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Post by sime66 on May 4, 2016 19:24:15 GMT
Ahh; you’ve all rushed off, never mind…… (it's quite lonely now though ) I’m pretty happy to tackle this drain repair now; just a couple of quick questions before I tackle it. 1) I’ve found a table of drill sizes for tapping holes, and I reckon a stripped M8 in aluminium is already too big to tap to M9. I did get some M9x1.25 bolts, which would have needed cutting down, but I think I’ll be better to go to M10 because of this:
So I’ve got M10x1.5 10mm and 12mm bolts, washers and fibre washers, which will give me the 8mm (or 10mm) in the casings that the M8 drain bolts have. I can try M9, but I’ll have to cut the bolts, and it seems like the stripped hole is too big anyway.
2) To make sure I’ve got the swarf out, I think I’ll have to split the casings, or do you think I could do it without if I ‘take precaustions’? If I split the casings, I’m thinking that I’ll just have to take the driveshaft out, so no bearings will need replacing, and maybe just the external hub and flyside seals? What to we reckon on that one?
Other than that, I’m quite happy to clean up the JB weld from the previous bolt cage bodgery I did as a temporary measure before, and get a new drain bolt in there. Then Old Faithful will be ready for reincarnation!
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Post by vespasco on May 4, 2016 19:58:50 GMT
use a 10mm bolt you shouldn't need to take out the drive shaft, you can always take off the gear cogs if you need a better look, leave the stator on remember to order some new gaskets. and oil! doing it without splitting the cases? im sure it must have been done successfully but i wouldn't advice it. Although you may find that you don't need to tap, or thread a bolt, all the way through... which would make less swarf inside the cases if you really have to When cutting a bolt, thread a nut all the way down first, when you wind it off it will clean the thread.
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Post by sime66 on May 4, 2016 20:08:37 GMT
Thanks. 10mm is easier so that's decided - don't have to cut those down. Splitting casings it is - no worries these days!! Cogs off if needed; leave shaft alone - good plan. I have to take stator off to get at engine bolts underneath it. Oil and gaskets - always trying to think of extra stuff to order when I'm paying postage for stuff, so good idea (though I won't be filling-'er-up for a while yet). Thanks mate.
(Did you find your little black book?)
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Post by henri on May 5, 2016 6:20:59 GMT
sorry to throw something else into the mix but . standard practice is usually to go upto a whitworth thread size if a metric one strips .thats the usual if a barrel stud pulls out .tho theres more meat around a drain hole ,are you sure theres enough to take a 10mm thread .am off to shed to stare at casings n think . H
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Post by sime66 on May 5, 2016 6:34:19 GMT
Not sure, sure, but I reckon 10mm will be OK; I’ll know better in a couple of days when my bits get here. It isn’t reamed-clean stripped M8 hole, the bolt is holding, just leaking. I’ll see how the 8.5mm drill and M10 tap feel in the hole before removing any metal. I’m off out shortly, but if you have shed-ponderings to share later, there’s plenty of time to add to the mix; always better to suss it out beforehand, even if I have to get different stuff, but I reckon 10mm will be good.
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Post by henri on May 5, 2016 6:41:23 GMT
the cases i just looked at are piaggio-lml ,carry both marks ,px ones . by eye it looks do-able but only just ,theres the meat for the hole but tip of threads going to be close .if i was you i'd strip case of box n crank an go see your lathe man engineer fellow . he might not hold whitworth taps but will have a engineers tables with tapping sizes .message me an i'll pop over to nut&bolt store an put together a "care package" , tap n couple of bolts an i'm sure ive got a spare whitworth spanner too . an tapping ali isnt as easy as it sounds ,but we'll get into that nearer the time .H
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Post by shipscat on May 5, 2016 8:14:43 GMT
if its not too late try get a helix type tap these work like a drill bit pushing the swarf out backwards normal taps push swarf forwards
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Post by sime66 on May 5, 2016 8:45:05 GMT
Whoa there! I Just popped out for an hour; I didn’t expect to return to all that…… I appreciate you venturing out to the shed in your pyjamas, but If it gets that complicated I’ll leave the job until I strip the casings, when I decide what to do with the engine; tuning-wise, but I wonder if it is that complicated. Before continuing, I do defer to your far greater knowledge and experience when it comes to dirty metal and all matters enignny; my interest in college waned considerably when we did this stuff – always preferring the drawing board to the lathe as you know, but hear me out anyway just in case a fresh look at it reveals something new. Here’s some metric nut and bolt dimension tables:
From the table: * I think it shows the max OD of a M8x1.25 bolt is 7.97mm * I think it shows that the max internal dimension for the threaded hole would be 8.34mm – even if it was fully stripped, but probably only bolt size max (7.97mm). * The correct drill size for tapping M10x1.5 is 8.5mm, which is greater than the stripped hole. * The min OD of a M10x1.5 is 9.73mm; that’s worst case (smallest bolt).
I reckon that shows that a Ø8.5mm drill (if even needed) and an M10 tap will put an M10x1.5 bolt in a stripped M8x1.25 hole perfectly. I also really don’t like the idea of tapping a Whitworth thread in 21st century, though I acknowledge your experience in this, and my complete lack of it, but wonder if those who you learnt from might have learnt from The Victorians, when a more modern solution is easily available with Metric bolts. Even 70 years ago Piaggio was Metric! My initial thoughts were to strip the casings to get someone like KTM or GLM to do it, but all I’m doing is repairing a stripped drain plug; if it really needs a skilled engineer then it can wait until I’ve decided if and what the new-life of these casings will be; I expect I’ll have them stripped and Dremelled-silly for tuning at sometime. I do wonder if this drain is such a big job though. I just want to do a couple of quick jobs to get this night-time obstacle course out of my bedroom, (or at least usable if needed), not start a new project just yet. BUT I won’t bodge it if you’re sure what I thought is nonsense. Take the above as an ignoramus asking why what he sees on paper won’t work, not questioning your experience, skill or judgement, and if it does turn out that what I’ve said above is nonsense I’ll gratefully draw on your experience and kind offer of ‘care package’ to ensure I do it properly, but allow me a moment to question the bits that seem dodgy to an unskilled and inexperienced chap. I know I've just asked for advice and am now questioning it, which I shouldn't do, but I just didn't expect such a palaver.
Shipscat: I saw those helix taps, wondered why – now I know; cheers. Never too late, this is why I like to thrash things out on here before I make a pigs-ear of things………
*Quick edit, after a read around:……Thinking I don’t need to reinvent the wheel, I had a very quick look elsewhere, I just found this: modernvespa.com/forum/topic82767(2 pages) They seem to agree that M10, drilled 8.5mm is the way to go; here’s a couple of edited highlights, including our mutual friend, who always seems to be a few steps ahead of me!
..…it was a happy ending too. I'm making no final conclusions, but it makes me think what I said above is less likely to be nonsense.
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Post by vespasco on May 5, 2016 11:06:09 GMT
hahahahahaha
i wish i knew then what i knew now
and i wish i knew/remember now what i knew then!!!
but 10mm, its easy...easy to find 'parts' etc and drilling a 8mm hole to 8.5mm is also easy
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Post by swm on May 5, 2016 13:03:32 GMT
I reckon if you drill out a stripped M8 threaded hole with an 8.5 diameter drill, the amount of metal you would remove would be roughly sweet F.A. !!! Or using the figures in the table say 7.972 + ish to 8.5 = 0.582 mm. I bet you could run a M10 taper tap straight down it without drilling depending on how badly the threads are damaged. (then a second and plug) As you say see how the drill and tap feel first before attacking it ! Good luck.
Cheers.
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Post by sime66 on May 5, 2016 14:24:22 GMT
I'm inclined to agree; just waiting for the big fella to see if he does too. Stuff ordered yesterday anyway, but not attacking it yet. Might as well have it right and agreed.
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Post by henri on May 5, 2016 16:51:52 GMT
wiped the sleep from my eyes an found a proper measuring stick ,reckon for ease of buyin taps n bolts a m10x1.5 will do the job .an for info roughly the pitch 1.5 is also the tooth height . an to find a tapping hole size subtract pitch from thread (10-1.5=8.5 ) ,ok . so ya on the money so far . i suggested whitworths , as metric is a "intermediate" tap form , made to do 2 jobs ,neither to the best . whit's designed for use in granular cast iron an softer brass n copper ,ali was still a precious jewelry metal back then ,but has similar qualitys . i noticed greaser125 ,a guy who's advice ive seen before an always seems sound says "5/16 npt " a unc coarse thread very similar to whit just yankee style . H
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Post by sime66 on May 5, 2016 19:12:09 GMT
Ahh, I missed this post earlier; glad you’re in agreement too – everybody’s happy! I did not know before, but I picked up this morning during my reading, that thread – pitch = drill size; that’s a nice little knowledge snippet to keep. I did already have 3/8” and 9mm bolts from last time I started thinking about this job (Some obscure French car part was 9mm about £5), but they weren’t going to be big enough as we agreed yesterday. I’ve got M10s now and the 1.5mm thread is good and coarse – not sure how many turns it’ll actually be in the casings though – not sure if 10mm or 12mm long will be best; 10mm looks short - not important; I'll know when I do it. I’d also read about Whitworth maybe being better because of coarser threads, but when I started reading more about Whitworth I promised myself that I’d never try to understand the tables and drill letters! – And to avoid them unless I build a steam engine. Not to mention any American Imperial standards, which I won’t mention. I’d also promised myself not to pay people for things I can learn to do myself, but these casings are pretty precious to me, so there has to be a reasonable chance of success. I’ve seen greasy125 quite a lot in the past too; he always seems confident in his posts. I think I follow what you were saying earlier about getting the tap all the way in to get the hole threaded fully; the cogs will have to come off or the driveshaft out to do it – probably (or maybe just flush with the bottom tap – don’t know). I also appreciate how important it is to get the tapping perpendicular to the surface, and I think using the taper, second and bottom will help that; I’ll get a proper set, rather than just the one. And use lots of oil! The job itself is still a while off, so I have time to learn-it-up yet; I still have my old rims and rear hub on my spare desk in the living room because I have two stripped studs with half-cut-off nuts spinning – it’s a work in progress that just needs another bash now I’m in the mood to tidy up, before I can repair the hub and store the rims and tyres, which will then make room for these couple of engine jobs on the conveyer belt (drain and engine mounts) – Then after those, the flat’s tidy and the scooter’s all sorted, and that’s me until the Autumn, except for enjoying the Summer (or nasty suprises)………. There will be no nasty suprises = (Here's a nice Whitworth for you - c1857): - They knew their nuts in them days -
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Post by henri on May 6, 2016 7:10:27 GMT
one of my fave pictures of the "genius-midget" ,but you cut off the best bit , the lovely hobnailed n blake-ed boots he's wearin , pure class . tappin ali's a bit tricky coz aswell as above stuff ,square,oil,etc . it has to be done slowly an with tap withdrawn an cleaned often . rushed an the cutting friction cause points of heat on cutting edges high enough to soften ali an smear it on tap .this can block the thread an cause the tap to strip out the new formed thread .or in bad cases "weld" tap in as ya pause to change grip ,an tap then shears off ,they shear very easily being high-speed-steel ,very sharp but very brittle . so lots of lube,wd40, an slowly slowly an it will be fine .as its not a blind hole a taper n second run right through will form the thread ,plug/bottom taps are just for blind holes .but price of a set off 3 will probs be same as 2 bought separate,an beware of super cheap sets ,probably chinese an they make em from tin pans in back gardens ,part of chairman maos "great experiment" . H
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Post by sime66 on May 6, 2016 12:34:11 GMT
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Post by henri on May 6, 2016 16:15:03 GMT
building the "great eastern" on side the thames ,thems the chains on steam winches was supposed to launch ship with . didnt work an it was 6 weeks of head scratching before he got hydraulic rams workin to shove ship into the water . full picture shows him stood in a suit n hobnailed boots in 3" of stinky thames mud . as youve probs guessed he's a hero of mine . fun fact ,if ya put the tamar bridge structure into a computer sim an run a intercity 125 over it ,it collapses every time . add in the tertiary structure, gangways/safety rails/walkways/etc an run sim again it passes with a 50% safety margin . an nobody yet can explain why ,or how he worked it out ,or wether it was a lucky guess . skools out , H
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Post by sime66 on May 6, 2016 17:46:43 GMT
There is a bend on each bank before and after, so I'm not surprised an Intercity 125 would be tricky at any speed - would keep the Emmets out if it fell down anyway. Liked the fun fact; thanks - it's the way you tell 'em. As you keep banging on about this photo, I dug out a full length one, and another photo of the SS Great Eastern too; it's Friday and you've been very helpful this week, so have some Victorian Porn:
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Post by vespasco on May 7, 2016 8:36:35 GMT
If you don't want to take off gears or shaft you will need a plug type tap but its easier enough to take off the gears.
Do drill the 8.5mm first, theres not much there to take out but what you have is a different pitch of thread and because its stripped you may find the tap doesn't want to go in straight/perpendicular.
Best leave the new bolt slightly short of the hole...otherwise, like a spark plug, the end threads could get full of debris and ruin all your hard work when you come to take out the bolt...but not too short that you don't have enough of the coarser thread!!
I still marvel in the triumph of those victorian engineers. .. back then, totally large scale and mostly done by hand...the opposite of today
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Post by sime66 on May 8, 2016 9:50:14 GMT
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Post by sime66 on May 13, 2016 17:54:57 GMT
Thinking about what you said about heat when tapping aluminium, H. Any dos and don'ts or words of wisdom or caution for drilling the hole? I've got a brand new 8.5mm super-sharp and hard drill bit. Now I've finished the engine mounts, this is next job on my list. I also meant to I say got a proper set of taps and the difference in quality is obvious; glad I didn't try to do it with a cheapy.
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Post by vespasco on May 13, 2016 18:42:04 GMT
ooh, a nice sharp drill bit! Clamp the cases down so they won't move Don't push on the drill. if anything, you will need to pull it rather than push it, as the drill will want to go straight through that hole with just 1 or 2 revolutions! you'll need a little more pressure when you tap it. Keep it straight! Doing it by hand you can use a light oil, 3 in 1, wd40 will all be ok. if you're stuck for something even gearbox oil, 2T oil will do. Just keep the threads nice and clean as you go 1/2 a turn forward, 1/4 turn back, along those lines try a practice one on something, even a smaller hole - in your swing arm/old cylinder head/saucepan/next door neighbours Harley Ferguson if you have to! just to get a feel for it but im sure youll be ok
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Post by sime66 on May 13, 2016 19:53:38 GMT
Got all the tools, picked all the brains, time to roll me sleeves up! Thanks for the pointers; slow and steady - will report back and share the good news soooooooon!
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Post by djloone on May 13, 2016 20:13:12 GMT
Good luck..if any of your other work is owt too go on mate you,ll smash it (in a good way), your mr meticulous...invaluable help for me LOON-E
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Post by sime66 on May 15, 2016 14:37:37 GMT
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Post by sime66 on May 16, 2016 12:28:16 GMT
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Post by vespasco on May 16, 2016 20:04:11 GMT
excellent, once again good job
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Post by sime66 on May 16, 2016 21:20:41 GMT
I was a bit nervous about doing that one, but something else I'll be able to tackle again now it's done once. Thanks again chaps.
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