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15th Sep 2018, 03:23 AM #1Most Valued Member
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Sewing machine variable controller
I'm in a position where I need to make a miniature welding rotator. Thinking of using a sewing machine motor to power it, but would need a variable switch to get the RPM right, would a fan control switch or light dimmer switch be sufficient to do it. The drive will be by toothed belt, so as not to interfere with the motor side of things
It'll be running a 4" 3jaw chuck and welding a bolt on the end of 15NB pipe, have several hundred of them to do, not all at once, thank God!!!!!
KrynTo grow old is mandatory, growing up is optional.
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15th Sep 2018, 05:49 AM #2
Hi Kryn,
Here you go !
motor-speed-regulator-schematic.gif
I know it says 230 VAC, it will happily work on 110 as well should you need it to.
C1, C2, R1 and L1 are interference suppression components. The circuit will work just as well without them.
If you get noise on your radio when running then include those components.Best Regards:
Baron J.
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15th Sep 2018, 08:44 AM #3Member: Blue and white apron brigade
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What sort of motor is it motor and what RPM do you require?
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15th Sep 2018, 09:00 AM #4Philomath in training
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My thoughts too. I would have thought for welding you would want something around 60rpm perhaps +60, -30rpm. A sewing machine motor is not going to do that straight out of the box. If the only thing you are doing are these bolts, perhaps a pin on a base plate and a socket on top of that would be enough to do the job (rotate by hand - use an old steering wheel, pulley or something similar)
Michael
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15th Sep 2018, 09:37 AM #5Member: Blue and white apron brigade
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Sewing machine motors are typically in the 6 to 10k rpm range so to get 30rpm requires at least 200:1 reduction. Doing this electrically is a big ask so you will need some mechanical reduction before hand. Even if you can get a 10:1 mechanical reduction that still leaves a 20:1 reduction electrically which is 95% speed reduction where the motor may have little or no torque left to drive any load.
If you wanted to pursue this I'd be looking at a 12/24V DC motor with a full reduction gear box as they go for about $20 on ebay..
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15th Sep 2018, 12:54 PM #6Most Valued Member
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Do you have access to a straight line oxy cutter? They make brilliant rotators as all the work has been done for you and you just need to mount a chuck or plate on the drive wheel.
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15th Sep 2018, 01:12 PM #7Senior Member
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Hmmm
Are we talking domestic motor or industrial?
A domestic sewing machine foot controller lets you sew really slowly.. Down to a single stitch at a time. And the old ones are just a variable resistance.
Sewing machines don't have a massive reduction inside. A universal motor does have good torque at low speed.
But your weld positioner will probably have a lot more mass than a sewing machine, so you should aim for as much reduction as you can arrange.
Russ
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15th Sep 2018, 03:41 PM #8Most Valued Member
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Thanks for that John, only problem is that, to me it's just squiggly lines and black triangles.
Electronics ain't my field/interests.
The reason I mentioned using a sewing machine motor, is that I have several of them, didn't think that they ran that fast though.
Oh Well, back to the drawing board, might look at microwave motors, as they run about 3 rpm, which should be enough.
Thanks everyone for their comments.
KrynTo grow old is mandatory, growing up is optional.
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15th Sep 2018, 08:36 PM #9
Hi Kryn,
OK point taken I won't suggest a light bulb dimmer switch then, which would also work.
You could look at an oven rotisserie motor ! I don't think you will get anyway near enough torque from a microwave turntable motor.Best Regards:
Baron J.
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15th Sep 2018, 08:37 PM #10Diamond Member
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What about an old cordless drill with a 2 speed gearbox? In low gear and with the trigger only just depressed, they go pretty slow. You could also drop the supply voltage to go even slower.
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15th Sep 2018, 09:00 PM #11Most Valued Member
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Thanks for that Rusty, as I mentioned to John, electrics is not a field that I'm familiar with nowadays, so I'd like to stay away from voltage reducing equipment.
Was hoping to do a plug and play sort of thing.
10 years ago I wired up my shed, can't remember how to do a light switch now.
KrynTo grow old is mandatory, growing up is optional.
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15th Sep 2018, 10:03 PM #12Philomath in training
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If you had a lathe, you could chuck up a broomstick (insulator) and then support the free end in a bush. Cover the bed, attach the chuck to the end of the broomstick and put it on a slow speed and you might just be able to do it.
Failing that, I do have surplus spankers 20:1 gearbox here.
Michael
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15th Sep 2018, 11:19 PM #13Most Valued Member
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Thanks for the offer, Michael. How big is it, shaft sizes, etc.and how much do you want for it?
KrynTo grow old is mandatory, growing up is optional.
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17th Sep 2018, 08:02 PM #14Diamond Member
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17th Sep 2018, 09:26 PM #15Most Valued Member
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Thanks for the idea Karl.
I don't have access to one but looked on gumtree and found one at a respectable price, no nozzle or track, not that I need them ATM.
Waiting on a reply from the seller. They're not a cheap item!!!!
KrynTo grow old is mandatory, growing up is optional.
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