Looking for some help....Motor woes

[GraemeD]

Guys, I'm looking for a bit of guidance or ideas with regard to a motor issue.

I've been rebuilding a gorgeous old Wadkin planer over the last couple of years....you know what it's like finding time for something like this. Anyway, I'm now on the last stretch and sorting out the motor....kind of excited to get it going finally!

I picked up a brand new ABB single phase 1HP motor some time back on Ebay....perfect for the job, as it has separate run and start caps, with a relay to switch out the start cap when the motor is up to speed.. Today I hooked it up, and connected the drive belt. On switching on, the motor powered up to speed lovely and smoothly, and then as the start cap relay dropped out, the motor slowed significantly, kind of struggling to drive the cutter block. The motor got hot and horrible smells started emerging as I hit the power off.

It kind of seemed like the motor was underpowered for the job, but the pulleys run smoothly by hand, with some resistance but not a lot. I tried the motor off load and it is sweet as a nut.....and the torque was such that I couldn't stop the drive pulley by hand.

Any ideas what is going on? Any help or suggestions would be most welcome as I am currently doing lots of head scratching!

Cheers
Graeme

 

[clewlowm]

forgive me for this. you say 1 hp motor? the wadkin should be at least 3hp?

 

[Doug B]

forgive me for this. you say 1 hp motor? the wadkin should be at least 3hp?

Agreed, my 12" wadkin surface planer came with a 3hp motor, you might get away with 2hp, i did for a while but it severely affected the depth of cut i could take.

 

[ProShop]

I'd go for a 4hp single phase motor, as in the real world of using these machines 3hp single phase hasn't got the torque of 3hp 3 phase.

 

[GraemeD]

Sorry, I should have mentioned....it's only a small 6" planer, so 1HP seemed to me a reasonable choice.....if at the low end of ideal. I realise it may bog under severe loads, but this won't even spin up the cutters! The weird thing is that when running off load, I can't stop the drive pulley with my hand, yet on load it can't turn the cutters.

Could it be the run capacitor? Does on-load torque fall off rapidly if this is bad? or have I got my drive belt too tight? I made it quite taught, but felt that was the right thing to do.

Any ideas very welcome!
Graeme

 

[ProShop]

As mentioned above, the original motor would most likely have been more than 1hp, so the machine is underpowered with a 1hp single phase motor.

You may also have burnt out the start capacitor. Or worse still damaged the new motor (hopefully not).

 

[GraemeD]

This really is an unusually small machine for Wadkin, and was fitted with 1HP originally. You can see the machine in its original glory in Wadkin's 1936 catalogue at http://www.titaniumstudios.com/tooljunk ... in1936.pdf . It's the "RA" on page 19.

It actually came with a 0,5HP motor fitted, which was claerly underpowered. I'm not saying a bigger motor wouldn't be a good thing, but this should at least spin the cutter block!

 

[Doug B]

Graeme.

This
http://www.axminster.co.uk/product.asp? ... =1&jump=44

Has a 1.5 hp motor & it will have a light weight block.

I think you are asking too much of a single phase 1hp motor, on an old machine with a heavy cutter block.

Doug.

 

[9fingers]

Guys, I'm looking for a bit of guidance or ideas with regard to a motor issue.

I've been rebuilding a gorgeous old Wadkin planer over the last couple of years....you know what it's like finding time for something like this. Anyway, I'm now on the last stretch and sorting out the motor....kind of excited to get it going finally!

I picked up a brand new ABB single phase 1HP motor some time back on Ebay....perfect for the job, as it has separate run and start caps, with a relay to switch out the start cap when the motor is up to speed.. Today I hooked it up, and connected the drive belt. On switching on, the motor powered up to speed lovely and smoothly, and then as the start cap relay dropped out, the motor slowed significantly, kind of struggling to drive the cutter block. The motor got hot and horrible smells started emerging as I hit the power off.

It kind of seemed like the motor was underpowered for the job, but the pulleys run smoothly by hand, with some resistance but not a lot. I tried the motor off load and it is sweet as a nut.....and the torque was such that I couldn't stop the drive pulley by hand.

Any ideas what is going on? Any help or suggestions would be most welcome as I am currently doing lots of head scratching!

Cheers
Graeme

I do not recognise the motor arrangement you describe.
Capacitor start and run motors that I have experienced do not have a relay to switch the start capacitor in/out.
I wonder if you have wired it correctly.

I don't disagree with those who have suggested it might be a bit underpowered BUT 1HP should be more than man enough to run the machine up to speed without letting the smoke out.

Can you give me the part number of the AAB motor so I can look it up in their catalogue and maybe make some suggestions. Are you sure it was absolutely new?? in its box, grease on the shaft, no screw marks on the shaft or key?

Cheers

Bob

 

[RobertMP]

If something is resisting turning then it will get hot. Did you check for bearings or pulleys etc getting warm after your overloaded motor episode?

Long time since I learnt about AC motors but I don't think the run capacitor actually does much once the motor is up to speed. If It runs fine with no load I'd check out the load for problems. Bearings or belt or something might bind at speed but not when turned slowly maybe?

Could be a faulty motor but ABB is a top brand so unlikely.

 

[9fingers]

If something is resisting turning then it will get hot. Did you check for bearings or pulleys etc getting warm after your overloaded motor episode?

Long time since I learnt about AC motors but I don't think the run capacitor actually does much once the motor is up to speed. If It runs fine with no load I'd check out the load for problems. Bearings or belt or something might bind at speed but not when turned slowly maybe?

Could be a faulty motor but ABB is a top brand so unlikely.

Just to put you back on track there Robert, in the case of a capacitor start and run capacitor motor which has two capacitors fitted, the run capacitor is used both when running and starting and is an essential part of the design during running. It is the start capacitor that is only used during starting and does nothing once the machine is up to speed.

Bob

 

[RobertMP]

Been a long time so i won't argue with you . Thought the run capacitor mostly just made it smoother on a start + run ....

 

[9fingers]

Graeme,

I've just had a look at the latest AAB catalogue and I see that they do now make motors with an electronic module to switch out the starting capacitor.

I have learned something - thanks.

They say that the capacitor is switched out when the motor is up to speed OR after 2 seconds whichever occurs first.

I wonder if the motor is not getting up to speed before the start capacitor is removed and is then running asynchronously with the 50hz supply which would indeed cause it to get hot and let out the magic smoke. Maybe I'm starting to support the underpowered/insufficient torque for the cutter block argument.

Bob

 

[GraemeD]

Bob,

Sorry for the delay in getting back. The motor I have is "new, old stock", and though unused, it has been sitting around for a few years idle. It has an electronic switch as you suggest, which decouples the much larger start cap after two seconds max.

After power up, the motor seems to hit speed very rapidly, and then a second or two later, behaves like you've just dialled in a lower motor speed (on a variable speed drive).....with heat and then smoke being the result.

The bearings I think are good, as I only stripped then down last weekend, cleaned and regreased them....and they seem to me to run sweetly. The whole load just to spin the cutter block seems not unreasonable....kind of more an inertial load rather than anything frictional, as you'd hope. The old planer came with a 0.5HP motor which span the cutter fine....though if cutting real wood would probably have stalled (I never tried).

So, I am guessing that the motor gets to its running speed before the start cap switches out, as its tone seems stable before the speed reduction occurs. Of course I may be mistaken here....it's not easy to be sure!

My other theory for proposal is that the run cap has gone bad in storage. This means that when the start cap is switched out, only the degraded cap remains in circuit. What I need to know I suppose, is what effect a duff cap might have? Would the motor torque be massively reduced on load? As I said, off load it runs lovely, and I can't stop it by hand.

Graeme

 

[Doug B]

As I said, off load it runs lovely, and I can't stop it by hand.

Graeme

Graeme.

The first single phase 2hp motor i tried to put on a planer had an overload switch on it. this would blow before i got a couple of revolutions out of the block.

I took the motor out turned it on & with one foot on the motor & the other on the pulley i couldn`t get the over load switch to trip & i`m not exactly a small chap.

My next course of action was to take out the over load switch, wiring straight through & re-fit to the planer, this time it blew the fuse in the plug. So i wired it straight to the board, this time it took the trip fuse out.
I finally got it going by putting a 30 amp trip in the board, it was a this point i realised that i was better off putting a 3 phase motor back on the planer & buying an inverter.

This is quite honestly my experience, i hope you can get yours working, but even if you do, i think you will still have problems when you put it under load.

Best of luck

 

[jhwbigley]

What you want is something like this..

3 hp, single phase 8)

It might be for sale when i have a clearout in the summer..

JH

 

[Doug B]

What you want is something like this..

3 hp, single phase 8)

It might be for sale when i have a clearout in the summer..

JH

I do, & i`ve a sander that would be perfect for a student :lol: :lol:

 

[jhwbigley]

What you want is something like this..

3 hp, single phase 8)

It might be for sale when i have a clearout in the summer..

JH

I do, & i`ve a sander that would be perfect for a student :lol: :lol:

I see a plan forming.... 8)

 

[9fingers]

Bob,

Sorry for the delay in getting back. The motor I have is "new, old stock", and though unused, it has been sitting around for a few years idle. It has an electronic switch as you suggest, which decouples the much larger start cap after two seconds max.

After power up, the motor seems to hit speed very rapidly, and then a second or two later, behaves like you've just dialled in a lower motor speed (on a variable speed drive).....with heat and then smoke being the result.

The bearings I think are good, as I only stripped then down last weekend, cleaned and regreased them....and they seem to me to run sweetly. The whole load just to spin the cutter block seems not unreasonable....kind of more an inertial load rather than anything frictional, as you'd hope. The old planer came with a 0.5HP motor which span the cutter fine....though if cutting real wood would probably have stalled (I never tried).

So, I am guessing that the motor gets to its running speed before the start cap switches out, as its tone seems stable before the speed reduction occurs. Of course I may be mistaken here....it's not easy to be sure!

My other theory for proposal is that the run cap has gone bad in storage. This means that when the start cap is switched out, only the degraded cap remains in circuit. What I need to know I suppose, is what effect a duff cap might have? Would the motor torque be massively reduced on load? As I said, off load it runs lovely, and I can't stop it by hand.

Graeme

Replacing the run capacitor would be a low cost logical next step. I think it may be a 20uF looking at the AAB literature.
About £10 for a wire ended one - let me know if you have difficulty finding one - I can get one delivered to you quite quickly.

HTH

Bob

 

[dickm]

FWIW, there was exactly that machine in a retired builder's garage sale near here a few weeks back, and I'm pretty sure that only had a very ancient Brook capacitor start motor of 1/2 hp on it. But there was a lot of cast iron in those old motors, which may help.