Drive motor for rotary welding table

Str8jacket

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H-M Supporter Gold Member
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Gday, i am looking at building a rotary welding table to do some repairs to some shafts and other bits and pieces.

The mechanical side is easy but i am stuck on what sort of drive motor. I have looked at sewing machine motors and pedals but cant find one with reverse. Also vague on specs for torque. I dont want to much but it needs to be enough to turn 20kg icluding table and chuck.

I can get a 0.18kw 3 phase motor but it seems over kill. And costs more. Bigger.

I have looked at little stepper motor kits but am unsure how to control start stop forward reverse. I dont want to spend a long time trying to get it going.

Or i can buy a small rotary table on aliexpress for $500 AU an be done with it.

I rhink i can build a beefier one for that money but the time is something i dont have lots of.

Any suggestions?
 
What speed are you looking for?
Are you going to use a reduction of some sort or expecting the motor to be direct drive and directly spin the table?
I have seen rotisserie motors for grills used with pretty good success but they are single direction setups.

If you are starting from scratch, you may locate a cheap dividing head and pull the dividing ring and crank off it, drive it with a variable speed reversable drill and figure a way to remove the trigger setup and mount it in a foot pedal. It would have reverse, variable speed and if a battery drill was used in the 12 volt size they typically have a brake that when you release the trigger the motor quickly stops. That may or may not be important to you.
 
Almost any WHEELCHAIR motor will work perfect. Being dc reverse is just switch wires. A potentiometer will vari speed . Id venture to guess under $100.00 for your electric parts, the steel and chuck is more. Bearings too. With those motors theres a freewheel lever to spin by hand if you want . Just what I plan on using for mine.
 
a very simple way is wrapping a rope around your shaft and hook a weight on and use the gravity to rotate the shaft till the weight hits the ground ---you can get many rotations each time and regulate the speed with a simple drag setup---it can work on vertical shafts or horizontal shafts and forward and reverse by the direction you wrap the rope--for each wrap of the rope around the shaft, will give your project one full turn-for more turns just lift the weight up and go again---you can make a couple simple wooden pulleys with a chain running around them like a drive belt and then have a hook on your weight to hook into the chain on either side for direction needed---several different weights can also determine your speed---for vertical shafts coil around shaft direction you want it to turn and run it horizontal over to a pulley on side and then the weight gravity will turn your shaft---no motor required---just some chain or rope with tied loops some very simple pulleys a bolt through your shaft to hold the end of the coiled rope end--a simple foot operated drag to control speed can also be very simple---no money required to rotate your projects efficiently in all directions---hope you get the picture--ask any more questions if you don't understand---Dave *note you really just need about a three or four foot small nylon rope with a loop on each end and a peg on each shaft to start your wraps and a simple 20 to 40 lb weight with a hook on the top---wrap your rope on the shaft several times and hang your weight on the other looped end
 
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Dave Smith,
That's brilliant, simple, elegant and affordable!!

Daryl
MN
 
Thanks for the replies guys, awesome suggestions. I am not sure how your idea will go on my job this time Dave, the shafts are only 3/4in thick and a foot loot long. If i ever have some bigger stuff to repair that is going to be my first approach.

I think a DC motor is the best bet. The table is only going to be enought for say a 10-15kg hub to sit on or shafts the size of the one i mentioned before.

I was thinking of using a trailer hub but mounted on a hollow tube so i could have it similar to a lathe headstock if needed.

There are some electric scooter motors that i found that have a bike chain sprocket. They may have a bit to much grunt though. Wheelchair motors seem expensive over here.

I have a few Doga 24v windscreen wiper motors that i think will do, need to work out the current draw so i can get a power supply to suit. Adapting a drive to the stub shaft will be the hardest bit.

A free wheeling clutch would be nice but not sure where to find one? Bike hubs free wheel one way. Belt drive was going to be the way i was going initially to help isolate the electrics
 
i believe it may have been mentioned before, but a transformer and PWM board may be the cheapest, simplest, and most robust answer to the powersupply issue.
i'd consider a footswitch, then maybe a potentiometer or other fixed resistor to control speed if the PWM was not available or desired
 
I see that you are still over thinking---and making it too complicated for a simple task----maybe you could take some pictures of your table for us to help you better---also how many rotations do you need to fix your projects, one, several or continuous ---are you welding them while rotating them ?----if you are determined to go with a motor then some of my suggestions would be---- a variable speed reversible drill(could be electric--cordless--or pneumatic)---an air motor which would be easy to control speed and direction easily----an air ratchet or air impact gun would also be very efficient and probably already in your mechanics tool box but a little noisy maybe----I would still just use a simple small nylon rope and a weight for best results and no money investment---there would be no noise--just nice simple rotation----five wraps around your shaft would only take about an inch of space on the shaft and give you five full rotations of your project---ten wraps would be about 2 inches and give you ten full rotations--speed control would be very easy-----Dave
 
I built one using a 110 volt dc gear head motor salvaged from a blue print machine. That drives a gear reducer. You need a lot of reduction to get the speed slow enough if you end up welding or cutting large diameters. I have a variable ac power supply, a bridge rectifier between it and the motor gives me dc. I made an adapter for the output of the gear reducer, 1 inch unc thread that fits a 3 jaw, 4 jaw and 12 inch face plate for a wood lathe. They're extremely useful. Welding sprockets to hubs, building driveshafts, building up shafts the list goes on and on.
Im surprised a sewing machine motor isn't reversible, would have thought they were dc.
A windshield wiper motor should work, Im currently building a bandsaw blade sharpener, and using a 12 v geared motor from some sort of golf bag cart to advance the blade. Im going to use a battery charger transformer after the 110 v variable supply to give me 0-12 v.
Variable power supplies are available for wood routers. Not sure if they're ac or dc output.

Greg
 
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