Making a frame for a generator

[Clay]

Can I use wood for the frame on my generator?

I have the ST5 mounted on one of these:



Can I bolt the 6/1 and the ST5 mounted on that bracket to some 6x6 redwood? I think I have seen pictures of this done.

[hotater]

Check out my 6x6 timber frame at..-- http://community.webshots.com/album/221767803TxfJoG

One warning about wood frames..... I used long lag bolts in several places to hold the frame-work to the wood.  After about 3,000 hours of operation some of these lags are loosening due to oily wood failing.   Plan on drilling all the way through and using big washers and nuts on the bottom.  I like the galvanized square plates found in the concrete section of Home Depot for washers.

[quinnf]

Hi Clay,

That's a good question.  Wood makes a great bed for an engine.  It's inexpensive, easy to work with, dampens vibration, looks traditional, is easy to modify and attach stuff to, and...and...and...   That said, you gotta use the right stuff, which redwood ain't it because it's so soft, weak, and prone to fracture under stress.  Because it's such a poor choice for structural applications, you'll commonly see redwood use restricted to exterior siding, decks, and fence posts.  How come you're thinking redwood?.  Is it because you need something that is rot resistant?  There are better alternatives.

You need something you can bolt together firmly without the washers crushing the wood.  Probably the cheapest and most common wood that is suitable is douglas fir.  It's strong, resilient, holds fasteners well, doesn't crush easily and smells great when it's sawed.  If you're in the southeast, yellow pine would (pun?) be a more common acceptable substitute, though I think it's a bit softer than fir.  Oak and maple are much more suitable than any of the softwoods, and were commonly used for mounting heavy equipment in the last century.. 

Whatever you do, you have to make sure the considerable torque your 'roid generates with each compression and power stroke doesn't end up tearing apart your engine bed.  For that reason, unless you use oak or maple it's a good idea to weld together a frame out of steel, and bolt or lag screw that to a wooden bed.  That way, the various jitters and gyrations the engine performs as it does its thing will be distributed evenly over the surface of the wooden engine bed, and the mass and relative flexibiilty of the wood will largely absorb the high frequency mechanical vibrations the engine generates.

I made my engine bed from 3/8" x 3" welded steel angle, then lag screwed that to a 4x6" douglas fir frame made from a single 12' long 4x6.  If you look carefully in the photo, you can see the steel angle frame protruding above the surface of the wooden frame.  Oh yes, if you're going to mount your engine on casters, don't even think of getting casters with rubber tires.  The thump-thump-thump of your 'roid will quickly pound rubber tires flat.  Steel wheels are much more suitable and roll easier.



Clay, that's a nice mount for the ST-5 you showed in your post.  Wish i had known those were available.  Wouldnt have had to reinvent the wheel.

Quinn

[Clay]

So, if I'm welding anyways, why use wood? For dampening of vibrations?

I didn't say Redwood for any particular reason, I realize it's soft. I live in CA, so Doug Fir is no problem 

One of the people that turned me on to Listers told me about the frame. It's from Grainger and supposedly will fit a 3, 5, and 7.5 kw ST head.

[Clay]

Check out my 6x6 timber frame at..-- http://community.webshots.com/album/221767803TxfJoG

One warning about wood frames..... I used long lag bolts in several places to hold the frame-work to the wood.  After about 3,000 hours of operation some of these lags are loosening due to oily wood failing.   Plan on drilling all the way through and using big washers and nuts on the bottom.  I like the galvanized square plates found in the concrete section of Home Depot for washers.

Thanks for the link. That was quite an experience.

[quinnf]

Clay,

Ever stood by a train track as a freight train is approaching?  The high frequency mechanical noise will telegraph through a pure steel frame just like the oncoming locomotive can be heard approaching through the rails.  Yes, vibration damping is a big reason to use wood, although if you're going to be bolting the engine down to a concrete pad, then the wood isn't really necessary since the vibration will be transferred to concrete.  Railroad ties work well, too.  Anything heavy but not likely to "ring" like steel would work.  Another possibliity I haven't tried, but expect would work well is to sandwich a piece of blown out truck tire tread between the engine and the steel frame.  That should damp a LOT of high frequency vibration.  In that case, wood probably wouldn't buy you much over the steel frame.  Just have to make sure the engine can't rock back and forth.  The engine sits on only a 13" square, and those flywheels offer a heck of a lot of inertial resistance to that big piston going up and down.

Quinn

[Clay]

I'd guess I could bolt it through metal frame and 6x6 to the concrete. Shouldn't be too hard.

As you can tell, I haven't even fired the engine up yet. I figured I had better bolt it up to some thing before I start it up, but I'm getting pretty anxious. Plus, I have 50 other projects to finish up as well.

[hotater]

I like the idea of bolting through wood into concrete.  Thats' how I mounted a MP pump and it's plumb solid.  I also placed a metal plate on top to shield the wood from the invariable fuel drips and oil spills.

[quinnf]

Yeah, I haven't had my coffee yet, but some things become clear when you're reading them a second time.  I think Jack's right.  You bolt wood between the engine and concrete and a lot of vibration is absorbed and you gain a bit of flexibility in case the slab isn't dead level, which if I were the guy finishing it, it wouldn't be!   

Bolting the engine or steel frame directly to the concrete might not give enough damping.  And speaking of damp, think about applying a layer of epoxy, roofing tar or Henry's roofing sealer between the wood and concrete.  If you're using untreated wood, and the ground is at all damp, you can end up with water wicking up through the concrete and slowly rotting the wood at the wood/concrete interface.  Pressure treated wood or good used railroad ties are another option.

Quinn

[lgsracer]

I spent twenty years riding submarines. A sub has a lot of vibrating machinery to isolate from the hull and it gets done. l. Some of this machinery is quite heavy. Here are a couple of companies that sell isolation mounts that might work for a lister.

http://www.novibes.com/vibration/productinfo/index.asp

http://www.qontrol.com/Machinery.htm

[kpgv]

This is cool stuff! I have also been thinking about the "Hockey Puck" idea.
The "low frequency" line is interesting. A coil spring encapsulated in a "rubber" block is "suspension".
I wonder what they cost?????

[cujet]

Carbon fiber is a fantastic vibration absorber. Bicycle frames made of CF nearly always ride smoother. Aircraft parts made of CF tend to reduce noise transmitted through the part. ETC. Maybe 4 CF suspension mounts of proper design could decouple the vibes from the floor while allowing the engine to remain quite steady. Another thought is elastomeric mounts. Though they tend to have a 5 or 6 year life.

I have 4 inch I beams to form a box. I plan on mounting this on wood beams. Maybe the wood can attach to the concrete with some form of high tech mount.

Also, I have an ACES balancing set. I will be able to graph the vibes and it is quite likely I will be able to balance the engine far better. From my experience I believe nearly any engine balance can be improved. It will be interesting to see what I end up with.

Chris

[johnny williams]

I have a friend that works at a lumber yard and he came across a section of laminated beam about 8' long. Works GREAT ...for now anyway. I used loooong lags to tie everything down with.
MY 2% worth.
Johnny Williams

[SHIPCHIEF]

WOOD; Natures natural carbon fiber