Royal Blue #3

[rdean]

Since the lock down I have been staying close to the shop and needed something to make I built a David Kerzel hit miss engine from plans. This is where the Chinese got the design of one of their engines they sell. I stayed close to the plans on this engine with just a few changes.
That model went along very nicely and is very reliable and starts on the second spin. I have been able to slow it down considerably as most model engines run far too fast as compared to the full size engines of the same design.
During this time I had ordered a casting kit for a Bob Shores Eagle engine. That casting kit got delayed in Detroit for two weeks so the Kerzel engine got first in line. The Bob shores engine has since also been completed and it runs fine but still not slow enough to suit me. I used the plans as a suggestion and the castings as raw material to build an engine that does resemble the original but that is about all, I changed about everything.

So now I want to build an engine my way with no plans, no drawings, and my little experience. Come along and see how things progress as I started this project about a week ago and will bring you up to speed quickly.

I started with this big chunk of aluminum 3.5" X 3.5" with the idea of having a larger cooling water tank and a larger piston. I cut 5/8" off the top to make the top water cover.




As you can see I have done some sculpting on the sides and installed a cast iron piston liner.
I decided on a 1" diameter piston because that is all the bigger I can go with the size of the cast iron rod I have on the shelf to make the liner. Many of the dimensions and sizes of the parts will be determined by what materials I have on hand.

Here it is with the fancy top and painted Royal Blue, thats where I got the engine name. Why did I paint it now and not wait until after all the holes are drilled and everything fitted? I just can"t bring my self to disassemble something that is working perfectly fine just to paint it. This will also make me be more careful so not to scratch the paint.



A chunk of 2.300 diameter solid steel about 8" long.



I did not weigh it but it is a good chunk and inside there somewhere is a crank shaft. (I hope)

That's all for today.
Thanks for looking

Ray

 

[Eddyde]

Wow an ambitious project, I'm stay'n tuned!

 

[ShagDog]

Watching closely .

 

[rdean]

Crankshaft
This first picture shows how I set up the material to make the crankshaft. I first put the bar in the vise horizontally and milled a groove all the way down the material. This will be my index in order to mark the center line of the connecting rod journal. I had already center drilled the part on each end when I had it in the lathe. I then stood the shaft up vertically with the groove clamped in the vise jaw and then lined up the center drill with the center hole and zeroed the DRO. My engine will have a 1.5" stroke so from the shaft center I moved over in X axis 0.750 and center drilled that location. Take the part out of the vise and turn it over with the index groove against vise jaw as before. Now find the center on this end and then move over in X to -0.750 and drill the new center. Don't forget to move the other direction this time or you will be sorry later. After all that I put the part back down in the vise with the groove still against the vice jaw and hanging out the end far enough for the end mill. There is a lot of material that has to be removed to get down to the rod journal so I used an end mill to get rid of as much as I could.



Back to the lathe and a cutoff blade to cut away down to the rod journal.
For me this is the hardest operation using a parting tool on an interrupted cut and this took a long time and several different tools. Note that the part is now being swung from the offset centers.



This is what it looks like when you finally get the journal to size.
As you can see there is only the rod journal, 0.500 in diameter, holding the whole part together and could easily be broken or bent.



My solution was to clamp both throws in the 3 jaw chuck which took any strain off the rod journal. From here just make lots of chips but stop just short of your shaft size. Flip the part around and repeat on the other end.





Now take the part out and put it back between canters and gently cut to your final shaft size.
This is what it looks like now.



And here it is after I cutout some of the webbing, cleaned and polished it up.



The crankshaft is basically done except for cutting it to length, adding a taper to each end for the flywheels, and threading each end for the flywheel nut.
The crankshaft took me 3 days to complete and it only has one design improvement (screw up) but that won't matter.

Thanks for looking
Ray

 

[Nogoingback]

Great job! It looks as though this isn't the first time you've made a crank...

 

[macardoso]

Awesome job on the crankshaft! I bet the lathe was really shaking with the offcenter mass.

 

[ShagDog]

Speaking of lathes, Ray, what lathe are you using for this interesting build?

 

[rdean]

The lathe is an Enco 12X36 a picture of it is in my name tag at the left of the screen.
This is the third crankshaft that I have made and the speed was set around 200 rpms so no shaking.

Thanks All
Ray

 

[rdean]

I need to backup a little and show you the piston I made last week.


It is cast iron 1 1/4" long and 1" in diameter. I have the internal cuts done for the connecting rod but I haven't drilled the wrist pin hole yet. I did make a groove for a cast iron piston ring but making the ring is above my pay scale. I tried several of differing thicknesses and even though I was able to get the ring to expand and hold its shape I couldn't get it on the piston. It wasn't even close to going on when they would break in half. I was resigned to making another piston and using an o-ring when I dropped the piston into the cylinder hole while it was standing up. The piston would only drop about 1/2" and then stop until I would pick up the cylinder and then it would fall through and out the bottom. The piston and cylinder are such a good fit that the air could not escape and would hold the piston in position. If it works that good dry then how will it seal when wet with a gas and oil film? I am going to try it without a ring and see what happens, wish me luck.

Next are the side rails that the cylinder and the crankshaft are attached to. Since most things are designed as I go along I found that a material thickness of 0.400 would be ideal and since I had 0.500 aluminum plate I will use that.
This shows taking 0.100 off the plate but not all in one pass.

That cutting head does such a nice job that the plate was with in 0.004 all the way around and that is close enough for me.
I cut the plate in half and cut out a section for the cylinder to mount to.
Then cut everything down to where the center of the crankshaft is inline with the center of the cylinder.


Just a mock up of where everything goes for now with a lot of machining left to do on the rails.



Now we are up to date and thanks for looking.

Ray

 

[rdean]

Some progress today I cut out the main bearing caps from pieces that I removed from the side rails yesterday. I then drilled and tapped the holes for the bearing caps.





Over to the milling machine and bored out the side rails for the bearings.
The vice grips are there just for insurance so nothing will move.


Another mock up and check.



I said I would not be using drawings but I had to make one to determine the distance between the center of the crank and the rear of the cylinder. I needed to know if the connecting rod would hit the cylinder liner as it moved in and out. With an 1 1/2" throw on the crank the connecting rod makes quite a large arc but according to my calculations every thing should be fine. (I hope)

Thanks for looking
Ray