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  1. #46
    Join Date
    Nov 2017
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    Geelong, Australia
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    57
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    Thanks, but nothing close in their catalogue.

    I'm a bit suspicious that it could be an oddball. The 8TPI worm in the oil pump in what is otherwise a completely metric machine makes me think the pump and drive came from a separate supplier and were just fitted to the machine.

    Steve

  2. #47
    Join Date
    May 2011
    Location
    Murray Bridge S Aust.
    Age
    71
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    5,942

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    I'd take the belt to your local belt/bearing place and they should be able to come up with something for you. They should have a multitude of suppliers to choose from.
    Kryn
    To grow old is mandatory, growing up is optional.

  3. #48
    Join Date
    Oct 2017
    Location
    Lismore, NSW
    Posts
    58

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    OxxAndBert,
    Try PIES Australia, I recently had dramas trying to find a suitable toothed belt for a model & this company were able to supply a belt when I could not find any other supplier.
    Regards,
    Don.

  4. #49
    Join Date
    Nov 2017
    Location
    Geelong, Australia
    Age
    57
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    2,651

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

    Thanks guys, I'll do some chasing for a belt tomorrow.

    After spending most of the day today doing jobs for everyone else, I decided to put move onto sorting out the power feed issue.
    I described earlier on that I wasn't getting positive drive with the normal feeds. The selected axis would start to move but then slow down and stop but the feed motor kept running normally.

    Firstly (now that I've worked it out) a bit of background on how the feed works on this machine:

    Separate feed motor located in the main column, drives the feed gearbox (above the motor) via vee belt.

    Output from the gearbox goes:
    - Via gear and electric clutch to the Y axis leadscrew located in the top of the feed gearbox (moves the ram containing the spindles)
    - Via duplex chain and bevel drive to the knee for the X and Z axis leadscrews.

    There are 5 electric clutches in the system:
    - normal feed output clutch (with a 0.8s delay timer in the circuit)
    - rapid override feed clutch
    - One clutch for each axis (X, Y, Z)

    There are also 3 electric clutch type brakes that are energised briefly when feed is stopped to prevent overrun.
    All the clutches/brakes are 24VDC

    Here's a drawing of the control console - all the feed buttons are momentary type:
    Console.JPG

    When you press one of the axis feed buttons on the console it:
    - energises and latches the contactor for the feed motor to power it in the appropriate direction
    - energises the normal feed output clutch via the timer
    - energises the feed clutch for the selected axis

    Pressing and holding the rapid feed override button while normal feed is running:
    - breaks the circuit to the normal feed output clutch (by removing power to the delay timer)
    - energises the rapid feed clutch increasing the output speed gearing

    When you release the rapid feed button (S14):
    - it de-energises the rapid feed clutch
    - energises the normal feed output clutch via the timer so feed returns to the normal rate

    Pressing the "Feed Stop" button (S15) turns off all the feed clutches and motors and briefly energises the axis brake.

    Clear as mud??

    Back to the original issue - non positive feed....
    My first thought was a slipping clutch, and since the problem affected all axes it indicated it would be in the feed box itself.

    The access to the guts of the feed box is through an access plate behind the electrical panel.
    Removed the panel and cashed in a few brownie points by getting my wife out to the workshop to push buttons while I looked.



    The current to the clutch goes via a spring loaded sintered bronze brush to the steel flange on the RH side of the clutch body. Interesting arrangement that I haven't come across before.

    NOTE FOR FIRST TIMERS: Pull the lube pump fuses now or you will regret it.....!!!!
    Turned on the feed and can see the main feed clutch is definitely slipping.
    Press the rapid button and that clutch engages OK.

    I confess I hadn't thought to pull the fuses at this point. Thankfully the back of the electrical cabinet (mostly) shielded my wife from the oil spray. Mostly.
    Lube pump fuses removed.....

    Regain my composure and check the voltage at the clutch when it should be engaged - less than a couple of volts.

    Continued troubleshooting the electrical side and finally worked out the issue was a faulty timer. Confirmed by shorting the input and output from the timer and the clutch engaged properly.



    One of these things is not like the others!!!

    Edit: bugger just hit my monthly Tapatalk upload limit so will have to post rest of photos from my computer



    Guessing this isn't the first timer that has failed and also guessing its not easy to find a replacement for that old style.



    Steve

  5. #50
    Join Date
    May 2011
    Location
    Murray Bridge S Aust.
    Age
    71
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    Thanks for the update on WotWentWong, any brownie points that you gave back, suddenly plummeted when someone didn't take out the pump fuse
    This pic looks like it came from a telephone exchange. https://uploads.tapatalk-cdn.com/202...5be1896f43.jpg
    Kryn
    To grow old is mandatory, growing up is optional.

  6. #51
    Join Date
    Sep 2012
    Location
    York, North Yorkshire UK
    Posts
    6,436

    Default

    Hi Steve,

    Quote Originally Posted by OxxAndBert View Post
    Thanks guys, I'll do some chasing for a belt tomorrow.

    Is that a plate nut hiding just under the yellow wire ? Bottom middle of the picture.

    Guessing this isn't the first timer that has failed and also guessing its not easy to find a replacement for that old style.



    Steve
    That relay is the first thing that I would suspect, I'll have a look for its details shortly. It looks like a standard PCB mounting relay and can be replaced pretty easily.

    It would help if you could get a good picture of the pin out on the PCB, even better if you can identify the coil pins, and super if you can identify the contact pins and arrangement.

    I've not seen any 11 pin timer relays for a good number of years, they used to be quite popular at one time.

    Have a look at
    https://martelbojnice.sk/en/time-delay-relays/

    and this picture from their web site
    rel_tx110-3.jpg
    11 pin base, same part.
    Best Regards:
    Baron J.

  7. #52
    Join Date
    Nov 2017
    Location
    Geelong, Australia
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    57
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    Default

    Thanks John. Appreciate the info and suggestions.

    Good spotting on the plate nut. Not the best thing to have floating around in an electrical cabinet!!
    Hopefully just the by-product of careless maintenance and no longer needed, but I'll check it out.

    The timer was making a regular ticking noise, and my gut feel is that its not latching on after the set time so just keeps re-starting.
    I'm not a trained master of sparks and smoke by any stretch, but replacing a PCB relay is definitely within my capabilities.

    There's always the option of replacing the base and timer with a modern one - I just need to make sure it works with 110VAC control rather than the usual 230V locally here.

    Steve

  8. #53
    Join Date
    Nov 2017
    Location
    Geelong, Australia
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    Quote Originally Posted by Don@2480 View Post
    OxxAndBert,
    Try PIES Australia, I recently had dramas trying to find a suitable toothed belt for a model & this company were able to supply a belt when I could not find any other supplier.
    Regards,
    Don.
    Thanks Don. I emailed PIES this morning and had a response within the hour with a suitable belt spec.
    No stock locally but the sales guy is checking offshore.
    Definitely impressed with their customer service so far.

    Steve

  9. #54
    Join Date
    Oct 2017
    Location
    Lismore, NSW
    Posts
    58

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    G'Day Steve,
    I found the Pies company very good to deal with also. I had the belt I required within a couple of day of payment.
    Regards,
    Don.

  10. #55
    Join Date
    Sep 2012
    Location
    York, North Yorkshire UK
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    Hi Steve,

    I don't see any latching circuit on this timer relay.

    timer.png

    You can check the contact resistance between pins 5 and 6 in the unenergised state and between 6 and 7 when energised. The other contact is between 3 and 4 and will be closed when the relay is energised. I'm not sure what the capacitor is doing, unless it is part of the timing circuit. In which case an external capacitor could be added to extend the time delay.

    I would investigate that internal relay first, particularly when you say it ticks regularly ! Since the label says zero to two seconds, that would be about right. The knob would alter the tick speed.
    Best Regards:
    Baron J.

  11. #56
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    Nov 2017
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    Geelong, Australia
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    Yes, the knob definitely adjusts the “tick” speed.

    6 is the 24vdc input for the clutch
    7 goes to the clutch itself

    5-6 unenergised 0 ohms
    6-7 energized I can’t easily test but it’s showing 24vdc across it all the time so it’s either very high resistance or not closing. No noticeable change in the reading on the (digital) meter while it’s “ticking”.

    There’s an external resistor and capacitor in series across 2 of the terminals.
    I’ve sketched out which terminals are connected but need to make it legible and see how fits with the wiring diagram so it makes more sense before I post it.

    BTW - the random loose plate in the previous photo was the lower plate from the timer that holds the clear cover in place. No sign of the screw...

    Steve

  12. #57
    Join Date
    Sep 2012
    Location
    York, North Yorkshire UK
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    Hi Steve,

    Based on a comment you made earlier, if the contacts 6-7 are not closing properly and the clutch is not operating properly ie not fully energised, but linking 6-7 with the link wire as in your picture, it is. Then the relay in the timer is shot.

    en-g5v_2.pdf

    Does this PDF help with the contact layout. I suspect that the relay will be a double pole changeover one.
    Best Regards:
    Baron J.

  13. #58
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    Nov 2017
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    Geelong, Australia
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    Thanks - I'll check out that PDF properly shortly.
    Its a pain that its a 110v unit as I can't easily test it on the bench.

    Steve

  14. #59
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    Nov 2017
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    Geelong, Australia
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    External connections to the relay itself are simple.
    On RH side there's a ground connection, and the output from the transistor to turn the relay on
    On LH side there are the connections to pins 5, 6, 7 (NC, COM, NO)

    My expectation is that the timing circuit should do its thing when power is applied, and then turn the output transistor on which energises the relay. What I'm not getting is why that timing circuit is cycling (ticking)....

    Steve

  15. #60
    Join Date
    Sep 2012
    Location
    York, North Yorkshire UK
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    Hi Steve,

    Quote Originally Posted by OxxAndBert View Post
    Thanks - I'll check out that PDF properly shortly.
    Its a pain that its a 110v unit as I can't easily test it on the bench.

    Steve
    That timer takes almost no current, maybe 20 ma, Two identical (ideally) transformers with the primary’s wired in series will give you about 115 volts at the centre tap with more than enough current to power the relay. If you are very lucky, you might have a transformer with a 0 - 110 - 220 volt primary that you could use.

    Since the connections would be directly in contact with the mains supply, please take care.

    I'm quite lucky in that I have a fully cased 2.5Kw 2:1:1:2 bench isolation transformer that is centre tapped on both sides. Mind you that its about a foot cube plus the end covers, I have real trouble picking it up nowadays.

    I don't think that there is any latching arrangement to lock the timer on at the end of the time period, so it will tick normally.
    You should be able to see the relay contact arm move as it ticks.
    Best Regards:
    Baron J.

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