Roughing FP4NC

So i have this little job here....Tasked to make a new flywheel for a 1913 Mercer Race-about.
Tried with no success to get local shops that have a VTL to do this with no success.

Now i own a nice 21 inch swing lathe that is large enough to turn the material, but no way to hold it to start, So.....................
Began with a hunk of 19+ inch diameter x 4.5" long Ductil iron slug....

So it begins. Set the blank on the table of my trusty FP4NC, setup on 2-4-6 blocks to get clearance off the table and drilled a hold through...
Hole would later be enlarged to 2.500" Id which will be the locating feature on the crankshaft.
Hole provides method for evacuating the chips from the pocket i will machine.
Tool is 1" HSS "Hog" mill.
Used coolant (cutting oil) to help flow the chips from pocket.
Pretty much used G76 canned cycle to cut the pocket......



Part is held using clamps on the face. This side of the flywheel has a shallow offset. Will be much deeper on the opposite side
Scroll ahead, and i have finished milling the rough step on the first side, cut in the step for the flywheel flange and finished bored the register diameter for locating the flywheel.

Have also finished drilling the holes for mounting the clutch (Outer bolt circle) and the crank mounting bolt hole circle (finished bored)



Here i have moved the hold downs to through bolts using the holes for the clutch.
Allows access to the face of the part. Here i have finished the face using a 3" face mill....Here i could not use the machines circular interpolation because the overall size was over the travel limits (19+")
I used the 2038 tables rotation to rotate and face the part.

Now i have a good surface to set the part on and it is turned over (thank heaven for cranes).
I cut in notches on the OD using a large "T" slot cutter. These notches will disappear when the OD is brought to the finished diameter of 17+ inch OD.....
Hold down clamps use the notch for purchase to hole the part.
Also note the quill extension , needed to allow clearance for the "Y" slide to clear the part when going to full depth.
Now begin cutting the deep pocket on the 2and side.....



Here is the pocket , pretty much to rough depth.....Hard to see in teh photo but there is a step left at the bottom /ID this is to account for a finished fillet that will blend the ID to the floor of the pocket....





More to follow.......if you aren't bored yet....

Ok, so off the mill and on to the lathe.....
Setup on my license copy of an Okuma....Korean built "Dong-Yang. Terrible name, gorgeous lathe. Accurate and extremely well built! Fit and finish second to none...
At any rate used the deep pocket side to hold the part with the 4-jaw gripping on the ID as shown.....




Note tooling.....Shop built boring bar. Setup needed to turn the OD of the blank. Too large for carriage to pass the part , so have to get the tool out in front.
Using an insert style stick tool here with high positive insert.....

Note the shoulder...i am only turning the OD long enough that i can finish when the part gets turned around.....
I finished the back face (where the crank mounts) by back facing through the hole in the center of the part....then i turned things around.

Here the part has been turned around....and mounted on a spud that has been finished in place to mimic the crank....(drill and tapping done on the mill of course....



Front vies of setup...Note the finished surface where the bolts are. Finished in previous setup by back facing with a boring bar and extended tool....bit rickety but it worked fine....



Now its just a matter of finishing the features on the flywheel with the lathe......

Cheers Ross

I love seeing this. Seems like starting weight was around 340 lb. Did the FP4NC Z axis complain at all?

Rich:
No complaints...but then i did not opt to peck drill the bolt circle holes....Just did the drilling by hand using the quill using "Jig Boring" positioning.
Did make a mess of the cutting oil with all the graphite from the cutting....

Did a Solid Works model of both teh original and the new design that will incorporate a ring gear for a starter (not original of course)
Used the model to check the weight...somewhere around 77# on the original. Somewhat heavier on teh new unit because i needed to step the OD to clear the starter pinion which meant that the mass was reduced a bit on OD.
Cheers Ross

Bored? I could read posts like this all day.
Thanks for taking us along the ride.

Valuable that 2038 table...

Thanks for sharing Ross, very welcome post!

BR,
Thanos

Nice.
Fits in with the old adage that a real machinist makes round things in a mill and flat things on a lathe

So here is the follow up on the flywheel job........
Some shots of the finished part...Still has to go out to be balanced.
Ring gear is shrunk on with about .020" of interference,and having retaining screws (12) for added security



The larger step on the inside of the flywheel is a register for the clutch basket ...a multi plate setup

Close observers will note the finish on the floor of the flywheel....In fact i finished the floor on the mill using a fly cutter. Making a good flat face with both an inner (clutch step) and outer (ID) step on the lathe is troublesome, so i opted to finish the step and ID on the mill. Allowed me to cut the ID fillet using a ball end mill(1")
Had trouble betting a good finish on that large radius without chatter on the lathe. Long reach and the flywheel wanted to ring.
Large radius tool presents too much contact to give good finish without chatter. Had this part been smaller i would have run it on the Romi where i could easily profile that inside radius and used a minimal contact tool....
All done using the rotary part of the 2038 table.



View of the installed ring gear. Step is there to provide clearance for the starter pinion end ....


Retaining screws located using jig boring coordinate math.

Front side. Crank registers off the center bore. Bolt holes are bored for .002" clearance on mounting studs.





Cheers Ross

Many thanks for taking the time to document this!