Altering a flywheel mounting PCD

[Bobtail4x4]

can you drill "between" the other holes?

 

[Smallfry]

If your mill has a DRO you can use co-ordinates or PCD function and dispense with the rotary table.

I wish. I am not a machinist Brad, probably very basic and obvious, for those who know, but all sound complicated to me.

What I had in mind was to turn a stepped bush, that will fit the centre hole of the rotary table and the centre bore of the flywheel, the centre this to the spindle.

Then wind the table along to the required position, and then turn the table 45 degrees, and repeat.

 

[Smallfry]

You could also spot face the clutch side of the flywheel to take a recessed thick washer, that would stop the bolt trying to walk in the new slot when you torque it up.

Bob

Unfortunately there is a plate that is fixed by small rivets (drive screws) that the bolt heads will clamp down on. I dont want to take the plate off, as knowing my luck, there will be springs and balls or similar that will fly out and disappear into dark corners of the workshop, only to be found by accident some years hence. You know how it goes

 

[Smallfry]

can you drill "between" the other holes?

I could, but the PCD is only 72mm, so I dont feel there is enough material left, and would weaken it considerably

 

[Smallfry]

Thanks for all the advice and suggestions chaps. This is only an experiment to see if I can physically adapt this and mate it to the gearbox.

Might not work out, but hey ho. Nothing ventured, nothing gained. Or lost.

 

[Agroshield]

What I had in mind was to turn a stepped bush, that will fit the centre hole of the rotary table and the centre bore of the flywheel, the centre this to the spindle.

Then wind the table along to the required position, and then turn the table 45 degrees, and repeat.

You will still need one pin that drops into the existing hole in the flywheel. You have to set the clock position of the flywheel in addition to locating its centre.

Set the RT concentric to the mill spindle and zero the mill dials (or DRO). Move in X (or Y) equal to the pitch circle radius of the existing hole. Put pin in spindle and wind RT around until pin drops into existing hole. Zero the dial on the RT handwheel (or if it does not have re-settable dials, use masking tape to make your own zero marks). That is your 12 o'clock position from where you now rotate 45 degrees. As the graduations on the main part of the RT will likely show some random reading at the 12 o'clock position you have established, you need to count handle turns.

 

[roofman]

I have just completed something with the same,ish problem as this on a pressure washer repair...working on @Pete. post and his fix, you could find an end mill the same diameter or very close to what you have now, the end mill would plunge cut the slot a millimeter at a time working from the hole and moving out to your required PCD, its what i have just done to a mounting wheel and it worked a treat but was mounted to my XY table after clocking the original hole 1st.

 

[Woody.v8]

Having seen what flywheels and clutches can do when either detaching or exploding I would want to be absolutely certain that this was the best solution to the problem.

 

[Smallfry]

You will still need one pin that drops into the existing hole in the flywheel. You have to set the clock position of the flywheel in addition to locating its centre.

Set the RT concentric to the mill spindle and zero the mill dials (or DRO). Move in X (or Y) equal to the pitch circle radius of the existing hole. Put pin in spindle and wind RT around until pin drops into existing hole. Zero the dial on the RT handwheel (or if it does not have re-settable dials, use masking tape to make your own zero marks). That is your 12 o'clock position from where you now rotate 45 degrees. As the graduations on the main part of the RT will likely show some random reading at the 12 o'clock position you have established, you need to count handle turns.

Thanks for that ! All I have to do now, it buy a 12.5mm longish end mill. I have a 1/2 inch one, but don't want to make it bigger than absolutely necessary.