Driving wheels: press on axle then machine or vice versa

[EOsteam]

Howdy again,

I'm ready to start machining my main drive wheels for the Northern and like most everything I'm doing on this project it's for the first time. In Joseph Nelson's book he shows one sequence for accomplishing the task. On this board I think I remember reading where some folks have bored the axle holes and pressed the wheels onto the axles and then machined the treads.

1) What are the advantages to this method?
2) Are there disadvantages to machining the wheels to their final form and then pressing onto the axles?

So many questions......

Thanks,

HJ

[gwrdriver]

One disadvantage to machining a wheel on the axle, as opposed to on a faceplate, is the reduced rigidity and the increased tendency (actually almost a certainty) for there to be harmonic chatter while turning, even with the rpm slowed way down. If one assumes you'll assemble the bearing boxes on the axle before machining you'll of course generate grit and dust which can find its way into the bearings if things aren't thoroughly masked off.

[Bill Wilkins]

I machined the wheels, cut keyways, and Loctite 680'd them onto the axles. No pressing. Had to remove one and had a hell of a time doing it. Leave 2 thousands clearance for Loctite.

[GS14403]

My experience has been to machine the drivers on a spud made for holding the drivers. A faceplate is a good option for holding the wheel. Once on the axle it is almost impossible to machine the treads without chatter.

We have had excellent results using a quartering jig instead of keyways when pressing the drivers on the axles.

Donald

[cbrew]

1) face the back and bore the axle hole to spec on the four jaw
2) using a fixture, bore crack pin
3) using a fixture, cut the key way
4) install casting on a fixture mounted to the faceplate, rough machine the front and tread/flange
5) press in the pins,
6) press on to axles
7) finish the tread profile between centers

[Bill Shields]

Keyways...who needs keyways? Another discussion for another time.

Anyway...one of the points that is not being made here is that you should be very careful when pressing axles into shafts.

Yes, it is possible to get them crooked and get wobbly wheels.

There is no alternative for being careful and pressing absolutely square on an axle that is already perfectly square on the wheel when you start pushing.

[gwilson0704]

There is another way to install wheels onto an axle, A lot of machine shops have ovens and Liquid Nitrogen. You heat up your wheels in the oven and have the axles in the Nitrogen. Only take a couple of minutes and the wheel will slide down onto the axle without having to use a press. You may want to use a press to make sure there set in place after you get the wheels on.

[Jim_Nolan]

I have always machined the wheels fully using a mandrel then pressed them on the axles. For a change most recently I made axle sets up and machined the tread on the axle between centres. I was machining steel tyres on about 5.5” dia wheels. I found that it was difficult to keep them from chattering at the live centre end so did all the turning nearest the chuck.

The machining sequence is shown on the 25NC > trailing truck section on the website.

Jim

[Greg_Lewis]

I pressed mine after rough turning and before final finishing. Turning the axle down just a few tenths at the end, just enough to take off the interference, makes it easier to get a straight press fit. The final turning on my Atlas 12-incher (a.k.a. The Flexible Flyer) was done by pulling the work over by hand.

[Bill Wilkins]

I used Loctite 680 on my drivers and had to take one off because it was out of quarter. I had a HELL OF A TIME getting it off using a rosebud axle clamped in the vise. Had to make a step key of 4 thou to get it in quarter. I figured if it was that hard to take off the axle it wasn't going to just fall off.

[steamin10]

A secret to getting metal parts COLD is to use a small tank/container that will fit your axle (part) fill with alcohol, and put a cake or two of dry ice in it. It will give you a very low temp in a hurry. Faster than just laying the part on a cake of CO2. unless your parts are dirty the canned alcohol is unaffected and can be saved for other use.

[cbrew]

has anyone sat down and ran the numbers for the amount of shrink one will get from a 1' steel axle using the chilling method? i remember dad and i have this discussion and after him running the numbers, the change was so little with out getting extreme with the chilling process that we just determined that it was not worth the effort. even with shrinking tires, the temp required to make a real difference was just not realistic from a home shop. so we just used heat (propane BBQ works great) with the tires (.010 interference ) and nothing with the axles. (.002 interference )