Broken Crankshaft on C&P 8 x 12

Hi y’all,
Two days ago I bought my first press and during moving today I watched as the crankshaft got snapped in two. The fly wheel is completely free of the press. I’m based out of Portland, Ore & am also in and out of Salem where the press will be stored until I can figure out what to do. Does anyone have advice or info on how to get a new piece machined? Will the whole press need to be taken apart as I suspect? How expensive is this type of repair/restoration? Anyone know a fella? I’m looking for whatever y’all got and any leads are much much appreciated. Thank you kindly.


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The crank shaft can be removed from the press without disassembly of the press. You will need to get the small gear off the end opposite the flywheel. There is one bearing for the shaft that is bolted to the frame and when that is removed the shaft slides out. However, repairing the shaft, while it can be done by a machine shop, will be somewhat expensive. I assume it broke flush with the frame, which is what usually happens. With luck you may find a press on which something else is broken but the shaft is intact. One other consideration is whether the shaft has the crank for the treadle, and whether you want to use the treadle — if not, a straight shaft can be made much more easily than the shaft with the crank.


Thanks for your reply Bob. This press is old style but motorized, no treadle. The shaft did not break flush with the frame. There’s maybe 3-4 inches of the crank jutting out. So here’s a few thoughts: would a new shaft need to be made out of cast iron or would another material do just as well? How much torque does the motor actually put out? Would a collar work in this situation? Or since there is some shaft poking out, can a different type of smaller wheel be designed around the new (accidental) shape?

Ramblings from U.K. which may or may not help. (generaly)
If the machine be a treadle model, even motorized later, the main frame has to incorporate the *pear* shaped removable bearing mount to facilitate crankshaft removal!!
As you imply 3-4” shaft still remaing, first option (possibly) have an adaptor boss turned up, to fit the shaft (remains of) to accomodate ANY configuration of pulley(s) required.
In the U.K. now we are well blessed with Slave Pulley adaptors, which come in a massive range, Metric & Imperial to fit whatever shaft, within reason,!!! which you then piggy back onto, almost any other master Pulley, be it *V* Belt, Flat belt, Cog, Sprocket, Drum, etc etc.
Same system must be available Stateside??
If it becomes an option to dispence with the CRANK, and revert to straight shaft, you will almost certainly find that the (plain) bearings, are of an exact imperial size/diameter, no need for fabrication, >other than key-way slot(s) or flats for grub screws<.?
I have just done, exactly this, for an adaption to motorize a previous treadle machine, I.E. Adana T.P. 48, replaced the original mainshaft @ 18” with 24” of machineable steel shaft, U.K. designation *E N 8* by 1” (one) diameter.
Had to mill one key way slot, and one grub screw flat.!!!
Cost of shafting £20, Sterling, approx, $35 ???
If the above be useless, apologies! or, possibly, Good Luck.

I agree with Mick, a replacement is in order.

Maybe a used one could be found, but they are likely the most often broken/damaged piece.

It will not be so cheap, but do-able… the stock will need to be the diameter of the bearing/journal and turned-down on a lathe in the areas for the pinion and flywheel, plus keyways need to be machined-in. Fortunately, you have the broken shaft to show a machine shop for dimensions and price quote.

Shaft collars could be used to keep the fabbed shaft from moving side to side.

If there are 3-4 inches of the shaft sticking out of the frame, check to see if the flywheel can be mounted that close to the frame — you might be able to get away with it. Another possibility is to have a machinist turn down the stub enough to fit a steel pipe sleeve (I’d suggest steam pipe as I believe it is stronger) over it and the broken-off piece and braze the sleeve and the broken piece onto the shaft, then remount the flywheel. For that repair turning the repair sleeve down to the diameter of the flywheel bore would not be necessary - just butt the flywheel against the outer end of the sleeve. Overall that work would probably be cheaper than having a replacement shaft made.


I’d consider sleeving it, except for the worry of a 3’ diameter, 100lb flywheel spinning at the very end of the 8” shaft. Any runout will be a significant stress on the joint. Maybe on the steam-pulley side, but not the flywheel side, in my opinion.

Yeah the collar as a solution seems pretty unsafe. I do like your second suggestion Bob, for remounting the flywheel onto the remains of the shaft. Ill have to look more closely into it, I know the motor mount will definitely have to move in that case. Worst case scenario, has anyone worked with DeFelice Engineering before? Thanks again y’all for all the advice, it’s certainly helping me through this unexpected setback.

If it’s motorized, just buy a new shaft. McMaster Carr should be able to sort you out for not too much. Make sure you get the right details on each end to mount the gear and its key, and the fly wheel.

Something along these lines:

The trick will be getting flywheel off fo the current shaft, and on to the new one. If it broke on the flywheel side it will be easier to pull it out. Maybe find a machine shop with an arbor press?

The trick is that the bearing/journal diameter is larger than the shaft where the keyways are. So, the bearing area would need a sleeve or the keyway sections would need to be turned down from a larger shaft.

On the original, the crank area is even larger and holds the shaft from moving laterally between the journal bosses. The keyway for the flywheel is machined at the end of one side, the keyway for the pinion is machined close to the journal and does not reach the end where the steam pulley is often mounted.

Don’t sweat it man, race cars send pieces through the hood all the time thats why, you want to find your self a first class machine shop, one that rebuilds big boy engines. They can weld it and balance it. I don’t see it costing an arm and ah leg either.