Will this motor work for Air Compressor?

[misterfixit]

I need a 5hp motor for an air compressor I'm building. The pump is a Harbor Freight v-twin and specs a 5hp motor. I have aquired a Baldor 5hp. It feels like it needs new bearings, it spins fine, but has a little gravel sound. My question is that this is a farm duty motor.



In case you cant see it well it is a TEFC motor, 80% efficient, 88% power factor, rated for continuous duty, 230v 23amp.

Would this be ok on a compressor. The plan for the compressor is just hobby use, occasional use with a sandblast cabinet. Mostly used to blow dust and run a fog buster type cooler for my milling machine.

 

[Packard V8]

Yes, that's a good power for a home shop compressor.

As to the scratchy bearings, you have three options:

1. Build it up, run it for a while and see what happens.
2. If you have more time than money, disassemble the motor, clean and lube the bearings and see what happens.
3. If you have more money than time, replace the bearings. They're usually a generic part number available at a bearing store. Sometimes a puller and a press is necessary, but not always.

jack vines

 

[pancho400cid]

That motor supposedly has sealed bearings and "high temp grease" per info below:

BALDOR FDL3612TM DATA

I would just replace the bearings. There may be a nameplate that gives the bearing numbers.

That motor should work fine on a compressor I would think. Farm duty motors generally have some upgrades over light industrial/ commercial motors. I can pretty much guarantee that is a better motor than you would get if you bought a Harbor Freight compressor assembled with their own 5 HP motor.

The published list price on it is $1500 and change so they're not giving them away....

...

 

[Bert_]

It's a better motor than what comes on 90% of the compressors that get discussed on this forum.

 

[nadogail]

If you have any doubts about that motor, somebod on this forum will gladly take it off your hands.

 

[The Cobbler]

the bearings numbers are listed on the spec plate, looks like 6208 & 6205 . probably worth replacing them. probably both end with 2rs or 2z for the style of seal they have
that's a nice motor you got there.

 

[TRWham]

A 4 pole 184T frame motor is a distinct step up from the 2 pole 56 frame motors we see on many compressors. Given that it’s a TEFC, the roughness you hear or feel might be bearings, but it might also be a broken fan or junk in the fan.

 

[misterfixit]

That motor supposedly has sealed bearings and "high temp grease" per info below:

BALDOR FDL3612TM DATA

I would just replace the bearings. There may be a nameplate that gives the bearing numbers.

That motor should work fine on a compressor I would think. Farm duty motors generally have some upgrades over light industrial/ commercial motors. I can pretty much guarantee that is a better motor than you would get if you bought a Harbor Freight compressor assembled with their own 5 HP motor.

The published list price on it is $1500 and change so they're not giving them away....

...

If you have any doubts about that motor, somebody on this forum will gladly take it off your hands.

Wow, I almost hate to say how much I paid......$20

 

[The Cobbler]

that's a YOU ****!

 

[nadogail]

That's a Mega ****.

 

[misterfixit]

I have to admit, I had to try really hard not act excited as we discussed it. Full story though, he told me it doesnt work. He said he thought the capacitor was blown as it wouldn't start on its own. I still figure for $20 plus bearings plus new caps I was doing ok, and even if it's junk after that.....I'm doing ok.

 

[Walkers]

Sorry, it is not a you **** until you find out if you can make it run.

 

[laser3kw]

Sorry, it is not a you **** until you find out if you can make it run.

So.. basically, there is no "you ****" until there is a happy ending?

 

[Walkers]

So.. basically, there is no "you ****" until there is a happy ending?

MmmHmm

 

[misterfixit]

lol, ok point made. I'm 'pretty sure' it runs. Should find out in a day or 2

 

[James-W]

That particular motor spins at 1725 RPM's. What does the compressor say it should be turning at? Before someone jumps down my throat, I realize you control the speed with different size pulleys. Just pointing out that the RPM's of the compressor determines the CFM of air that it puts out. You may need to do some figuring to get the right size pulleys and the right length belt to get it performing to specs.

 

[csp]

That particular motor spins at 1725 RPM's. What does the compressor say it should be turning at?

Good point, I'm betting the HF compressor had a 3450 rpm motor on it originally.

 

[misterfixit]

That particular motor spins at 1725 RPM's. What does the compressor say it should be turning at? Before someone jumps down my throat, I realize you control the speed with different size pulleys. Just pointing out that the RPM's of the compressor determines the CFM of air that it puts out. You may need to do some figuring to get the right size pulleys and the right length belt to get it performing to specs.

Good point, I'm betting the HF compressor had a 3450 rpm motor on it originally.

This is a build from scratch. I got a killer deal on a new 80 gallon air compressor tank. Found it basically mispriced on a parts website. If I remember right it was a replacement tank for a Husky brand. I came black and unmarked, factory pressure tested and all fittings and motor shelf welded in. I got the tank for $150 plus free shipping. To be fair, I called the company and asked if the price was right, he said yes, so I ordered right then. About a week later when I got the tank I called to get another and they had changed price. Anyway, got the tank, so I bought a harbor Freight Compressor pump. Says it puts out 17cfm@40 and 15cfm@90. The manual puts this at 1050 pump RPM, a 14.5" pump pully, which would make the motor pully 8.7" to be precise.

I got it this way because I was really trying to do a budget build, and because I really seem to like doing things the hard way.

 

[misterfixit]

Looks like someone definitely let the magic smoke out of the capacitors. Got all new ones on the way, as well as a new set of bearings. I got the fan cover off, fan looks good but bearings still just a little rough. They may only need lube but I'll replace them anyway. Holiday weekend so shipping may take some time. Hope to know in a week or so.

 

[Walkers]

Looks more like someone robbed it for parts and put their crappy dead cap back in the motor.

 

[Bert_]

Looks like someone definitely let the magic smoke out of the capacitors. Got all new ones on the way, as well as a new set of bearings. I got the fan cover off, fan looks good but bearings still just a little rough. They may only need lube but I'll replace them anyway. Holiday weekend so shipping may take some time. Hope to know in a week or so.

I'd power it up and give it a spin by hand before I spent any money on parts. Or if you have any other capacitors around then use them to test. Most any value will get it to start unloaded.

 

[Bert_]

Looks more like someone robbed it for parts and put their crappy dead cap back in the motor.

It's pretty standard fare to see both start caps blown when you work on one. The first one fails and then the motor is slow to start so it takes out the second one.

 

[jubilee]

I have basically the same motor and HF compressor fabbed up on a two wheeled cart. No tank. I use to use it to plug into the shop tank when I needed a boost ( ten semi truck tires for example).
Worked great. Haven’t used it years, though. I ran a 9” pully on the motor.

 

[Monza Harry]

This is a build from scratch. I got a killer deal on a new 80 gallon air compressor tank. Found it basically mispriced on a parts website. If I remember right it was a replacement tank for a Husky brand. I came black and unmarked, factory pressure tested and all fittings and motor shelf welded in. I got the tank for $150 plus free shipping. To be fair, I called the company and asked if the price was right, he said yes, so I ordered right then. About a week later when I got the tank I called to get another and they had changed price. Anyway, got the tank, so I bought a harbor Freight Compressor pump. Says it puts out 17cfm@40 and 15cfm@90. The manual puts this at 1050 pump RPM, a 14.5" pump pully, which would make the motor pully 8.7" to be precise.

I got it this way because I was really trying to do a budget build, and because I really seem to like doing things the hard way.

In your best "Yoda" voice: "Alone you are not!" When I too was trying to do the same thing, my trips to the local compressor shops all would quote the same message about speed they all said RPM limit for life, noise, and efficiency was 900 RPM's for what little the theoretical loss that 150 RPM will cost I would aim for 900 RPM or less. And as for a Baldor 5HP for $20 that is a win at some level I am sure, even if you resell you should be able to double your $$$ for fun. I consider Farm Duty to be towards the bottom of Industrial motors but so far above consumer grade you'll need a ladder to touch them. Harry

 

[Hobby_Man22]

Grease the zerk fittings.

 

[Bert_]

Grease the zerk fitting.

I swear every time I go to work on a motor it has fresh grease on the zerks. As if that might fix any problem.

 

[Hobby_Man22]

I swear every time I go to work on a motor it has fresh grease on the zerks. As if that might fix any problem.

Simple things first my friend.

 

[misterfixit]

I'm not going to 'dirty it up' by adding grease now, although if I was trying to make it run as is that would defiantly be an option to try. I have a friend from our congregation that has a motor shop, he can rebuild and rewind if needed. He agrees with me that it's likely only the caps and a set of bearings that would make 'like new again'. I've already ordered new sealed bearings to replace the one's it has. Also have all new capacitors on the way. I'll even paint it while I have it apart, although I'm trying real hard to decide if I want it the original color or close to the compressor I'm building. My compressor tank is black, and the pump is black. Might be that a black motor is the way to go?

 

[Bert_]

If you can find them BMI caps are about the best at this point. Sometimes if there is room you can go to a 330v cap instead of 250v. Doing that vs cheap capacitors lasts a lot longer

 

[pancho400cid]

I've already ordered new sealed bearings to replace the one's it has.

The on-line data says that motor part number has sealed bearings, but the pics don't actually look like the bearings are sealed. One of your pics shows grease fittings at both bearings, and the pic of the nameplate says "6206" bearings at DE (drive end = shaft end) & "6205" at ODE (opposite drive end) which are just deep-groove ball bearings. If you just ordered "6206" and "6205" bearings they are not sealed - which appears to be what you need. I think that usually the letter "Z" specs sealed on one side, and "ZZ" specs sealed on both sides (ex: 6206ZZ).

...

 

[Cruzan80]

Z's means metal shield. 2RS is rubber sealed.

 

[misterfixit]

If you can find them BMI caps are about the best at this point. Sometimes if there is room you can go to a 330v cap instead of 250v. Doing that vs cheap capacitors lasts a lot longer

I looked and found what were listed as replacements with the Baldor part numbers, right now I can't remember the brand.

As for bearings, I went with the 2RS sealed bearings. I've used them in motors before, including the motor on my B'port Clone Mill. I don't think for my purposes and uses there will be much difference. Having said that, I am aware that this particular motor is of a quality and meant for continuous service that would make good use of greaseable bearings. I just don't think in my case it's needed.

 

[pancho400cid]

In my experience greasable motor bearings cause about as many problems as they solve.

I've seen many motors pumped full of grease.

 

[DeeKay]

In my experience greasable motor bearings cause about as many problems as they solve.

I've seen many motors pumped full of grease.

THIS! Too much grease or the wrong grease is worse than just leaving it alone in a lot of cases.
I've also seen motors that came with sealed bearings (not shielded) where someone came along and pulled the pipe plugs out of the end bells and put zerk fittings in, I guess they thought the manufacturer forgot to install them when they built the motor? Little did they know they were just pumping the housing full of grease which eventually cooks the windings.

OP if you're curious here's the info packet for that motor.

https://www.baldorvip.com/Product/InfoPacketExternal/?id=FDL3612TM

 

[misterfixit]

*update*
I got the new capacitors in and fired it up. Motor works fine. I have also ordered new bearings. I will be repainting and using this motor on my air compressor build. Probably start a thread on that soon. Thanks for all the help folks!

 

[The Cobbler]

super! thanks for the update!
Oh, and it's a major YOU **** !