Best Material for Locomotive Frames

[dcutting]

For the OP's problem, I'd seriously consider having Shapeways (or a similar company) produce the wax masters, or even do the lost-wax investment brass castings.  All he'd need to do would be to produce the 3-D model, which can be easily modified if necessary...which I think will probably happen, and let Shapeways take care of the rest.

Well... I guess I should give some more details. The discussion about this came about because I'm considering doing that 3D printing myself as I'm considering acquiring a printer that can print castable wax. Shapeways is already far above the prices that I've calculated being able to hit with this printer, where I could print up a full split frame for about $5.00 in materials as opposed to their $30+. I do have to take into account the cost of the printer, which is by no means inexpensive, but that's already taken care of by other projects that I'm working on... this is more of an aside that would be cool if it works.

David

[Lemosteam]

David, have you considered the sintered Stainless steel from SW?  My kit uses this for the tender frame.  The the right speeds and feeds it is definitely machine-able (even by hand.  I would think that a solid printed frame in this material would be comparable to existing models at 7.86 g/cm^3 and costs far less than the lost wax process for brass.

Here is the data sheet:
https://static1.sw-cdn.net/files/cms/materials/steel_data_sheet.pdf

There are odd shrinkage factors to consider in the 3d model though which I can share with you offline (note easily explained here).

[u18b]

Soooooo.......

Are you looking at making frames for the TP56/70 in N and HO?

 

[u18b]

And BTW-

I'm pretty sure Atlas/Kato etc changed the way they make frames several years ago because of the legal/state regulations related to lead content in the frame alloys.

Frames today are lighter than in "the old days."  Probably higher on the zinc side.


Also, per this thread..... I don't know what Bachmann uses, but it looks like a Zamac silvery metal material which is then coated in some kind of brass or other copper colored alloy- which is then blackened.  So they use a three step process!  Cast, coat, blacken.

And as far as pewter goes....  It would be easier to cast than brass.   But if this is a loco frame..... the softness could become an issue.
1.  Don't use pewter if it needs to be tapped for any machine screws.  Pewter is too soft for long time use.

2.  The frame itself can bend.  Anybody remember back to the mid 80s when Atlas had their GP7/9 disaster on the RS-3 chassis?

At least Two companies (maybe 3) came out with retro-frames.
JnJ had frames that were higher in the zinc portion of the alloy.  Man, they were HARD to cut!
I think N Scale of Nevada and maybe Republic Loco works had one.... but theirs was higher on the lead content.  Heavier but softer.

The JnJ frames were rock solid but very hard to work with if you wanted to make changes.  But the other could bend from handling and/or shipping.  I remember laying the softer frame on the table to try to flatten it out!

[metalworkertom]

Well... I guess I should give some more details. The discussion about this came about because I'm considering doing that 3D printing myself as I'm considering acquiring a printer that can print castable wax. Shapeways is already far above the prices that I've calculated being able to hit with this printer, where I could print up a full split frame for about $5.00 in materials as opposed to their $30+. I do have to take into account the cost of the printer, which is by no means inexpensive, but that's already taken care of by other projects that I'm working on... this is more of an aside that would be cool if it works.

David

 1.You can adjust for shrinkage when you print the wax master but a test run will have to be done to insure accuracy. 2. By printing each wax you are a step ahead because you will not need rubber molds , taking away one problem area. 3. Have you checked with your local blacksmith group to see if any of their members cast metals , here in Louisiana the Blacksmith group I'm President of has several members who cast brass and bronze. Or a local collage may have casting equipment. not sure where you are located but I could help find someone local to you through my contacts.

[Sokramiketes]

I beg to differ.  Sure, you can tree up your wax shots, but that involves a certain amount of previous experience and involves knowing what size flask you're going to use, buying and using a flask base and probably a flask too to make sure it all fits properly inside it.  Then, if you can't take it all down to where you're having the casting done, you have to ship it, and unsupported wax trees won't hold up to shipping because they are EXTREMELY FRAGILE.

Secondly, you don't just mix up and dump investment into a flask with a tree inside it.  There's a definite protocol to mixing investment, and then de-airing it, then how your pour it into your flask, then having the equipment...which involves special mixing bowls, a vibrating table, a vacuum table and bell jar.  This equipment is going to run about $500 if you can find a good deal.

Thirdly, when I was producing investment cast brass HO scale detail parts, there is a definite time window when flasks and invested wax trees can be burnt out...because the burning out process utilizes superheated steam from the still wet (but hard) investment to clean the voids of any residue.  I don't believe you could feasibly invest your tree, pack it up and ship it and have it still be usable whenever the casting company gets around to burning it out.

Just sayin'...

Cheerio!
Bob Gilmore

Dcutting asked a what if... what if he had the investment ready to go.  If he did, then I think he could find a company to insert brass into cavity.

Ultimately I agree that there's a learning curve, an investment (pun intended) in materials and tools, and a time component.  Could it be done in a garage?  Sure it could.  Would I do it?  Nope.  I love learning manufacturing processes.  But the more I get into laser cutting, photo etching, 3D parts, and lost-wax brass, the more I realize that I'm not going to bring all those methods in house.  Let someone else maintain the machines, and use my designs.  Could I do it cheaper on a strictly material basis, sure, but that's not the only cost.

There's two components to this conversation.  How much is doable in your own garage.  And then, will it work for locomotive mechanisms. 

My recommendation would be to send a cad file to Best Cast, have them do a run of part(s) as professionals, and then you can see what the output is.  If it works for you, then you can spend the time buying materials and learning.  If it doesn't work, well you're only out the $2-300 for your first part as a learning expense.  Not a couple thousand dollars in equipment and materials and time. 

[dcutting]

Thanks everyone for the comments and help so far. I am doing all of this under the assumption that I have a wax part ready to go and just need someone to cast it. I contacted best cast as they are on this side of the country and the prices look very, very, promising. More to come, for sure.

David

[bbussey]

I like brass.  Heavier than the conventional zinc-based frames used today, easy to fabricate, and affordable.

[dcutting]

I like brass.  Heavier than the conventional zinc-based frames used today, easy to fabricate, and affordable.

@bbussey How did you deal with the shrinkage of the shapeways sintered parts with your metal frames? I had some major issues getting a part right that was copied almost completely from atlas geometry.

David

[bbussey]

I don't get my stainless steel frames rendered at Shapeways. The contractor must compensate for the shrink factor because the frames are spot on.

[dcutting]

I don't get my stainless steel frames rendered at Shapeways. The contractor must compensate for the shrink factor because the frames are spot on.

I do remember us having this very discussion a while back, and I ended up ordering parts from that supplier. The cost was too high though, so I'm hoping that once I get a more detailed quote from best cast the cost will be a little more attractive.

Maybe I can start giving some more info on what I'm trying to do as I'm hitting a few binding points. I've figured out almost all of the supply chain besides two critical parts. Those are...

...the motor. I'm looking for something that runs like a 5-pole skew wound Kato motor for well... not as much as a Faulhaber or Maxon. As far as I can tell, this is a really tall order. Any help there? I'm not stoked about buying cheap ebay motors or gizmozone motors. NWSL is the best place that I can think of now... but at $23 a motor it would be nice to find a lower cost version. I'm not worried about speed too much because I can simply add more gearing, but slower speed motor tends to allow more weight in the end. So unless anything other than NWSL turns up, that's where I'm headed next.

...and the worms/wheels. These are tricky because they have to be machined. If you guys have anyone that can do the CNC work on these, that would help a ton. NWSL does them, but the wheels alone could double the cost of the model not to mention the worms. I'd like to hear what the best material is for wheels from you guys, sort of like the frame discussion we've had.

David

[bbussey]

You have to lessen the secondary labor that isn't necessary for something that will be hidden inside another object (such as a locomotive frame).  No need for polishing.  No need for them to remove the posts/stilts added for building, which is done manually (I remove them myself with a Dremel).  I commission material S4, bead blasted, no other operations, and it costs between $20-$25 per part depending upon the complexity.  That's no more than $50 per engine frame for a two-part split frame, which is a lot less than what it would cost you in time and materials to mill it yourself and worth it for a unique one-off or two-off project where the frame can't be used for anything else (such as a New Haven EP-3 electric).

If you're looking at a mass-production project, then the Best-Cast option is probably the best .

[mmagliaro]

I do remember us having this very discussion a while back, and I ended up ordering parts from that supplier. The cost was too high though, so I'm hoping that once I get a more detailed quote from best cast the cost will be a little more attractive.

Maybe I can start giving some more info on what I'm trying to do as I'm hitting a few binding points. I've figured out almost all of the supply chain besides two critical parts. Those are...

...the motor. I'm looking for something that runs like a 5-pole skew wound Kato motor for well... not as much as a Faulhaber or Maxon. As far as I can tell, this is a really tall order. Any help there? I'm not stoked about buying cheap ebay motors or gizmozone motors. NWSL is the best place that I can think of now... but at $23 a motor it would be nice to find a lower cost version. I'm not worried about speed too much because I can simply add more gearing, but slower speed motor tends to allow more weight in the end. So unless anything other than NWSL turns up, that's where I'm headed next.

...and the worms/wheels. These are tricky because they have to be machined. If you guys have anyone that can do the CNC work on these, that would help a ton. NWSL does them, but the wheels alone could double the cost of the model not to mention the worms. I'd like to hear what the best material is for wheels from you guys, sort of like the frame discussion we've had.

David

I don't think you are going to get your hands on a quality motor for less than $23 unless you are out there buying 1000 of them on the surplus market.   Faulhaber and Maxon come up on eBay for less than that from time to time, IF you have the patience to refit them with a correct pinion gear, remove unwanted encoders from the the back, and so on.     You can get Mashima 1015's for about $18 from http://www.pojezdy.eu/eshop/6-motory-mashima
That place also has worms and gears at really good prices.

Also: https://shop.kkpmo.com/index.php
A superb assortment of worm and gears in acetal and brass in every module, bore, diameter, and thickness you could want.  They are typically a few dollars per gear.

I have purchased from both of those sources myself.  I never got stiffed, the shipping costs were very reasonable (like, under 10 bucks coming from Poland, which I consider to be quite fair).

Wheels... well, I don't have an easy answer for that one.

[narrowminded]

As one who was involved in manufacturing mostly custom parts, then "standard customs", then some quantity production parts, I don't see any way to get truly custom parts at low enough prices to make them even close to the cost of quantity production parts.  Not even close and because of tooling and setup costs.  If you're doing that yourself and literally giving it away it helps but it's still going to be fairly costly. 

Your best shot is finding an existing part that does what you need and incorporating that into your design.  And it will work well as long as the part is available.  That can be very risky.

Your next best shot is finding someone who specializes in the product you're looking for where the part becomes a "standard custom" as they will already have a huge head start on the tooling for the thing you're looking for and as such has that cost amortized over a large quantity of parts from a lot of small orders.  That would be the nature of the supplier from Poland that Max linked to.  An outfit who specializes in small gears and has worked out a system to supply in short quantities.  And if your quantities went up much at all they would probably be willing to quote you a surprisingly better price as their costs to set up for just one, while reasonable as it's their specialty, can be spread out over 10, 20, etc. which will translate to whole dollars very quickly. 

Finding a supplier who fits this bill, the meat of your question, isn't always easy as there are few who have the skills, the market, the investment, then the desire to work this way.  Max's link to Poland is the only one I'm aware of that offers that flexibility for miniature gears at all much less anywhere near those prices.  It's a specialty in all ways and really a specialty in the sizes and quantities he's offering.  An indicator of just how special that is is it's the only supplier I'm aware of that offers that degree of customization in small gears, at those prices, and it's all of the way in Poland.  And even if you found another I can't imagine a measurably better price. 

The obvious solution is to make a couple of thousand or better of something and you can get all of the things you want at a reasonable cost... except tungsten.