"Old school" making an axle for a water wheel

[scsmith42]

I don't think that I'd want to arm wrestle any of these guys!  It's amazing what they accomplished with minimal tools and a lot of skill / hard work.

[Jeff]

That has been on my recommended list for 3 or 4 days npw. Ill have to watch it.

[Magicman]

I don't think that I'd want to arm wrestle any of these guys! 

That should not be a problem as long as you can beat him!!   

[doc henderson]

Lynn, you garner so much respect.  I believe if it came down to it, he would have you throw him on the ground!

[jpassardi]

 I watched that last night. Talk about work...
Looked like they ground coals from the fire to make a chalk line.

[customsawyer]

I'm guessing they went with a log that big to be able to peel/chop/cut the sap wood off. 

[jpassardi]

I think you're right Jake - knowing it would be in a wet environment. It was a butt log so it did have a good amount of flare.
Looked like a red oak didn't it?

[YellowHammer]

I'm kind of amazed of how cheap man power was back in the day, those guys are tough as nails, for sure.

I would love to talk to them, ask them why they did what they did, in the order they did, because it seems counter intuitive to me.  For example, taking 4 men to spin a log?  Did they not have one mule?

Why would they not put in the axle studs on the tapered ends first, after roughing to basic shape, before lathe turning, so that the axle studs were guaranteed to be centered and solid?    Or I wonder why they overcut the axle mortise so much? and put the wedges in after they shrunk the bands, (after the original constraining band) and not before?  Or why they used such thick wedges to begin with and didn't cut the mortise tighter, like a barrel Cooper?  Or why the metal axle stud plate wasn't balcksmithed like a metal wedge and driven in the mortises and then shrunk with bands. 

From an engineering and process standpoint, I really like watching these old time videos, and I know they are doing it right, but I just would like to know why they did it like they did, in the order they did. 

[customsawyer]

With it being in a constant wet environment, I wouldn't think that the sap wood matters. If it does, I can see why they don't want to have to make very many of these things.  

[Resonator]

All of those guys got a workout, I think I'd rather be the one using the scraper on the lathe than the guys spinning it.
I noticed they were working in winter with ice on the trees, good chance the log was frozen. At one point the guy warms the axe over the fire. Definitely skilled axemen, especially that wide blade hewing axe (looked it up, called a goose-wing). Though as mentioned does seem counter intuitive, to make a perfectly square beam only to round it.
Makes one appreciate all the labor men had to do in years past, thinking of all the barns and structures with hand hewn beams.

[rusticretreater]

I think I can answer a few of those questions as I own an old mill and have had to research these things.  First the metal ends inserted into the log are called gudgeons. 

To answer the questions:
Why would they not put in the axle studs on the tapered ends first, after roughing to basic shape, before lathe turning, so that the axle studs were guaranteed to be centered and solid?

As you saw in the video, they put in drive cranks so that they could manually spin the log. That would be difficult with the gudgeons in place. But there is another reason as you will learn in the following answers.

Why isn't metal axle stud plate blacksmithed like a metal wedge and driven in the mortises and then shrunk with bands?

A knife edge on the metal plate, when driven in, starts a split of the log lengthwise.  The rotational torque applied by the water wheel would then constantly flex the split, destroying the axle over time.

Why do they overcut the axle mortise so much? and put the wedges in after they shrunk the bands, (after the original constraining band) and not before?  And why do they used such thick wedges to begin with and didn't cut the mortise tighter, like a barrel Cooper?

This is a battle of opposing forces used to mechanical benefit. The bands, made to a standard size are not meant to be the clamping force to hold the gudgeons in.  They are the reinforcement of the wood to allow the clamping forces to be used.  The key part about installing the bands is that they are driven on and into the wood, burning a flatter seat for them to sit on.  Yes, yes they do contract when cooled but that is just part of the clamping/seating process.

The wedges are needed to secure the gudgeon into the shaft as it does not have any biting/cutting edges.  They are large so that they can be driven in without breaking.  As this is part art form, they don't closely measure the diameters of the shafts, the bands and their cuts.  The wedges take up all the slack from the previous steps in the process.

It does take a good deal of force to get them in.  If you noticed, they are a different species of wood. In this case it appears to be white oak, but it could be another type.  When the wood gets wet, it expands and clamps everything even more tightly than by mechanical force alone.  Also, since it absorbs the water it doesn't decay or dry out that rapidly, giving a long service life.

Another thing that most folks don't pick up on right away is that the power transfer from water turning the wheel to rotational power is not smooth.  There is a pulse that goes through the parts every time water slams into one of the wheel buckets.  The axle ends are one place where this pulse is absorbed and the wet wedges help cushion the blows.

You also might find it interesting in that having a perfectly spinning cylinder is not all that important as a water wheel only spins 6-8 times a minute when in use.  Plus the shaft is dressed where the wheel is attached creating a true centerline of the shaft.  There is a process for that too.