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22nd December 2019, 09:35 PM #31GOLD MEMBER
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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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22nd December 2019 09:35 PM # ADSGoogle Adsense Advertisement
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22nd December 2019, 09:50 PM #32.
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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?
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23rd December 2019, 07:16 AM #33GOLD MEMBER
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23rd December 2019, 07:51 AM #34GOLD MEMBER
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- Oct 2002
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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
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23rd December 2019, 12:09 PM #35GOLD MEMBER
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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.
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23rd December 2019, 04:57 PM #36GOLD MEMBER
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- May 2003
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- Central Coast, NSW
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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
ArronApologies for unnoticed autocomplete errors.
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23rd December 2019, 06:30 PM #37GOLD MEMBER
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- 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.
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23rd December 2019, 07:18 PM #38
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.
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23rd December 2019, 07:37 PM #39GOLD MEMBER
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23rd December 2019, 09:05 PM #40Woodworking mechanic
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- Jan 2014
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- Sydney Upper North Shore
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- 4,470
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
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23rd December 2019, 09:41 PM #41China
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- Dec 2005
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- South Australia
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- 4,475
Those tachos are getting cheaper by the day they will giving them away next
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23rd December 2019, 11:05 PM #42Woodworking mechanic
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- Jan 2014
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- Sydney Upper North Shore
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24th December 2019, 08:05 AM #43GOLD MEMBER
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- 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.
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24th December 2019, 08:05 AM #44GOLD MEMBER
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- 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.
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24th December 2019, 11:11 AM #45.
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- Feb 2006
- Location
- Perth
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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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