Sprocket question and others

[Harold_V]

I worked in a shop where there were nine owners. Last job I held before becoming self employed. The philosophy of one of the owners (each of whom considered themselves your direct leader) was to spend as little time as you could on each and every job in the hopes that they could sell the resulting work, even with defects. If not, there was time enough left to do it again. A lousy philosophy when one takes in to account that the work one delivers has one's signature on it.

If one hopes to build trust in a customer, a good way to start is to deliver work of high quality, work that conforms to the print. Submitting work of questionable quality isn't going to accomplish that goal.

Takes time? So you have plenty of time to do it wrong, but not enough time to do it right? If I was still running my commercial shop, you'd be the guy who got fired, or never hired in the first place.

When a guy has a low skill level (lack of experience), sure, it takes a little more time to do things properly, but if one works to rigid specifications routinely, speed comes. That was my philosophy and I reaped the reward of being able to work to that level of quality and produce as much work in the day as the guy who worked using questionable practices. When someone explores work I've done on the machines, I don't want to make any apologies (remember, the work you do bears your signature). Your mileage may vary.

H

[Pontiacguy1]

you'd be the guy who got fired, or never hired in the first place.

Wow, It's obvious you have an extremely poor opinion of me. It also appears to me that you didn't understand what I was trying to say.

I think that in our projects, we tend to use which one we have more of... If I need something done more quickly, I will buy more of the components instead of make them. The reverse is true if you have less money to put into a project.

[Harold_V]

you'd be the guy who got fired, or never hired in the first place.

<snip> It also appears to me that you didn't understand what I was trying to say.

Yeah, me too! My comment was simply addressing the fact that some folks never have enough time to do a project properly, but all the time in the world to do it time and again until they achieve some level of success. Didn't mean to address you personally. Sorry 'bout that!

H

[Brakeman7.5]

Next questions if I may.
RMI Railworks sells a 5" wheel with a 3/4" Keyed Axle bore.
https://www.rmirailworks.com/mi-WHL-250 ... chined.asp

McMasters sells rotary shafts that

are turned, precision ground, and polished to meet tight diameter and straightness tolerances.

It's 3/4" shaft has a (Tolerance: -0.003" to 0")

Excluding the need to mill a keyway, is it possible to anticipate a slip fit, press fit or you really don't know till you get them both together?

Also, McMasters sells keyway stock that is either "oversized" or "undersized". Since it's only around $1.25 for 12" of each do you just buy both kinds and see what works best?

[Bill Shields]

You really do not know if you are assembly only without metalworking capabilities.

Each component can be within spec and you can have either a slip or press fit.

This is why where are machinists, blacksmiths and loctite.

You can cut, heat or glue..

[SPSteam2491]

Since RMI does not list their tolerances for the wheel, I echo what Bill said as you won't know until you receive the product.

Go with "Undersized" material for the key stock as that will allow a slip fit between those parts.

How do you plan to retain the wheels on the axle and hold the correct spacing between the wheels?

[Bill Shields]

In reality, you are going to need some machining capabilities to set your wheels.

Recommend purchasing the wheels and seeing what you have before proceeding with axles.

Are they all exactly the same bore? Do not assume. Everything has tolerances.
Are there chamfers on the inside face of the bore?

There are a lot of places where you can cut corners in assembly, but the wheel sets is NOT one of them.

Even if you have to $ someone to make your axles, you will be $ ahead.

NOTHING ANNOYS A CLUB MORE than a loco with incorrect gauging..and a loose wheel on an axle is headed straight in that direction.

A loco that tears up the track is loco-non-grata forever more....and its builder is forever under close scrutiny

Just ask NS about loose wheels and incorrect gauge and the havoc it can cause.

FWIW

I have seen locos where large circlips were used to set the wheel spacing...and seen where one eventually came loose and the wheel moved.

Theoretically you could use clamping shaft collars and set them with dog point set screws...but by the time you go through all of that, having someone make you proper axles will be $ ahead.

[Glenn Brooks]

Little surprised no one has mentioned the possibility of sweating the wheels on your axles. Sweating them on involves heating up the wheels a little bit so that they swell a thousand of an inch or so and simply slipping them over an appropriately sized axle. Once they cool the gripping force of the wheel on the axle will negate any need for set screws, keyways etc. with small 4” or 5” wheels, you can actually build a simple small foundry with a few stacked fire bricks and a 5gal propane tank and weed burner. I’ve done this a couple of times and have been amazed at how effective and easy it is. IF you turn the axles to size, leave a small ridge on the inside to hold the wheels to your desired gauge. (Although, you probably still need to use a keyway and set screws to hold the sprockets).

Plus, you would start building your expertise with machining and fabricating practices. Also give you a good excuse to go out and buy a small lathe and start making some chips! Hahah welcome to the live steam rabbit hole. Might as well dive in and have fun!

[Pontiacguy1]

Best advice was given above. Have someone either make your axles and press your wheels on there, or purchase the wheel/axle sets from someone like the supplier listed above. You can do a lot of stuff on a locomotive in a cheaper/quicker manner, but as stated above, the wheels, axles, frame, and suspension should be done properly and with good fitting robust parts, or the engine will not perform well. You will start having problems, it won't stay on the track very well, and it will always be ruining your day by something breaking, coming loose, slipping on you, etc.

Why Not Send John L. who posted that drawing a note and see what he would charge for a set of wheels, axles, and axle boxes? If you buy those from him you KNOW you are going to get something that will work together, will be strong, and will last.

Good luck with whatever you decide to do. The wheels/axles and framework are the most critical parts. Above the frame, you can basically do whatever you want with it.

[Brakeman7.5]

Thanks for all the help everyone.
Getting the wheels first then building the axle for them appears to be the best answer.
Which leads to a couple more interrelated questions about machining and hardening.
My goto for carbon steel rod offers 1018, 1045 and 12L14 which each claim ease of machining.
12L14 does list slightly weaker to other alloys since it contains lead.
Is anyone of these better than the others for hardening?

[SPSteam2491]

If you are using ball bearings (which I highly suggest) than no hardening of the axle is required. 1018 CR rod is a good material for an axle.

I wouldn't recommend using roller bearings and having to harden the axle.

[Glenn Brooks]

1018 CF (cold formed) steel would be ideal for your axles. CF round stock is ground and finished to a higher precision than 1018 hot formed, and you don’t have to deal with removing the typical dull grey mill scale coating on the surface of the more common hot rolled material. 1018 CF is Probably your best option of the three you mention. 12L40 gives you the best finish of the three, due to lead content, but for this application 1018 likely will have a higher modulus of elasticity, strength and hardness rating, and maybe less expensive to purchase. So a good all around choice for the axle- bearing interface.