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Please join me in building a poor-man's quiet generator

Please join me in building a poor-man's quiet generator

Please join me in building a poor-man's quiet generator

(OP)
I'm siding with the group who thinks this winter is going to be a gully-washer on the west coast. We have lots of trees and they've all been horribly stressed by 5 years of drought, so when the rain comes with the big winds I expect the power to fail often and for long periods. That, since it appears the POCO has shaved its staffing down to nothing in the annoying quest to raise its stock value.

I had an air-cooled, four cylinder, mixed fuel, single phase, 15kW Onan generator drop into my lap a few years ago (well, not literally or I'd have died, but you get my point). It was kicked out of rail service because someone at Amtrak correctly recognized the horror of adding a ruptured multi-hundred gallon propane tank into a passenger train derailment.

On receiving it I tested it fully loaded with bar heaters in a pail of water and it ran great. Loud but great. I ran it on propane.

It's a 15 JCB 60Hz 1-phase.

Here's the spec sheet for it:
Onan Specs PDF

Here's what one looks like. Note, this isn't mine as mine is currently residing three stories up in a ceramics warehouse in the racks amongst tons of pottery clay.


The plan is to build it onto a small trailer, your classic Harbor Freight $200 type. Sort of like the one in the picture except with much shorter wheels. I have the trailer! It's waiting for me to assemble it. However, I think I might want to make it narrower than stock to make it more manageable around the homestead.

The generator, as mentioned, is air cooled. Notice in the picture above, the grill on the front? There is a mondo squirrel-cage blower in that box that forces gobs of air up and around to one side of the four cylinders and then thru them and out the big rectangular opening you can see. The cylinders look very much like motorcycle heads with big fins on them.

Where I'm hoping to get help from you folks is in suggestions for making this whole thing as quiet as reasonably possible. I need to completely enclose it, I'm sure, but I suspect some simple details I'm ignorant about could make a huge difference in noise suppression.

I'm seeking any knowledge you're willing to impart on what I should do for:

1) The trailer base. Do I mount the genny on heavy plywood? On steel structure with some sort of vibration isolation? On a sandwich of something?

2) For the enclosure, sheet-metal covered plywood? Fiberglass?

3) Sound attenuating materials? Know of any?

4) Do I need to labyrinth the cooling air in and out of the enclosure? Suggestions?

5) The muffler... Anyone have a suggestion for one for this size engine(flow)? Should I look for a criticality 1 muffler? (hospital grade)

6) I have a 30gal propane tank I plan to use. Any info/suggestions?

I need to start moving on this sooner than later, so the first thing is '1' above so I can retrieve the generator onto the trailer and get it to my place.

Let the fun begin!



Keith Cress
kcress - http://www.flaminsystems.com

RE: Please join me in building a poor-man's quiet generator

I'd suggest doing only the easiest things (good muffler, easy sound dampening), and then - if required - buying a longer electrical cord to move it further from the house. An extra 50 or 100 feet of cable is probably much cheaper than other options (assuming you don't need all 15 kW and use a smaller-than-60A CB at the source). If you need all 60A, then the cable might be pricey.

This also assumes that you have enough room and a suitable spot on the property.

RE: Please join me in building a poor-man's quiet generator

With all respects to easy, and I'm no expert, but any dampining needs to happen between the gen/engine assembly and anything else. Even rubber/spring mounting would help.

The issue is with any large surface being vibrated in air, tends to act like a speaker. If the only vibration dampining is the tires, then you have a large surface to transmit sound.

With engines, you never get a perfectly balanced system. And with single phase generators, like motors, they are not balanced due to the loading. So the vibration of the assembly is a concern.

I do agree a good muffler is easy, quick noise reduction.

RE: Please join me in building a poor-man's quiet generator

Mount exactly a shown in the picture. No floor. Put a catch tray full of cat litter under it when in operation to catch the inevitable drips of oil and offer a small degree of sound attenuation.

Get a good muffler for the exhaust and see where that puts you for noise. You might not even need an enclosure.

Looks like the cooling air discharge is intended to have something connected to it. Maybe something like http://www.ruskin.com/catalog/category/597~Sound-C...

RE: Please join me in building a poor-man's quiet generator

Here's another option.

If you don't need 15kW, then sell it and use the proceeds to purchase a newer, quieter, smaller generator.

I assume that 15kW is far enough above the norm to perhaps attract a substantial offer.


RE: Please join me in building a poor-man's quiet generator

I must admit that selling that brute (I own a 4 kW diesel genny and that is most unpopular with my only neighbour, 5 minutes walk away) and replacing it with something small modern and quiet is the easy option.

Failing that, the tires are nice isolation but you need the same at the jockey wheel.
In order to isolate effectively you'll need bigger softer bushings than those shown.

You then have 3 major noise sources

1) exhaust - get a truck silencer.
2) intake - stick the intake pipe into a large isolated box with foam around the wallls inside
3) case radiated - put the thing in a brick enclosure


Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?

RE: Please join me in building a poor-man's quiet generator

It smoked,
You could look at this material.
B.E.

You are judged not by what you know, but by what you can do.

RE: Please join me in building a poor-man's quiet generator

(OP)
Thanks for the great input so far!

I couldn't care less about a loud generator from my perspective. The long cord solution doesn't work because it's the neighbors I'm concerned about. I have an inefficient 6kW screamer that brought a neighbor over a six foot fence, thru a creek, across an alley, thru a hedge, over another 6 foot board fence, around an interposing cottage, to beat on my back door in complaint. So moving it farther from my abode probably makes the problem worse.

Thanks for the rigidity lessons!

Not sure a smaller unit is worth the hassle either since all but inverter gens seem to still need quieting efforts and inverter gens range on the small crazy expensive side. I actually have to run two refrigerators, central heating, and heat a cottage purely electrically, and both homes have electric stoves, (thank goodness for gas water heaters). I should probably recheck my realistic demand needs. I'll do that today.

Thanks a bunch for the Ruskin and Acustiblok links. Fabulous!

Keith Cress
kcress - http://www.flaminsystems.com

RE: Please join me in building a poor-man's quiet generator

Biggest hitters will likely be intake and exhaust mufflers. Intake is often neglected and can be as loud as exhaust. Volume is your friend, so long as size and portability constraits are met.

Steve

RE: Please join me in building a poor-man's quiet generator

When the power goes out, your neighbors will follow the generator noise, their extension cords trailing behind.

RE: Please join me in building a poor-man's quiet generator

Modern fridges need next to no power. If your fridges aren't new, then get new fridges immediately as they'll often pay for themselves. Trashing old fridges is high on the list for energy and money savings. Then the new ones would be in the hundreds of watts.

Can you pipe the generator's waste heat into the building in a manner that avoids CO poisoning? Co-gen concept.

Speaking of which, be extremely cautious where the exhaust goes. Plenty of deaths just from the wind blowing the wrong way, generator exhaust straight into a residence's ventilation air inlet (more common in cold locations with air-tight houses).

RE: Please join me in building a poor-man's quiet generator

I suggested to a customer to put a receptacle on a 5 Amp or 10 amp breaker on the fence facing the other way.I thoght that the neighbour may complain less about the generator if they could run a few lights when the power was out.
Instead he had me build an enclosure for the generator.
Some of the techniques I have used to quiet generators are as follows:

1> Good muffler. Sched 40 pipe for the exhaust. Stainless from a muffler shop may be better, but that option wasn't available to me. Electrical Metalic Conduit (EMT or Thinwall). Thinwall conduit looks like a good ide but it only lasts about a year. Aim the exaust discharge away from noise sensitive areas. Run the exhaust discharge up at a 45 degree angle and then cut back at about 60 degrees to discourage rain entry. I never liked flap valves. I have alway been concerned with failure without maintenance.

2> Enclosure; I often had a generator room built out of concrete blocks. I would put a false wall about two or three feet from one end. I would butt the radiator discharge up to an appropriate opening. Then the top foot of the wall would be open to allow the hot air to discharge. Don't forget an access entry into the cavity. You don't want to have to move the generator to retrieve some kids new baseball from the dead space.
One install I needed more attenuation. I added air-conditioning duct board to the walls inside the generator room. The board I used was about 1 thick and came in sheets. It was constructed of a fiberous material. One side was covered and the other side was kind of "furry". When mounted "furry" side out it absorbed a lot of sound. This stuff is cut into strips to form the sides of air ducts and the four sides are "Duct taped" together to form an air duct. Actually one of the first uses of duct tape.

3> Sound sources. On some engines the fan is a major source of noise, but at frequencies that seem to be easier to control than exhaust noise. With an air cooled unit, fan noise may be a major contributor.

4> As dangerous is it is to assume or guess at generator sizing, my gut says that the size (15 kW) is about right for your application.
Already owning the unit You can get by with a set possibly a little smaller than you would purchase based on load surveys.
You may have to curtail the electric heat a little. How about some propane powered heaters to reduce the load? Burning propane to generate electricity to produce heat may not be the most efficient use of your propane dollars.

5> Vibration: If you build an enclosure or room to house the generator you may want to consider mounting the generator on a block of concrete. My rule of thumb was to try for a concrete block at least twice the weight of the set above the rubber mounts.

I don't ssee any major issues with your general plan.
Good luck and keep sharing.
Your's
Bill

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Please join me in building a poor-man's quiet generator

If you do chose to build a 'dog house' for it you might tackle the air cooling. A larger fan turning more slowly will make less objectionable noise. And if it is noisy it will be lower frequency and less directional. Remember though if you change fans that you still the need the same volume and velocity across the heads to keep them cool. But if the ducting is in the 'house' it will muffle a lot of the noise.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

RE: Please join me in building a poor-man's quiet generator

To amplify Bill's suggestions about the enclosure, I've seen a number of commercial buildings in the city here with exterior generator sheds.
Some have double-walls, as Bill says. Maybe there are some like this in your area, too, that you can look at, get ideas.

STF

RE: Please join me in building a poor-man's quiet generator

Bill covered it pretty well. I have owned a few of those Onan JC sets and the exhaust is not terribly loud compared to the noise transmitted from the block itself. With a muffler of any kind, it probably won't be as loud as the 6kW unit you have now. It will use about 3 gallons an hour of propane if you load it up. IMHO, the JC is one of the best sets in that size range ever made. You will need the Onan mounts for the base or some equal way to allow for movement- else the base mounting ears will break off.

You may find that the sound of any generator, no matter how well muffled, will "generate" complaints from neighbors who don't have one of their own. I have a 15kW diesel (an Onan RDJC), and have developed a response that you may find useful. When my neighbor complained, I pointed out that the primary cause of his discomfort was not my generator, but rather the fact that the utility had failed - and that when the utility power is restored, the generator shuts off minutes later. I then provided a phone number for the local utility. After a couple of sessions, he learned that complaints to me are a waste of time, and they stopped.

RE: Please join me in building a poor-man's quiet generator

WRT exhaust mufflers, a 'hospital grade' unit will occupy about the same volume as the engine does.
NOT the cylinder displacement; the HxWxD of the entire engine.
So just scrounge a really big one for a start. Stuffing a chamber with fiberglass may help if it's not the exact right size.

WRT engine cooling, you need the engine's cooling air to flow pretty much unimpeded, so your intake and exhaust ducts through your enclosure walls need a lot of open area. ... which does not mean one large serpentine tube for each flow, but several conduits in parallel, each having one dimension relatively small, like an inch or so, and the tube and baffles lined with maybe an inch of 'mass loaded' material. ... so the unlined serpentine may have a smallest dimension of three inches or so per channel.

Soundown sells mass loaded sheet. It basically comprises two layers of polyurethane foam laminated to a core of what might be lead-filled PVC sheet, or something similar. You could homebrew your own mass-loaded liner with generic foam and a core of plywood or metal. ... and a lot of spray adhesive or contact cement. You don't need to first laminate a big sheet and then bend it; you can line the ducts with foam, then attach sheets of massive material to the planar surfaces, then add another layer of foam. It isn't necessary that the massive material be continuous around corners and such.

Keep the plastic foam away from the engine exhaust and the muffler; not a problem when using concrete block as your massive barrier.

You need vibration isolators under the engine. Try to select them for maximum static deflection without overloading.

You need an oil drip tray under the engine. A ball valve in the crankcase drain speeds the oil change process for an engine in a box. Stock up on lube oil for the engine; generators tend to use quite a lot of it.


ANY generator is going to be annoying at night when nobody has house power. If you need the gen for heat, everyone's windows will be closed, so maybe noise is less of an issue in winter.

We were without power (in sunny SoFla) for several weeks after Wilma, and learned a little:
- A modern-ish fridge will stay cool, and the freezer above freezing, for ~8 hours without power, if it's not opened. So we tried to run our noisy little 1.6kW generator in daylight, and shut it off at night in consideration of the neighbors, who did the same on learning of our results.
- I had a wired temperature probe in our freezer, and logged the freezer temp as a way of deciding when we absolutely had to run the generator.
- Our gas supply and water supply were uninterrupted, and our old school water heater with a pilot light worked just fine, so we were able to shower; it felt great, even in the dark.

I have since learned that wireless indoor/outdoor thermometers can transmit data through a normal freezer wall and at least ten feet beyond, so you don't have to run a probe wire in and risk damaging the seal; just put the little 'outdoor' sender in the freezer.

Mike Halloran
Pembroke Pines, FL, USA

RE: Please join me in building a poor-man's quiet generator

(OP)
I wish I could go the brick/cinder block route blocking the sound outright but since I have to go with a trailer I need to go the more acoustical absorption/trapping method. I do have hope since the quietest generators I've ever seen have all been trailer mounted. I've seen three WisperGens that were nothing short of amazing. One was on at my old high school supporting a movie shoot. It was 100Kw and I didn't realize it was running until I got about 10 feet from it!

Another was laying in the gutter (coincidentally across the street from the high school) supporting a deep street excavation. It was running a sump pump to prevent flooding. It ran day and night and I'm sure it didn't bother any of the nearby houses cuz it was quiet!

I got the trailer 4/5th built today before the mosquitoes decided to run me off.
5 year drought = mosquitoes; go figger.

I hear you EdStainless on the potential fan noise. Once I get the genny on the trailer unsurrounded I'll get it running again and do an actual sound assay with a buddies decibel meter to try to come up with the abatement plan.

I'll investigate the intake SomptingGuy! Volume.. Check!

VE1BLL, I shant monoxide myself as I'm the neighborhood monoxide cop. Saved a family from monoxide death with a bad furnace negative pressure issue. I've had monoxide sensors in the house for more than 20 years, long before they became fashionable.

Our fridge could certainly stand replacement but one expense stream at a time. :)

waross; 2) Furry?? Interesting. I'll keep my eye peeled. I was just told that Home Despot carries sound absorbing material.

4) Size. Good! I'm really trying to avoid becoming the "power conductor" where I'm continually running around monitoring the loads and capacity. That gets really old really fast. "The heat is on! Limit yourself to only one stove burner. If you want to use the oven then turn off the heater." Blaa blaa blaaaaaaa. Ugh.
5) Trailer.. No concrete period.. :/

SparWeb; I believe an effective method of sound attenuation is actually screwing with the acoustical impedances by mixing materials. Sort of like how electrical impedances can cause reflections, acoustical ones also do. I think that may be how WhisperGens are silenced, double walls. Since my project needs to provide operation in pouring rain I probably need to skin the thing in sheet metal anyway so I'll have the two materials, some sort of sound board material + sheetmetal.

wayne440; Thanks for the mounting ears warning and thanks for the encouraging Onan model report!! And thank you for the defence algorithm. I like it!
I don't even recall what the muffler is on my genny, I think some flex pipe to a crappy glass pack or something so there is probably a lot of room for improvement.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Please join me in building a poor-man's quiet generator

(OP)
MikeH;

Quote:

WRT exhaust mufflers, a 'hospital grade' unit will occupy about the same volume as the engine does.
Gag!! Probably means its cost will probably amount to about the same too. Ack!


http://www.soundown.com/Industrial.htm
Nice!

So you're saying the air in and out should serpentine so there's no straight-shot out of the enclosure. And smaller tubes are more effective than a large opening..

Quote:

Soundown sells mass loaded sheet. It basically comprises two layers of polyurethane foam laminated to a core of what might be lead-filled PVC sheet, or something similar. You could homebrew your own mass-loaded liner with generic foam and a core of plywood or metal. ... and a lot of spray adhesive or contact cement. You don't need to first laminate a big sheet and then bend it; you can line the ducts with foam, then attach sheets of massive material to the planar surfaces, then add another layer of foam. It isn't necessary that the massive material be continuous around corners and such.

Not sure I'm following the layup here. From the inside of a tube to the outside what's the layup? Is the 'soft' material on the inside face then massive(hard) material then soft material then the tube enclosure material(structural)?? Do I have that right?

Quote:

Keep the plastic foam away from the engine exhaust and the muffler; not a problem when using concrete block as your massive barrier.
Check.√

Quote:

You need vibration isolators under the engine. Try to select them for maximum static deflection without overloading.
So as spongy as possible but still up to the task. Understood.

Quote:

You need an oil drip tray under the engine. A ball valve in the crankcase drain speeds the oil change process for an engine in a box. Stock up on lube oil for the engine; generators tend to use quite a lot of it.
Excellent point! Hadn't thought that far ahead.

Quote:

ANY generator is going to be annoying at night when nobody has house power. If you need the gen for heat, everyone's windows will be closed, so maybe noise is less of an issue in winter.
Yet another good point. My aim is to be able to run till 10pm without major neighbor meltdown. Hopefully the refrigerators will coast till morning with their doors not being fanned.

Quote:

several weeks after Wilma
Ah man! We we were without for about a week after the 1989 Loma Prieta earthquake turned the Moss Landing switchyard into spaghetti and that was nearly intolerable. But weeks...

Quote:

I have since learned that wireless indoor/outdoor thermometers can transmit data through a normal freezer wall and at least ten feet beyond, so you don't have to run a probe wire in and risk damaging the seal; just put the little 'outdoor' sender in the freezer.
Outstanding. I'll get two so we can monitor both reefers. In a normal refer I take it you just monitor the freezer compartment?

Thanks a lot Mike for your experiential wisdom.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Please join me in building a poor-man's quiet generator

BTW, the O.E. muffler was probably made by Burgess-Manning. They make several grades, quieter for more $$ of course. They are expensive, but will probably last the life of the set.

RE: Please join me in building a poor-man's quiet generator

Quote:

So you're saying the air in and out should serpentine so there's no straight-shot out of the enclosure. And smaller tubes are more effective than a large opening..
Not quite.

The silenced generators with which I have a little experience all have serpentine ducts which have at least two direction changes.
Their cross section is not small holes, but wide slots.
The topology is as follows:

duct structure
contact cement
foam \
massive sheet } supplied prelaminated and rolled up by Soundown
foam /

air channel ~1" x >>1"

foam \
massive sheet } prelaminated
foam /
contact cement
duct structure

Come to think of it, the slot topology is probably more important than the direction changes. I have seen noise insulators for engineroom ventilation that have no direction changes. They comprise multiple parallel slotted air ducts, each opening being ~1" high x several feet wide (normal to the airflow direction), and less than a foot long (parallel to the airflow direction). The 'bars' in between the airflow channels appear to be black plastic foam maybe an inch thick (but they are stiff enough that they must be internally reinforced, e.g. two sheets of foam bonded to a stiff plastic or maybe metal core plate. (Or maybe four sheets of foam and two sheets of massive material; I only saw the finished product.) The air to/from the engineroom flows right through them, and you can see directly through the slots, but essentially no noise goes through.

Think of a louver/shutter sort of thing made entirely of 1x8 or maybe 2x10 wood, except the wood is really thick black plastic foam, or more likely something rigid covered with thick black plastic foam. The whole assembly was installed in a bulkhead via flanges like a framed window. It must have been made commercially, but I don't recall a nametag on it, and I've seen them only in large yachts, so they must have yacht pricing.

It looks like the sort of thing you could effectively approximate for relatively little material cost and quite a bit of sweat equity and adhesive.



Mike Halloran
Pembroke Pines, FL, USA

RE: Please join me in building a poor-man's quiet generator

My uncle (civil engineer) had a generator about that size in a shed to supplement his solar system (completely off grid), his nearest neighbor was ~1/2 mile away. He got no end of complaints if he ran it on a quiet evening. He tried bigger mufflers, sound proofing the building, replacing the gen set with a quieter one, etc. It's not going to be "quiet" when everything else is off because the power is out. His final solution was to double the number of solar panels and get rid of the gen set. Not a cheap solution as you need storage batteries and inverters as well.

Better off buying your neighbor some of these:

----------------------------------------

The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.

RE: Please join me in building a poor-man's quiet generator

Here are some references that may help, note many are based on larger units, but it may add some ideas to your current plans,
http://www.dieselserviceandsupply.com/Sound_Attenu...
http://www.csemag.com/single-article/understanding...
http://www.csemag.com/industry-news/codes-and-stan...
http://www.earsc.com/pdfs/StandbyGeneratorsWhitePa...
http://www.aksapowergen.com/pdf/other/operation%20...
http://www.vanjen.net/vibration-isolators--sound-a...
http://www.harcomanufacturing.com/products.html
http://www.allnoisecontrol.com/Industrial-Noise-Co...
http://www.rvnetwork.com/index.php?showtopic=10609...
http://stopthesound.com/generator-soundproofing/so...
http://www.enoisecontrol.com/wp-content/uploads/20...

Some of these may not work as this is an old collections of sites.

I helped a friend a couple of years ago with a similar problem, we used a junk commercial chest freezer as our "box", with a bit (ok a LOT) of sawzall work we ended up doing a pretty decent enclosure for a trailer mounted air cooled Duetz unit. Last year for someone else I found a used enclosure from a rental yard that had burned up a generator, and the replacement unit already had an enclosure. I tried to find the pictures but couldn't.

Hope that helps, MikeL

RE: Please join me in building a poor-man's quiet generator

"...an effective method of sound attenuation is actually screwing with the acoustical impedances by mixing materials. Sort of like how electrical impedances can cause reflections, acoustical ones also do..."

That's been my instinct as well, specifically layers of alternating density. Obviously due the wavelength at low frequencies, it's nothing to do with phase cancellation. But it seems obvious that layers of alternating density would impede acoustic transmission.

If the frequency was low, then the entire surface would try to act as a drum head. So such an impedance approach may have little effect, depending on the scale and frequency. If so, then back to use of simple heavy mass.

Beware that, a bit like EMI, there may be several radiation or conduction mechanisms and/or paths. For example, if you've made the enclosure walls sound-proof, then you'll need to pay attention to the openings (air, exhaust, heat, wires). Tiny openings can eventually dominate at higher frequencies.

In house building, there are tubes of 'Acoustic Sealant'. The usual caulking tubes. Black rubbery material, can be messy. The intent of the product is to use between studs and wall board, to reduce conduction of sound. In Canada it's been used more for sealing the edges of 6 mil poly vapor barrier to build airtight houses. My house contains a hundred of tubes worth, for both purposes.

In home theater room construction, sometimes the wall will contain a 'Bass Trap'. A big tube. It's intended to notch out the room's natural peak. Mentioned in case required. It's perhaps applicable if you've got one dominant low throbbing frequency.





RE: Please join me in building a poor-man's quiet generator

If you want to start tuning out your peak frequencies, Oxford Wave Research makes a free audio spectrum analyzer app for the iPhone that comes in really handy for identifying your peaks. There are probably others.

Z

RE: Please join me in building a poor-man's quiet generator

(OP)
KENAT; A berm around a trailer??! LOL

MikeL many thanks for the pile 'O links!
Those are some really choice links I'm enjoying reading.

VE1BLL; Thanks for the foam info. I like it. And, the impedance logic backup as we apply our electronics to the sound/vibration realm with broad strokes. To the guy with the hammer and all the solutions looking like nails. Hahaha.

Zapped; That Oxford SW looks like a whole lotta fun. Too bad I'm an Android user. Wish they'd port it over.

UPDATE:
I finished the trailer. It's nice. It's been hovering around 100F most days so I'm heavily de-motivated to go out in the sun drenched driveway and proceed.

I'm looking for four vibration isolators that can stand lateral movement for when the trailer is braked or accelerated. The ones made by Soundown look great but I'm afraid they're going to be absurdly priced since they don't even have a price-sheet and they present the absolutely dreaded; "contact us for a quote" :/

Keith Cress
kcress - http://www.flaminsystems.com

RE: Please join me in building a poor-man's quiet generator

The OE style mount is not bad, one example is Onan part #402-0286. They cost about $15 each. The rest of the mount might be easily fabricated.

RE: Please join me in building a poor-man's quiet generator

Why not a berm or series of berms anywhere you might need them.

Your property could end up looking like a soviet era missile site.winky smile

"I'm looking for four vibration isolators that can stand lateral movement for when the trailer is braked or accelerated."

Or - you have a way of locking it down for transport. Of course doing that in a way that you don't forget to lock/unlock it as required may be more tricky. If you could tie it in with a parking brake or something that might work. (i.e. parking brake on, unlocked, parking brake off, locked.)

Posting guidelines FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm? (probably not aimed specifically at you)
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?

RE: Please join me in building a poor-man's quiet generator

Use automotive type motor mounts. They seem to take the acceleration quite well. Some mounts have a metal overlap that will make metal to metal contact to limit movement in the event of severe events or the complete failure of the motor mount.
I just went outside and checked my trailer mounted gen-set. It's a 6 kW 3 cyl. diesel with a light tower. It uses four simple mounts. There is no added provision for side movement.
I wouldn't worry about side movement. One of the issues with issues with automotive mounts is the possibility of extreme motor movement during hard accelleration in the event of the failure of a motor mount. I believe that at least onepast model of Chevrolet was prone to the motor movement pulling and holding the throttle wide open in the event of a broken motor mount under acceleration.There is not much chance of that with a trailer mounted generator.
When do we see some pics?
Yours
Bill

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Please join me in building a poor-man's quiet generator

I have used a lot of these on small generators and oil field portable equipment, never had one cause a problem and they have been very robust in my experience,
http://www.novibes.com/Products#/filters=/detail=C..._ This company has a bunch of different styles and price ranges.

Another option is Korfund products, a lower price option than the above but pretty good results in a number of applications, Davidson Sales is usually helpful and they list prices without having to call them, http://www.davidsonsalesshop.com/templates/product...

Make sure any mount you get is "restrained" for mobile equipment, some inexpensive mounts count on the fact the engine/generator will always be sitting on a pad and gravity will hold the mount together. A few years ago a packager getting into the portable generator market found out about that the hard way. The mounts were cheap, the end results were not.

Enjoy! MikeL

RE: Please join me in building a poor-man's quiet generator

(OP)
Hi All,
Thought I'd entertain with a a few pictures finally. (Sorry for the delay Bill) (smirk)

So here is the assembled smallest Harbor Freight trailer. It went together very well, was easy to square up. Took a leisurely two hours with no help. Weighs about 120#



First thing I noticed?
Dang, no trailer jack, so it, of course, lays there looking all.. slanted. Back to the drawing board. I looked around and ended up coming back to HF again for their smallest simplest jack. It was $25.

There was a catch though. It has to be welded on! The clamp-on ones were $40 and rated at a bazzillion pounds. This one is only rated for 2,000# which is only about 1,900 more than I need. I didn't want to blitz my new trailer by grinding all the paint off the tongue so I decided to modify the jack mount so it could be bolted on. After wrestling off a monster clip ring I got the back half of the jack mount off and then TIG welded two tabs onto the mount.


------------
My first weld in about two years. I wasn't enjoying myself before because my eyes are not so great close up anymore. (I used to be able to see protozoa with my naked eyes.) (Those were the days) But, this time I put on my reading glasses inside my helmet. WOW! Fun again.

I then cast about for some paint to prevent rust. After finding the usual 6 cans - none with working nozzles - I swear I always invert the cans and "clean" them too. At any rate all I had was a can of white with a non-removable nozzle. Turning that can over never provides a clear stream as the pickup must be a weighted hose. I sure waste a lot trying to clear it, but it never clogs. Go figure.

So I paint it. I take a piece of TIG rod and thread it thru to hold the work piece. I spray it nice and white.:



Then because I'm holding the rod in my glove I can't feel the F=ma worth a dang and the rod slowly slides thru my gloved hand while I'm not looking until the finished, just painted piece falls into a weedy dirt strip next to my shed. ARGH!!! I'm glad no one was in earshot. I snatched it up and wiped the dirt, leaves, and grass off with my dirty gloves and lathered on more paint.
------------
Then I drill the tabs out for some 3/8" bolts.



I then drilled and mounted it to the trailer, slid on the jack and my son and I did battle with the muther-of-all-clip-rings and got it back on.

Ta da:



Works great! The rotating jack half doesn't even collide with the bolt heads!! What a treat.

So now the level trailer:












Keith Cress
kcress - http://www.flaminsystems.com

RE: Please join me in building a poor-man's quiet generator

You've been busy!

Does that frame need a diagonal brace? Looks like it would turn into a parallelogram given a moderate force.

RE: Please join me in building a poor-man's quiet generator

(OP)
Hi Scotty;

It seems pretty stiff at this point. Note the pieces are all sporting multiple bends making them individually pretty dang stiff. After adding some thick plywood it will probably get stiffer yet. All the bots are impact tightened.

I'm about to do that but need to check a few things as the CG needs to be reasonable so the tongue weight stays around 100 lbs.

Keith Cress
kcress - http://www.flaminsystems.com

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