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  1. #31
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    May 2003
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    Lappa, Pagie. I think the speed is Ok. It can do any speed from zero to 1750 rpm.

    There is no speed controller because it is a clutch motor. Actuate the clutch rod and the drive shaft starts spinning. Speed depends upon how far you move the actuator, and running it all day long at a low speed with the clutch ‘slipping’ shouldn’t be a problem as that’s what its designed for.

    I suspect time will prove that it’s not really ideal for this task, but when I fully understand the requirement I can swap it out for another motor if need be.
    Apologies for unnoticed autocomplete errors.

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  3. #32
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    Perth
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    Quote Originally Posted by Arron View Post
    Lappa, Pagie. I think the speed is Ok. It can do any speed from zero to 1750 rpm..
    I doubt its 1750 rpm, 1750 RPM will be for a 60Hz supply.
    For a 50Hz supply it will be something like 1450 RPM.

    However, if you are going to buy another pulley I'd definitely be looking for something that drops the max speed.
    For example, what would happen to the clay object if the motor is accidentally kicked to max speed of 1450 rpm?
    Maybe you can fit a "stop" or "limit" of some kind to prevent this?

  4. #33
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    May 2003
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    Central Coast, NSW
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    Quote Originally Posted by BobL View Post
    I doubt its 1750 rpm, 1750 RPM will be for a 60Hz supply.
    For a 50Hz supply it will be something like 1450 RPM.

    However, if you are going to buy another pulley I'd definitely be looking for something that drops the max speed.
    For example, what would happen to the clay object if the motor is accidentally kicked to max speed of 1450 rpm?
    Maybe you can fit a "stop" or "limit" of some kind to prevent this?
    Yes, good idea.
    If I had thought of that when it was in the sewing machine then I would never have had to replace it with a servo motor.
    Apologies for unnoticed autocomplete errors.

  5. #34
    Join Date
    Oct 2002
    Location
    NSW
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    Do you have some way of stopping the clay slurry from running down the drive shaft where it comes through the bottom of the splash guard?

    Wheels tend to have a tube coming up from the base of the splash guard, inside a tubular flange(s) coming down from the wheel head, so the water/clay mix would have to follow an S-shaped path to get onto the drive shaft and destroy the bearings.
    Screenshot_20191223-074155.jpg
    Cross-section, green = splash tray, blue = wheel head, red = drive shaft

  6. #35
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    May 2003
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    Central Coast, NSW
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    My solution to that is to soften the splashguard in the region of the shaft, bend it upwards to create a dam and then let it harden.
    I hope it works.
    Apologies for unnoticed autocomplete errors.

  7. #36
    Join Date
    May 2003
    Location
    Central Coast, NSW
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    Default And more ‘progress’

    So I did a bit more to the wheel this morning.

    First thing was that I found another pulley - this one with a grub screw. Unfortunately it’s only the same diameter as the previous one. Nevertheless I flattened a bit of the shaft, mounted it, and it works very well.

    Then I drilled the shaft for a roll pin to engage the turntable.

    Then I took it for its maiden voyage.

    Results fell short of expectations.

    The turntable unfortunately is made from melamine coated mdf and it has a bit of wobble - just a little bit but any is bad. It will have to stay till I get access to a decent lathe to true it up.

    The clutch motor is a disappointment. At low rpm the torque is minimal - and 300 rpm is in that zone. Perhaps when I get a larger pulley the motor will be turning at higher speed and that will overcome the problem.

    Plus it’s hard to get it running at the right speed too. It needs a lot of force to overcome inertia, but once overcome that measure of force produces a speed much too high, so I have to back it off preemptively and often end up yo-yo-ing. I think maybe it would be better with a foot pedal.

    I’m not sure whether it’s usable or not. I’ll get some clay soon and find out.

    Meanwhile, any good ideas on how to measure the speed (besides the obvious of counting against a stopwatch).

    Cheers
    Arron
    Attached Images Attached Images
    Apologies for unnoticed autocomplete errors.

  8. #37
    Join Date
    Oct 2002
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    NSW
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    Re: the wobble - "throwing off the hump" can overcome that. YouTube has lots of examples of developing countries where rudimentary potter's wheels have large amounts of wobble.

  9. #38
    Join Date
    Dec 2006
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    East of Melbourne Aus.
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    Yes you need full power at low speeds to throw pots. Any jerking will not be help full. WSnKMKvVTbed+YdVg3YCEQ.jpgI throw these vases.
    I am learning, slowley.

  10. #39
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    Quote Originally Posted by arose62 View Post
    Re: the wobble - "throwing off the hump" can overcome that. YouTube has lots of examples of developing countries where rudimentary potter's wheels have large amounts of wobble.
    Ok, I had to look up what that is, but it puts my mind at ease.

    Cheers
    Arron
    Apologies for unnoticed autocomplete errors.

  11. #40
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    Jan 2014
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    Sydney Upper North Shore
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    I bought a cheap photo tachometer from eBay to measure my router speed. Compared it to our high end one at work and its not bad at all.
    This one is very similar

    https://www.ebay.com.au/i/2334357096...4aApNNEALw_wcB

  12. #41
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    Dec 2005
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    South Australia
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    Those tachos are getting cheaper by the day they will giving them away next

  13. #42
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    Jan 2014
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    Quote Originally Posted by China View Post
    Those tachos are getting cheaper by the day they will giving them away next
    Yep.
    I paid $22.99 for mine back in 2017

  14. #43
    Join Date
    May 2003
    Location
    Central Coast, NSW
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    To measure the speed, not wanting to wait for the delivery of a cheap tacho, this is what I did.

    Put a large black dot on the edge of the turntable
    Video it in slow-mo with iPad - up real close, capturing just the edge where the dot is
    Record a 15 second video
    Play it back and count the flashes.

    It works very well.
    Apologies for unnoticed autocomplete errors.

  15. #44
    Join Date
    May 2003
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    Central Coast, NSW
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    To measure the speed, not wanting to wait for the delivery of a cheap tacho, this is what I did.

    Put a large black dot on the edge of the turntable
    Video it in slow-mo with iPad - up real close, capturing just the edge where the dot is
    Record a 15 second video
    Play it back and count the flashes.

    It works very well.
    Apologies for unnoticed autocomplete errors.

  16. #45
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    Perth
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    Quote Originally Posted by Lappa View Post
    Yep.
    I paid $22.99 for mine back in 2017
    I got mine (Branded as a Digitech QM1448 but they are all the same) in 2007 from USA Farnell and thought I had paid about $20 for it but I did manage to find an email which said the price was $44.75 plus $15 shipping. It's been used it extensively on my small motor dyno and only recently replaced the original battery and it's still working well.

    I see that the same tacos are also priced on eBay as high as $100!

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