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Thread: have you seen one of these?

  1. #1
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    Default have you seen one of these?

    I need;

    Stainless Steel, M12 1.75mm pitch, Hex driven, grub, inside outside thread, for a 1/4" machine screw with bsp thread.
    Same as this without the broken off cross threaded screw jammed inside.......

    Nobody seems to stock them.

    IMG_5311.jpg
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  2. #2
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    Default Re: have you seen one of these?

    Can you not drill out the broken screw?
    It really is quite difficult to build an ugly wooden boat.

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  3. #3
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    Default Re: have you seen one of these?

    When no-one stocks 'em... make it
    "Travel is fatal to prejudice, bigotry and narrow-mindedness, and many of our people need it sorely on these accounts. Broad, wholesome and charitable views of men and things cannot be acquired by vegetating in one little corner of the earth all one's lifetime" Mark Twain... so... Carpe the living sh!t out of the Diem

  4. #4
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    Default Re: have you seen one of these?

    Quote Originally Posted by Peerie Maa View Post
    Can you not drill out the broken screw?
    I don't have the tools for it. But it'd be tricky i think. there's not much material and retapping would be thin.

    At worst I'll sink in a few nuts into the hole instead, epoxied in place.
    All the forces are lateral, no pull on the plate. Its for the base plate for my deck mounted mast. One of four.
    Philip K. Dick — 'Reality is that which, when you stop believing in it, doesn't go away'.

  5. #5
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    Default Re: have you seen one of these?

    Start with the outer hex drive screw, and tap it for the inside one? Taps are cheap.

    A left hand drill bit would probably get the old screw out.

    That is one weird mishmosh of threads. I haven't seen anything like that since I got a job to design adapters to standardize on a single vibration sensor, throughout a very large, old paper mill.

  6. #6
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    Default Re: have you seen one of these?

    Why not just use lags or hanger bolts and avoid the hassle?

    If you do go with nuts in epoxy perhaps a coupling nut with some groves filed into the sides would be easier.

  7. #7
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    Default Re: have you seen one of these?

    Quote Originally Posted by gypsie View Post
    I need;

    Stainless Steel, M12 1.75mm pitch, Hex driven, grub, inside outside thread, for a 1/4" machine screw with bsp thread.
    Same as this without the broken off cross threaded screw jammed inside.......

    Nobody seems to stock them.

    IMG_5311.jpg
    Are you sure that it is a 1/4 bsp internal thread? According to https://www.valvesonline.com.au/references/threads/ the major diameter of a 1/4 bsp thread is 13.157mm, which is kind of difficult inside a M12. You might have a 1/4-20 SAE thread on the ID. The standard external thread on a threaded insert seems to be M12-1.25, so that's not going to work. I have found Metric internal, SAE external inserts, but not Metric external / SAE internal. https://www.ondrives.com/kihd-6

    It looks like you could make it from a metric socket set or grub screw. I think grub screw is British English and set screw is American English.
    The hex drive socket is 6mm, which makes it easy to center the drill, and explains the threads on the hex drive portion. I think it was made from a set screw. The internal thread is not too hadr to tap, but as it is 304 stainless, it will put up a fight. The third link gives the material as A2-21H, Which is 304 stainless and 21H is 210 Vickers which is off my hardness conversion scale, but looks like cold rolled stainless. (harder than mild steel, but not very hard)
    https://www.amazon.com/M12-1-75-Sock.../dp/B01JAL9K1Y
    https://www.accu.co.uk/en/cup-point-...M12-25-A2-R360
    https://www.fastenal.com/content/pro...SS.4029.A2.pdf
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  8. #8
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    Default Re: have you seen one of these?

    Are you having trouble finding SS grub screws in general or just that size?

    http://www.anzor.com.au/stainless-st...screws/product

    or try a local bearing supplier
    Larks

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  9. #9
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    Default Re: have you seen one of these?

    Quote Originally Posted by MN Dave View Post
    Are you sure that it is a 1/4 bsp internal thread?
    Not something i know a lot about.
    When i pulled it off, someone had simply used 6mm self tappers in the holes. So i tried a few different screws.
    In the mix i bought some 1/4" screws, which the label said have BSP thread, and they fit beautifully.
    This one i drove in while someone popped up my ladder to have a chat and distracted me. I didn't make sure it was going in straight.

    The guy i bought the boat from was an engineer. His hobby is to make bespoke engine parts for race cars. It is entirely possible he machined these himself (which makes the self tappers a bit odd).
    Philip K. Dick — 'Reality is that which, when you stop believing in it, doesn't go away'.

  10. #10
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    Default Re: have you seen one of these?

    Quote Originally Posted by Larks View Post
    Are you having trouble finding SS grub screws in general or just that size?

    http://www.anzor.com.au/stainless-st...screws/product

    or try a local bearing supplier
    Thanks for that link.
    Philip K. Dick — 'Reality is that which, when you stop believing in it, doesn't go away'.

  11. #11
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    Default have you seen one of these?

    Of course, someone just bought a grub screw and tapped it themselves!

    Hence the bizarre thread combination.

    I can do that.

    Thanks all

    Trev


    Sent from my iPhone using Tapatalk
    Last edited by gypsie; 11-15-2018 at 02:32 AM.
    Philip K. Dick — 'Reality is that which, when you stop believing in it, doesn't go away'.

  12. #12
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    Default Re: have you seen one of these?

    There is a 1/16" BSP thread size, the major dia is .308" or metric; https://www.amesweb.info/Screws/BSP-Thread-Chart.aspx

    Possibly you have 1/4 BSF threads - Major dia is .250, 26 TPI ?

  13. #13
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    Default

    Quote Originally Posted by Canoeyawl View Post
    There is a 1/16" BSP thread size, the major dia is .308" or metric; https://www.amesweb.info/Screws/BSP-Thread-Chart.aspx

    Possibly you have 1/4 BSF threads - Major dia is .250, 26 TPI ?


    Je ne sais pas.
    The screw is 1/4” diameter with a bsp thread.
    But I am beginning to question my own existence at the moment. Between this project, a suite of bewildering metric verses bsp threads and pitches, and Ishmael questioning my perception of life itself - I am not sure how much of a grasp I have on reality.
    It might be some Egyptian standard imported in the 10th century BC from Sulawesi. There is definitely some magic involved.

    I’ll take a pic.

    T




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  14. #14
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    Default Re: have you seen one of these?

    Quote Originally Posted by gypsie View Post
    I don't have the tools for it. But it'd be tricky i think. there's not much material and retapping would be thin.

    At worst I'll sink in a few nuts into the hole instead, epoxied in place.
    All the forces are lateral, no pull on the plate. Its for the base plate for my deck mounted mast. One of four.
    It is easy.
    Screw it into a couple of M12 nuts and lock them together so that you can hold it in the vice, and then drill out with a drill of smaller diameter than the clear hole.
    Then run a larger drill through that is as close to the clear hole diameter as you can. The remains of the male thread should come out, either by picking it out with a sharp point or by running a new 1/4 screw into the grub screw.
    It really is quite difficult to build an ugly wooden boat.

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  15. #15
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    Default Re: have you seen one of these?

    bsp is a pipe thread. You said there was a machine screw marked bsp. It could have been the manufacturer's initials, not the thread type. More likely a 1/4-20.

    Try to dig out the screw as Nick said. If that doesn't work out, you will have had some practice at drilling out a grub screw and tapping the hole. If you can find some A1 stainless (free machining) it will be easier, but not worth a big search.
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  16. #16
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    Default Re: have you seen one of these?

    Threaded parts are the bane of repairmen. I run into this almost every day with various hydraulic fittings, mechanical assemblies, and other fasteners.

    Occasionally it is simple, but more often it is very complicated. The only way to know for certain is to measure the thing. This would be the diameters (minor and major) and thread count and pitch angle. Metric threads have different criteria than "English" or "American" (which are different from each other in several ways including pitch diameter, thread count and angle) There is a lot of "industrial incest" often combining all these things. It is a jungle out there!

    BSP is rarely used to describe a specific thread because it exists in several forms. Labeled BSPP (parallel), BSPT (taper) or BSPM (mechanical) which has all been rendered obsolete. http://www.ring-plug-thread-gages.co...Mechanical.htm

    Look here to become completely bewildered. http://www.ring-plug-thread-gages.com/tech_info.htm

    Or here; http://www.ring-plug-thread-gages.co...o.htm#Articles

  17. #17
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    Default Re: have you seen one of these?

    '' You ain't gonna learn what you don't want to know. ''
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  18. #18
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    Default Re: have you seen one of these?

    I'm going to take up the challenge and follow Nick's suggestion.
    I'll bring a sample screw into an engineers supplies close by the boat, make sure i get the right tap (start and end maybe). Also a decent carbide bit with correct dimension.

    I've got a drill press and clamp.

    I'll try and drill out the existing and re-tap - but i've also ordered some new grub screws to do fresh.
    Philip K. Dick — 'Reality is that which, when you stop believing in it, doesn't go away'.

  19. #19
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    Default Re: have you seen one of these?

    Quote Originally Posted by gypsie View Post
    I'm going to take up the challenge and follow Nick's suggestion.
    I'll bring a sample screw into an engineers supplies close by the boat, make sure i get the right tap (start and end maybe). Also a decent carbide bit with correct dimension.

    I've got a drill press and clamp.

    I'll try and drill out the existing and re-tap - but i've also ordered some new grub screws to do fresh.
    You will only need a bottoming tap to clean out the remains of the broken screw, less risk of cutting new threads and damaging the old ones.
    It really is quite difficult to build an ugly wooden boat.

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  20. #20
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    Default Re: have you seen one of these?

    Sorted,

    A mate very meekly gave my two of his brand new, sharp as anything, carbide bits to drill it out. Smearing of cutting compound and it was like a knife through butter.
    I got a tap and inserted it from the back to clean out the thread. I gifted my mate the tap as thanks for trusting me with his new bits.

    Nick - you're right a bottom tap would have been the way to go, the tap i had tapered just before the end, but i could only get my hands on that one. As it is, the last turn or two was easy to clean up with a screw from the back.

    The thread was a BSW 20 on a quarter inch screw. Apologies for the BSP - I've been buying plumbing parts recently and must have read it too hastily.

    Thanks for your helpful advice all.
    Philip K. Dick — 'Reality is that which, when you stop believing in it, doesn't go away'.

  21. #21
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    Default Re: have you seen one of these?

    British Standard W​hitworth !

  22. #22
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    Default Re: have you seen one of these?

    I love it when a plan comes together.
    It really is quite difficult to build an ugly wooden boat.

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  23. #23
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    Default Re: have you seen one of these?

    Quote Originally Posted by Canoeyawl View Post
    British Standard W​hitworth !
    There are only a few dozen threads to choose from. This is the most complete list I have run across:
    http://historicmotorcycle.org.au/ima...ead_Tables.pdf
    BRITISH THREADS
    US THREADS METRIC PIPE
    BSW USS BA No BSP
    BSF SAE Regular BA Briggs
    ADM Fine SAE Fine S.I. Copper
    CEI ASME No. Metric Fine
    Brass ASME Standard Swiss Std
    Conduit ASME Special Swiss Fine
    NC S.I. DIN
    NF S.I. Fine DIN
    Lowenhurz
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  24. #24
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    Default Re: have you seen one of these?

    In the pipe dept. just to keep things simple
    We have;


    • UN/UNF
    • NPT/NPTF
    • BSPP (BSP, Parallel)
    • BSPT (BSP, Tapered)
    • Metric Parallel
    • Metric Tapered

  25. #25
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    Default Re: have you seen one of these?

    Then there's this one (no mention of the pitch);

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    Default Re: have you seen one of these?

    A metal working lathe ,a few books ,patience and interest ,ancillary tooling and the world is yours .. Mechanically anyway ..
    Cheers

  27. #27
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    Default Re: have you seen one of these?

    What are you actually trying to achieve - why an internally threaded grub screw? Is there a better (more standard) way of solving whatever this thing does at the moment?

    Pete
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  28. #28
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    Default Re: have you seen one of these?

    Quote Originally Posted by gypsie View Post
    I don't have the tools for it. But it'd be tricky i think. there's not much material and retapping would be thin.

    At worst I'll sink in a few nuts into the hole instead, epoxied in place.
    All the forces are lateral, no pull on the plate. Its for the base plate for my deck mounted mast. One of four.
    Quote Originally Posted by epoxyboy View Post
    What are you actually trying to achieve - why an internally threaded grub screw? Is there a better (more standard) way of solving whatever this thing does at the moment?

    Pete
    I think that it is a refit, not a new build. So it is reinstalling what was already there.
    It really is quite difficult to build an ugly wooden boat.

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  29. #29
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    Default Re: have you seen one of these?

    For extraction of a broken screw, Snap On offers a system that uses a reverse spiral drill and a fluted pin that can be driven into the hole and
    turned with a special collet to remove the broken screw.
    https://cyber-monday.us/Snap On Screw Extractor?p=scb&gclid=EAIaIQobChMI The site will open on Cyber Monday then type in
    Snap On Screw Extractor?p=scb&gclid=EAIaIQobChMI
    So far as the insert is concerned, they are marketed under the name "EZ-lok" and come in a large variety of sizes both SAE and Metric in stainless steel or brass. They are available for wood applications as well as metal. https://www.amazon.com/s/?ie=UTF8&ke...d+inserts&tag=
    I often have to resort to installing a bolt into an area where there is no access to the underside of the timber. The EZ-loc fasteners are a Godsend for solving this problem.
    Jay
    Last edited by Jay Greer; 11-29-2018 at 01:31 PM.

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