Sunday, October 30, 2011

Millie - Flywheel

Ok, as I've promised, I'm back in machining related posts from this post on. I've started on my very first engine, the simplest one I can find with the least parts - Millie. The Sherline distributor here, Mike of SG Tooling, gave me the kit many months ago but I've not the time to start building it.

I spent some bit of time on Saturday figuring out how to best convert the plan to metric. The rounding up and down of the dimensions are tricky; I need to make sure that mating parts still fit and work together after the conversion & rounding off. At the end, I decided to adjust as I move along.

I've the lathe just trammed and so decided to do the round parts first. I may even bore the piston hole on the brass cylinder on the lathe, if I feel I'm up to task later.

The OD of the flywheel was turned from the supplied 1" 12L14 steel rod to the 3/4" called for in the plan. in fact, I wanted 19mm instead of the 3/4" diameter (which converts to 19.05mm). But I went over a bit and ended with 18.92mm. I don't think this would affect the running of the engine. It will be left as that.

I went on with center drilling and drilling of the 1/8" hole for the crankshaft. I don't have a 1/8" reamer so the 1/8" drill will be it.

The crankshaft of 12L14 steel supplied was inserted into the drilled hole to test fit. The fit was a little loose. A little loctite will be used to keep it in place.

Before parting off, the recess has to be machined on the face. I wasn't sure how I should do this and so put my question on the groups after cleaning up. I was on the bed when I received replies to my post. Both Mr Kieffer & Mr Glickstein suggested using boring bar for the job. Why didn't I think of that?! I jumped off my bed and headed for the shop. My first attempt ended in failure.

I went back to bed as it was late, though still trying to think of a solution before falling asleep. Then, I remembered that I ever bought a grooving tool insert. That should be the right tool to use for this job. But it's too late to do anything; I was already too tired.

This morning I got up to complete the job.

The recess on one side is now done. Time to part it off.

Comparing with parting off aluminum rods, this was much easier and quick. Maybe because of the little experiences I gained, the operation went smoothly without a glitch.

I re-chuck the flywheel to work on the other side. In my excitement, I forgot to face it to the thickness according to plan. This, I don't think is critical. I align the flywheel in the 3 jaw by tapping on the face while the spindle turns. Didn't want to pull out the DTI as my shop time was running out.

Both sides now done. Instead of 1/4" (or 6.35mm) thick, I ended up with 6.59mm. The chatter mark can be seen near the hub.

Measuring the completed flywheel.

I'm going leave this flywheel as it is. Will decide if I need to make another one after I have the rest of the parts done. May even drill holes around the face to represent spokes of some sort.

Let's see when I've time in the shop this coming week to continue this project.

Have a blessed week.

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