graffian
Seer unto the end of his beard
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like harleys.
- Thread starter mowersman
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like harleys.
normspanners
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There are hundreds of cranks with tapers nearly every motorcycle, listers , vw,minis etc .
I am talking with some experience, having made many competion flywheels and mods to engines etc, I made an extension to the front of a lister crank only last week it had a generator head at the rear (on a taper!) and the customer wanted a different spec generator head to run off the front, I made the ext from the hand starter dog in the same fashion as above and it runs a treat. btw The flywheel has everything to do with harmonics that is why they fit them. When the first cyl fires and is driving into the second (main) crank the one with the flywheel it will tend to tighten, when the second cyl fires the shock will be absorbed by the flywheel and it will tend to soften that shock, and as long as the drive (if any) is taken from the fly wheel end of the crank I believe there would be no problems. In my humble opinion that is how I would do it, I would NOT weld it at all because it WILL break and putting extreme heat near a crank will cause it to distort and then fret.
mowersman
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I'm afraid I don't like the taper idea, I don't think I would be able to make it accurately enough for it to work. Also the drive cannot be taken from the flywheel end. I'm not sure the welding will break, but I shall continue beating my test piece with a hammer tomorrow, see what happens. My current favorite idea is to press a sleeve on.
Andrew
Andrew
normspanners
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I totally agree re the angle I was only using morse as an example hense the 'ala morse taper' here is a couple of little pictures re roller cranks these are nutted ones but there are many many ones that are not just search for roller crank images his only prob is the possition of his join as you press the two together you may tend to bend the crank but putting a bolt through would just give it extra rigidity = safety also allowing it to be timed up perfectly.
ronan
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Those engines look like the little bsa stationary engine i bought at a jumble a few weeks back. I think the welds will be ok if they stand bashing with a hammer, when i was trying to weld the en24t crank flywheel it was cracking as i was welding it.
If you had access to a tig plant you could get a far better cleaner weld and the ability to straighten the shaft running the arc over the weld again as needed.
If you had access to a tig plant you could get a far better cleaner weld and the ability to straighten the shaft running the arc over the weld again as needed.
normspanners
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The problem with welding is the fact that it may allow the crank to distort a few thou and when the centre bearing is fitted it will force the crank to be straight making it fret at the weld as I mentioned earlier the ONLY failure I have had was when the guy decided to weld the join 'just to make sure' and SURE enough it broke !! Try googleing roller crank images and have alook at the way the various elements go together with hundreds of different manufactures.
btw it is not the same hitting it with a hammer it is the harmonics/high frequency vibration that will break it even at modest rpm because of the poss missalignment.
I really like the concept if it works you could build a multi cyl in line power house and have you mower at santa pod doing the flyin 1/4 with smoke porin from ya cutter bar!!! a little methanol n nitro and your next post will be how to weld arms back on !! (because they have been pulled outa ya sockets).
Good luck with this, nobody will be 'right' untill its done whichever way and its been running few days AND is still running, then YOU can say 'nah nah told ya so'
or---- you dont post 
btw it is not the same hitting it with a hammer it is the harmonics/high frequency vibration that will break it even at modest rpm because of the poss missalignment.
I really like the concept if it works you could build a multi cyl in line power house and have you mower at santa pod doing the flyin 1/4 with smoke porin from ya cutter bar!!! a little methanol n nitro and your next post will be how to weld arms back on !! (because they have been pulled outa ya sockets).
Good luck with this, nobody will be 'right' untill its done whichever way and its been running few days AND is still running, then YOU can say 'nah nah told ya so'
or---- you dont post normspanners
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Ha just remembered not my only failure!!! I made a extra VEE belt pulley for the front of an vw lt 40 and the quickest way was to weld it, thatl do nicely, we said, well it ended up, literally up, in a tree on the side of the M6 !!! last place to look was in the trees! took us hours to find it,that was in the days when you could park on the motorway and not be bothered by, Mr enforcment officer!!. it made a lovely noise as it said goodbyeeeee it was a sort of zinging whistling tune with a bit of heavy metal, as the finallay
Pete.
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None of those are built-up with taper-fit elements, as I said. Stuffing a flywheel or other rotor on the end isn't included in the crank build-up. Show me an example of a crankshaft that is actually BUILT using tapers. I don't doubt there are examples but I'm pretty damn sure I never heard of one and they won't be prevalent.
normspanners
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I am not getting into an argument over this, as I know there are hundreds and I have worked on lots of them, some nutted and some just pressed together, just goole roller brg crank images and look at the number of manufactors that build their cranks with shafts and pins all seperates just pressed together or nutted with tapers, thats how you change the bearings ! as I said most mcycles and in the car world VW, buggatti to name some from either end of the sectrum, one of the reasons the manufacturers use a solid crank is economics they are much cheaper to produce and easy to grind straight n true, the biggest saving is the setting up and not having to press all the elements together accurately which takes hours of man power. I know having done my first when I was twelve or thirteen ( working out how to do it for myself) and working and tuning racing two n four strokes etc from that age for many works teams.
N
N
normspanners
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Ha. I give up!. Have it your way Pete your right there aren't any.
Every one has and should have their own opinion, as far as I see it this is a forum to try to learn n help n amuse and thats what I try to do. I mostly learn from it, as far as this item goes I have had some experience to pass on to try to help, but nitpicking is not helping anyone . OK bye
Every one has and should have their own opinion, as far as I see it this is a forum to try to learn n help n amuse and thats what I try to do. I mostly learn from it, as far as this item goes I have had some experience to pass on to try to help, but nitpicking is not helping anyone . OK bye
Lawnmowerboy
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What about turn the ends of the cranks down say 4mm on the OD and we turn up a sleeve then press together and align and straighten and then just run round the ends of the sleeve where it joins the cranks autogenously without any filler then surface grind the center journal round and to size. We'll have the workshop for as long as we need over christmas, Andrew.
Pete.
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No need to be precious norm. You've put a lot of energy into telling us how tapers are used to build up crankshafts and how you've so much experience in building and tuning engines - all I've done is asked for an example.
Yes, the mini flywheel is set on a taper but it is also keyed, as are bike flywheels. With your exprience you must have come across a sheared woodruff key on a bike flywheel, which is only holding timing and loaded by the charging circuit - not transmitting drive - yet these keys can only get sheared because the taper has slipped. Pressed-up crankshafts are almost universally only pressed at the big-end, not the main journal which is machined as a single part with it's crank web because that part is in pure torsion where the drive is transmitted. The fact that pressed-up cranks still twist at the big-end which is not so much in torsion as the main journal bears it out further that a non-positively driven connection is not ideal for joining two cranks.
Yes, the mini flywheel is set on a taper but it is also keyed, as are bike flywheels. With your exprience you must have come across a sheared woodruff key on a bike flywheel, which is only holding timing and loaded by the charging circuit - not transmitting drive - yet these keys can only get sheared because the taper has slipped. Pressed-up crankshafts are almost universally only pressed at the big-end, not the main journal which is machined as a single part with it's crank web because that part is in pure torsion where the drive is transmitted. The fact that pressed-up cranks still twist at the big-end which is not so much in torsion as the main journal bears it out further that a non-positively driven connection is not ideal for joining two cranks.
mowersman
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Hmmmm, nah, still don't like it as much as my sleeve idea
Think I'll get the engine block done at college on the CNC, can just set it to do a circular pocket and let it get on with it.
As to the argument going on. I can see a taper working, if there was something else to hold it as well. Also the taper would have to be done well for it to be any good, thats where the problem is for me. I can't be certain of a decent taper, so I think its out.
I'll do it with the sleeve first, if that doesn't work, then I have 2 spare cranks at home, so will try welding.
Andrew
jinjahbiscuit
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"Lightweight 6.625” diameter crankshaft assembly on larger (1.125”) diameter mainshafts. Titanium conrod running on Ina bearing on 40mm crankpin, pressed up crank assembly."
Well, a couple of us have a little experience in this area. And believe me, you'd be surprised how difficult it can be to take them apart.
Well, a couple of us have a little experience in this area. And believe me, you'd be surprised how difficult it can be to take them apart.
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ronan
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Manx norton crank ? I have only ever replaced the crankpin on a triumph tiger cub and that was simply pressed up , no crankpin nuts as used on bsa goldies for instance, but a low power engine, much as i suspect the two engines in question are.
A good few lads i know were having trouble with clutch centres coming loose on the mainshaft tapers on their bsa pre unit twins (a7 , a10) one fix is to make sure the centre is a good fit on the shaft , this being done by applying grinding paste to the taper and grinding the two parts together, just like a valve in a head, then finally assembled with one of the stronger grades of loctite.
normspanners
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normspanners
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Exactlly right, I did that lapping job on a cable granulating machine, flywheel taper that I made, only prob was the shaft was 600 mm dia and 2metres long the taper was 200mm ish and the flywheel weighed 1500 kg, we put the shaft vertical and the flywheel on top, bit of a job getting enough men to actually turn the flywheel but we used a little oil with the grinding paste to actually get it to move, it worked though ended up with a perfect matched finish.
