Build an air compressor

[bsaunder]

I have my eye on this Harbor Freight air compressor:

5 HP AIR COMPRESSOR PUMP
An ideal replacement pump designed to fit compressors from a wide range of manufacturers.
* Two cylinder, single stage * Splash lubrication keeps pump running cool * Oil level viewing window * Oil plug with ball-bearing release valve * Long stroke design * Heavy duty cast iron construction * Dual high efficiency intake filters * Cast iron flywheel with dual belt V groove * Air delivery: 18 CFM @ 40 PSI, 13.4 CFM @ 90 PSI
* 145 PSI max. * 3/4''-14 NPT male outlet
ITEM 91982-5VGA

I know zippo about fabricating and mechanical stuff.

I have a John Deere 300 with an engine speed PTO having a dual V-belt pulley.

Cant I just hook this up and produce a lot of hot air?

Compressor claims 13.4 CFM at 90psi...if my tool takes less than that do I even need a tank?

I'd need some sort of blow off valve, an oil/water filter, and a regulator.

What do you guys think?
Bill

[smithboy]

Seems like a pretty dangerous thing to try...a hose and a person around a tractor pto running at engine speed (800-2400 rpms?). I know dead folks and folks without major body parts because of tractor pto's. Also, I think you'ld still need an at least a small tank (pancake compressor sized maybe) to smooth out the air flow. Might be just as easy to hook an air conditioner pump to the main pulley at the front of the tractor and find a truck (with air brakes) air tank for the air reservoir. Just a couple of thoughts...Maybe others will provide some more. What ever you decide, be careful around those pto's.

[KEENAVV]

Check the want adds,Ebay,craigs list, but save your body parts!!

[GoberRacing71t]

I have seen a homemade air compressor made from a tank and AC compressor explode. The tank was mounted in the pickup bed and when it exploded it blew all the windows, blew a hole in the bed and the blew the driveshaft driveshaft out. The mechanic driving the truck did survive but was very lucky....

[smithboy]

Sounds like a problem with the pressure release valve. Ac compressors will compress to a few hundred PSI. You have to be careful to get that part right. But you make a good point....There is still dangers with my suggestion also.

[Sandy]

I'm kinda running with smithboy on this one. It would be about my last choice for a compressor set up. Unless of course it served some very necessary application where it was better suited than conventional ones. If that was the case I'd put my heart into it and make it a bang up job with tank and all.

Number one 13 to 18 cfm isn't really a lot of air. It's plenty for most air driven hand tools of the home shop variety, but not as much volume as you'd think.

Next would be RPM. Check around to see about what most compressors of that style run at. I couldn't give a class air compressors, but if you look around I think you'll see most are off a 1700+ rpm electric motor along with speed reduction through a large and small pulley. SO let's guess they run at 190 to 300 rpm. Can you pulley yours down that much? Don't wanna cook that puppy.

Thirdly would be pressure regulation/safety devices. There are fixed value pop offs, not exact but close. You'd have to get one around 120 psi to be safe. There are also variable range ones, and again not real accurate. If you want to do any painting at all you'll darn sure require a good regulator + filter + moisture trap.

That's just some of my thoughts.

[comp]

play it safe,,,#1

[bsaunder]

Yes, you guys are correct VERY dangerous.
That being said, everything has a risk and must be designed for it.
If I built this, the PTO/belt/compressor interface would be completely shielded. Ie hook up the belt, attach the cover, then start it up. The tiller that comes with it has a lever to engage/disengage. It doesnt have a shield but anything I build will have one.

After I had thought about it some more, the tank became necessary. As someone said above it evens out the air flow.

The pressure regulator is what bothers me. Electric motors have a pressure disconnect right. "once we reach 125psi, cut power to the electric motor". Seems simple enough. On the other hand that's tougher to do with the tractor. BUT aren't there compressors powered by small 5hp engines? Do they cut the engine off once pressures been reached? How does the engine restart once the tanks empty? I assumed(yes I know bad), that there was a type of blowby valve that once pressure crept above 125psi it started venting any extra. Can someone explain how the 5hp gasoline compressors work?

Thanks, after we finish this we'll talk about the 10kw generator head hooked up to the PTO also. :) make a nice welder hey? (said something about needing a line conditioner for tv's/electronics, anyone know where to get one capable of 10kw?)

[TxRedneck]

Alright bud, heres teh talk. Just my story. I have a leg that got kinda chewed up at work. There telling me I came very close to amputation at the knee as a result. Well actually as a result of an ER dr who sewed me up wihtout getting "ALL" the foreign matter out. I know you sitting there going yeah yeah what does this gotta do with me. THis. The thing that tore my leg up with an abrasive disc. I may never walk normal again because of a freak accident. Ive done this for use...cut off wheel on grinder. ANd lots of others have to. BUt this time it dint work. Blew apart into my leg and tore it up good. now, the tractor pto's as Smitty put are real dangerous. Ive been around them since I was knee high to a grasshopper. They maintain as much power as that tractor engine can kick out...too much for an aircompressor. Not that it will destroy or specifcally cause failure...but building a compressor from scratch is asking for complete and utter failure. IF that tank were to blow it would kill you if you were lucky. Unlucky, youd be mamed for life, or mame someone you love. less than that you could kill someone else, hurt them or kill or hurt pets, lifestock or any other personal property. After an injury like ive sustained I must say I look at things a whole new way. Not that I was entirely careless before. I wouldnt have done this befroe either. ANd for using a cut off with the what I was offered onthe job I did what I could to be as safe as possible. HEck I wore a respirator for the dust! I never do that. Youve always gotta be thinking about the what ifs. True you can what if yourself outta all your money and all your happiness. But to me everything is a calculated risk. Sure this sounds like a neat idea. And your frends on here will all say damn your ingenioius. I must say Im impressed with the idea, but at the same time I feel its not going to work...too dangerous. Not worth you life, or your familes. And yes your life even if it doesnt end it, it changes it forever. I have a cousin, well dad has a cousin. Was in naval construction back in the 'Nam. In 1968 stepped on a land mine. He lost some portion of his foot and leg. Dad says it wasnt much, but still enough. The man was given a purple heart and sent home with a prostesis. With his prostesis he couldnt weld. HE was given a full grant to go to college all expenses paid as an archetict. I dont know the exact conditions, but it paid his living expenses and everything, books, food. But whats it worth? Was it worth his leg? He now owns a welding business. He does the drafting nad design., His sons weld. Its gotta be hard, I know it is and other can attest when you are a welder, to be told one day you aint weldin no more son! I am still at risk of being told that. Its really scarey. Please all of y'all consider what you do and how it will affect you and your family, cause yeah it affects them too. Not just you. Well thanks for your time and reading.

[Sandy]

Couple of thoughts.

Go look at, let's say sears, little portable oiless compressors with no tank they have an adjustable pop-off/blow by valve. Not that that is what you should buy, but it gives you the concept.

Go check in with an air hydaulics shop. They can give you info on industrial models. For instance take notice of any of the commercial portables used for jack hammers, air tamps and whackers and such. They are gas powered and do not shut off. They have a combo unloader/by-pass valve couple with an auto idle solenoid.

One more time------------remember the torque supplied by a PTO shaft.:)

Nag nag nag.

[steve45]

As an engineer, I would highly recommend against trying to build your own compressor. Compressed air is extremely dangerous if it is not contained properly. There is a LOT more to it than you may think.

Are you aware that you can actually blow up an oil-type compressor if the compression ratio is too high? (The oil will ignite under the heat of compression, just like a Diesel).

That said, Grainger's has a wide variety of compressor parts. If you want to build your own, you can buy a motor, tank, regulator, pressure relief valve, etc. from them. Don't use a PTO.

[gimpyrobb]

So the question doesn't go un answered, THIS IS A GUESS. I would imagine that the gas powered compressors have an electromagnetic clutch on the air pump. The gas motor turns all the time while the unit is on. The pump turns till the tanks are full. Then the regulator turns off the current to the clutch on the pump. Once more air is needed the clutch engages. I picture this working like an airconditioning compressor on an automobile.

To answer your second question, you don't need a line conditioner the size of your generator, you need it rated at the size of the draw, draw meaning the appliance in use. If you plug a hair dryer into the generator it doesn't use 10kw does it?

[wagabond]

I feel the need to let you keep thinking outside the box about building a PTO driven aircompressor. It is safe as you make it, there are tons of gas, diesel, remotely powered air compressors out there. There is not difference with you driving it with a tractors PTO, versus some of the field service trucks that have them being driven by the vehicles' engine running. At work we have a field truck with a boom crane body that has a hydraulically driven aircompressor. When the diesel is idling, it runs a PTO that drives a hydraulic pump, that then forces oil pressure to a hydraulic motor, attached to a compressor pump. Even with this set up there is a over ride valve that cuts in and out when preset tank pressure is met. The diesel engine, pump, is continuously running, recirculating oil past the hyd, motor until air pressure drops, then it cuts in again. Gasoline powered compressors work the same way. They have pressure regulators that cut in and out while engine keeps going. Also, torque is defined as twisting force, its only as much as you demand it to be. The load of the compressor head is what would determine that force on the drive. You have me curious about your idea, I am searching for more tech info.

Thats my story, I am sticking to it, keep up the ideas.
Russ

[steve45]

I'm certainly not saying that it can't be done, and done safely. However, Bill said that he doesn't know much about fabrication and mechanical things. For this reason, I think he would be much better off to BUY something that has an ASTM certified tank and properly sized pressure relief valve, etc.

I've heard a number of horror stories concerning compressed air systems including portable tanks blowing up, PVC lines blowing up, etc. Compressors are getting cheaper all the time, no point in taking chances.

[TxRedneck]

i agree with steve. i can build and weld like the sun, but this is an undertaking Im just not interested in. Can it be done? sure. but why and at what cost(risk factor) for someone who is new to the trade compressors are getting cheaper and better. For me a major factor is I can buy one for less than I can build one for my time. This should amount to something

[krazirbar]

It shouldn't be to hard to setup. is your PTO electric or manual. is electric if you just have to push/pull a small switch/button. if it is just hook your electric psi switch into the circuit then when your compressor reaches 120 psi will automatically stop PTO, when drops to 90 psi OR so will engage. still need to have tank,pop-off valve, check valve, psi gage, and outlets not that hard to do. i am doing almost the same thing on my welding trailer using 9 hp briggs with a service truck compressor that has a electromagnetic clutch on the comp. motor is not big enough, but with the right pulley setup will work great for every thing i need it for.:cool: :cool2:

[Dashek]

Why not take a page from us guys with jeeps and do what we do. OBA (http://www.webejeepin.com/Glenns_Jeep/onboard-air1.htm), I run the same setup on my YJ and I really don't know how I gotten along all those years wheeling with out it. Yorks can be picked up and most pull&save's for under 30 buck. All said and done I have about 100 bucks tied up in mine.

[halbritt]

If there's no risk of death, it can't be much fun.

When did so many mother hens join this site? It should be enough to simply state that compressed air systems are dangerous business and that there are risks involved when working with this equipment. It's up to the builder to figure out what those risks are and attempt to mitigate them to an acceptable level. If one builds their own air tank, for example, then it can be hydro-tested to determine its operating characteristics.

As for myself, I've got a nice 9HP horizontal shaft gasoline engine on a dead generator head. I think I'm going to hook that up to a 2-stage compressor at some point and use it for sandblasting and whatnot.

[TxRedneck]

If there's no risk of death, it can't be much fun.

When did so many mother hens join this site? .
I find this to be a very arrogant and just plain dispicable statement coming from someone who piosts as much and comes across with such an authoratative perspective. Youre cocky, youre arrogant, and your lack of experience is obvious. May not be to a youngster, but it is to someone who welds for a living. As far as I am concerened its idiots like you that make our world a much more dangerous place. Yes risks are to be taken. But unnecessary risks that could be easily avoided should as well. When tanks are tested by testing facilites and other things, they are done in a safe way. Sure its crazy and you dont know how its gonna end up. But they do everything they can to make it as safe as possible before doing something thats inheriently deadly. This way nobody gets hurt. Even still, accidents can still happen. Its just still remarkable the stupid thigns you come on this forum with Heath. I mean I remember how stupid it was when you posted a picture of you haning from your trailer sayin this was your way of testing the welds. It may have been a joke. But I dont know. But for a lot of new guys, they might look at that and say hell yeah thats what I do! Or oh yeah thats a great idea or god only knows what. Ever seen a trailer driving down the hghway? Well dumb @sses lke you or those who learn from you build trailers like that. Why???? cause they can. Cause they say well I read it in a book. Or cause somone told them it was alright. Im thoroughly disgusted by this attidude and its very unsafe. Very unprofessional as well. Shame on you Heath! :nono:

:realmad:

[halbritt]

How to begin? You are correct, I am cocky and many people think I'm arrogant. You might consider that to be a slight, but I certainly don't take it as an insult. From my perspective, I realize that I am very knowledgeable, but what's more important is understanding what knowledge I lack. My lack of experience in the field of welding should be obvious to anyone that has a good grasp of the language. I almost universally preface what I write with a disclaimer that indicates whether it's something I've read, something I have personal experience with, or something that I'm just guessing at.

I'd never advise someone not to do something because it's an inherently unsafe task. That sort of behavior is contrary to my philosophy. I'd never seek to constrain an individual from doing something that they chose to do, however I might suggest that someone isn't competent enough to complete a given task or I may simply just illustrate the risks involved.

In the case of building an air compressor that's designed to work off of a PTO there are numerous risks. I assume that the person wanting to do this has a tractor with a PTO and some knowledge of how they work and the dangers involved. They have a bad habit of eating body parts. There are ways to mitigate that risk by examining existing PTO equipment. For any compressed air system there can be a great deal of stored energy which can lead to lead to an explosion. That risk can be mitigated by using pressure relief valves and components rated for the pressures involved. If someone is going to build their own tank, it should be hydro-tested to a degree that includes a reasonable safety margin. Compressed gas systems aren't a new thing, so there's a great deal of prior art in this regard to work from. It is a known thing and it can be replicated pretty readily.

If you really thought that the photo of me hanging upside down on the trailer that I built was stupid then you should probably go visit a doctor and have him examine your funny bone. It might be broken. As for the trailer itself, it doesn't qualify as "one of those trailers" you see cruising down the highway that shouldn't. A great deal of engineering effort went into that trailer with good result. I've towed a number of commercially manufactured trailers in my life and but never towed one that handled quite so well in all the ways that matter. I had never built a trailer before that point, but I felt comfortable doing it because I examined a number of commercial designs, reviewed a number of amateur builds, and very closely followed the engineering guidelines published by the running gear manufacturer.

My point is that if someone wants to build something, the trick is figuring out how. It would be unwise for someone to build something based on advice from a stranger on an Internet forum without validating the information first. Each person has to choose the level of risk he's willing to accept. As for myself, I have some extraordinarily risky pastimes, but that risk is usually mitigated to an acceptable degree.

[TxRedneck]

Well thank you for that. I hope all understand that the situtation, in my life, as recently changed and Ive got a whole new insight on safety. I was always safe, or atleast tried to be within reason. However, after my accident I had a serious come to jesus and I look at things way different. Us welders get payed the big bucks cause of our training, skills and the fact weere not suppose to be getting hurt. When these things happen, its really bad. Inaddition to us nothing getting hurt were also suppose to build things so that others cant get hurt either. Infortuatnely I knew a young girl who was killed because a guy built a trailer and the trailer dint like being told where to go. The trailer disconceted istelf from the pickup and took off down the highway, across the median and saw this girl in her monte carlo and decieded the trailer wanted to be led by it. Well of course at them speeds it doesnt work. She was killed. For this I am very serious about things lke hobby welders building things tlike trailers and hitches cause it killed the daughter of a very close friend of the family. 19 years and it was all over. Why, cause a hobby welder did what he thought was acceptable. There are no mother hens on this site. Only folks who at various ages, stages and occupations have seen what nature can do when man gets too eat up with stupidity. well thats my story and im stickin gto it, but thank you Heath for your explanation.

[Pentawelder]

Halbritt and TxRedneck, You are absolutely correct!!!!
Nothing is scarier than some posts on welding boards,
"I've never welded in my life butÏ just bougnt $150 dollar welder and I'm going to build a -----"
Insert name of dangerous device above.
My stairs and deck were so over engineered that they'd have held up with hot glue!
Welds with little penetration can look good especially the inexperienced weldor who just made them. The deck test involved some VERY vigorous kicking early on and a friend who was observing told me to back off before I broke something!!! I didn't and nothing broke either!.

[TxRedneck]

Thats a good one pent, Well Ive seen it enough times some really purdy cold @ss welds. Watched in an inspection class once a guy ran a weld on 1in plate. he had his settings pretty low of course, but the weld actually looked pretty...except that it curled up at the end a little. Then he took a pair of pliers and peeled the weld all the way off. Im not saying a hobbiest cant build a trailer safely. Or that they cant even do other things. But its easy for things to be built improperly, or the welds to be inferior and unsafe. IVe seen so many welds over the years that I was soo unimpressed with. A lot of the work I did when I was in college was on the farm rewelding and repairng things that the welds were giving. Some things were alright, but we rewelded them anyway cause they were really not proper...Lot of undercut and such. Trailers were a big problem though. I wont say theres not a lot of crappy looking welds that are fine for a lot of applications cause in all honesty they are. But there are also a lot of welds that look good, or may not and they arent good enoguh. Anyway, its just my way of looking at it. I weld for a living and people cant sue me if its built righ thte first time. :D

[comp]

If there's no risk of death, it can't be much fun.

When did so many mother hens join this site? It should be enough to simply state that compressed air systems are dangerous business and that there are risks involved when working with this equipment. It's up to the builder to figure out what those risks are and attempt to mitigate them to an acceptable level. If one builds their own air tank, for example, then it can be hydro-tested to determine its operating characteristics.

As for myself, I've got a nice 9HP horizontal shaft gasoline engine on a dead generator head. I think I'm going to hook that up to a 2-stage compressor at some point and use it for sandblasting and whatnot.
mother hens:laugh: :laugh: your right i do like to drink and play with guns :laugh: :laugh:

[halbritt]

mother hens:laugh: :laugh: your right i do like to drink and play with guns :laugh: :laugh:

I know you're joking, but the thought of playing with guns while my alertness is compromised with drink puts other people at risk and is pretty reprehensible to me. I shoot a great deal (action pistol) and I'm pretty serious about safety when I do. With that said, I have gotten hammered and gone target shooting with a friend's airsoft that is a replica of the pistol that I normally use. Everyone wore safety glasses and thick clothing and I had a great time. In some shooting games they have a concept called "reloading with retention" where one is supposed to pocket any magazine that isn't empty. Shooting with a beer in hand gives a whole new meaning to reloading with retention.

[TEK]

Tx, Halbritt- Credit given where due. You guys handled that very well,imo. It could have gotten ugly but it didn't. Thanks.:cool:

[TxRedneck]

see the way I look at it the internet sucks on this. In my field when you got a good dispute with someone theres one way to settle it. Usually you both end up on the tailgate later that day one beer on the eye, other beer gettin consumed....its a dandy way to do things. :D nobody holds a grudge

[halbritt]

If we had the benefit of physical presence, I doubt there would be a dispute at all.

[CarterKraft]

to use that compressor properly you will need one of these devices.http://www.mastertoolrepair.com/combination-check-pilot-unloader-style-p-847.html?osCsid=7b927fb118dae02b609b081fb279279b

This will "unload" the pump at 125psi and "load" it again at 95psi. You will also need a pop off valve of some sort rated for the capacity of the tank (psi) and the CFM of your compressor.

Fairly simple to plumb, however you could have a much easier to use OBA system as described above, for the price of the compressor alone.

[halbritt]

That's just the part that I was looking for. Thanks for the link.

[CarterKraft]

not a problem, though we will need pix when done :)

[Joker11]

I live on the border of Arizona and Mexico. At this point, I might as well be IN Mexico, cuz they are all here in Arizona. The story is like this, I have a guy working across the parking lot from me in his shop, opposite my shop. He runs PVC for all his air lines. I walk in and say "WHOOOAAAA" what the heck? He tells me that's how he has done it for years. Ok, so you haven't had a disaster yet. That doesn't make it safe. He welds roll cages with mig all the time. Is he using DOM tubing? I doubt it. Is he using Chromemoly or mild steel? Dunno. Do his customers know what they are getting? Of course! It's all nice and pretty. He can lay a nice bead. Doesn't mean I would trust my life to one of his roll bars. But when I try to ask him any questions about the technical side of welding in regards to metallurgy, he just gives me the same dumb look and argues that he is making a living running his shop and what do I have to show for all my time spent in community college welding labs? I backed off, cuz he is very successful in his business. But it won't be long before some yahoo thinks he can run the baja 1000 with what comes out of that shop. I have never welded a full roll cage for anyone and I won't. Not that I can't, but I don't want to be responsible for anyones death. The point is that I don't trust a lot of people's welding knowledge. Any monkey can pick up a mig and run a bead. If I don't trust someones fab skills to build a rollbar, and he does it all day long. I don't think I would trust someone's home made compressor after they admitted they know "zippo". So, my advice would be to buy a nice compressor that will last a long time and have proper safety mechanisms. That doesn't guarantee that it won't explode, but it means you can recover your losses from the manufacturer when it does.
Take that to the bank and tell em Beretta sent you. But don't mention his wife....bad story.

[kolot]

I have built my own 8 HP gas engine compressor from components, what happens is that there is and air pressure operated solenoid, when the max. set pressure reached it idles the motor and the compressed air is dumped into the atmosphere. As you consume the air in the tank it gets down to the set cut in pressure, The motor throttles back up , the pressure then build in the tank and the process repeats. I have installed multiple blow off safety valves. You can also get the old truck ones that are ajustable if money is and issue.

[sunpowered]

ok, if this loads I have a real Air compressor here 3500 psi 3 stage,which is driven by a electric motor,which is driven by the AC generator of this same truck which also has a DC generator which both generators are driven by a y split pto off of a 312 Y block .Ohh and it is 4x4 too. I picked it up it trade the DC is 500 continus and 1000 watts intermitent, I I am thinking from what I read on the panels 3 phase and 1 plase is available on this truck, but I am damned if I know how to make it work.:blob2:

[sunpowered]

ohhh, and the main generator is a 22KW anyone have a small town to light up?
:blob2:

[Joker11]

Other than paintball and scuba, who needs 3500psi? That is wild!

[sunpowered]

I think it was a jet jumper, but I had to have it,I had to have it don't have any idea why but I had to have it.:blob2:

[smithboy]

Sunpowered,
It's completely understandable...so, you just had to have it...because, you needed it for satisfying an impending need. I am a fan of circular reasoning in tool purchases...or in your case trades. I mean, the real question is who doesn't need one? I am already looking for one myself.:D

[sunpowered]

well I had dreams of sandblasting rocks and powering the world from my own generating station when the big one hit, but then I put my beer down and thought I would sell it on ebay.:blob2:

[Joker11]

Ok, I retract my question. I can see the logic now. My bad.

[Rojodiablo]

There are a few compressors in the 4wd off road world that power tools, and some are driven by electricity from the alt. and a few run off power pumps/ air pumps like power steering and I saw one that had a pump like a smog pump/ air into exhaust pump. Look into those for some ideas and safety features. Clutches like the ones on my gas powered air compressor. The gas motor never stops, just a pressure relay and an electro-magnetic clutch to engage/ disengage. I agree on all points here. #1. It CAN be done. SAFE. 2. A resevoir tank is necessary, as are a simple filter.3. If you do this on the sly, I would like to see pics posted on the busted parts on you and the machine.... you can make a great compressor, it will take a bit of planning. Good luck. Paul.

[rvannatta]

i agree with steve. i can build and weld like the sun, but this is an undertaking Im just not interested in. Can it be done? sure. but why and at what cost(risk factor) for someone who is new to the trade compressors are getting cheaper and better. For me a major factor is I can buy one for less than I can build one for my time. This should amount to something

Certainly every air compressor set up needs an air tank, and it would take some sort of a fool attempt to make his own air tank.

As for the compressor, it depends on whether it has it's own unloader or not.

Many years ago we made a tractor mounted compressor setup to run an air saw for brush cutting. It was based on a Qunicy 20 CFM 2 stage compressor. we didn't use the PTO but rather used the tractor belt pully and carefully engineered RPM so the compressor would not turn beyond its design speed. -- that particular compressor had its own unloader built into it.
We then used a properly rated tank, and of course included a pop off valve.

this is considerably short of 'building your own compressor' however.



Interestingly the first 'air compressor' we ever had was a PTO compressor that we bought from John Deere for pumping up tires.

It slipped directly over the PTO and chained to the drawbar. It was a single cylinder with an open crankshaft (with a grease fitting on it). there was no air tank--- just 15 feet of air hose and a connector on the end that would screw on a valve stem. the whole thing wasn't much larger than a quart jar.

[steve45]

Interestingly the first 'air compressor' we ever had was a PTO compressor that we bought from John Deere for pumping up tires.

It slipped directly over the PTO and chained to the drawbar. It was a single cylinder with an open crankshaft (with a grease fitting on it). there was no air tank--- just 15 feet of air hose and a connector on the end that would screw on a valve stem. the whole thing wasn't much larger than a quart jar.
I like that idea! The tire serves as a tank and pressure relief valve all in one!

[htsmo@yahoo.com]

I found a pretty good set of plans at Innovation Super Highway (http://www.innovationsuperhighway.com:9080/ishweb/loadArticle.do?articleId=5)for an air compressor.

[65535]

Safe bet is just hook a generator up to the PTO with a break right off the output and connect a normal compressor to that.

[Stever Passonar]

Mcastercar has some things you may need for making a compresser, i cant get a link though. they have pressure switches, check valves, and safty cutoffs. I am in the process of making on out of two old lawn mower engines.

[Alan N]

I don't know that I have ever seen such a bunch of negativism from a pretty simple question. Somebody made a comment about what a bunch of Mother Hens we've got here. Someone also commented on PTO shafts eat body parts. Might be wise to remember they only do that if some idiot feeds them into the shaft.

Nobody seems to be able to understand that what he's got a 13-14 hp garden tractor. There's no fearsome PTO shaft involved, he pointed out that it has a double vee belt pulley. Deere made compressors for just that application, not sure if they had one for the 300 but they did for some of their models.

So how about, instead of capitalizing on how dangerous this could be, the energy was spent on trying to figure out how to make it work safely?

So, BSaunder, I wish I was next door to you, we could build two versions, one for you and one to go on my 400.

Can't use an electric system, which I think somebody suggested, as the 300 may have a 15 amp charging system at full throttle. Going to need to belt drive it. Got the drive pulley already in place so that's a good start. Need to play with the pulley sizes to spin the compressor at the right speed. No need to run the engine at full throttle, there's plenty of power available at a fast idle. Need to incorporate a tank, bigger would be better, but the Deere ones weren't anything over 5 gallons. Big item to keep the danger factor way down in that you need a compressor that has, or can be rigged with a pressure activated unloader. So when it hits the high-pressure point the pump stops pumping. I don't know how they work but they are out there and do work as I've used constant speed, unloader regulated compressors. Also going to need relief valves, at least one, big enough to bleed off the full capacity of the compressor, preferably a couple to be on the safe side.

Is it dangerous? What isn't? But it's sure no worse than mowing your lawn with that same tractor and it would be a nice little "See what I built" project.

Might not be easy and it sure will need a bunch of research done first but it would be hell for neat!

[steve45]

I don't know that I have ever seen such a bunch of negativism from a pretty simple question. Somebody made a comment about what a bunch of Mother Hens we've got here. Someone also commented on PTO shafts eat body parts. Might be wise to remember they only do that if some idiot feeds them into the shaft.

Nobody seems to be able to understand that what he's got a 13-14 hp garden tractor. There's no fearsome PTO shaft involved, he pointed out that it has a double vee belt pulley. Deere made compressors for just that application, not sure if they had one for the 300 but they did for some of their models.

So how about, instead of capitalizing on how dangerous this could be, the energy was spent on trying to figure out how to make it work safely?

...Is it dangerous? What isn't? But it's sure no worse than mowing your lawn with that same tractor and it would be a nice little "See what I built" project.

Might not be easy and it sure will need a bunch of research done first but it would be hell for neat!

The real problem with the internet is that you don't know the knowledge level of the person you are communicating with. Compressors can be extremely dangerous. That's why there are safety standards for them.

You act like a 13 HP prime mover is a toy, couldn't possibly be dangerous. Well, people have been killed by 3/4 HP drill presses and other such devices. You just have to get a loose shirt sleeve, etc. tangled and kiss it goodbye.

This is to not to say that it can't be done safely, but I want the original poster to think of all the possible pitfalls before he builds his compressor. Compressor design is NOT for amateurs.

[Mandau]

Buy a chinese junk engine and a pump, use a big LP cyclinder and you have a compressoer... KISS

[Oldtimer]

"It would take some kind of fool attempt to build his own tank".

Any competent welder, the qualifing word being competent, can do it and it will be perfectly safe.

[Me!]

Other than paintball and scuba, who needs 3500psi? That is wild!

Spud Gun! :drinkup: