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Post by henri on Jul 29, 2015 15:13:29 GMT
the other way ive done when stuck before is to file a stepped key ,H
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Post by tzsteve on Jul 29, 2015 15:31:09 GMT
i have considered that as an option. did you find it easy enough? as i`ve just been looking at slot cutters an 4mm seems like a hard size to get hold of.
another option i`m considering is to use a die grinder to open the slot but i have doubts about the finished accuracy
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Post by unclechufty on Jul 29, 2015 16:36:07 GMT
Alternately, could you not broach another groove inthe rotor using the lathe to hold it, and a fixed tool on the toolpost?
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Post by henri on Jul 30, 2015 14:17:38 GMT
yep that would do it ,when i had to file a stepped key i think it took 3 or 4 goes til i got 1 i was happy with ,an was only a stop-gap/emergency fix ,was always worried the 90 degree un-radiused corner was a weak spot an failure waiting to happen ,it was on a driving wheel on a belt chicken feeder .so low revs but a fair bit of torque .probs about 30rpm n 40-50 pounds load H.
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Post by tzsteve on Jul 30, 2015 15:35:31 GMT
i did seriously consider broaching a fresh slot in the flywheel but setting up accuratly could have been a never ending task. so i settled on making a stepped key.
got a bit of bar machined it to 13.5mm dia. parted off a 4mm slice. ( a disk of 13.5 x 4) then used an end mill in my drill press and a piece of scrap metel bolted to the drill table as a guide while i moved the drill vice across the drill table. then used a hacksaw to cut of the part of the disk that i needed
quite happy with the result.
thanks gents for the ideas
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Post by unclechufty on Jul 30, 2015 16:04:10 GMT
Smart, lateral approach. That's cool buddy.
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Post by tzsteve on Jul 30, 2015 16:11:45 GMT
a new slot would have been the best but i just took the easy way out
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Post by henri on Jul 30, 2015 17:57:31 GMT
bugger , an i spent 2 hours with a vice bolted to the bumper of my landy nxt to a pile of chicken shite 10 ft high , an a file , how the other half live/mechanic , tad jealous now,H
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Post by tzsteve on Aug 7, 2015 15:04:58 GMT
the super duper magnets arived today 1 magnet 0f 5mm dia x 5mm long can lift a weight of 100 gramms almost 4 ounces, quite strong.
so doing a little testing on fitting them, used a bit of scap aluminum and made a few holes. exactly 5mm the drill said and of course they drill a hole of 5.1mm so that gives me a chance to test a couple of different types of loctite and some araldite for metal to see which gives the best bond. i also had a go at drilling holes of 4.9mm and pressing the magnets in just to see if could get them into a realy tight hole without breaking the magnets.
so it looks like the press fit might be the way i go but i`ll also use a drop of loctie once i know which is the best to use.
i can still see a potential problem with stray magnetic flux making the ignition fire 3 times per rev if this happens it will be back to the drawing board. this is something that i will not be able to test untill i have a few bits inside the case (kick start, primaries, etc etc)
i`ll get the magnets fitted into the flywheel over the weekend.
fingers crossed i aint been wasting my time.
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Post by henri on Aug 8, 2015 8:22:28 GMT
a "wasted" spark type set up shouldnt be too much hassle , brains slow today but wouldnt it be firing at 120degree intervals ,so long as theres enuff dwell for ht coil to build a decent discharge/spark , an a press fit sounds safest option to me , H
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Post by tzsteve on Aug 8, 2015 15:31:27 GMT
it could even be 6 sparks per rev double bugger. if that`s the case it`s something to put down to a learning experiance. however keep on going till it becomes a problem. this morning i managed to press the 2 magnets in, it took about 500Kg force to push them in so i doubt they will simply drop out... here`s the results both sides of the ally disk with the magnets in place. the air gap between the pickup and the magnets is about 1mm so thats not too bad not much more i can do to the real engine bits till i get my rod kit, so i may have a go at getting the fan fitted over the next couple of days.. i gave the flywheel a quick turn or two by hand and the pickup voltage seems ok. but i do suspect that i am getting some stray flux from the flywheel, bugger bugger.
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Post by pugwash on Aug 8, 2015 17:47:16 GMT
If you do start getting interference from the rotor, then..... Could you mount the pickup on the outside of the flywheel still triggered by the two small magnets, maybe the fan disc might then act as a shield from the internal rotor magnets ?
Most likely not possible but it was just a thought.
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Post by tzsteve on Aug 8, 2015 20:52:57 GMT
it would mean making a larger dia fan backplate, but it is an option. it would mean extra stress on each of the 3 M7 studs holding the backplate on. as it is i estimate about 200N shear force on the studs at about 10,000RPM if i make the backplate an extra 60mm wider the shear force would go up to about 300N there is another version of the cb125 rotor which has laminated pole pieces so i could ask a realy good welder to weld some little tabs on to the rotor and then put the pickup horizontal, that means waiting till i see another flywheel and stator going very cheap. so even if it is a failure it is not a total failure.
I`ll just have to suck it and see.
how was the holiday ? ?
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Post by pugwash on Aug 8, 2015 21:46:36 GMT
Holiday was good
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Post by vader19 on Aug 9, 2015 3:27:39 GMT
Hey Steve.. you don't happen to have any pics of the magnets before you stuffed them in there do you? Did you use a curved "guide" "buffer" when you pressed them in? cool stuff!
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Post by tzsteve on Aug 12, 2015 15:19:23 GMT
pm`d you mate
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Post by tzsteve on Aug 12, 2015 16:25:03 GMT
i recently had some welding done to a diskbrake/hub mount. i`m happy with the welding and subsequent work however the paint that was on the aluminium lump had been burnt and left a lot of ash and paint residue that i could not fully shift. little bits in the nooks and crannies of the casting. i had tried a bit of paint stipper, wirewool and emery cloth but i still couldn`t get it clean enough for repainting. i saw some cheap DIY soda blasting demonstrated on the landrover forum so gave it a try. this is handy if you have a compressor but no blasting gun. you need one of these a lenght of stiff tubing and some bicarb soda £5 for 3 Kg in the local chinese supermarket (they use it for soaking the mushy peas in the chippy). the tube just needs a small hole cut in so that it is a tight fit on the blow gun. the soda goes into a tub of some type and the tube is just shoved into the soda this is the lump before and after. i was very impressed at the result and thought i`d try a test on an old cylinderhead from the scrap bin to see how good it was at dealing with aluminium corrosion. judge for yourself, i only did a few inches near the plug hole. in all i used about 1KG of soda and had to stop a few times to let the air in the compressor build up again as blasting makes heavy demands on the air supply. a dust mask may be handy but the soda is cheap and clean.
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Post by tzsteve on Aug 12, 2015 16:39:53 GMT
Quite simple stuff but to be honest it took a lot longer than i expected, probaly due to stopping for a coffee every half hour. i need a steel ring (megga washer) on the front of the flywheel. this is to stop the studs which hold it all together from flexing and to help clamp all bits together. rather than buy an 80mm dia bar at a couple of £`s an inch i put a bit of scrap aluminium in the chuck and glued a piece of scrap 8mm plate to it with some araldite (much cheaper). after all the turning and drilling work is done just heat it up and the glue brakes down. so after a bit of turning and drilling i ended up with this steel ring with six holes in it, 3 of the holes are for a flywheel holder (yet to be made). now the ring is secured with plenty of loctite on the studs and nuts. the fan from a central heating boiler has an 80mm hole cut in the center and that gets bolted on. again plenty of loctite. the fins were miles to high. so back in the lathe. this is half of a pk50 crankshaft setup as a mandrel (the best way of holding a flywheel if you need to lighten one ). then after a bit more turning i end up with this. the weight is 1.2Kg and the diameter is 150mm. i will need to cut the threaded part of the crank taper off then drill and tap the end of the crank taper. this type of flywheel like most bike ones has a bolt that goes into the crank rather than a simple nut to hold the flywheel on. the flywheel extractor is simply a 16mm fine thread bolt ....................................................... i was talking to a top lambretta man who has a lot more experiance than me with stators, and he is convinced that i will not have problems with stray flux on the stator causing interferance to the pickup (hope he`s right). ....................................................... the flywheel is still a bit taller than a standard item so the cowling will need to be altered and posibly the engine door aswell, but that`s a later problem. now the job goes on hold for a while as i need to spend on car and bike insurance. anyone feeling generous/rich?
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Post by ttscshaggy on Aug 12, 2015 21:33:32 GMT
You can buy fly cowling spacers to save a bit of messing about. I'd say make one but it would be an awkward lengthy process
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Post by henri on Aug 13, 2015 8:09:53 GMT
as shaggys says ,its nice to look at it n say "all my own work" but time saved buying a spacer rather than snipping one out of sheet steel,or jigsawing ali is better spent doing the other stuff .really impressive stuff by the way ,am loving watching it come together . 1.2kg so a really revvy engines ya hopes eh . the later lml large frames use a external pick up on the fly ,think its because theres 12 coils n no space inside fly ,not because of stray flux causing timing scatter .6 sparks a revolution ,1 every 60 degrees ,shouldnt give backfires an if they could run straight 6's n v8's n suchlike with single points/distributors there must be enough dwell to build a charge .is going to be tricky dialling in a lectronic tacho tho , if your thinking of using 1 . H
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