HOW LONG DOES IT TAKE TO MAKE A BLOODY FLYWHEEL?Well certainly not the two weeks it has taken me. About 3 to 4 hours if you are up to concentrating that long.
I have a bit of a confession to make, this is a new setup from where I last left it, I had a little job come in that required the RT to be removed from the table. So the RT had to be set up from scratch and the job realigned perfectly to how it was.
So what you see here was my next step. I have blued up the whole lot, and using an old ballpoint (doesn't scratch like a scriber) I drew on what needed to be removed. I also fitted a one sized smaller SLOT DRILL. The slot drill will cut all the gooves much easier that an end mill, and by going one size smaller, if I cut to the original dimensions used for the holes, it will leave a small amount of material to be removed to clean up all the edges. You could use the correct size of end mill for doing this first stage and miss out the second, but your hand cleanup time will take much longer.
I will be going thru the whole sequence twice, the cleanup one takes hardly any time at all.
The top slot is done first, but if you remember, the holes were drilled offset to allow for spoke width. So what we do is have no offset, and just set the Y distance at 38mm, the distance we used for the original holes.
Now there is no angle used for this part, it is all done by eyeball. What you do is start in the middle of the arc and cut using the RT wheel until the cutter reaches about half way across each end hole. I did these at a cut of 1mm deep each time until it had penetrated thru (8mm), in fact I took mine to 9mm, but don't go much further or you will be cutting chuck jaws. It will also get you into the correct routine for which way to turn the RT wheel. That becomes critical, as you will see later.
So all you do is jump to the next sector and repeat the same. This shot shows how far I went into the end holes.
Eventually you will have all the top arcs roughed out.
This is where the angles now come into play. 360/0, 60, 120, 180, 240, 300. and also the spoke offsets.
When the first outer holes were drilled, they had a positive offset of 6.5mm in the X axis, and the inner holes were drilled at 13mm from the centre of the wheel in the Y axis. Forget about the 30 degree setting for the inner holes, that is all taken care of. Just set up with 6.5mm offset, 38mm in the Y axis and 0 degrees on the RT.
So basically, with the cutter at the above setting, put a cut on and wind it fwds in the Y axis until you hit the hole at 13mm. Again, I tend to only cut part way thru the holes at either end. Keep repeating until all the way thru.
This is what it should look like while cutting. If you notice, the inner hole is automatically lined up.
Once you have completed one slot, move fwds 60 degs and do the next one using the same technique, carry on until all are completed.
Put the offset to minus 6.5mm in the X axis and repeat the same for the slots on the other side.
This is what it should look like for this operation.
Once you get to the bottom of the cut, the redundant middle bit SHOULD fall away, but sometimes they can fly, so be ready for it.
We have a rough flywheel. The next stage is to clean it all up.
So the cleanup begins. I fitted a correct sized END mill (8mm). What you will be doing is plunge cut the full depth, then proceed to cut along the slot edge until you reach exactly 13mm. I will only say this the once. NO CLIMB MILLING, use standard cut only. So that means, on the minus X offset, you move from 38mm to 13mm, on the plus offset, from 13mm to 38mm.
So using the same settings as the rough cut.
Plunge down until the cutter is just thru the spoke depth, then a nice smooth feed in the Y axis until you reach exactly 13mm, then retract the cutter. Do your 60 deg fwds feed on the RT and repeat until all sides are done. Put the X axis onto the positive offset, and starting the cut at 13mm, move to 38mm. Repeat as before for all six.
We now need to clean up the 13mm holes, So using 30, 90, 150, 210, 270 & 330 degree settings, we are going to plunge down each hole to clean them up.
Set up with zero X offset, Y distance to 13mm, and just plunge thru with the cutter at the above angle settings.
The next bit is cleaning up the outer radii. So X offsets to 0, and Y to 38mm. Again this is a bit of an eyeball job, you take the cutter until it just touches the original walls of the drilled holes. To do a standard cut you should be moving from the left hole to right. So plunge cut as close to the left hand hole as possible and wind until the cutter is in the correct hole position, then gently wind on the RT until you reach the other hole.
If you do it all right, you should end up with a flywheel that requires very little hand dressing to get it looking great.
Unlike myself, who turned the handle the wrong way and cut in to one of the spokes, no excuses, I balls up at the final hurdle.
I did a quickie rescue job on it by putting the same cutout in each spoke, and in fact it looks rather good to my clapped out eyes.
Finished on the RT (maybe), time to do a bit of a tidy up on the lathe.
Remounted onto my favourite soft jawed chuck. Even though the chuck had been off the lathe, after it was remounted in the same position, it was still spot on.
A quickie grind up of a quarter round edged boring tool (make 'em up as you need 'em).
It blended the spoke outer faces nicely into the rim.
Remounted and the hole opened up with drills, boring tool to make sure everythin was straight, then cleaned up with an 11mm chucking reamer.
I didn't go any further as I need to fit a brass hub to the flywheel, and I am a bit undecided what type of clamping device would be best. A grubscrew is easy but crap looking, a taper lock looks the part and does a grand job of keeping everything from wobbling. So a decision will be made when I have had a good look at the full sized engine plans.
I think you must all be thinking, 'all that crap just to make a flywheel'.
In fact it is a lot more difficult to describe how to do it, than it is to actually make one.
If you followed these posts to the letter, you should end up with the flywheel I need to make. This is just an exercise to show you all the different things that are involved, not for you to make one. It is the principle you need to get your heads around. If you can do that, flywheel making becomes just another job.
The final bit of this project will be shaft fixing and bling.
John
