Changing air compressor motor

[mr mechanic]

Hi there, maybe somebody can give me a bit of info here.

I have a wolf air compressor, 3HP 14cfm 90 litre (this one to be exact: http://www.ukhs.tv/Workshop/Air-Compressors/Dakota-14-CFM-Air-Compressor) and was hoping I could do a few modifications to it. As it's a 3HP motor it tripped of as soon as I turned it on (I was expecting it to) and so was wondering would it at all be possible to change the motor on it from 3HP to 2HP, something like this one:
http://www.ebay.co.uk/itm/ELECTRIC-...al_Components_Supplies_ET&hash=item2ec03bf7f5
Would a 2HP motor have enough torque in it to turn a pump of this size or not?

I know the best solution would be to rewire the shed electrics so that it can handle the compressor but that's not really an option at the moment. One day i'll do it (maybe!) but that would limit the compressor to being stuck in the shed and being able to move it around would be quite useful.

Also while we're at it it's rather noisy, so would swapping the motor from the 3000 rpm one that's on it for one that spins maybe 1400 rpm reduce the noise. Obviously I understand that this would give less output if at all it worked, but that's just it; would it work? In theory (or mine anyway!) it would just take twice as long to fill the tank (and the pump might run cooler?)

 

[rtbcomp]

A 2hp 3000 rpm motor would work, but it will struggle as pressure builds up. You could fit a smaller pulley on the motor (say2/3 the diameter of the existing one) but the pump would turn slower so you'd get less cfm.

A 2hp 1400 rpm motor would build the pressure OK, but at half the speed, thus 1/2 the cfm. It should be quieter.

 

[mr mechanic]

Wow thank you for such a swift reply!

Would we be seeing a significant decrease in cfm if I put a smaller pulley on the motor or would it not be terribly noticable? i.e. would it still be OK for doing the odd bit of spot blasting in a small cabinet or would it not cope with the demand of air? The only reason I'm asking this is because my current project involves restoring an SL125 bike and I have a couple of parts that could do with being blasted: chain guard, rear brake lever, gear lever - parts approximately this size but nothing bigger.

Also if I were to put a 2hp 1400 rpm motor on the compressor would it be detrimental to it to let it run for longer periods without stopping or would this be a no-no?

Sorry to be asking a lot of questions but I need to decide if it's worth doing before I go out and buy a new motor. Do you think it's worth doing?

 

[ford34/2]

Before you go Changing Motors and maybe pulleys, why not look at the problem???? You know what it is--Its the electric supply or the circuit you are using, Try another circuit or upgrade the one you are using. The correct supply and ancillaries will power a 3 Hp Motor.

What did it trip, an MCB or blow a 13amp fuse in the plug???
What Cable and ancillaries supply the shed at the moment??

Stan

 

[SmartWerks]

I gather your running an extension to the shed? That will probably be the problem. Also this time of year the comp requires more juice to get her going from cold. As for swapping the motor, self and buy a 2hp if that's the route you want to take. But a 2hp won't really do anything of any use.

 

[normspanners]

I agree with above why mess with the compressor when it is the supply a normal 13 A supply should do it if it is the o/l on the motor these do get tired as they age and after having tripped a few times. Also the oil could be thick if you look for other posts on this it will explain, a little better.
we need more info on this to advise more.

 

[mr mechanic]

It tripped the mcb. I know what the problem is. I need to upgrade the mcb from a type B to a type C but i then also need to completely upgrade the supply cable, which will take a quite a bit of work.

 

[rtbcomp]

...........
Would we be seeing a significant decrease in cfm if I put a smaller pulley on the motor or would it not be terribly noticable? i.e. would it still be OK for doing the odd bit of spot blasting in a small cabinet or would it not cope with the demand of air? The only reason I'm asking this is because my current project involves restoring an SL125 bike and I have a couple of parts that could do with being blasted: chain guard, rear brake lever, gear lever - parts approximately this size but nothing bigger.

Also if I were to put a 2hp 1400 rpm motor on the compressor would it be detrimental to it to let it run for longer periods without stopping or would this be a no-no?

Sorry to be asking a lot of questions but I need to decide if it's worth doing before I go out and buy a new motor. Do you think it's worth doing?

new cfm/old cfm = new pulley dia/old pulley dia (approx)

It should be OK running for a longer period. I Have a SIP compressor similar to yours and run it continuously.

Does it trip only when you first start up or does it trip starting when warm also?

Personally I'd go with the crowd, sort the electrics or could you place the compressor nearer the house and run a longer airline to the shed?

 

[mr mechanic]

I gather your running an extension to the shed? That will probably be the problem. Also this time of year the comp requires more juice to get her going from cold. As for swapping the motor, self and buy a 2hp if that's the route you want to take. But a 2hp won't really do anything of any use.

That's the reason I went for this one. I know anything smaller is not really much use for what I want to do with it and this was the largest I could afford and actually have room for.

 

[mr mechanic]

new cfm/old cfm = new pulley dia/old pulley dia (approx)

It should be OK running for a longer period. I Have a SIP compressor similar to yours and run it continuously.

Does it trip only when you first start up or does it trip starting when warm also?

Personally I'd go with the crowd, sort the electrics or could you place the compressor nearer the house and run a longer airline to the shed?

Would/should it run off a b type mcb if it were closer to the main house consumer unit then?

 

[ford34/2]

It tripped the mcb. I know what the problem is. I need to upgrade the mcb from a type B to a type C but i then also need to completely upgrade the supply cable, which will take a quite a bit of work.

I wee bit sad as you know the problem and you know the solution, I think I would bite the bullet and spend whatever you budgetd for on the Motor etc upgrading the supply, theres no easy short cut solutions I`m afraid, once upgraded it might well open up options for other machinery and welders.

I need a new wife, I know what the problem is and I know how to solve itand like you--but i then also need to completely upgrade the supply which will take a quite a bit of work.

Fortunatly the Electric supply is smashing and runs 3Hp Ingersol Rand no prob at all,14CuFt.

Also the oil could be thick if you look for other posts on this it will explain, a little better.

This was mentioned in a thread just the last few days, very very cold oil = Thick lubrication and very hard work for the Motor to get going and warmed up, pulling a few more amps than usual, consider warming it up-heater,etc.

Nowt positive--sorry.

Stan

 

[normspanners]

I f every thing stays the same ie pulley ratio etc putting a smaller motor on will do nothing except make it worse, the load is the load, you have to reduce the load or the smaller motor will just try and pull the same current as the bigger one or even more, the only thing is then the motor will burn out

 

[mr mechanic]

I wee bit sad as you know the problem and you know the solution, I think I would bite the bullet and spend whatever you budgetd for on the Motor etc upgrading the supply, theres no easy short cut solutions I`m afraid, once upgraded it might well open up options for other machinery and welders.

I need a new wife, I know what the problem is and I know how to solve itand like you--but i then also need to completely upgrade the supply which will take a quite a bit of work.

Fortunatly the Electric supply is smashing and runs 3Hp Ingersol Rand no prob at all,14CuFt.



This was mentioned in a thread just the last few days, very very cold oil = Thick lubrication and very hard work for the Motor to get going and warmed up, pulling a few more amps than usual, consider warming it up-heater,etc.

Nowt positive--sorry.

Stan

As for being able run other machines/welders in the shed- not an option. It's a wooden shed. Welding in there would probably result in me not having a shed for much longer. And it's not a big enough shed to be able to put any decent size machines in. It started off as a 6 x 4 ft shed, after which I bought an 8 x 6 ft shed, coupled them together, and even then, I had to build an extension to it on top of that. And I still have no room . That's what's putting me off wanting to completely upgrade the supply. It's not really worth it.

 

[ford34/2]

. It started off as a 6 x 4 ft shed, after which I bought an 8 x 6 ft shed, coupled them together, and even then, I had to build an extension to it on top of that. And I still have no room . That's what's putting me off wanting to completely upgrade the supply. It's not really worth it.[/QUOTE]

welcome to almost every ones problem on Mig Welding Forum--SPACE , but Honest a new supply will be worth it, to start with you will be able to run the compressor without a problem, once new Cable is in leave plenty sparecable in case you ever get a bigger shed or have to move the two you have.
Sorry I cant see a way forward for you, possibly change the breaker to a "C" But we realy need to know what the cable and protection is now. It can be a bit like putting a six litre engine in a corsa, the brakes cant cope the wheels are too small the chassis cant handle the power, the list is endless.

Stan

 

[normspanners]

Take the compressor in the house overnight and try it starting in there when warmed up, and let it run for a while.

 

[SmartWerks]

I used to warm mine with a hair dryer, 2 minute job. Now I've got it into a 16amp socket no more problems but i still give it a lil pre warm. Although I'm insulating my workshop and building a acoustic box which will be insulated so no more cold soon

it does say in the manual for my sealey not to operate in temps below 5 degrees c tho?

 

[mr mechanic]

once new Cable is in leave plenty sparecable in case you ever get a bigger shed or have to move the two you have.
Sorry I cant see a way forward for you, possibly change the breaker to a "C" But we realy need to know what the cable and protection is now. It can be a bit like putting a six litre engine in a corsa, the brakes cant cope the wheels are too small the chassis cant handle the power, the list is endless.

Stan

I've exhausted all possibilities of ever getting a bigger shed or extending the one I've got, as I've run out of space in the garden to extent onto. Admittedly the supply to the shed is far from perfect- it's currently just a spur of the ring main in the house.

 

[SmartWerks]

And I forgot, when mine used to trip out the 13amp supply my old man wired me a continental plug and socket which solved the problem. Now I'm redoing the shop it's all 16amp sockets and a future proof 32amp.

 

[octo0072000]

It tripped the mcb. I know what the problem is. I need to upgrade the mcb from a type B to a type C but i then also need to completely upgrade the supply cable, which will take a quite a bit of work.

mine runs on a caravan extension lead 16amp cable on a D type MCB no problems at all
and yes cold weather will make it harder to start

lots of Dtype MCBs on ebay 2000 of them

http://www.ebay.co.uk/sch/i.html?_from=R40&_sacat=0&_nkw=D+type++MCB&rt=nc&LH_BIN=1

 

[mr mechanic]

I used to warm mine with a hair dryer, 2 minute job. Now I've got it into a 16amp socket no more problems but i still give it a lil pre warm. Although I'm insulating my workshop and building a acoustic box which will be insulated so no more cold soon

it does say in the manual for my sealey not to operate in temps below 5 degrees c tho?

Well when I was using my old smaller compressor that made my ears bleed so I decides to try and build a sound deadening enclosure but then it started overheating. Mind if I ask you what you're using to build your enclosure?