Author Topic: Rockerblock I.C.--Something a little different-  (Read 45227 times)

Offline Brian Rupnow

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Re: Rockerblock I.C.--Something a little different-
« Reply #60 on: April 21, 2017, 10:13:01 PM »
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 b.lindsey

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Re: Rockerblock I.C.--Something a little different-
« Reply #61 on: April 22, 2017, 01:44:57 AM »
Things are looking good Brian and those flywheels look amazing!!

Bill

Offline Brian Rupnow

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Re: Rockerblock I.C.--Something a little different-
« Reply #62 on: April 22, 2017, 01:50:14 AM »
Thank you, Bill. If they ever hang me it won't be for not trying something new. On every one of my builds I try and expand my knowledge base and my machining skills. Sometimes it works------

Offline Brian Rupnow

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Re: Rockerblock I.C.--Something a little different-
« Reply #63 on: April 22, 2017, 04:43:04 PM »
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 24, 2017, 01:48:32 AM by Brian Rupnow »

Offline Roger B

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Re: Rockerblock I.C.--Something a little different-
« Reply #64 on: April 23, 2017, 08:32:58 AM »
Still following along  :ThumbsUp:  :ThumbsUp:  :wine1: That water jet cutting looks interesting  :headscratch:
Best regards

Roger

Offline Brian Rupnow

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Re: Rockerblock I.C.--Something a little different-
« Reply #65 on: April 23, 2017, 12:13:55 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.
« Last Edit: April 24, 2017, 01:48:58 AM by Brian Rupnow »

Offline Brian Rupnow

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Re: Rockerblock I.C.--Something a little different-
« Reply #66 on: April 23, 2017, 01:40:45 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.
« Last Edit: April 24, 2017, 01:49:27 AM by Brian Rupnow »

Offline Brian Rupnow

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Re: Rockerblock I.C.--Something a little different-
« Reply #67 on: April 23, 2017, 10:43:12 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.
« Last Edit: April 24, 2017, 01:50:08 AM by Brian Rupnow »

Offline crueby

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Re: Rockerblock I.C.--Something a little different-
« Reply #68 on: April 23, 2017, 10:44:43 PM »
They look great! Lots for one day!

Offline Brian Rupnow

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Re: Rockerblock I.C.--Something a little different-
« Reply #69 on: April 24, 2017, 01:47:00 AM »
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
« Last Edit: April 24, 2017, 01:50:51 AM by Brian Rupnow »

Offline Ian S C

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Re: Rockerblock I.C.--Something a little different-
« Reply #70 on: April 24, 2017, 12:21:31 PM »
Even in a big Ruston Hornsby 6HR(28HP, 6ft flywheel), the crankshaft can bend quite a bit, a gauge is supplied to measure the gap between the inside of the crank cheeks, crank up measure, crank down, measure, adjust outboard bearing height, and measure again until the distance  is equal.
Ian S C

Offline Brian Rupnow

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Re: Rockerblock I.C.--Something a little different-
« Reply #71 on: April 25, 2017, 12:01:10 AM »
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 Ian S C

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Re: Rockerblock I.C.--Something a little different-
« Reply #72 on: April 25, 2017, 01:18:57 PM »
Brian, the way I turn flywheels is to use an ordinary general purpose tool torough out most of the bit between rim and hub, I then change to a boring bar to clean up toward the rim. I then move the boring bar past the hub, reverse the rotation of the chuck, and very carefully(screw on chuck)finish up to the hub.  Preferred tool HSS. Have not thought of using a parting tool, might try it next time.
This is going to be a great wee motor, most interesting.
Ian S C

Offline Roger B

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Re: Rockerblock I.C.--Something a little different-
« Reply #73 on: April 25, 2017, 01:52:29 PM »
I use a boring bar to work out from the hub and then use a normal LH tool to work back in. The angle on the back of the boring bar will determine how far you can go in before you change tools to clean up back to the hub. I hope the pictures make things clear.
Best regards

Roger

Offline Brian Rupnow

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Re: Rockerblock I.C.--Something a little different-
« Reply #74 on: April 25, 2017, 09:11:26 PM »
Great ideas guys. I like the boring bar trick.---thank you.---Brian

 

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