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+--- Thread: lapping arbor (/thread-541.html)
RE: lapping arbor - ScrapMetal - 06-23-2012
The last couple of days I haven't been able to rub two ideas together and get a spark, too much going on around the office and home (nothing bad, just busy).
I really need to spend some time alone in the shop.
-Ron
RE: lapping arbor - Bill Gruby - 06-24-2012
(06-23-2012, 07:46 PM)ScrapMetal Wrote:
The last couple of days I haven't been able to rub two ideas together and get a spark, too much going on around the office and home (nothing bad, just busy).
I really need to spend some time alone in the shop.
-Ron
Go for it Bro, that always works for me.
"Billy G"
RE: lapping arbor - Rickabilly - 06-24-2012
I have used this method before to clean up scoring in similar parts, you really only need to run it for a few seconds, so not enough to move position, just to clean out the raised edges that muck up the alignment.
You need to remember that taking out enough material to change position would advance the taper so far that the flywheels would be useless, at least without a custom crank pin, keeping in mind that the taper pictured has a taper of approximately 1 in 10 so taking out just 0.002" from each taper will narrow the assembly by 0.040" and then the con rods won't fit. but cleaning surface finish will allow better alignment without removing much material at all.
Best Regards
Rick
RE: lapping arbor - ScrapMetal - 06-24-2012
Rick, did that take care of the problem and have you tried to true up the halves again?
I'd also be interested in seeing pics of the whole project.
Thanks,
-Ron
RE: lapping arbor - Rickabilly - 06-25-2012
Hello Ron,
My "similar job" wasn't for a crankshaft but it was for a fit between a tapered hole and length critical pin in an experimental precision fuel pump, the hole had been accurately bored but was too rough to get a friction lock on the taper and didn't seem very square to the working surface, the lap was made from a piece of car axle, it was what I had and pretty hard, and was set up much like the pictures above, and after a few seconds of running the high spots were knocked off, a friction lock was possible and the pin didn't wobble any more, the taper on the lap was cut without moving the compound setting after turning the actual "crankpin" (although it wasn't really a crankpin as such)
Sorry for no pictures this was ten years ago when working in an R&D facility, where cameras were not allowed for patent security reasons, It was just a day's work, so I probably would not have taken a photo anyway.
Best regards
Rick
RE: lapping arbor - TomG - 06-25-2012
(06-25-2012, 02:14 AM)Rickabilly Wrote: Hello Ron,
My "similar job" wasn't for a crankshaft but it was for a fit between a tapered hole and length critical pin in an experimental precision fuel pump, the hole had been accurately bored but was too rough to get a friction lock on the taper and didn't seem very square to the working surface, the lap was made from a piece of car axle, it was what I had and pretty hard, and was set up much like the pictures above, and after a few seconds of running the high spots were knocked off, a friction lock was possible and the pin didn't wobble any more, the taper on the lap was cut without moving the compound setting after turning the actual "crankpin" (although it wasn't really a crankpin as such)
Sorry for no pictures this was ten years ago when working in an R&D facility, where cameras were not allowed for patent security reasons, It was just a day's work, so I probably would not have taken a photo anyway.
Best regards
Rick
Hey Rick,
It sounds like we have a similar background. I spent 23 years working for a DOD contractor in R&D. Most of the work was in developing synthetic aperture radar for remote sensing applications. Yes, cameras were definitely a no, no.
Tom
RE: lapping arbor - Rickabilly - 06-25-2012
Hello Tom,
Alternate Fuel systems R&D for about 16 years, before that there was a few years R&D in Mechanical vibration analysis and a stint in Race engine building, all of which were IP sensitive areas.
When working in fuels, I would move between "Big Name" Motor vehicle manufacturers and Oil companies, Banks and funding agencies, Government departments in various countries and sometimes UN representatives solving issues, and then proving through the appropriate testing agencies. None of these companies would allow cameras in workshops, or recording devices in meetings, some would even censor notes taken during briefings.
My last 10 years from 1999 - 2009 I was running my own R&D shop and trying to keep a workforce in compliance with the basic confidentiality rules, not so bad here in the UK, but some of the Australian workforce were difficult, some just didn't want to understand how they were endangering our Patent viability, On occasion it led to dismissals.
I'm sure you've seen it first hand, It's nice to know that other folks here understand what it's like.
Best regards
Rick