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Crankshaft grinding. 15:11 video.
https://www.youtube.com/watch?v=VDx7gU-fXcs
Previously:
https://www.homemadetools.net/forum/...562#post174092
https://www.homemadetools.net/forum/...0885#post73315
https://www.homemadetools.net/forum/...565#post166765
https://www.homemadetools.net/forum/...031#post157113
https://www.homemadetools.net/forum/...735#post155884
I could only watch a couple of minutes of it. The camera movements destroyed any chance that I could watch more. Tripods are not expensive but just a steady hand would help a lot.
I remember when the one automotive machine shop in the small town where I grew up got a crankshaft grinder back in the mid ‘70s. I worked at a local garage and had to drop something off at the machine shop one day, since I was friendly with the guys that worked in the shop I had access to the inner sanctum and got to see it in operation. Amazing watching the crankshaft spin off center while grinding the rod journals.
I agree the video is hard to watch, but the real crime happens 10:14 into it. He says says "We're not Rick Hendrick here, this isn't Robert Yates...a thousandth or two is not going to do anything..."
I could put up with the bad camera work, but not that attitude.
attitudes like that guy had is exactly why they will never get to do the ultra high performance grinding I wouldn't want to see what he does with camshafts.Quote:
Originally Posted by hemmjo
While technically he is correct being off a thousandth here or a thousandth there may be acceptable for a regrind everything become accumulative. If the cumulative amount of half a millimeter off in a series of holes in red iron can be enough to cause a beam to be rejected on a super tall building, then blasé' attitude of the total or 8 to 10 thou on a shaft spinning several thousand RPMs is not something I want to hear from the guy grinding my crankshafts even if it will not cause failure
There is a point "we're not_______, this isn't ______" is the very edge of OK or not. I've talked to guys just like in the video, declaring themselves 'Machinists'?
In reality, most are little more than operators. Controlling machines and part results is one thing, if the machine is purpose-built, not so impressive.
Obviously, I'm not discounting the men like Jenkins, Yunick, Black, Pink, Nicholson, Rollings, the Unsers...
yup he needs another job.as well as the grinding rock needs segmented so it dont burn the thrust serfaces. there are way to many "good enough" machinist out there.and almost good enough guys too. I made a very good living fixing the **** work they did. as well as machining and building totaly new assemblys. cars,trucks,jet skis,offshore race boats, drag cars, dirt track cars circle jerkers,most everything even some aero plane stuff. good enough isant good enough.
he finds .008" stroke difference...or did he? is he off that much?or off .004 or .006" square deck the block and you will know for sure just how bad he effed it up.as well as indexing. do it right, do it 1 time and be done, forget about it and have fun.
Doing this one right, is the ONLY way to sell the next job.
no, they do it all day long.and 98% of the people having it done, do not know 1 that it isant right 2, that it matters,3, how to check it.4 that it can be done right...5 dont give a **** how it is done or looks...and more.
the sad thing is.... way to many good cranks get ****ed up when they did not need and should not of been turned....just go by a local auto machine shop that does crank grinding and have a look at the stack of good cranks awaiting thier time to get ****ed up....grind it and loose the hardening.along with the precision it was made with. most all bearaing are availble is .001"~.003 if you only look.and yes you can mix and match to get the clearance you want.just dont get the uppers and lowers mixed up...some are specific...some arnt. also many times reconing the rods you can put them on the low side to tighten it up a little.as well as seprate main cap engines can be adjusted too. Im a big fan of thin synthetic oils I like tight clearance.as well as all my bearings and most other engine componets get either ceramic coated or DFL coatings. they work oh so awesome!!!
most cranks need a light fine/mirrior polish, deburing, balancing,chamfering oil gally holes.and cleaning good proper cleaning.and of coarse lightening before balancing.....for performance stuff.
Me thinks a set of video would answer, next person asking "why not" to running engine work.
They have no clue degrees of specialization between common machine tools and engine-work machinery with built in fixturing.
I'm guessing not too many guys ever saw a crank ground while still in the block. Wouldn't work on today's high revving precision clearance engines, but back in the day my dad and I long before I was in my teens ground many a rod journals on an old tractor engine even some big truck gas engines without doing much more than dropping the pan and puling the head, snatching out the pistons and rods then grinding the journals enough to clean them up to an undersized bearing. usually right in the field with the plow still in the furrow. He and I sat on the side of the road once and he made a rod bearing out of a piece of his belt so we could make it the 100 or so miles home. Got home yanked the head and pan shoved his crank grinder down the cylinder bore ground that 1 journal installed an undersized bearing and ran the old truck for several more years.
I noticed there are several vintage in the block crank grinders for sale on Ebay similar to the one he had.
Not I certainly, least-ways in person, yet aware; especially tricks performed completing in frame overhauls.
Quite a range exists in 'bolt-on' aka 'portable' machine tools; journal squirrels, facing machines, boring bars (ie Frank S's avatar), keyway cutters, hand lathes... There might be portable broaches; mass needed to deliver rigidity makes that hard to imagine.
My avatar wasn't named a Do- More- versi- mill for nothing. I use that thing for a multitude of things and since I has the 48" way bed for it I could either mount it on 1 end and use it like a lathe or mount it on the carriage and use it to mill long groves or whatever I used it as a drill press or a mill at times, as a tool post grinder at others it was a great supplementary tool for other machines or a standalone machine of its own.Quote:
Originally Posted by Toolmaker51
My dad had an early model Kwik-way cylinder borer that we sometimes used to bore out a single cylinder of a tractor engine in the field or in the case of a @ cyl popping johnny John Deere tractor just bore out both cylinders as much as 0.100" on 1 old tractor, or bore out an entire engine if doing a rebuild.
People today would look on in horror if they saw someone do the things, we did without the aid of several hundred thousand of dollars' worth of fancy machines.
When you are in a "make do with what you got" situation, the goals and tolerances are different. This is especially true for an engine that is going to spend its life seldom running more that 1500-1600 RPM
I expect someone with a dedicated crankshaft grinding machine to do much better than "close is good enough".
Or at least not say it out loud for everyone to hear. It would have been the last one he would do for me. the old engines my dad did would last for 10 to 20 years seeing some pretty rough service even with the portable equipment he had there was no such thing as close enough unless the damage was to the extent that it could only be a temporary fix until it could be brought to him for a good tear down, which he would always tell the guy what really needed to be done. sometimes they listened and my dad would send the cranks and blocks out to a real engine machine shop to have all bores and journals matched correctly then build up the engines for them, other times it might be a couple years before they would have him pull an engine, transmission or rear end and replace with new parts. I never heard of one of his repairs even the ones he told the guy were only patch jobs to be the reason for causing a failure. After I got older learned how to weld and eventually bought my first lathe and welding machine his health had started going downhill so he had gotten rid of most of his equipment. When I finally brought the lathe home from the Blacksmith shop, he told me one day if he would have had one of those things back in the day, plus the portable equipment, he had sold he and I could have really done some things.Quote:
Originally Posted by hemmjo