The second one shows lapping of a crankpin to correct a misalignment where it fits in the flywheel which was picked up in the first video. It occurs to me that a similar technique could perhaps be used in your situation except you are correcting a issue with the shafts rather than the pin.
I am just guessing here but it might be worth checking out unless anyone has a better idea or if just careful reassembly reduces your run out to an acceptable level.
Slightly off topic: Bore: Why does it matter which end you bore a cylinder from if - you are holding on a surface with a known relationship to the cylinder and you are allowing for any error?
It's the "if" which can bite. The bore needs to be absolutely perpendicular to the crankshaft so the piston runs parallel to the bore. Provided the top face of the crankcase is parallel to the crankshaft (and MM's will be), the bottom face of the cylinder flange is also parallel to the crankshaft and forms the reference face for boring.
Thanks, but I'm set for now with the Kapton for the bearing but welcome ideas of a substance to paint on the camshaft that's insoluble in water but easily dissolves afterwards in acetone, ethanol, or whatever.
Originally Posted by Alan_nc
Why does it matter which end you bore a cylinder from if - you are holding on a surface with a known relationship to the cylinder
It doesn't matter if the top of the cylinder is accurately parallel to the base of the mounting flange. But, you can't count on that happening. Actually, it's best to count on it not happening. In the case of my Ariel I had to remove 0.015" from the base to make it parallel to the top face. Had I not done that, and if it were bored upside down. the cylinder would have ended up tilted by that amount with respect to the base. If that tilt all were in the side-to-side direction it would have forced the piston back and forth by that amount on each revolution.
It took ~150 ft.lbs. to loosen the nut holding the drive-side spindle then ~3800 lbs in the press to pop it loose.
With a torque wrench, big copper hammer, and more than a dozen trips between the lathe and vise, I now have the drive side wobble reduced from 0.016" to 0.0035". I torqued the nut in stages, each time measuring the wobble, marking with paint, and developing a calibrated hammer arm to whack it and remeasure to see what I had accomplished. Whacking components of a machine with a big hammer seems so very, very wrong.
I now hope someone like chaterlea25 with experience in such matters weighs in with advice on whether ~0.003" is enough for now, given I'll have to go through it again when the crankpin is installed, or if I need to continue until I get both shafts individually closer to 0.000" in order to ensure I'll be able to get the overall runout of the assembled flywheel no worse than 0.001".
While I had the spindle removed I used the opportunity to Magnaflux it and the flywheel. Both passed the test (I'll do the other flywheel/spindle and connecting rod later today, or tomorrow). I also used a wire brush and two hours in my favorite de-rusting solution to make the end of the spindle that sticks into the primary case look a lot better than it was.
p.s. several replies came in while I was composing my post off-line so I'll read them and watch those videos.
p.p.s. 0.016" at a distance 4" from the spindle means the the ~1" taper would have to have ~0.004" removed from it. Not only would that require a lot of lapping, it would make the taper too large for the spindle to fit without bottoming out on the shoulder before it was seated.
Last edited by Magnetoman; 12/24/1712:07 am. Reason: p.s., p.p.s. and torque/pressure paragraph
You're doing a cracking job MM. I am relieved that you are taking the trouble to double-check the balance calculations. Ideally, another technically minded peep would work through it independently. However, most of it is straightforward, and any error should be obvious as you go through it again. My query about the 38.9g was only that I couldn't see how it was being employed. My point about the mass of the small end bush is absolute, and I wouldn't like you to make calculations based on a false quantity.
I first converted all of your dimensions into cm:
conrod eye radius R = 1.508 R sq = 2.274
ID of original bush radius Ro = 1.270 Ro sq = 1.613
ID of reducing bush radius Rr = 1.032 Rr sq = 1.065
Cross sectional areas:
original bush = pi X (2.274 - 1.613) = 2.077
reducing bush = pi X (2.274 - 1.065) = 3,798
X - sectional difference between bushes = 1.71 cm sq
Now, say both bushes are just the width of the conrod = 2.210 cm
Volumetric difference = 2.210 X 1.71 = 3.78 cm3 X density 8.7 = 32.9g
This doesn't allow for the reducing bush extending beyond the limits of the small end eye.
I didnt see a 3rd finale to that lapping video, probably bell mouthed the female hole, the bigger OD cuts faster than the minor, where the paste goes is critical for lapping tapers. At work , the large machines ( 240 ton rotating mass, 500 rpm) were allowed 0.008" radial run out over a 26 foot shaft supported/ aligned by a taper fitted thrust collar, best I ever saw was 0.003 " , at 4 inches from the collar the runout would have been so low we would not have been able to detect it with the clocks we used.. The collar was stretched hydraulically and pushed down then retained by semi circular keys like giant circlip, To seat the collar the weight of the machine was allowed to bear on it as the pressure from the expander gear was relaxed, usually with a decent bang . Sometimes we honed keys , other times we used shims, 2 thou max., if a key was out by a 1/10 of a baw hair it would throw the run out . Not quite the same scale though! Does illustrate how the top register fit will influence final run out.
Last edited by gavin eisler; 12/23/1711:55 pm.
71 Devimead A65 750 56 Norbsa 68 Longstroke A65 Cagiva Raptor 650 MZ TS 250 The poster formerly known as Pod
I am relieved that you are taking the trouble to double-check the balance calculations.
Even though I might not immediately act or reply to them, I definitely appreciate all input and suggestions. I'm certainly not proceeding in a linear fashion through this rebuild but there are limits to my ability to multitask and work in parallel. This means when I've put something aside I might need to leave it dormant for a while. Earlier this month I was in the UAE and from there to Australia so in the runup to that long trip I devoted quite a bit of my time to getting items ordered so they could start arriving while I was away. I wrote the draft of the balance factor post at 30,000 ft. and then checked it while still jet lagged after my return from having gone through 24 time zones so would be disappointed, but not surprised, if an error slipped through.
Originally Posted by robcurrie
Rustoleum make a flexible rubber spray-on coating which can be peeled off.
'Flexidip'. Thanks for pointing that out. It looks like it might be perfect, as long as it doesn't leave too much residue behind in the nooks and crannies when it's pealed off. I'll buy a can and try it. Thanks again.
The connecting rod passed the Magnaflux test, leaving the timing side spindle and flywheel yet to test.
I'm not comfortable about the wire around the outside of the bearing. For one, it will have a higher potential than the bearing outer, distorting the migration, possibly even ending up welded to the bearing.
I'm trying to think of a way to put the cathode wires into a bearing, such that electrical contact is perfect to the outer race, without the wire itself interfering electrically.
I have a germ of an idea. Suppose the bearing is perfectly degreased. Then a multistrand copper cable is stripped back ~2", frayed out and the strands stuck in the bearing (maybe even anneal the strands) so that they jam between the balls and race, with a modicum of force to ensure contact. Wiggling back and forth with enough wires in enough places will get a jammed situation soon enough. This will give a more even potential around the bearing.
Now the insulated wire must be embedded in wax, with the bearing.
Then carefully remove the wax from the perimeter, now I'm losing faith!
This plating business is easier said than done, for instance you don't want copper on the bearings, the tiniest leak will allow that to happen. Interesting stuff.
MM, No, of all people you should know that potential difference changes with resistance, so for instance 4V supply when it gets to the bearing, could be 3.9V. Now, a 4V cathode vs a 3.9V cathode will make a difference, in ion migration. All I am saying is that the wire should be insulated from the electrolyte. Dave
Yes, but the contact resistance will be milliohms or less in air, let alone in a conductive solution, and the current less than 500 mA, so the potential drop will be less than a mV. This will have a totally negligible effect.
Fair dinkum, lets see. Where I'm coming from is to give you the best chance of an even coating of copper in the right place. It is all about how charged particles move in an electric field. A voltage of X will be imposed on the object, a similar voltage will exist on the wires leading to the object. The field around the wires will be more attractive to the cations than the more surface-rich object. I do think that the feed wires should be isolated from the electrolyte, but this is new to me too, but I do want you to be successful! Dave
"I'll curve the Cu anode into a cylinder"---from an earlier posting by MMan. I would certainly recommend an anode exactly the shape of the outer bearing surface. This will give as even a coating as possible. In my first job as a development engineer I was involved in electrochemical machining (the reverse of plating) and the electrode shape was critical in getting the desired results. We even experimented with electrodes that were moved during the process to achieve the desired result. Then did things like rotating the workpiece and made things that are impossible to machine using conventional means. Bit of a solution looking for a problem situation as we couldn't figure out a use for it! Very far sighted organization---Friday afternoons were free--you could do anything using the companies facilities. A couple of the things coming out of that were the automatic choke for carbs on cars and the first gas engine fuel injection system that was economic to produce. But I digress----keep up the good work ,MMan. Do you have the dates for the Cannonball Run in 2018?---particularly the start date? Over Christmas I want to start planting some seeds about how nice a vacation would be in Maine next year!
As 2017 draws to a close and the 2018 Cannonball draws rapidly nearer, best holiday wishes to everyone who has been following along on this thread. My special thanks to those who have taken the time to contribute. The Honor Roll of contributors, in order of appearance, for whom I hope Santa will be especially nice tomorrow (or today, if you're from down under), is:
robcurrie kevin roberts Adam M. gRegg-K gavin eisler Triless Shane in Oz Richard Kal Hillbilly bike johnm Stuart Bruce Martin Alan_nc norton bob Tridentman RPM JubeePrince Villiers franko kommando No Name Man Lannis edunham KevinN chaterlea25 Tribsauk old mule triton thrasher George Kaplan koncretekid Rich B gunner koan58 L.A.kevin (and apologies to anyone I accidentally left off this list)