Transferring 500 degree locomotive wheels

Topics include, Machine Tools & Tooling, Precision Measuring, Materials and their Properties, Electrical discussions related to machine tools, setups, fixtures and jigs and other general discussion related to amateur machining.

Moderators: GlennW, Harold_V

User avatar
Harold_V
Posts: 20231
Joined: Fri Dec 20, 2002 11:02 pm
Location: Onalaska, WA USA

Re: Transferring 500 degree locomotive wheels

Post by Harold_V »

Bill Shields wrote: Thu Feb 02, 2023 12:09 am Pressing a pin straight is not a big deal.

Depends on what you call straight. If a thou or two matter, it's challenging. If you ignore minor error, yeah, it's no big deal. It takes very little to create minor misalignment. That's why the talk of ground pins and honed holes, where there is little to give cause of misalignment. The slightest lean when pressing will translate into error on the assembled parts, especially if they gall in the process of assembling. It's a matter of how much you care to live with. Been there, done that, just not on a locomotive.

Next time you're faced with a similar assembly, you might be surprised when you check the results. Most of us usually are.

H
Wise people talk because they have something to say. Fools talk because they have to say something.
User avatar
Bill Shields
Posts: 10463
Joined: Fri Dec 21, 2007 4:57 am
Location: 39.367, -75.765
Contact:

Re: Transferring 500 degree locomotive wheels

Post by Bill Shields »

giggle....we are building locomotives, .....and 'straight', as you say, is relative.... :mrgreen:

i would never make it as a horologist.....
Too many things going on to bother listing them.
User avatar
Harold_V
Posts: 20231
Joined: Fri Dec 20, 2002 11:02 pm
Location: Onalaska, WA USA

Re: Transferring 500 degree locomotive wheels

Post by Harold_V »

That's the message I'm trying to convey. When you have a background like the one I've experienced, you come to understand that the slightest thing causes variations. What each must do is determine if they are important for them in their purpose. To pretend they don't exist just leads to unanswered questions of "why am I having trouble with this thing?"

There's one misconception that should be addressed. All too many demand that tight tolerance isn't a good thing with locomotives. They are wrong. The word "tolerance" has nothing to do with clearance, and that is what they really mean. It would be a blessing if readers started using the proper terminology so the wrong message wasn't promoted endlessly.

Harsh reality. Tight tolerance is NEVER a bad thing, aside from the time it takes. Tight tolerance assures that a size is maintained. If parts are dimensioned correctly, tight tolerance assures function. Loose tolerance pretty much assures failure.

Get it? (not directed at you, Bill).

H
Wise people talk because they have something to say. Fools talk because they have to say something.
Post Reply