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  1. #31
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    Nov 2017
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    Geelong, Australia
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    Quote Originally Posted by BaronJ View Post
    Hi Steve,

    Yes it does look as if the worm wheel has taken a hammering ! Are you going to make or buy a new one and replace it ?
    Most likely Iíll just make a replacement unless it happens to be a size thatís easy/cheap/quick to get.

    Steve

  2. #32
    Join Date
    Nov 2017
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    Geelong, Australia
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    Default The joy of having a TOS.... ( FNGJ32 mill )

    Not surprisingly the worm itself has a bit of corrosion pitting once cleaned up, but will be good enough for now.
    Weird, itís a completely metric machine but the worm is 8tpi.
    I happened to have a 24x3 cap screw sitting in the scrap box - should be hard enough to cut a bronze wheel.
    3mm is slight bit finer than 8tpi but since thereís only about 4 teeth in mesh I figure it will be close enough.

    6 flutes should do it, but I didnít have any convenient way of indexing it, so welded a flange but on the end to give me something.



    Clamp it in one of the tee slots with one of the flats on the nut vertical.



    It looks like a fancy setup, but truth is the head was already at 45deg and I couldnít be bothered changing it!!

    The cheap insert shoulder mill raised a lot of burrs, so I did another pass after this photo using a HSS end mill.



    The end result with the bronze blank for the wheel.



    Steve

  3. #33
    Join Date
    Sep 2012
    Location
    North Yorkshire UK
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    Hi Steve Guys,

    Based on my recent experience with bronze, is that it is tougher than you think !

    Anyway good luck with it.

    Edit: Would you believe that I actually have an M24 X 3 HSS steel die in my collection along with an M24 X 3, 2nd tap and a metre of M24 all thread.
    Best Regards:
    Baron J.

  4. #34
    Join Date
    Nov 2017
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    Geelong, Australia
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    Default The joy of having a TOS.... ( FNGJ32 mill )

    Slowly been working on making the worm wheel in between other jobs.
    Wheel is 36T, and I happened to have a 36T spur gear lying around so decided to use that for indexing. Mounted the gear to a shaft made from an old shoulder bolt, and used the thread and shoulder to hold the blank.



    Found a lump of scrap that already had the right size hole in it for the bolt shank/shaft, so gave that a quick skim in the mill to clean it up and then split it in the bandsaw so it would clamp the shaft.
    Fitted the shaft and drilled an index hole.



    Mounted it in the vice and cut some slots to help the "hob" get a decent bite.




    Mounted the blank on a couple of bearings and bolted it to a bit of hot rolled square clamped in a tool holder.



    It came out much better than I expected.





    Steve

  5. #35
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    Nov 2017
    Location
    Geelong, Australia
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    I noticed in that photo that there are a couple of slots not lining up with the valleys.
    Turns out I have 37 teeth on the wheel instead of 36.
    Guess that's what you get when you use 3mm pitch thread instead of 8TPI !!!

    Edit: And the grooves aren't centered in the wheel width due to the fact that I eyeballed it roughly from a distance just to do a test run - not expecting it might turn out half decent...

    Steve

  6. #36
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    Sep 2012
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    North Yorkshire UK
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    Hi Steve,

    That's a bugger ! When I looked at your pictures, I thought that you were doing so well it looks like a very nice gear.
    Best Regards:
    Baron J.

  7. #37
    Join Date
    Aug 2009
    Location
    Lara, Vic, Oz
    Posts
    19

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    Yeah, nice looking gear, like your approach to hobbing - as it is not particularly timed to anything (36 vs 37T), I'd have though a great job! Good work Steve!

  8. #38
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    Nov 2017
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    Geelong, Australia
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    I did a quick trial fit of that gear tonight thinking that if it ran nicely Iíd just use it to get me going for now. It just didnít feel quite right - turned ok then got stiff and either freed up or got tighter from there. When I took it apart again I could see where the teeth that were slotted had started to deform - so itís no go on that one.

    The only 8TPI male thread I had around was some all thread. I was pretty sure it wouldnít be hard enough but gave it a go.
    It wasnít. After a good start for the first couple of gear revolutions, the cutting pressure just rounded the teeth over (blank wasnít slotted first).

    Without getting into single point threading and heat treating an 8TPI hob, my other options are to get a hi-tensile bolt to hack up into a hob, buy a 1Ē UNC tap or just give the 3mm pitch one another go without slotting the gear first.
    Given that going out to buy anything is getting less attractive by the hour, I think Iíll give the 8TPI another go for a start.

    Steve

  9. #39
    Join Date
    May 2011
    Location
    Murray Bridge S Aust.
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    67
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    4,439

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    Does it have to be a UNC tap, asking as I may have a Whitworth at work? Will check tomorrow.
    Kryn
    To grow old is mandatory, growing up is optional.

  10. #40
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    Nov 2017
    Location
    Geelong, Australia
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    53
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    Quote Originally Posted by KBs PensNmore View Post
    Does it have to be a UNC tap, asking as I may have a Whitworth at work? Will check tomorrow.
    Kryn
    Thanks Kryn. I'm guessing that the couple of degrees difference between UNC and Whitworth wouldn't be a problem.
    Would certainly give me another option if you had one I could borrow.

    Steve

  11. #41
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    Nov 2017
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    Geelong, Australia
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    Had another go with the 3mm pitch hob tonight, didnít bother with any slotting.
    Came out really well, and seems to run nicely when fitted.



    Refitted the pump, motor and belt without connecting the oil lines (gave the worm area a decent squirt with the oil can beforehand) and it runs happily.
    The belt is showing its age so Iíll replace that while itís easily accessible.

    Next will be to clean up the mess in the workshop a bit before I attack checking the oil lines are clear and cleaning up the knee.

    Hereís a couple of photos of the cam plate on the pump and how it moves the pistons in case anyone is interested.




    Steve

  12. #42
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    Sep 2012
    Location
    North Yorkshire UK
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    Hi Steve,

    Great stuff, that is a nice looking gear, what happened to muck it up first time around ?
    Best Regards:
    Baron J.

  13. #43
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    Nov 2017
    Location
    Geelong, Australia
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    Thanks John.
    First time came out nicely except having the 36 slots pre-cut and ending up with 37 teeth from the 3mm hob pitch meant it had slots through the teeth.
    I didnít count the teeth on this one but assume itís 37.

    The hi-tensile bolt/hob held up really well. Still cutting nicely after doing both gears.

    Steve

  14. #44
    Join Date
    Nov 2017
    Location
    Geelong, Australia
    Age
    53
    Posts
    745

    Default The joy of having a TOS.... ( FNGJ32 mill )

    Spent about 5 hours over the last couple of days battling to get the oil pump pumping. It wasn't priming so I went through the saga of removing the suction line from the pump and blowing back through it with compressed air to make sure it was clear.
    That cleared a little bit of snot, but the pump still wouldn't prime.

    The bottom end of the tube is retained in a strainer affair that is bolted to the bottom of the sump. I removed it, blew it out some more, cleaned the strainer while I was at it, but still wouldn't prime while holding it in sump.
    To add to that when I tried to refit it I couldn't get the bolts started - I'd stirred up a bit of a cloud in the sump so couldn't see the holes and no luck doing it by feel - so had to drain the oil.
    Thankfully that was an easy job with a vacuum pump and a container.

    Reattached the strainer/pickup to the bottom of the sump and refilled it with fresh oil
    STILL wouldn't prime even after running the pump for 5 mins straight
    I was starting to get worried that either the pump had an issue or the suction line was broken inside the knee and pulling air instead of oil....

    So I removed the suction line from the pump AGAIN, and sucked the oil up the tube using the vacuum pump.
    Refitted it, and finally after running for a couple of minutes it started to pump out the one outlet that is still disconnected from its hose.

    Still took about 15mins more of running the pump constantly before all the lines were full and I could see the oil was being delivered to the far side of the knee.

    Nearly there with the oiling - just need to replace one length of plastic delivery hose, and get a new belt.

    Speaking of which - anyone have experience with timing belts?

    This one is 55 tooth, 345mm long (measured by rolling it on its back along the bench), and 12mm wide.
    That works out at 6.27mm pitch, which I can't find anything close to online in either metric or imperial.
    Any ideas?



    Steve

  15. #45
    Join Date
    Sep 2012
    Location
    North Yorkshire UK
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    Hi Steve,

    Try these people,

    https://www.brecoflex.com/products/timing-belts/

    I suspect that you have a slightly stretched belt there.
    Best Regards:
    Baron J.

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