Author Topic: Rockerblock engine--something a little different--  (Read 3821 times)

Offline Brian Rupnow

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Rockerblock engine--something a little different--
« on: April 22, 2017, 06:59:07 AM »
And I do mean different. I want to machine something---but--Something I haven't seen or done before. This is destined to become a water-jacketed engine, 1" bore x 1.125" stroke. I have been casting around for something new to build, and I thought this up last night while fighting off my insomnia. A couple of hours spent on the CAD system this evening just to see if it could be done, and yes, it can. There will probably be many redesigns and changes along the way, but basically this is the overall framework I will stick to.

Offline Brian Rupnow

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Re: Rockerblock engine--something a little different--
« Reply #1 on: April 22, 2017, 07:00:39 AM »
And yes, I'm even toying with the idea of water-jet cut flywheels.

Offline Brian Rupnow

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Re: Rockerblock engine--something a little different--
« Reply #2 on: April 22, 2017, 07:03:41 AM »
Well Sir, This is getting exciting. I love it when a plan begins to come together.


Offline Brian Rupnow

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Re: Rockerblock engine--something a little different--
« Reply #3 on: April 22, 2017, 07:04:27 AM »
Now my engine can breath in and breath out. Another hours work and it will have ignition.--And yes, it does even have pushrods.--Little short ones at that, with little swivels where they attach to the rockers to take out any binding.

Offline Brian Rupnow

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Re: Rockerblock engine--something a little different--
« Reply #4 on: April 22, 2017, 07:05:05 AM »
I almost got caught. Look at the creative carving I had to do on the bottom of that water jacket to clear the revolving crankshaft.

Offline Brian Rupnow

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Re: Rockerblock engine--something a little different--
« Reply #5 on: April 22, 2017, 07:05:42 AM »
Pete--There is no pressure in the water reservoir. As long as it doesn`t cut thru and leak water, there isn`t any problem. Speaking of the water jacket, my plan for sealing the jacket to the o.d. of the cylinder is shown in this section view of the water jacket. An annular groove cut at each end, just slightly shallower than the cross sectional thickness of a .094 Viton o-ring. Hopefully an o-ring in each groove will seal any water leaks. I will be able to get two or three bolts thru from the flange on the cylinder  into one end of the water jacket to keep it from turning on the cylinder.

Offline Brian Rupnow

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Re: Rockerblock engine--something a little different--
« Reply #6 on: April 22, 2017, 07:06:24 AM »
Well Hot-Dog!! I even managed to sneak an ignition cam and my old stand by Chrysler ignition points in behind the offside flywheel.

Offline Brian Rupnow

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Re: Rockerblock engine--something a little different--
« Reply #7 on: April 22, 2017, 07:07:06 AM »
There. That's a solid 8 hours playing. I have to dwell a bit on whether or not I have the crankshaft counterbalances on the correct side of the crankshaft or not, but other than that and a gas tank, the engine design/modelling is finished. Now I have to go shovel out the end of the driveway. We got 5" of April Fools last night. Yuk!! I was hoping we were done with that white stuff!!

Offline Brian Rupnow

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Re: Rockerblock engine--something a little different--
« Reply #8 on: April 22, 2017, 07:07:44 AM »
I always think it sucks to design a nicely proportioned engine, and then stick a gas tank on it. Gas tanks don't leave you with a whole lot of options. They have to be near the carburetor, they have to set below the carburetor throat (but not too far below), they shouldn't block any other equipment which needs frequent adjusting, and they shouldn't be directly in line with the exhaust. That being said, you just do the best you can and hope it doesn't ugly things up too much. This is not an improvement over the normally configured gas engine. It's just a different, artsy fartsy way of doing it.

Offline Brian Rupnow

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Re: Rockerblock engine--something a little different--
« Reply #9 on: April 22, 2017, 07:08:59 AM »
--I've been trying to wrap my head around your concept of reversing the crankshaft counterweights. I have three books here that deal with balancing of small engines, and they are all rather vague. In a vertical cylinder engine, if you remove the piston rings and assume no friction whatsoever, then when the piston is at mid stroke, the counterweights on the crankshaft should, theoretically balance the piston and connecting rod perfectly so that the piston doesn't fall any farther under the influence of gravity, and so that the weight of the offset in the crankshaft doesn't cause the piston to raise back up in the cylinder due to gravity acting on the offset weight of the crankshaft throw.--When you have a horizontal cylinder, then a lot of that reasoning goes out the window, because gravity isn't really acting to move the rod and piston one way or the other, although it still acts on the offset weight of the throw on the crankshaft.  Indeed, the biggest job of balancing that the crankshaft counterweights have is to balance the con-rod journal and the portion of the "throws" that support it on the far side of the crankshaft centerline. In a perfect world, if you set the crankshaft alone on a pair of knife edges, it should be perfectly balanced with no tendency to roll one way or the other because of a "heavy" side. If there is a heavy side to the crankshaft, or due to the weight/drag of the piston in the cylinder, the twin flywheels should compensate for that. The fact that the engine is intended to be a "low speed" engine also does a lot to nullify any great "out of balance" issue. The bottom line is that I don't really know. I'm just running my mouth here. I know that the counterbalances make the crankshaft "look better" to my eye anyways. I think in the end the only way I'm going to know is to build it and run it, and then perhaps I'll know. I always bolt my engines down before I fire them, so even if it is out of balance, it won't run off the end of my reference table and fall on my foot.

Offline Brian Rupnow

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Re: Rockerblock engine--something a little different--
« Reply #10 on: April 22, 2017, 07:09:29 AM »
I ended up having to angle both the exhaust and the carburetor out 12 degrees from centerline to clear the gas tank. I could have squeaked by with leaving them "in line" but it would have been severely crowded, and since I have to make the yellow "elbows" anyways, I might as well do this and buy a bit of room.

Offline Brian Rupnow

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Re: Rockerblock engine--something a little different--
« Reply #11 on: April 22, 2017, 07:10:02 AM »
Has anybody used this type of con-rod connection at the crankshaft? I'm pressed for room where my rod attaches to the one piece crankshaft, and this would get me out of trouble. I think the actual hole for the rod journal would be the last step in the fabricating operation so everything would run true. I haven't used this before, but there's a first time for everything.--Brian

Offline Brian Rupnow

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Re: Rockerblock engine--something a little different--
« Reply #12 on: April 22, 2017, 07:10:47 AM »
Dang, this thing is like a big chocolate cake!! All the pieces look so good, I don't know where to start. The beauty is in the simplicity. I shouldn't get so excited about my own work. Every time I do this I swear to myself that I'm going to take it easy, there's no rush, I'll just work on it in my spare time. Then it takes over my life and making another part is all I can think about. Good wife is away at her job in the local library, and won't be home until 3:00, so I think I'll make gears today. Gears are always fun. A bit intimidating, but fun, nonetheless.

Offline Brian Rupnow

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Re: Rockerblock engine--something a little different--
« Reply #13 on: April 22, 2017, 07:11:26 AM »
The only real bad dancer I had was the first "Rupnow Engine" which was a horizontal hit and miss single with a set of flyball govenors. It had full diameter brass discs for crank throws, and they were heavy. Since I always bolt or clamp my engines down, I never realized how badly out of balance those full discs made it. A guy from Australia built it and posted a video of it "walking" across his fathers living room floor. He hadn't bolted the engine down when he started it, and they were all amazed to see an engine take off and try to walk back to Canada by itself.

Offline Brian Rupnow

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Re: Rockerblock engine--something a little different--
« Reply #14 on: April 22, 2017, 07:12:00 AM »
What good is a build thread without "in process" shots? This is my 50 tooth gear, emerging from another "chucking stub" left over  from making a cast iron cylinder. It was barely, barely long enough. I hate doing really short stubs, because if you get to close to those hardened chuck jaws with the gear cutter you can kiss $80 goodbye. The 25 tooth gear which I will do next is on a comfortably longer piece of 1045 steel that was left over from a customer job.

Offline Brian Rupnow

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Re: Rockerblock engine--something a little different--
« Reply #15 on: April 22, 2017, 07:12:29 AM »
So--Today we made a start. I like cutting gears. I especially like making gears from left over bits and pieces that I have laying about. I always drill a pair of holes the calculated distance apart in a piece of scrap and fit the gears to shafts which set in the reamed holes. It is much better to do it this way and correct any "tightness" in the mesh, rather than trying to do it in a partially assembled engine. These gears seem to be "just right", although that is never a certain thing.

Offline Brian Rupnow

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Re: Rockerblock engine--something a little different--
« Reply #16 on: April 22, 2017, 07:13:02 AM »
The crankshaft is a much more convenient place for the points. True, you get a spark with every engine revolution, but so what? There is nothing in the cylinder to burn on the exhaust stroke, so it doesn't matter. This is known as a "waste spark" ignition.  Almost all of my single cylinder engines are built that way.--Brian

Offline Brian Rupnow

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Re: Rockerblock engine--something a little different--
« Reply #17 on: April 22, 2017, 07:13:36 AM »
I think that to make the con rod a two piece like I'm thinking of, two separate pieces would have to be machined and bolted (and possibly dowelled) together as shown in the first picture. Then after they are firmly bolted and possibly dowelled together, the hole gets put in as shown in the second picture. The sides would have to be match marked to make sure they went back together the same way they came apart. Then they could be separated and put back together around the rod journal.


Offline Brian Rupnow

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Re: Rockerblock engine--something a little different--
« Reply #18 on: April 22, 2017, 07:14:05 AM »
Here is a cross section thru the centerline of the engine. You can see how tight it gets between the rod cap and the underside of the water jacket. Of course, since it is a pressed together crankshaft, I could use a conventional closed rod end and assemble the rod when the crankshaft is pressed together. there's just something about doing that that makes me quiver all over----

Offline Brian Rupnow

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Re: Rockerblock engine--something a little different--
« Reply #19 on: April 22, 2017, 07:14:47 AM »
Nope, flywheels won't drag. Won't clear by very much, but won't drag either.

Offline Brian Rupnow

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Re: Rockerblock engine--something a little different--
« Reply #20 on: April 22, 2017, 07:15:36 AM »
Okay--Back to business. Immediately after I had machined the gears my phone rang about 5 times in a row, each time with a customer I couldn't turn down, and each customer wanted to be looked after "right now". Being a slave to my bank balance, I said yes to all of them, and haven't had time to play "small engine" since. I have discovered one thing, and I'm not sure yet whether it is really a problem or not. When I make built up crankshafts from 3/8" diameter stock, I ream the holes which I am pressing shafts into with a 0.3735" reamer. I use 3/8" drill rod for the shafts, which always seems to come in at .0005" oversize. This gives a VERY hard press fit, with .002" interference, and I have never had one "slip" after the fact. I don't use 3/8" cold rolled steel because it comes in at about .0005 to .0001" undersize, and though it does give a press fit, it is quite a light press fit, and it WILL slip after the fact. Last year I purchased a 0.4985" diameter reamer in case I wanted to make a crankshaft using 1/2" nominal shafting. The problem is, that I just stopped at my metal supplier today  and micrometer measured all of their "01" drill rod, and it all comes in exactly at 0.500" diameter. So--I will only achieve a .0015" interference fit. I have to think on this a bit before I proceed. ---Brian

Offline Brian Rupnow

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Re: Rockerblock engine--something a little different--
« Reply #21 on: April 22, 2017, 07:16:11 AM »
What to do--What to do??--Well, we'll make a little test. I drilled and reamed a 0.4985 hole in a piece of 3/8" mild steel, and I turned a very slight "lead" on the end of a piece of 1/2" drill rod, and I pressed it to see what happens. This type of pressing can not be done on a manual arbor press. It gets done in my vice. This was tight, but not "Oh my God, I've just given myself a hernia" tight. (That's the way it is with a .002" interference.) So, to farther quantify the results (We're getting really scientific here), I put the piece of plate in the vice, clamped my vice grips on the 1/2" round stock, and gave it the old "Reef your guts out" test.--And it slipped---Just like I thought might happen. The fit is tight enough to withstand moderate abuse, but not exceptional abuse such as backfire, pre-ignition, or nuclear Armageddon. I do however, think it would work fine if the components were cross drilled and pinned. Probably with .094" (3/32") dowel pins.


Offline Brian Rupnow

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Re: Rockerblock engine--something a little different--
« Reply #22 on: April 22, 2017, 07:17:05 AM »
I've been thinkin', Lincoln---if I do get the flywheels waterjet cut, why not do something fancy? so, I got my old Philip Duclos  book out and using the information in it, created curved spoke flywheels. I think it adds a lot of "pizazz" to the overall engine.

Offline Brian Rupnow

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Re: Rockerblock engine--something a little different--
« Reply #23 on: April 22, 2017, 07:17:39 AM »
I just ordered Jerry Howells gas valve plans and components to run this engine on propane, and ditched the gas tank. There is just too much beautiful "monkey motion" in those long rocker arms to cover them up with a gas tank, in my opinion. Also, if I do get the water-jet cut flywheels, there will be a relief machined in both sides to accentuate the spoked area.

Offline Brian Rupnow

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Re: Rockerblock engine--something a little different--
« Reply #24 on: April 22, 2017, 07:18:28 AM »
Running the engine on propane is not going to let me mix a little two cycle oil with the gas to keep the viton o-ring lubricated. The simple fix for this is to add a small oil cup with a very small "dribble hole" of about 0.030" diameter to the rear of the cylinder, tucked up tight against the back of the cooling water reservoir.  This will let enough oil onto the piston skirt with each revolution of the crankshaft to carry oil thru the rest of the piston stroke and spread it throughout the cylinder while the engine is running. This was very common on the old hit and miss engines.

Offline Brian Rupnow

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Re: Rockerblock engine--something a little different--
« Reply #25 on: April 22, 2017, 07:19:00 AM »
When  built my Kerzel hit and miss engine a few years ago, I intended to run cooling water in the reservoir to keep the cylinder cool, but I didn't want the cylinder to rust. So---Not knowing any better, I made the cylinder from 316 stainless steel and the piston from aluminum. This has proved to be a very good combination of materials over the years. It seems to work fine when using a Viton o-ring and a bit of oil in the fuel. I don't think I would want to try it with cast iron rings, but it worked great with the much softer Viton.

Offline Brian Rupnow

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Re: Rockerblock engine--something a little different--
« Reply #26 on: April 22, 2017, 07:19:34 AM »
I just got a price to waterjet cut 2 curved spoke flywheels.---$69.50 each. So----I called the guy up and whined at him. The price dropped to $49.50 each. That's 2 1/2 hours setting at my computer designing something for a customer. If I tried to machine them myself I might be 80 years old before I got them finished. I said "Go ahead and make them!!" This should be very interesting.

Offline Brian Rupnow

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Re: Rockerblock engine--something a little different--
« Reply #27 on: April 22, 2017, 07:20:19 AM »
Don't ask!! This is about one of those "Having your cake and eating it too" things.

Offline Brian Rupnow

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Re: Rockerblock engine--something a little different--
« Reply #28 on: April 22, 2017, 07:21:14 AM »
My "Gas demand valve" plans from Jerry Howell came today, along with some very small Tecumseh engine carburetor needle and seats parts and a diaphragm. The detail drawing of the parts I have to make seem to be well done, but it's pretty damned sparse on assembly drawings. In fact, there are no "assembly drawings" as such, just printed instructions that eventually make sense after you have read them and taken all the tiny parts out of the bags and studied on them to see how this thing works. Apparently I now have to buy a propane regulator to use with this thing, and I have no idea what that will cost, but will try to find out tomorrow. I had an email today from the waterjet cutter saying I could pick up my curved spoke flywheels tomorrow, so I'm fair excited about that. I am going nuts right now with design work, to the point where I can't get time to do my own "hobby" stuff.

Offline Brian Rupnow

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Re: Rockerblock engine--something a little different--
« Reply #29 on: April 22, 2017, 07:21:57 AM »
Today we are talking "beautiful things". I went this morning and picked up my waterjet cut flywheels. Man, are they ever nice. These are 3/4" thick mild steel, and the finish on the inside of the cutouts is very, very nice. The man who cut them said he can cut up to 6" mild steel. I will be machining the outside diameter, the 3/8" bore thru the center, and will take a 3/16" deep "face" cut on both sides in the spoke area. I may paint the parts of the flywheel I don't machine. These flywheels are 4 7/8" diameter and have about 1 1/8" diameter inside the cutouts in what will become the hub area. These are the first parts I have had waterjet cut, and although they are pretty, they are not for the faint of wallet. I paid $90 for these two. Fortunately, I got a $100 bonus last week for finishing a "panic" design job ahead of schedule.--that worked out well!!! Laying on my old blue steel handbook you can see my two finished crankshaft webs. If anybody wants the dxf file for these flywheels, email me at brupnow@rogers.com and I will send it to you. I have to give credit to Philip Duclos for the pretty shape of the spokes/cut-out areas. I didn't copy his numbers, but his "How to" article in "The Shop Wisdom of Philip Duclos" was certainly a big help to get me started in the right direction.---Brian

Offline Brian Rupnow

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Re: Rockerblock engine--something a little different--
« Reply #30 on: April 22, 2017, 07:22:32 AM »
I'm going to get bold here, and do something I haven't done before. Since my crankshaft is built up from individual components pressed, Loctited, and possibly pinned together, I'm going to make up a one piece con-rod and assemble it with the crankshaft. If it works, then great, I'm way ahead of the game. If it doesn't, all I've wasted is a bit of time. Since this is a "demonstration" engine and is not going to see long hard hours of use, I'm not going to run any bearings on the con rod. Aluminum rod running on steel crankshaft lasts a long time if it is kept well lubricated.

Offline Brian Rupnow

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Re: Rockerblock engine--something a little different--
« Reply #31 on: April 22, 2017, 07:23:02 AM »
I'm not blazing thru this build like I have some others, but I did manage to get some machining time in today. The con-rod still has to have the center relieved, but at least I did something. I can't assemble the crankshaft until I have the con-rod finished so I thought this had better be a priority.

Offline Brian Rupnow

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Re: Rockerblock engine--something a little different--
« Reply #32 on: April 22, 2017, 07:23:38 AM »
I got so tired of bodging up temporary fixtures to relieve the center portion of connecting rods that today I actually took an hour and built a dedicated fixture for it. I will post a clearer picture of it when I get the other side of the rod finished. It works like a charm.

Offline Brian Rupnow

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Re: Rockerblock engine--something a little different--
« Reply #33 on: April 22, 2017, 07:24:06 AM »
This is the finished con-rod, along with a shot of the fixture I made for relieving the section of rod between the two end bosses. The round rod in the center is turned to 3/8" x about 0.290" long. The remainder of the round rod is 9/16" diameter and passes thru a 9/16" reamed hole in the flatbar, and is welded a coupe of places on the side which fits into the chuck. The other bolt passes thru the far end of the con-rod and holds it snug against the flatbar, with the help of a flatwasher. The piece of flatbar which sticks out on the other side of center gives the fixture balance and can be tapped anywhere to accept a different length con rod.

Offline Brian Rupnow

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Re: Rockerblock engine--something a little different--
« Reply #34 on: April 22, 2017, 07:24:54 AM »
The first stage of crankshaft assembly is completed. There is a lot going on here!! The large shaft is an alignment shaft only, turned to be "size on size" with the largest holes in the web plates---not a press fit, but a damned close sliding fit. The small shaft is a piece of 3/8" drill rod, at about half a thou oversize. It is a hard press fit (with 638 Loctite) into and thru the first web plate (0.3735" hole), then wiped down with solvent, then oiled and fit thru the bore of the con-rod, then wiped down with solvent a second time and coated with Loctite 638, then pressed thru the second web plate.  You don't see it, but there is a "washer" made from cardboard cereal box at 0.018" thickness setting on one side of the con-rod, because the con-rod is squeezed in there very tightly. After an overnight dry, I will make both ends of the crankshaft in one long piece and press it thru all in one blast. After the Loctite on it sets up, I will mill the piece out from between the web plates. Then I will soak the entire thing in water for a couple of hours to dissolve the cardboard washer and give the con-rod some side clearance. One thing to note---When you ream a con-rod to 0.375" diameter, a 0.3755" diameter rod will not fit thru it without pressing. I had to open the bore in the con rod by about .0005" to get a proper fit over the .3755" drill rod. I don't have any oversize reamers, so had to do a lot of persuading to get the bore opened out. This type of "persuading" is accomplished by sanding a taper on a piece of the drill rod in the lathe, coating it with cutting oil, and then CAREFULLY working the rod up and down the taper until it slides over the main diameter.

Offline Joules

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Re: Rockerblock engine--something a little different--
« Reply #35 on: April 22, 2017, 08:29:43 AM »
VERY nice...  Wish I had the time, skill and local water jet cutter I could haggle with...   :thumbup:
Just get doing and make swarf, you can decide what its going to be later.   :thumbup:

Offline Brian Rupnow

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Re: Rockerblock engine--something a little different--
« Reply #36 on: April 22, 2017, 11:43:44 AM »
I turned the ends of the main crankshaft down to match the 12 mm sealed ball bearings (that I already had) and left it full diameter in the center area that had to be press fitted to the webs. I coated the critical areas with Loctite 638, and since I have a limited throat opening on my vice, I did it in my two ton arbor press with a cheater bar about 3 foot long on the handle I had prepared a brass "cup" to fit over one end and had my 3 pound hammer ready in case I needed to do some constructive pounding to get things into home position, but they slid right into place on the arbor press, no "pounding" was needed. After pressing  things into place, I set it up in the three jaw and checked for runout. Right now it has .008" total indicated runout, which isn't that bad. I just need that figure for comparisons sake when I mill the center portion out tomorrow. If it moves enough to trouble me, I will give it a few good whacks with the dead blow hammer to bring it "true". The jury is still out on whether or not I'm going to pin this crank together or not. Photobucket is being oinky today, but I will put up a picture when it decides to work for me.
« Last Edit: April 22, 2017, 06:15:00 PM by Brian Rupnow »

Offline Brian Rupnow

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Re: Rockerblock engine--something a little different--
« Reply #37 on: April 23, 2017, 08:49:09 PM »
My little pile of parts is growing. Today I will finish off the crankshaft, and build the engine sideplates. I made the rocker yesterday afternoon, and for a simple enough part, there are a world of set-ups in it. I used my new con-rod fixture to relieve the material around the bosses on each side of the rocker, and it worked great for that too.

Offline Brian Rupnow

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Re: Rockerblock engine--something a little different--
« Reply #38 on: April 23, 2017, 08:49:49 PM »
And just for the fun of it---here is the crankshaft, luxuriating in it's custom made water filled bath-tub. (which may have been a juice bottle at one time.) I trimmed away all of the unwanted parts this morning. Right now the con-rod appears to be Loctited to everything else, but I'm hoping that with a four hour soak, the .016" cardboard washer on one side of the con-rod will dissolve, and I can break the con-rod free of everything else. I may have to apply a little heat to the center of the con-rod and let it work its way down until the con-rod lets go and decides to turn for me.

Offline Brian Rupnow

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Re: Rockerblock engine--something a little different--
« Reply #39 on: April 23, 2017, 08:50:33 PM »
Well there!! I've had as much fun as I can stand for one day. Those sideplates aren't quite finished yet, but they are awfully close. I'm tuckered out.

Offline Brian Rupnow

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Re: Rockerblock engine--something a little different--
« Reply #40 on: April 23, 2017, 08:51:05 PM »
After a nice break and a drive with good wife, I had to come down and check on the state of my crankshaft, which has been basking in its own private bathtub. The water didn't have as much effect on the cardboard "washer" as I had hoped for. The next trick was to put one end of the crankshaft in my shop vice with aluminum soft jaws and carefully apply some heat to the center of the con-rod, while applying fairly gentle pressure on the con-rod. Once the heat migrated down the con-rod and softened up the Loctite which was preventing it from moving, it began to move freely, and I immediately squirted everything with lubricating oil to keep the heat from affecting the crankshaft itself.  The rod now moves freely. I set the crankshaft up in my lathe and put an indicator on it to see if the runout had changed after I cut the center out between the web plates. I discovered that this crankshaft is quite a "flexible flyer". Initially it had about .015" total indicated runout. I grabbed the free end and gave it a tug in the direction it had to move and after doing that a couple of times I had it down to .004" total indicated runout.  I had read before about how flexible these single throw crankshafts are, and as I understand it some snowmobile crankshafts with integrated connecting rod are adjusted for runout in the same manner. At any rate, I'm happy, and I think the crankshaft will work fine. I'm not going to pin the pressed connections. Both the rod journal and the crankshaft itself are small enough that I don't want to weaken it by drilling for pins.----Brian

Offline Brian Rupnow

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Re: Rockerblock engine--something a little different--
« Reply #41 on: April 24, 2017, 07:01:59 PM »
Those curved spoke flywheels are really, really nice.--But---Oh my God--What horrible little piggies to machine. The worst part is figuring out where to start. I opted to plunge at the major diameter of the recess in the side of the flywheel. Just because of the geometries involved, you can only plunge about 0.050" before the heel of the parting off tool starts to drag. Then you move in towards center the width of the parting off tool you are using to plunge with and plunge again. Moving back and forth between the two positions you keep plunging until you reach the depth you were aiming for. Then grind an HSS tool with the cutting face reversed to what you would normally see, and cut in towards the center in auto-feed mode, taking 0.010" depth of cut. This requires nerves of steel and eagle eyes on the digital readout. When you get about .050" from the minor diameter of the recess in the face, kick out the automatic feed and take the last .050" by hand feed. I have one side of one flywheel finished. I'm going upstairs now and have a strong drink now to calm my shattered nerves.
   

Offline AdeV

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Re: Rockerblock engine--something a little different--
« Reply #42 on: April 25, 2017, 12:33:31 AM »
You need one of these Brian:

http://www.ebay.com/itm/391730204091

See attached (large) pic for details. It takes a V-bottomed insert, so you can plunge AND cut sideways with it. SO with that particular tool, you'd plunge at between 60-75mm diameter, then cut inwards/outwards as required. That particular one is a bit of a fat one - requires a 6mm wide insert - they come in anything from 3mm upward (insert width).

I have several of these tools, but never actually found a use for them... maybe I need to set up a flywheel relieving service  :D
Cheers!
Ade.
--
Location: Wallasey, Merseyside. A long way from anywhere.
Or: Zhengzhou, China. An even longer way from anywhere...
Skype: adev73

Offline awemawson

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Re: Rockerblock engine--something a little different--
« Reply #43 on: April 25, 2017, 02:27:54 AM »
Brian, could you not have machined it on the vertical milling machine on a rotary table with less strain on your nerves?
Andrew Mawson
East Sussex

Offline Brian Rupnow

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Re: Rockerblock engine--something a little different--
« Reply #44 on: April 25, 2017, 09:00:28 PM »
Brian, could you not have machined it on the vertical milling machine on a rotary table with less strain on your nerves?
Awemawson--The thought did cross my mind. I opted for the lathe because it is marginally quicker. I have a 3 jaw chuck mounted on my rotary table, and I think that with the reverse jaws it could hold the part. Even so, considering a .010" depth of cut and a 3/4" endmill, that's a lot of cranking to put in a recess 1/4" deep.

Offline Brian Rupnow

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Re: Rockerblock engine--something a little different--
« Reply #45 on: April 25, 2017, 09:03:13 PM »
How do I enable email notification of new posts in a thread I have started? I can't seem to find how to do that.---brian

Offline awemawson

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Re: Rockerblock engine--something a little different--
« Reply #46 on: April 26, 2017, 02:15:28 AM »
At the top of the very first posting in the thread there is a 'Notify' button.
Andrew Mawson
East Sussex