The Home Machinist!

I've completed disassembly of my unfinished Pacific project. Working to correct various builder mistakes along the way. Today the drivers were removed from the chassis, and found that the crank pins are not at 90° to each other. The builder had likely stacked up the drivers and broached all of them in one shot, the problem is that the keyway was misaligned with the crank pin by 10°, but when assembled to the axle which was milled offset 90° put the crankpins at 110° to each other. my first thought is to remake each axle, or will it run fine as is with just an uneven beat to the exhaust.

So new axles or leave it as is.

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My wheels don't slow me down

I'm thinking that if they were off by just a degree or two it would be fine, but off by 20 degrees is too much. Also, I would be concerned that they are all exactly the same if there is that much error.

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Dan Watson
Building IC mikado in 1.5" scale

Save yourself some headaches.... Make new axles.

LL

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i ran into the same thing with bought parts but didn't realize it till i ran it on air. very noticable off beat to the exhaust. i fixed it by broaching new key ways in the drivers on the opposite side and kept the axle as it was. worked fine.

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Fred V
Pensacola, Fl.
home track:
http://www.waleswest.com

I'd also check the alignment of the keyways to the crank pins before I stuck everything back together. If you find them off you can do the same I did because of an oversized bore - I bored the wheel slightly larger than the keyway, Loctited in a cast iron plug, and then rebored and cut the keyway. You might also verify that the axle to crankpin distance is correct while you have the wheels off.

If the wheels are not quartered properly they will bind on the quarters. Offset keys will correct this problem if the quartering is not off by much. I made a fixture that I use to press the wheels on the axles without keys. Works perfect. Also keys are not needed to keep the wheels from slipping on the axle if you have a proper fit. Diesels do not have keys on the axles or gears.

LSGOD

we all know the cranks dont have to be exactly 90 degrees, but they Must be all the same, or binding will exist.

knowing how i quartered my drivers, I would not want to be in your shoes trying to fix someone else s screw-up.
did the chassis have the side rods installed? and did it roll? (I did not see this stated)

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LOCTITE???

someone else uses loctite?

Hold on - world coming to an end...

that's my favorite choice!

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Fred V
Pensacola, Fl.
home track:
http://www.waleswest.com

When I keyed my drivers I did not feel like spending another day to make a jig for one job. It is common practice to key driver pairs back-to-back with the crankpin holes lined up (I machined a pin to fit tightly). Keying drivers back-to-back in pairs allows the key slot to be off; however, when both are off equally the error cancels out. I would check to see if the drivers you have were keyed in this manner. Place the driver pairs together back to back and see if they line up.

George

I used loctite to quarter my drivers. See setups in my A3 build thread. And if you screw up it's easy to undo it and try again.

Thanks to all for your replies. In the case of back to back broaching, that was the PO mistake, it appears the they may have been stack, as pancakes, not back to back. So think of the crankpin at 12:00, the keyway on all 6 wheels is at 1:00, on all 6 wheels, not 3 at 1:00 and 3 at 11:00. So I've choosen to rebroach the wheels, and made a jig to do so. in keeping with the type of work found on this project, the crankpin center is off by .020 on the first 2 wheels checked, the wheels were slip fit on the axle, the key was made tapered to hold it on, one whack with a DB hammer and it fell off. So new crankpin bores, and pins will be done, as well as axles.

The loco has a axle driven pump, with split eccentric, I'll toss that setup and machine the eccentric into the axle, which should open up some room there to add a whistle above the axles.

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My wheels don't slow me down