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PostPosted: 14 Jun 2010, 10:35 
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I have no idea how well this works but this guy has been advertising on some of the engineering forums. He makes a box of tricks that allow simple powering and speed control of washing machine motors. May be worth a look.
http://www.calenterprises.co.uk/speed.html

James


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PostPosted: 14 Jun 2010, 12:52 
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I think we need a sticky on this as well.
Years ago WMs spun at less than 500 revs and used conventional AC motors. As the lady of the house demanded higher spin speed DC motors were introduced. Bear in mind that I have been retired for some years, but before I retired 18000 revs was a common motor speed.
None of the motors had a thrust bearing so would be unsuitable for attaching a sanding disc to the shaft.
As regards purchasing a speed control unit, save your money, there's one in the machine!

Roy.

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PostPosted: 17 Jun 2010, 23:14 
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Yes Digit, definitely need a sticky on this subject.

As I was intrigued, and also have an old washing machine motor that I would like to use, I had a Google to find a simple explanation of how the speed control works. I found this at rcgroups.com posted by pentagrid@yahoo.com.

Many of the early UK front loading washing machines used multi winding squirrel cage capacitor start and run induction motors. These had typically a high power (about 1/3HP) 2 pole winding for the spin cycle and a low power (about 1/8 HP) 6 or 8 pole winding for low speed wash cycle. Because these were induction motors the natural speed regulation was quite good and electronic control was not needed.

Later machines needed a lot more power for the high speed spin cycles and these used high speed series wound commutator motors because these can deliver much more power (1/2 to 1Hp short term rated) for a given size and cost. The natural speed regulation of series wound machines is inherently poor and electronic control is essential for washing machine service. While crude form of speed control is possible by sensing the back EMF of the motor this is not good enough for the wide range of speed and loads needed for the wash/spin cycles. Because of this pretty well all motors are fitted with a "tacho" (tachometer) which is a very small (and very crude!) AC generator which produces an electrical output directly proportional to speed. A closed loop electronic speed control is used to adjust the power input to the motor until it delivers the the desired speed sensed by the tacho output.

Tacho output voltage or tacho output frequency can be used to sense motor speed. Early controllers used discrete transistors and a triac output. Later boards integrated most of the control functions into a single IC - Motorola TDA1085C is typical.


The thread is at
http://www.rcgroups.com/forums/showthread.php?t=129261

The Quasar motor speed control, linked to by George, appears to be only a pulse width modulation circuit without a tacho feedback circuit so, if the post above is to be believed, may not give good motor speed control.
The Calenterprises.co.uk box has a tacho reading circuit (tacho generator frequency) to provide speed control.

If you fancied a bit of DIY, A circuit for a washing machine controller with 4 speeds (800, 1,300, 7,500 & 15,000 rpm) is shown in the data sheet available at
http://www.onsemi.com/pub_link/Collater ... 085C-D.PDF
This could be modified to give variable speed using a variable resistance. The TDA 1085c controller chip can be bought for £2 and a Triac for less than £4 but, adding in the other components and the time in making, I would probably try to salvage the original speed control, as Digit suggests, or buy the Calenterprises.co.uk box ready made.

The Calenterprises.co.uk manual and video (downloadable from the web site) shows a metalwork lathe with two sets of reduction pulleys the first taken from the washing machine gives 11:1 reduction and an additional pair of pulleys giving a 2:1 reduction so 22:1 in all. Result is a variable speed control shown driving a metalwork lathe. The gearing might be adjusted to provide a speed range to suit a woodturning lathe, a grinder or sander to give the right range of surface speeds to suit the diameter of turned onject, grinding wheel or sanding disc.

It still sounds like a a fair bit of trouble and expense, £40 for the controller, make an enclosure for the open frame motor etc etc. The large pulley from the washing machine is LARGE!

Maybe there is an easier way. I sometimes see cheap lathes on ebay. Last week an old NuTool (same as Clarke Woodworker), complete except for drive belt, went for £1.20. A better quality Elu lathe went for £20. Both these have induction motors and variable speed by pulley blocks and could easily convert to sanding or sharpening duty. Just saw off the bit of lathe bed you don’t need.

Graham


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PostPosted: 17 Jun 2010, 23:30 
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Without the tacho the set speed will not be maintained under load. Frankly the speed is such that for most purposes the motors are useless! Tumble dryer motors are much more useful.

Roy.

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PostPosted: 18 Jun 2010, 00:02 
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Every year Aldi have a bench saw for £29.99,I've seen one of these in actiion and believe me you don't wan't to be within 10 feet of it. :shock:

However should we get one we have a cradle for the motor,the motor itself,the safty cutout switch box,the blade is held on via a large collar and nut,take this off and replace with a pully gear? or control the motor electronically?

I'll pop up to the bloke who's got it and have a look at the RPM and wattage because if its a saw it has to have a good RPM?

What RPM speed are we talking about for the drum sander?

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PostPosted: 18 Jun 2010, 08:13 
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I bought an old single speed bandsaw some time back with a burnt out motor George and followed your procedure. I now have a machine capable of cutting both wood and some metals.

Roy.

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PostPosted: 18 Jun 2010, 08:34 
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The motor on the Aldi tablesaw is...

1 1/4 Hp and RPM is 2950rpm

Thats one and a quarter horespower.

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PostPosted: 18 Jun 2010, 11:14 
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George,

from the Axminster web site

Jet 10-20 drum sander, Axminster’s cheapest 250mm width: 1400rpm Motor is 1200watt

Axminster AWDS12H their cheapest disc sander 300 diameter disc: 1400rpm Motor is 750watt

Rojek CB600/1 600mm Disc Sander: speed not stated** and Motor is 1500watt 3 phase

Axminster BS648 Belt Sander: speed not stated** Motor is 750watt

Axminster AW130BD2 Belt & Disc Sander: speed not stated* Motor is 190watt

Axminster AWEBDS46 MkII Belt & Disc Sander: speed not stated* Motor is 375watt

750 watts is 1 horse, Shire or Shetland Pony not specified!
*The speed is not stated for the last two but they are direct drive so likely to be 1400 rpm.
**The other two where speed not stated might have belt drive hidden within the enclosure so could be any speed.

The noise of brush motors would put me off using them if avoidable. My Kity saw with induction motor is quieter and has a more pleasant sound than the old contractors type table saw with brush motor I used before but the old saw is torquey and good for ripping so I kept it for when needed. When I get a bigger workshop I will have it with a rip blade in and the Kity with a fine cross cut blade.

The Aldi saw with a reduction pulley drive to give 1400rpm would give twice the torque, I am sure it will be much more than enough!

I have not seen a discarded tumble drier but have seen old spin driers with working motors but broken lids etc. They didn’t seem so noisy. I thought they had stopped making these but had a look on the web and found some which all run at 2800 rpm. Perhaps Digit could advise what motors they have inside them? Maybe a case of old UK made being better than newer imported models with throw away motors?

Graham


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PostPosted: 18 Jun 2010, 17:37 
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The problem anyone is faced with once they have the motor and speed regulator is the drum and bearings that hold the drum.

Be alright if you had a decent scrapyard by you or one that does industrial scrapping,these yards contain an alladins cave of machine components.

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PostPosted: 19 Jun 2010, 17:01 
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Using a WM motor, say 15000 revs needs a 10 to 1 reduction to get down to 'normal' induction motor speeds. If pulleys are used it becomes very bulky, it is important to understand that the closer you bring the motor pulley to the driven pulley the smaller the contact area between belt and driver becomes, and the greater risk of slippage/burnt belt etc.
Gears would overcome this.
The motors normally only run flat out for a few minutes, the high speed spin cycle, and they get hot!
The motors are not shrouded IME and without a cooling fan.
Is it worth the trouble to overcome these defects?
At the end you get a 2HP fully reversible/controllable stepless drive, so it's up to you.
TD motors are normally about 1/3 HP.

Roy.

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PostPosted: 20 Jun 2010, 13:38 
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Sifting through ebay machine parts before and came across these bearings for holding the drum.

http://cgi.ebay.co.uk/UCP207-20-Pillow- ... 4a998997b2

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PostPosted: 03 Jul 2010, 14:58 
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Nice one Brendon.


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PostPosted: 06 Sep 2010, 20:39 
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Really wish I hadnt looked at this thread, now I want to make a drum sander......damn!! Another project to add to the list of projects! :P

Anyway, the Aldi saws were mentioned and it occured to me that I have one of those saws sitting on a shelf in the shop collecting dust these past few years!

Had a look at the ratings, it says:

Power:
S1 750W
S2 30min 1000W
2950RPM

Then, I pulled it assunder, I've been contemplating chucking it out numerous times but always thought 'but what if I need a small saw for something', but all that ended tonight, its in 100 parts now, so, its either a drum sander or keep the motor and switch and chuck the rest! :)

Would that be adequate for such a drum sander? And, while I'm here, I was just wondering, what is the actual drum made of?


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PostPosted: 08 Sep 2010, 10:56 
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Actually, disregard my last question, it seems the drum can be made up of numerous MDF or plywood rings glued and sandwiched together and then wrapped with self adhesive velcro.......simples! :wink:

A lenght of mild steel tubing, say 5" diameter or so (for a 12" drum) would do the job also I presume? With a rin cut and fitted into either end and perhaps one or two in the middle to support the shaft?

I'm going to make one of these I think, however as I'm very limited for space I'd have to make a bench top one that I can store when not in use. I was thinking of making the frame out of steel, 30mm box section or so and welted/bolting it together. Is there any disadvantage of using steel over timber? Would a timber frame absort some of the vibration etc better than a steel frame? It'll be bolted to a workbench when I'm using it so I cant see it being a problem.

Here's a few links that I found helpful!

http://www.rockslide.org/drum%20sander.html (plenty of WIP pics!)
http://www.areddy.net/wood/tools.html
http://lumberjocks.com/projects/7641 (a really nicely made one!)


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PostPosted: 16 Dec 2010, 05:03 
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I think the link will work. But I don't know exactly how this going to work though. One tip, I am only trusting big companies, as a matter of fact, I have been using my GE washing machine for many years now and no worries at all!

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