Tungsten flywheels anyone?

[Lemosteam]

What are the calcs for startup torque? More mass on the shaft at startup will put a higher load on the motor right?  Could this lessen the life of the motor?

[daniel_leavitt2000]

Haha.  There is no way I would google something like that.... and not expect someone from homeland security showing up at my door.

Now back to trains.

I can unequivocally testify that DHS will not show up at your door if you research how to make an A-bomb. That includes borrowing books, searching the net, reading Wikipedia and technical/scientific journals. This was to solve a bet on the smallest amount of material to create a supercritical reaction (about 2.2KG - or about the size of a lime) I had with a friend.

[mmagliaro]

What are the calcs for startup torque? More mass on the shaft at startup will put a higher load on the motor right?  Could this lessen the life of the motor?

I don't think so.  I mean, sure, it does put more load on the motor, but I can't see how spinning a nicely balanced weight around the motor
shaft would put anywhere near as much load on that motor as the mechanism friction and a string of cars being pulled.

And remember, tungsten isn't getting us that much more flywheel force anyway (that's why I wanted to pull the plug on this
idea after I did some calculations).    I was looking for something that was going to make a 10mm flywheel have the
momentum of a 14mm flywheel, and it's nowhere near that.

[daniel_leavitt2000]

While we are on the subject, why did Athearn stop using lead for their flywheels? If malleability was a problem they could mix in some brass or steel dust and still be cheaper and heavier than all brass ones.

[peteski]

While we are on the subject, why did Athearn stop using lead for their flywheels? If malleability was a problem they could mix in some brass or steel dust and still be cheaper and heavier than all brass ones.

I have never ever seen a lead flywheel in any of the N scale models. Lead frames yes, flywheels no.  Which specific Athearn model has lead flywheels?  I would love to see one.

As for reasons to stop using lead, it is just like everywhere else lead was eliminated - it is very, very, very dangerous metal (according to the government studies).  Even electronic solders are now lead-free.  Kato GP38-2 had a lead (or lead alloy) chassis wich was nice and heavy and the model pulled like a team of horses.  No more - all the mechanisms are now made out of some sort of lighter white metal (Zamak?)

[daniel_leavitt2000]

Pete, you are right. I was referring to early Athearn blue box HO engines that are equipped with lead flywheels. They stopped production of these in the 80's... Long before California laws.

[Specter3]

Lockheed used DU to balance the ailerons on the Jetstar business jet. I had a customer with a Jetstar II and it had red markings on the balance weights and printing that said do not touch. The maintenance guy said the manual said you could touch that area 7 times a year for maintenence work. That was it.

[peteski]

Lockheed used DU to balance the ailerons on the Jetstar business jet. I had a customer with a Jetstar II and it had red markings on the balance weights and printing that said do not touch. The maintenance guy said the manual said you could touch that area 7 times a year for maintenence work. That was it.

Similar use in Boeing 747s.

[narrowminded]

Machinable tungsten alloys are still about 90% tungsten, therefore are within about 5% or better the weight of pure tungsten while about twice the weight of brass, the measure that matters. They are machinable but much more difficult to machine than brass (but then so is just about every metal other than aluminum).  Pure tungsten is not a viable option as it is nearly impossible to machine conventionally.  The machinability of tungsten alloy contributes measurably to a higher cost but on a simple part like a flywheel it is not the biggest problem. The material cost IS the problem.  And with material, you're buying the part plus all that has been removed.  To machine a balanced part like a flywheel you take a cut on all surfaces with all of the cuts, including deburring, completed in one setup, no chance for concentricity problems, but also little chance for elaborate machining.  Straightforward  cuts like bore, turn the OD, face both ends, and deburr, all concentric and square around the center, can be readily accomplished in one setup in a lathe.  Additional machined features in the ends or elsewhere would likely require a second setup (or a lathe with high speed live tooling but who has that for a relatively short run at a reasonable shop rate?) which invites problems with balance or adds measurably to the cost, sometimes double and more for the fussiness of set-up that assures a concentric part, exactly what you need in a flywheel, much less the actual cut.  Making them as washers seems like a good idea until you figure that in tungsten, each piece adds cost measurable in whole dollars for the material consumed and the additional cuts taken.  Stamping completed washers out of inexpensive sheet doesn't have this problem.  Machining in a lathe and parting off does.

Bottom line, if deemed necessary or useful, $50 each for round ones with a concentric hole sounds about right for this part, viewed from a galloping horse.  And an oversize of .0002"  +/- .0001" should be attainable and adequate for concentricity and with the use of loctite.  Use low strength so there's a chance of getting it off someday or use blue with a  film of oil left on the shaft, as left when wiping the oil from the shaft with a cloth wipe, which considerably reduces the strength.  Hope that adds something to the conversation.

[narrowminded]

I took some time to look at this a little further and hopefully this could help move the discussion along.  I am confident that I could get you a price of $20 each for those parts, precision CNC machined, 10mm dia. X 7mm length, 1.5mm bore through (final tolerance to be determined) if you arranged a group buy of at least 50 pieces.  At 100 pieces estimate about 20% less than that.  All it would take is the commitments and once all details finalized, give or take two weeks to ship.  That's the normal time to procure the material and schedule them into the machine.  A sample motor might be handy to reverse engineer the final shaft bore dimension and tolerance although I suspect a dimension from 0 to 3 tenths over 1.5mm would be suitable for a light press and/ or affixed with low strength loctite. (1.5mm reamed).  The material would be a tungsten alloy at about 90% tungsten alloyed with copper and nickle.  The weight is about twice that of brass.  Hope that helps.

[mmagliaro]

My innate scientific curiosity requires me to pony up a pledge for at least 3 of those things.
So if you do it, there's your start.  I'm in for 3.

Having been on the "collecting" side of things like this myself, my only advice is that you collect at least enough
"pledges" to break even on the deal before you  go ahead.    And don't be shy about charging a little more than
it is actually costing you to get them made.  You did the digging to find a supplier who can make them,
and you will have to collect names, addresses and money, and do all the mailing.   Let us know if you need to
revise your price.

[narrowminded]

 I hadn't intended to perform that service. lol  What I was offering as a contribution to the effort was the contact for the order with someone I trust could fulfill the order reliably and with the highest of quality.  He is a customer of mine in the manufacturing consulting I do and I saw this as a very simple job for him because of his equipment that suits a part like this perfectly.  I spoke to him briefly and he concurred, therefore the above post.  I neither needed nor wanted a mark-up for that.  It was simply something I saw that I could contribute.  If someone wants to take that function on as a volunteer, the offer is good.

What is rapidly discovered in these endeavors is the function, or maybe the plight, of the manufacturer or retailer who commits to a product with what seems to be sound logic and expectations and then has it go sideways on him.  And at the custom part level the potential risk goes up exponentially.  It is why so many things we wish were available because WE see them as necessary, aren't available because we're really a minority in the scheme of things and the market DOESN'T actually support our so thoroughly clear vision of the next greatest thing.  And sometimes it IS the experts who missed the boat on a good thing.  At some level we've all been there, I suppose.  It's life in manufacturing.  Also, this is really premium stuff that while interesting to many is rapidly found not so necessary once the reality of the cost roosts.  I'm confronted with this exact dilemma in the venture I've undertaken to produce a reliable running ultra miniature power chassis.  I can do it but at what cost?  Fortunately, my life situation isn't in jeopardy if I complete the project and find the market is less than I thought, or maybe more accurately, hoped.  It's my hobby job that I'm doing firstly because I want to, accepting the challenge, and secondly to at least move the goal line a little, and finally, maybe some eggs and butter money along the way.   Ahhh, the luxury a retirement job affords.  As far as these flywheels go, let's see what happens.  All those interested, post up!   And then a facilitator needs to step up.  Maybe that should be me.

 

[mmagliaro]

Sorry!  Didn't mean to put you on the spot and assume you were offering to do it.

Okay, well regardless... does anybody else want these things?

If we can get an approximate count, that will let us know if this is even economically feasible.

[peteski]

It is fun to mull over the possibilities of making these flywheels but to me they aren't worth the money.  The size of these seems to be geared towards using them in N scale diesels or possibly larger steam locos. To me most N scale diesels have good enough pulling ability, even with brass flywheels. So do the recent large steam loco models.

What would be useful is t increase the pulling ability (and smoothness of running) of the smaller steam locos.  But these models usually don't have a room for such a large flywheel.     For those models, making as much of the model as possible from tungsten would improve its pulling ability.  Companies such as Dapol are heading in that direction (having custom-fit tungsten weights in their model).  But it would be even better if there were more tungsten parts in those tiny locos.

[mmagliaro]

It is fun to mull over the possibilities of making these flywheels but to me they aren't worth the money.  The size of these seems to be geared towards using them in N scale diesels or possibly larger steam locos. To me most N scale diesels have good enough pulling ability, even with brass flywheels. So do the recent large steam loco models.

What would be useful is t increase the pulling ability (and smoothness of running) of the smaller steam locos.  But these models usually don't have a room for such a large flywheel.     For those models, making as much of the model as possible from tungsten would improve its pulling ability.  Companies such as Dapol are heading in that direction (having custom-fit tungsten weights in their model).  But it would be even better if there were more tungsten parts in those tiny locos.

For me, I'm far more interested in the increased momentum than in the weight.   The tungsten flywheel looks like
it would yield 2x the momentum vs brass.  I don't know if I will try that and go, "wow!", or if I'll think, "eh... okay, not worth it."
But I would like to try it.