
It's not that I'm apathetic, I just flat don't care
An Intellectual is nothing more than an Over-Educated IDIOT
Blogs: Where people with nothing to say..... Say it
I have no life. Therefore, I have a hobby
It's not that I'm apathetic, I just flat don't care
An Intellectual is nothing more than an Over-Educated IDIOT
Blogs: Where people with nothing to say..... Say it
Re: Allen mogul siderod project
...I would have thought a "castrated nut" had no flats for sides! Made a few of those in my time...might even share a recent (similar) experience here in the next few days. Carl B.
Life is like a sewer...what you get out of it depends on what you put into it!
I don't walk on water...I just learned where some of the stepping stones are!
I love mankind...it's some of the people I can't stand!
I don't walk on water...I just learned where some of the stepping stones are!
I love mankind...it's some of the people I can't stand!
Re: Allen mogul siderod project
Blink! Blink!John_S wrote:to "It'll beat your crankpins to death."
Delrin AF will beat crank pins to death?
One of the most absurd comments I've heard in a long time. Did the individual who dispensed this little tidbit happen to manage to describe the mechanism by which that would work? To me, it sounds a lot like denting an anvil with a feather.
Harold
Wise people talk because they have something to say. Fools talk because they have to say something.
Re: Allen mogul siderod project
John, your new rods look great! Thanks for posting the update.
Bill C.
Bill C.
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Re: Allen mogul siderod project
John, your rods look good! If you add a pin in the back of the knuckle pin you can tighten the nut without it spinning - this is full size practice. The Allen/Harpur Mogul was designed to be simple, low cost, and easy to build. It lends itself well to refinements and improvements like yours.
Re: Allen mogul siderod project
Thanks Marty! Are you making changes to the drawings to improve the pin's design? I know there's been a bunch of different methods folks have used (I saw at least four different solutions at Mid-South last spring!) to remedy the problem.Marty_Knox wrote:John, your rods look good! If you add a pin in the back of the knuckle pin you can tighten the nut without it spinning - this is full size practice. The Allen/Harpur Mogul was designed to be simple, low cost, and easy to build. It lends itself well to refinements and improvements like yours.
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Re: Allen mogul siderod project
I want to update all the drawings eventually. For some reason, I think the first one that will be done is the boiler.John_S wrote:Thanks Marty! Are you making changes to the drawings to improve the pin's design? I know there's been a bunch of different methods folks have used (I saw at least four different solutions at Mid-South last spring!) to remedy the problem.