Where do you buy electric motors?

[S. Heslop]

Bit of a blunt question. I'm building a centrifugal blower for a furnace burner and the motor I was originally planning to use had a potentially deadly ground leak, and then the motor I replaced it with has it's own problems.



From an aldi tile saw that was on offer. Looked like a great deal for a 600w motor but it vibrates a fair bit and seems to have a terrible duty cycle. I ran it this morning to test the duty cycle just in case and it quickly got too hot to touch before I unplugged it. It's been about half an hour now and it's still quite hot.

I've had a look through ebay and like everything on ebay, the listed motors are either suspicious, overpriced, or the seller lives in Lizard Point and insists on collecting in person. I also had no luck at today's boot sale. So i'm wondering if there's a better way to go about acquiring motors.

[Bigbadbugga]

Seller on eBay called 'electricmotorman' was were I got the one for my Boxford.

http://www.ebay.co.uk/sch/electric-motor-man/m.html?item=271249401835&pt=UK_BOI_Electrical_Components_Supplies_ET&var=&hash=item3f27b967eb&rt=nc&_trksid=p2047675.l2562

Found him very helpful.

[awemawson]

The last three or four I've ordered have come from Bearingboys:

http://www.bearingboys.co.uk/Electric_Motors-1047-c

They are good for all sorts of bits and bobs as well as motors

[Fergus OMore]

I thought that the Aldi tile cutter had most of the things to make a tool and cutter grinder but I suspect that you should have gone for their vacuum cleaner for removing ashes and whatever from barbeques. I did- and it is in the workshop picking up swarf.

Difficult to know just how big your blower is but I'd have gone for a old 1440 rpm 1/4 hp washing machine motor which was the standard( or normal) for yesterday's small lathes. I suspect that I have the one that came off my Quorn prior to the smaller 1/6th 2880rpm one. I suppose that my ex- out of Myford 1440 1/3 or 1/2 variety is still around somewhere.

Regrettably, when I put my family and self out to give things away for nothing, people still don't materialise.

So the future for such things is  the tip - next to 'Armstrong's factory just past the railway bridge and the Robin Adair'

[S. Heslop]

I had a collection of washing machine motors i'd been pulling from neighbour's and family's old appliances, but the new 'universal' kind. After some reading about how to wire them up I found out that they're generally not so useful. Supposedly they try accelerate towards infinity rpm and quickly wear themselves out, unless controlled via fancy electronics, so definitely not ideal for a blower that may be running for a couple of hours at a time and can't risk cutting out. So I ended up pulling those motors apart for the aluminium shells.

The blower rotor is 200mm in diameter but I haven't decided on the thickness yet. I'm not actually sure how much power is required to turn one of these things under load so i'm trying to err on the small side.

Thanks for the links to those motors but at £70 and beyond, it's not really cost effective for this role. Nor can I afford it on my budget! I'm mostly trying to make the blower just for it's own sake (or the sake of a video) but if it becomes too expensive I suppose i'll just use the exhaust of my old shop vac.


The blue cover on the back of that aldi motor is covering a small centrifugal fan over some holes in the back casting. There aren't any holes in the front for a through draught though, maybe because of the water in a wet tile saw, so I might have a go at maybe drilling some in. It's a pretty useless motor if I can only run it for a couple of minutes at a time.

[Fergus OMore]

I suppose that a so called 'universal motor' will not blow up if it has a fan as part of the set up.

Another 'moonbeam' is the famous/infamous  double ended grinder from Aldi and elsewhere.
I was in the other day and they still had ones with a belt sander on one end and a grindstone on the other.
Oddly, I have one- unused or merely switched on to see the wheels go round.

Too much traffic delays  to try the Swalwell branch

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I have a couple of fans in my various bedrooms in Spain and they run all night in the summer. Not suitable?

[S. Heslop]

I suppose that a so called 'universal motor' will not blow up if it has a fan as part of the set up.

Another 'moonbeam' is the famous/infamous  double ended grinder from Aldi and elsewhere.
I was in the other day and they still had ones with a belt sander on one end and a grindstone on the other.
Oddly, I have one- unused or merely switched on to see the wheels go round.

Too much traffic delays  to try the Swalwell branch

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I have a couple of fans in my various bedrooms in Spain and they run all night in the summer. Not suitable?

I think the bathroom vent fans won't put enough pressure out to work in a furnace. I think there's plenty of things I could use though (i've seen photos of people using old hair driers taped on), it's just i've gotten this far with the home built centrifugal blower that I may as well try and see it through.

The aldi up in Consett (I was just there today) has a whole stack of those bench grinders/ sanders unsold and reduced to (if I remember right) £25. Although again, i'm not sure if they'd have a 100% duty cycle since the average hobbyist isn't going to be grinding on them all day.

I've drilled a bunch of holes into the front of this thing now and i'm gonna see if that helps. Just need to get it back together again...

[S. Heslop]

I'm always amazed when I take something to bits and somehow manage to get it working again. It's vibrating a bit less now too even. The holes in the front have some gentle hot air coming out, but the centrifugal blower just blows most of the air around the outside of the thing. Maybe that's how it's supposed to cool it down in the first place, passing air over the outer casing, but I can't see it being hugely efficient. Maybe i'll look at trying to direct more air through the centre of the motor.

[Fergus OMore]

I was in Hexham- 40 years ago or so. There was a firm called Submarine Products making diving gear.

I was in on business and had a walk around. The test rig for the demand valves had me interested it was familiar but painted cream . I dawned on me that all that it was an old upright vacuum cleaner.

Today, I'm fiddling with an old Alba DVD player which got a doze of cleaner for my Spectacles as I couldn't buy iso propyl alcohol. to do the laser. My mate uses one to drive his radio control models. Another world, eh?

Good hunting!

[angus]

how big is the blower you are trying to make ?

i may have something suitable.....


where are you ?

[S. Heslop]

how big is the blower you are trying to make ?

i may have something suitable.....


where are you ?

Thanks for the offer but i'm mostly building a blower out of interest.

I couldn't get any more air to flow through the motor by blocking bits up. So I guess the final test would be to set it running for an hour and see what happens, if air flowing around the outside case is enough to stop the windings from melting. I'll try that tomorrow.

[micktoon]

 Hi Simon , you can't beat of destruction testing lol, make sure you have the video running  . I know you just want to make the blower for a project and you have got this far so you want to finish it but dont want to spend a great deal on it.
     I think I have an old style washing machine motor, no fancy stuff, just good old sturdy built thing, I am not sure what size it is ......1/8th or 1/4HP rings a bell, probably half inch shaft and 1425 rpm? , I will have to check . You can have it if you want it and I am just in Newcastle. Just PM me if you think it will be any good and I will hunt it out and check the spec.................... good luck with your tests anyway.
  Cheers Mick.

[S. Heslop]

Hi Simon , you can't beat of destruction testing lol, make sure you have the video running  . I know you just want to make the blower for a project and you have got this far so you want to finish it but dont want to spend a great deal on it.
     I think I have an old style washing machine motor, no fancy stuff, just good old sturdy built thing, I am not sure what size it is ......1/8th or 1/4HP rings a bell, probably half inch shaft and 1425 rpm? , I will have to check . You can have it if you want it and I am just in Newcastle. Just PM me if you think it will be any good and I will hunt it out and check the spec.................... good luck with your tests anyway.
  Cheers Mick.

I'll probably take you up on the offer if this motor fails tomorrow. So thanks very much.

[vtsteam]

Steve, I'm surprised the washers and dryers had universal motors. Granted this was ten years ago, but I went to an appliance dealer and asked if I could remove some motors for a lathe project  and was directed to a large pile of machines in the rear of the building outside. I removed every one that looked good to me and none of them were universal motors. Most were 1/4 to 1/2 hp 1725 and 3450 rpm and have run fine for various projects. The only caveat is that they are all open frame motors and need some kind of housing bent up to be respectable.

Your fan blade is 8" diameter from what you've mentioned already -- can you give the blade width and some idea of what you'd like to see for output pressure? I can give you back reqd fan RPM, fan capacity, motor power requirements, and pulley ratios for a particular RPM motor to get you in the ballpark.

[S. Heslop]

Steve, I'm surprised the washers and dryers had universal motors. Granted this was ten years ago, but I went to an appliance dealer and asked if I could remove some motors for a lathe project  and was directed to a large pile of machines in the rear of the building outside. I removed every one that looked good to me and none of them were universal motors. Most were 1/4 to 1/2 hp 1725 and 3450 rpm and have run fine for various projects. The only caveat is that they are all open frame motors and need some kind of housing bent up to be respectable.

Your fan blade is 8" diameter from what you've mentioned already -- can you give the blade width and some idea of what you'd like to see for output pressure? I can give you back reqd fan RPM, fan capacity, motor power requirements, and pulley ratios for a particular RPM motor to get you in the ballpark.

All of the motors I'd found were skeletal deals like this with 7 or 10 pins. I read what I'd read about them when looking up how to wire them, but i'm no motor expert so I'm only regurgitating what other people have said.

The 2 red leads on the right connect to a tiny crude generator that's used to monitor the motor's speed.

The rotor thickness i've got in my sketchup plan is 40mm at the moment but I'm thinking of bumping it up to 50mm (2 inches). The only thing i've found for suggested air rates is ~25cfm but I can imagine it varies from furnace to furnace. I've also read the Dave Gingery gas furnace book for ideas but i'm building mine quite different to his for the sake of the matrial I have available (I've got a huge amount of 2mm hot rolled sheet left over from the helmet). I'm really just hoping i'll manage to build something that provides more air flow than I need, so I can adjust it down to whatever is required with a sliding cover over the intake.

[vtsteam]

Steve, I guess times have changed, at least for washing machine motors. But i imagine it should be possible to find some older washers or dryers still? I imagine the giveway of what type you are looking at is the motor speed sensor you mention.

Fixed speed motors generally have a throwout set of contacts the changes the motor over from its starting windings to its run windings when it gets up to speed. They are also mostly skeletal as you say -- and look quite similar.

For the fan for your furnace, generally the two things you're looking for are capacity (you mentioned cfm) and blast pressure (in the same units, generally "inches of water column"). If you describe what type of furnace you plan to build I can probably figure what you need for those -- if you want. Helpful info would be the kind of metal you want to melt, furnace bore, and the fuel you want to use.

On the other hand, I'm sure your vacuum cleaner would work as a backup in case you can't find a motor to suit.

[RussellT]

If you keep your eye out for twin tub type washing mashines or the little upright spin dryers they seem to have induction type motors - I have found a couple from them even in the era when automatics have the multispeed motors you have found.

Russell

[S. Heslop]

Steve, I guess times have changed, at least for washing machine motors. But i imagine it should be possible to find some older washers or dryers still? I imagine the giveway of what type you are looking at is the motor speed sensor you mention.

Fixed speed motors generally have a throwout set of contacts the changes the motor over from its starting windings to its run windings when it gets up to speed. They are also mostly skeletal as you say -- and look quite similar.

For the fan for your furnace, generally the two things you're looking for are capacity (you mentioned cfm) and blast pressure (in the same units, generally "inches of water column"). If you describe what type of furnace you plan to build I can probably figure what you need for those -- if you want. Helpful info would be the kind of metal you want to melt, furnace bore, and the fuel you want to use.

On the other hand, I'm sure your vacuum cleaner would work as a backup in case you can't find a motor to suit.

Here's an old photo of the furnace with some of the form still on.


The diameter of the inside hollow is 200mm (8") and it's 240mm (9.5") tall. The lining is the dense commercial refractory that Rob gave me (thanks again Rob!) and is 50mm (2") thick. I'm not sure how insulative it is but I think it's the same as Rob uses in his gas furnace.

I'm mostly wanting to melt brass with it for the sake of casting banjo parts (banjos as in the musical instrument). I can't see myself needing to melt iron any time soon.

The fuel i'm going to use is propane. Although my experience with the sheet metal forge was that you can really burn through a tank in a hurry when using it for this kind of thing, so i've been looking into oil burners too.

I made the inlet hole for the burner 30mm in diameter although the former crumpled a bit (even though it was packed with sand) so it might be a bit less than that, but it fits an inch diameter tube with room to spare. I'm worrying that this might be on the thin side at this point for volume of air.

[S. Heslop]

If you keep your eye out for twin tub type washing mashines or the little upright spin dryers they seem to have induction type motors - I have found a couple from them even in the era when automatics have the multispeed motors you have found.

Russell

Thanks for the tip. I should try catch the rag n bone men and ask if they'd be willing to keep an eye out for stuff like this, might be able to score some motors for scrap value. They must arrive in the real early morning though most of the time. It's amazing how quickly old appliances disappear when left on the curb.

[vtsteam]

Steve your furnace is similar in size to the Gingery furnace you mention. And it looks like your fan is the same diameter.

The theoretical output fan calculations for his furnace fan work out to 160 cubic feet per minute (CFM) at 3.3 inches of water column (WC) pressure. The horsepower required to drive that is 0.168 hp.

That's assuming his 1-1/2" wide fan.

The speed of the fan itself is 3450 rpm. You would use pulleys in whatever ratio necessary to get that fan speed with the motor you choose.

So basically you can use a 1/4 hp motor (or more) to drive it.

Your burner inlet of 30 mm (if you can re-open it to that) is okay -- or a few mm larger. You would want a minumum of about 25 mm ID pipe in for a gas burner.

Hope that helps.

[vtsteam]

Probably a motor as small as 200 watts nameplate would work with that fan for your purposes.

[S. Heslop]

Thanks very much for that. I was hoping i'd get away with mounting the fan directly to the motor spindle (to save myself a shaft and pair of bearings) but i'll have to check the speed first, I suspect it's a fair bit slower than 3500 rpm but i'm not really great at estimating things. But it's definitely nice to have a bit more direction.

[vtsteam]

Thanks very much for that. I was hoping i'd get away with mounting the fan directly to the motor spindle (to save myself a shaft and pair of bearings) but i'll have to check the speed first, I suspect it's a fair bit slower than 3500 rpm but i'm not really great at estimating things. But it's definitely nice to have a bit more direction.

Since you work on musical instruments, if you can estimate the musical note of the motor running you can work out the RPM.

Also, it is possible to match a fan to a motor of different RPM to eliminate the reduction pulleys, but that would mean a different size fan and it looks like you've already begun construction of the fan.

[Meldonmech]

Hi n
     I have two suggestions, a cheap electric paint stripper, which I have successfully used, needs an adequate length of pipe to ensure it does not melt.  Secondly a centrifugal fan unit from a combo boiler.

                                                                                                          Cheers David

[Jonfb64]

Hi,

As meldonman suggests i have sucessfully used  the fan from a combi boiler to melt brass and copper in my furnace which is made from a propane tank with 1700c refractory very much like yours. You can also easily control the speed with a light dimmer.

Jon

[S. Heslop]

I helped my grandad replace a combi boiler just last year. He said he was holding onto the old boiler for spare parts so hopefully he still has it. I can't imagine many boilers need blowers replaced so he might let me have that.

I'll still finish off this other blower but it'll be nice to have a backup just in case.

Oh yeah I also ran the motor for 45 minutes this morning. It got hot to the touch and smelled a bit but I didn't see any smoke. It wasn't hot enough on the outer case to boil water so i'd guess maybe 80-90°C

[vtsteam]

Sounds like your motor needs a fan......  

You can make one for that, too out a bit of sheet metal. Or direct some of the main fan flow somehow over the motor case.

And if you want to get really tricky, a housing to direct the inlet air to your main fan after passing over the motor case would preheat your blast a little....

[S. Heslop]

Sounds like your motor needs a fan......  

You can make one for that, too out a bit of sheet metal. Or direct some of the main fan flow somehow over the motor case.

And if you want to get really tricky, a housing to direct the inlet air to your main fan after passing over the motor case would preheat your blast a little....

That blue lump on the back of the motor covers a fan. I think that fan is designed to just blow air over the outside casing, even though there are holes in the back of the thing (there aren't any through holes for air flow, and the ones I added don't seem to be doing much anyways).

I was considering making just the inlet of the blower on the same side as the motor so that air pulled in would come from it's general direction. The motor is face mounting only though and I sorta want to try and make something a bit professional looking (paint n all!) rather than something jury rigged with scrap steel brackets and jubilee clips.

As always there's problems every step of the way and now my jigsaw blade is drifting 10 degrees but I think if I bolt a secondary foot to the thing at 10 degrees, it'll hopefully keep the blade straight. I don't particularly like jigsaws much and don't particularly want to have to buy an expensive one. As a side, I'd bought a pack of 'cheap' blades from a real hardware store and i'm amazed by how well they hold together. By the time I noticed the blade was wandering (because it was sparking so much!) it was bent about 45 degrees. And then it sprung back to straight when I removed it. I'd previously been trying to use brand name diy store blades and they just lost teeth and snapped all the time, and cost about 10 times as much for a pack of 2. It's amazing what those diy stores manage to get away with.

[75Plus]

You might also consider adapting a vacuum cleaner (Hoover) as a blower. Nice thing about them is the air flows over the motor as it operates thus cooling it and sending the heat along to your furnace.

Joe

[tom osselton]

You should let Bob have a go at it !! I usually buy motor's from princess auto here in calgary I also have all the motors dad collected.