T head engine by Brian

[brian Rupnow]

I am now at the "What do I do next" phase of this build. The only outstanding things are the flywheels, the gear cases and the rings and the gaskets. I don't really want to do anything on the cast iron rings until the flywheels have been machined and mounted. This leaves only the gear cases to be machined, so that is where I will start my next round of machining. the two gear cases will have a slight difference, because one has to be cut away on the bottom side to clear the ignition points. This will mean purchasing a foot of 2 1/2" x 1" aluminum flatbar. I'm beginning to get enquiries from old customers about design work. I don't really want to turn them down, because if it worked out right I might buy a real vertical metal cutting bandsaw. The saw I have now is an old wood cutting bandsaw that I modified to cut metal

[brian Rupnow]

Decided to get up off my lazy butt and actually do something this afternoon. I purchased some 2 1/2" x 1" aluminum bar, cut it to two lengths, laid the outline on it with a template, then set it up in my milling vice and used the DRO to position things accurately. The template helps me figure out what I'm doing, and gives me a visual check, to see if my DRO is giving me the same information. The 0.201" bolt holes were drilled and a 1/2" drill ran thru at the appropriate centers. Next trick will be to mount the pieces one at a time in the four jaw lathe chuck and bore the blind cavities that the gears fit into as well as the thru holes where the gear hubs stick through.

[Willy]

I can almost smell the exhaust fumes.

[brian Rupnow]

First I bore the blind hole for the big gear---then I bore the blind hole for the small gear. Then after much sanding, filing, and sanding some more I have an awesome set of gear guards.

[aostling]

It's a beautiful 16cc engine, and looks almost ready to pull a load.

[DrMike]

Nicely done, Brian

[rdfeil]

Outstanding

[Willy]

Yes very nicely done.
First class and in keeping with the rest of this massive little engine, looks industrial.
No shoddy tin can gear covers for Brian, gear housings by golly!

[brian Rupnow]

The gear guards certainly will protect fingers. Oddly enough, that's not the real purpose I put them on there. I find that exposed spur gears make a terrible lot of noise. It seems that if they have a guard made of brass or aluminum (not sheet metal) around them, it quiets them down a lot. and they certainly make the engine look more robust. I am now at the point where I have nothing left to make except the cast iron rings. Earlier this year I did a thread on making my own cast iron rings. There was a great deal of trial and error, but I finally did successfully make a set that worked very well on one of my 1" bore engines. I made a lot of notes about what I did, and I still have all the fixtures I used. This engine is also a 1" bore, so I'm hopeful that I learned enough from my previous ring making exercise to do it again. I'm still waiting to hear from the flywheel people---they are supposed to contact me when the rings are shipped.

[brian Rupnow]

Okay, here's what we've got going. Thats a piece of 1 3/8" diameter grey cast iron in the chuck. The o.d. is turned down to the diameter of the cylinder, not the piston. My rings are going to be .038" (1 mm) thick radially so the inside is drilled out to 0.925" diameter. The o.d of what will become the rings is polished with a fine whet stone, or a piece of 400 grit paper backed up by a file or piece of flat-bar. This time my rings are going to be 0.045" thick, and my specially ground cut off tool is 0.038" wide, so .045 plus .038 plus .003" to have a bit extra length equals 0.086", so thats how far I advance the carriage before taking another cut. The rod held in the tailstock chuck is something to catch the rings as they are parted off. I have to remember that each time I cut a ring off, I have to deburr the outside and inside diameter of the piece held in the chuck, so that at least one side of the ring is deburred.---It is remarkably easy to forget that step. Each ring will now be measured with my micrometer to make sure it is the right thickness, and then held in a fixture with a 0.020" deep x 1" diameter recess. It is then slid around in a figure 8 on a piece of 600 grit paper until it reaches the magic 0.045" thickness. Then it is fitted into the piston ring groove to make sure that it actually will go down to the bottom of the groove. My chuck has about 0.003" total indicated runout, so I cut off a bunch of rings while in this set up, because if I take that piece of round stock out of the chuck, I will never get it back in the same spot, and I don't want to make rings that are not truly concentric.

[Sparky_NY]

I see you are making quite a few extras. That will allow for a few rejects and still give you extra rings for future motors so you don't have to make rings every time. Just look at the money you are saving compared to when you bought rings !

[Willy]

.............
I have to remember that each time I cut a ring off, I have to deburr the outside and inside diameter of the piece held in the chuck, so that at least one side of the ring is deburred.---It is remarkably easy to forget that step.
....................

Whenever I part something like this off I do much as you do. I will also deburr the other outside edge after I'm into the cut about 10-15 thou. Much faster in the lathe and only leaves me one surface to deburr by hand.

Looking good Brian, we're getting close. We can hardly wait for you to breathe life into the engine.

[brian Rupnow]

We're up, up and away!! I managed to harvest ten rings. They were all deburred both sides, and the faces were sanded on 600 grit paper attached to a cast iron surface plate until they were 0.045" to 0.043" thick. They were all spread over a .150" diameter pin and sandwiched and clamped between two sides of a heat treat fixture. They are now in my heat treat oven, soaking at 1100 degrees for three hours. I decided that I didn't really like the "cleaver" that Trimble designed and I built, because it seemed to bend the rings a bit when it cleaved them. I ended up using a sharp cold chisel to "break" each ring, then filed the ends with a points file until they had the correct 0.004" end gap when installed in the cylinder.

[brian Rupnow]

I let the rings cool overnight in the heat treat oven, then this morning I brought the heat treat fixture into my office and disassembled everything. The rings and fixture look rather grotty, but they will all clean up nicely with a small brass brush and running water. You can see that all of the rings have now taken a "set" with the end gap at 0.150" which is the diameter of the post in the heat treat fixture.
I will give the rings one or two small swipes on 600 grit paper to get any residue off the flat surfaces, and give the inside of the rings a bit of deburring with my Dremel tool, then pick out the two I like best and install them on my piston.

[brian Rupnow]

Rings are cleaned up and two of them installed on the piston. I don't have a small ring compressor, so I used a trick I learned on one of the forums. Took a piece of 2" round steel x 1" long, drilled and reamed a 1.000" hole through it, then put a 25 degree taper on one side and sanded the transition smooth. Set it on top of the cylinder, started the piston with rings thru it. The 25 degree angle compressed the rings to 1" and the piston sticking out thru the bottom fit into the engine cylinder to line everything up. A few careful taps with a soft faced hammer and the piston with rings slid right into place. Hooked up the con rod to the crank journal, and everything goes round and round very smoothly.