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  1. #2266
    Join Date
    Sep 2012
    Location
    York, North Yorkshire UK
    Posts
    6,444

    Default

    Hi Bill,

    Nice one I've seen wobbler’s driving small electric motors as generators, so I don't think driving a pencil sharpener is beyond you.
    Best Regards:
    Baron J.

  2. #2267
    Join Date
    Feb 2013
    Location
    Laidley, SE Qld
    Posts
    1,038

    Default Re-threading an unusual internal thread.

    Hudson Motors from the 30s to the 50s used double threaded suspension bushes, the ID was threaded 11/16" x 11 tpi (UNC), the OD was 7/8" x 11 tpi but a very shallow thread with an included angle of 150°, thread depth is .3mm. (Sounds weird but there were good reasons for using the shallow thread). This particular bush screws into a matching thread in a cast steel chassis member but unfortunately the thread was stripped and the bush wouldn't tighten up, it wasn't secure in the chassis. The problem was doubtless caused by years of pounding along rough dusty roads.

    IMG_2262.jpg

    So how to fix it? I briefly contemplated using one of the high tech epoxies to bond the bush in place but decided that the best course would be to make an oversize tap, clean up the threads and then make a bush with an oversize OD to suit the new hole.

    Step 1 was to make a 150° threading tool, which I made from silver steel.
    IMG_2266.jpg

    Step 2 was to make the tap. I decided on an OD of 0.9" (7/8" + 2 x thread depth), I figured (hoped) that would be enough to clean up the damage inside. I roughed out the tap, cut the 6 flutes on the mill and then single pointed the threads, the threading tool worked very well. I didn't have a suitable piece of silver steel from which to make the tap so I used 1020 and hardened it with cherry red case hardening powder. After hardening I used a 4" cut-off blade in the angle grinder to hone the teeth, running the blade along the flutes just kissing the edge of the teeth. All very high tech.
    IMG_2259.jpg

    The tap worked, I don't know how many more holes it would have cleaned up but it got this job done.
    After that it was plain sailing. I made the oversize bush from a piece of 4130 using the same 150° threading tool and oil quenched it. The new bush screws up tight in the chassis, all is well with the world.
    IMG_2260.jpg

  3. #2268
    Join Date
    Apr 2009
    Location
    Ballina N.S.W.
    Posts
    644

    Default

    bob ward,
    I like your well thought out fix, a bit of a project to make up the tap and thread tool but now you have it as good as new. Did you do both sides ?
    Bob

  4. #2269
    Join Date
    May 2010
    Location
    Perth
    Posts
    135

    Default

    so what is the reason for the (Sounds weird but there were good reasons for using the shallow thread).? ????


    Quote Originally Posted by bob ward View Post
    Hudson Motors from the 30s to the 50s used double threaded suspension bushes, the ID was threaded 11/16" x 11 tpi (UNC), the OD was 7/8" x 11 tpi but a very shallow thread with an included angle of 150°, thread depth is .3mm. (Sounds weird but there were good reasons for using the shallow thread). This particular bush screws into a matching thread in a cast steel chassis member but unfortunately the thread was stripped and the bush wouldn't tighten up, it wasn't secure in the chassis. The problem was doubtless caused by years of pounding along rough dusty roads.

    IMG_2262.jpg

    So how to fix it? I briefly contemplated using one of the high tech epoxies to bond the bush in place but decided that the best course would be to make an oversize tap, clean up the threads and then make a bush with an oversize OD to suit the new hole.

    Step 1 was to make a 150° threading tool, which I made from silver steel.
    IMG_2266.jpg

    Step 2 was to make the tap. I decided on an OD of 0.9" (7/8" + 2 x thread depth), I figured (hoped) that would be enough to clean up the damage inside. I roughed out the tap, cut the 6 flutes on the mill and then single pointed the threads, the threading tool worked very well. I didn't have a suitable piece of silver steel from which to make the tap so I used 1020 and hardened it with cherry red case hardening powder. After hardening I used a 4" cut-off blade in the angle grinder to hone the teeth, running the blade along the flutes just kissing the edge of the teeth. All very high tech.
    IMG_2259.jpg

    The tap worked, I don't know how many more holes it would have cleaned up but it got this job done.
    After that it was plain sailing. I made the oversize bush from a piece of 4130 using the same 150° threading tool and oil quenched it. The new bush screws up tight in the chassis, all is well with the world.
    IMG_2260.jpg

  5. #2270
    Join Date
    Feb 2013
    Location
    Laidley, SE Qld
    Posts
    1,038

    Default

    Yes, the other side has a fresh thread as well.

    Quote Originally Posted by krisfarm View Post
    bob ward,
    I like your well thought out fix, a bit of a project to make up the tap and thread tool but now you have it as good as new. Did you do both sides ?
    Bob

  6. #2271
    Join Date
    Feb 2013
    Location
    Laidley, SE Qld
    Posts
    1,038

    Default

    That one bush was used throughout the car’s suspension system, including the eyes of the leaf springs. The insides of the leaf spring eyes were left plain (rather being tapped) and the shallow thread bush could burrow its way in and hold tight, think of a 7/8” self tapping screw.



    Quote Originally Posted by desbromilow View Post
    so what is the reason for the (Sounds weird but there were good reasons for using the shallow thread).? ????

  7. #2272
    Join Date
    Oct 2008
    Location
    N.W.Tasmania
    Posts
    1,407

    Default

    Quote Originally Posted by jack620 View Post
    I made a few of these to give to friends and work colleagues. They are a real hit.
    Chris, I can see why they would be a hit, But AFAIK tampering with such items is considered a little naughty, and possibly best not widely publicised on forums such as this. We don't want to see your toes crunched by some overly zealous bureaucratic type. I must stress that I am no lawyer, and it certainly does not offend me, but unless you have good advice to say there are no ramifications to worry about, a quick edit of the post to remove any offending bits may save you some un-needed hassle. Just my 20 cents worth anyway

  8. #2273
    Join Date
    Nov 2007
    Location
    melbourne australia
    Posts
    3,228

    Default

    Oh alright, post deleted.

    BTW ropetangler, it cost 40c to make.
    Chris

  9. #2274
    Join Date
    Oct 2015
    Location
    melbourne
    Posts
    473

    Default

    So now I am curious... Tampering with what is 'naughty'...

    '

    Russ

  10. #2275
    Join Date
    Aug 2008
    Location
    near Rockhampton
    Posts
    6,216

    Default

    Quote Originally Posted by russ57 View Post
    So now I am curious... Tampering with what is 'naughty'...

    '

    Russ
    I guess he has made a real perpetual motion machine but has decided to keep it secret, denying us all cheap free energy.
    Gold, the colour of choice for the discerning person.

  11. #2276
    Join Date
    Nov 2007
    Location
    melbourne australia
    Posts
    3,228

    Default

    How am I going to achieve world domination if I let you all in on the secret to free energy?
    Chris

  12. #2277
    Join Date
    Jul 2006
    Location
    Athelstone, SA 5076
    Posts
    4,255

    Default

    mmm? what did I miss

  13. #2278
    Join Date
    Oct 2015
    Location
    melbourne
    Posts
    473

    Default

    I did wonder if it was a coin...
    And I was about to say that wasn't illegal but it turns out it is in Australia.


    Russ

  14. #2279
    Join Date
    Jan 2016
    Location
    Wodonga Vic
    Age
    38
    Posts
    633

    Default

    Did you make some jewellery out of currency?

    Coin rings perhaps...?

  15. #2280
    BobL is offline Member: Blue and white apron brigade
    Join Date
    Feb 2006
    Location
    Perth
    Posts
    7,183

    Default Heat sink

    This is a bit of nonsense that I probably shouldn’t have started with but as I got further and further involved with it I wouldn’t let it defeat me.

    A while back I pulled apart an old electrical fan/heater to recover the electrical parts.
    The heater was the type that has the fake/plastic logs under which a slowly rotating flickering mechanism scatters reflected light from an orange coloured incandescent globe.

    The rotating flickering mechanism (the reflective tree like thing in the photo) was rotated by a small mains powered motor shown in this photo.
    The reflector is connected to the motor axel via a stiff piece of thick black rubber tubing.
    refelectormotor.JPG


    I put the motor inside a stub of 100 mm PVC pipe, capped at both ends with PVC end caps, with the motor drive axel poking through one of the caps.
    For a bit of colour I added 6 coloured LEDs inset into the cap around the axel.
    All well and dandy and feeling very pleased with myself because apart from the LEDs everything else came from the heater itself (cable/gland/switch), and the 15V power adapter to run the LEDs came from my box of adapters.
    The plan was to give it to my son for my grandsons bedroom as a sort of an hypnotic night light.


    Then I fired it up and after about 15 minute I notice the PVC around the motor was relatively warm and followup testing with an IR meter showed the outer PVC eventually reached ~45ºC while the motor inside was over 60º.
    I then remembered that inside the heater a fan drove air past the motor and out over the heater element.

    I was loath to add a fan so I decided to make a heat sink to see if that would drop the temperature.
    Making the heat sink turned out to be a bit of PITA because the motor axel is off centre but I persisted and turned it up out of stub of solid Al.
    IHSink1.JPG



    I then added some small vent holes to the PVC, and thermal paste between the motor and the heat sink now the heat sink reaches ~40ºC while the motor now seems to plateau at about 45º so it's clearly working.
    I’m going to run it for several days just to see where it really gets to.

    Here's what it looks like in its entirety
    The LEDs are faintly reflected by the reflectors a bit like a kaleidoscope onto light coloured walls of a darkened room.

    Gizmo2.JPG


    Gizmo1.JPG

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