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Post by henri on Jan 7, 2019 13:00:40 GMT
jan 005 by henri briggs, on Flickr . had some spare time ,an mate with a lathes flat out on it so i cant cadge the odd half hour .so grabbed 2 extending live centres from fleabay an some steel . grinder 001 by henri briggs, on Flickr . couple of cuts an 4 holes .an voila jig 001 by henri briggs, on Flickr need to get some lathe time to turn brass bar into a check-bar an set the centres dead in line .have checked there run-out an its under half a thou ,better than what i expected for 9 quid the pair ,steel cost me 7 quid so £16 in total . bout what a trip across town an a drink to my mate to use lathe would cost in time n trouble .just to find cranks ok ,its for rough checking an any trueing to be done measurements will be done on lathe . funnily i stuck a picture up on facebooger , to get told it would never work an wasnt the right way to "balance" a crank , an that i'd never fix that crank that way . its a dummy crank used in cases when being welded or decked ,they missed seeing its got no conrod in there critical expert opinion . made me laugh ,but had a drink in me . H
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Post by tzsteve on Jan 9, 2019 16:41:05 GMT
dont worry too much over the technicalities as long as the thing is rigid it will be ok
nice work by the way
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Post by henri on Jan 10, 2019 7:24:14 GMT
oh its rigid , 5mm steel throughout ,just some "facebook expert" with a £250 set of knife edges an dti as his toy in the garage telling me i hadnt a clue .most others ,some from here were saying "ah the old measure n mallet procedure ,good oh" . i did put it up with the tag-line "ill leave this here,get me coat n run" expecting some bad reactions .but the experts? one made me laugh ,finally found my dti stand yesterday so will put a new crank in today n see .expecting to have to level centres so it can run true .wont use it in "anger" til ive got a check-bar made . H
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Post by tzsteve on Jan 10, 2019 18:43:23 GMT
i love experts. they always start with i have been reliably informed. and never name the text book
real engineers will say from my experience ............... but there other ways of doing it
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Post by henri on Jan 11, 2019 7:31:09 GMT
ex-spurt , as my dad use to say , "a drip that was under pressure" . H
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Post by henri on Jan 11, 2019 12:29:42 GMT
jiggy 001 by henri briggs, on Flickr . borrowed a triumph gearbox layshaft of right length an "known" true/run out to use as a test bar . new stoffis ets crank , fly bearing 0.011mm/.433 thou , clutch side 0.01mm/.393 run out . turn crank around an same readings on each side ,turn back again an still same readings . i believe a repeatable experiment that gives same data is taken as "proof" in scientific circles , engineers just measure twice ,then once again to be sure ,then believe there figures . now for cutting an welding ,then back to be checked again . H
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Post by tzsteve on Jan 11, 2019 15:50:51 GMT
it is quicker and a lot easier with 2 DTI`s also check the faces of the crank webs
it will pull when you do the welding, but dont worry about it
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