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Thread: Where to get unusual size allen bolts?

  1. #16
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    Quote Originally Posted by Rickenbacker View Post
    Cheers Tom, but 60mm won't do.

    Material doesn't really matter too much, though stainless would be nice.

    It's a long stock bolt for a FT stock.

    I can get M7x70mm in a hex bolt, but I'd have to try to put a screwdriver slot in it, which ain't going to end up looking very pretty.

    That's because I couldn't get a slim 11mm socket in the recessed stock bolt cup, to do up the hex.
    Easy answer; drill/ream out the stock cup until you can fit a thin wall socket down it, you can also turn/file/grind a socket down ultra thin as a specialist tool or try a nut driver as they're usually much thinner walled than a conventional socket.

  2. #17
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    M7 is found on motorcycles, scooters and pushbikes, rarely long stuff though, usually 25mm for holding ignition rotors and similar stuff.
    M7 is 1mm pitch, so is M6, try fitting a 6mm helicoil and using an M6 hex bolt, 70mm length is available. Seeing as it is only a stock bolt M6 will be strong enough, fit the helicoil correctly and again it will be strong enough, I would suggest using a 1.5D length, you will need to run a 1/4" drill down the existing M7 thread, seeing as it is 1mm pitch the helicoil tap will run in very easily as you will only be cutting a few thou with the tap. You may need a washer as the M6 hex head will be smaller than the M7 one you are replacing.
    BSA Super10 addict, other BSA's inc GoldstarSE, Original (Diana) Mod75's, Diana Mod5, HW80's, SAM 11K... All sorted!

  3. #18
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    Pricey as they're in the states but bay item 262791087273 would seem to fit the bill or try asking your local Yamaha dealer for pt no 132-81252-10 there might be one sat on a shelf somewhere gathering dust

  4. #19
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    if you are going down the insert to 6mm route , i would not use a helicoil if you could use a timesert. https://www.amazon.co.uk/TIME-SERT-M.../dp/B001JK802K

    yes a kit is pricey but a local engineering place may be able to do it if they have them. they are a more permanent fix compared to helicoils

  5. #20
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    M7 bolt

    Hi, if you was to purchase two M7 X 40 stainless steel cap heads I could cut and laser weld to make you a 70mm one.

  6. #21
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    Thank you fellas, and specially Mick and Jezz for offering to spin something up for me!

    Seem there's a few ways to do this job, but for now, I think I'll order a few M7x70mm hex head bolts (8.8 zinc plated is all I can find right now). I'm sure I can fashion a screwdriver slot into one, that'll do for now. And I'll have spare ones for a more professional job later on.

    I did try a bodge using a M6x70mm socket screw that I do have:

    WP_20171130_21_58_14_Pro.jpg

    This involved grinding two 'flats' in a M6 flanged nut, which was then a snug fit in the trigger block. The threads of this nut can just about be seen here, when the trigger block is fitted back in the cylinder:

    WP_20171130_21_57_19_Pro.jpg

    The above mentioned nut is a replacement for this thing, which is the factory HW95/98 part:

    WP_20171130_22_14_15_Pro.jpg

    I don't really like this fix, as I feel the thinner M6 screw will deflect easier, and could allow the action to move in the stock under recoil/surge, possibly damaging the stock.

    Also don't like the idea of trying to remove the screw cup and boring the stock deeper for a shorter M7 screw... the screw cup is already 20mm deep:

    WP_20171130_21_53_18_Pro.jpg

    The forend is pretty deep, see? And I definately don't want to muck the stock up:

    WP_20171130_22_02_30_Pro.jpg

    I suppose the best job (given that it's a long bolt, and a recoiling rifle), would be to use an M8 socket screw (which is available in stainless, and 70mm long).

    But that would involve shaping an M8 nut to fit the trigger block, slightly enlarging the fixing hole in the cylinder, and slightly enlarging the hole in the bottom of the screw cup (the hole bored through the stock is already a nice snug fit for an M8, which is why this is tempting).

    As a favorite gunsmith of mine might ask: "Worth the trouble? Ahh, what trouble?"



    Anyway, thanks for looking. It's taken me longer to type this than it would to do the flippin' job...

  7. #22
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    Last edited by JB101; 01-12-2017 at 06:18 PM.

  8. #23
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    Quote Originally Posted by --ped-- View Post
    easier to rethread a m8 to m7
    Agreed ... and if the head is a tad too wide, it can be turned down a tad.
    Then maybe oil blue it.
    Cheers, Phil

  9. #24
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    We have a place in Lowestoft called Westgate Fastenings, they do all sorts of nuts and bolts, I could give them a ring Monday morning if you like and see if they've got an M7 x 70mm cap head bolt in stock, it's worth a shot, would save you a lot of faffing about ( I could then post it to you )

    Nice thing is they'll sell you a single bolt or nut if you want !

    Norm

  10. #25
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    If you're going to use an M8 then you need to start with at least 70mm plain shank so you're looking at a 100mm bolt minimum. You can't use the threaded part as it's too small when you turn the thread down, tried it today on a stainless bolt and turned down to 6.4ish mm still with a bit of the thread showing, threaded it just to see , the thread was there but probably only half proper depth I wouldn't like to trust it for holding anything.

  11. #26
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    Thanks Bez', that's good info.

    Quote Originally Posted by JB101 View Post
    Thanks James, First link: Nothing M7 in the way of socket screws, but they do some nice other bits n' pieces. Nice site.

    Quote Originally Posted by Mr.Fixit-Norm View Post
    We have a place in Lowestoft called Westgate Fastenings, they do all sorts of nuts and bolts, I could give them a ring Monday morning if you like and see if they've got an M7 x 70mm cap head bolt in stock, it's worth a shot, would save you a lot of faffing about ( I could then post it to you )

    Nice thing is they'll sell you a single bolt or nut if you want !

    Norm
    If you wouldn't mind, Norm - that'd be great. But I'm not hopeful. It seems to be a very odd size.

  12. #27
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    No probs, I'll give them a ring 1st thing Monday, then pm you with the result. I have a feeling they do do stuff in M7 as I've got it in the back of my mind we had to get some M7 bolts for something on a mobility scooter when I was working as a workshop manager at my brother-in-laws shop.

    Norm

  13. #28
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    That's very good of you, thanks Norm.

  14. #29
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    Quote Originally Posted by Rickenbacker View Post
    That's very good of you, thanks Norm.

    Hi,
    No luck I'm afraid, I gave both the Lowestoft branch and the Gt Yarmouth one call, both branch's had M7 x 70 in hex head but nothing in a cap head ( Allen head ). They said that M7 bolts are rarely asked for being an inbetween 'foreign' size ( had to laugh at that ! ).

    Best I could do would be to weld a M6 cap head to the head of a M7x70 hex bolt then turn the hex bit down to match the diameter of an M7 !
    To be honest if you went this route there's probably people on here better skilled at welding and turning than me but if you get stuck I'd have a go !

    Norm

  15. #30
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    As a thread above said, turning down an M8 is not really on ... I should have realised that ... but turning down an M10 by removing the thread and cutting to M7 should work. It could well mean turning down the head diameter but, if there is enough meat on it, it should work.
    Cheers, Phil

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