stryped wrote:
On Thursday, June 18, 2015 at 10:02:22 PM UTC-5, Steve W. wrote:
Carl Ijames wrote:
"stryped" wrote in message
...

On Thursday, June 18, 2015 at 12:17:07 PM UTC-5, Carl Ijames
wrote:
"stryped" wrote in message
...

On Thursday, June 18, 2015 at 11:28:01 AM UTC-5, Carl Ijames
wrote:
"Jim Wilkins" wrote in message
...

"stryped" wrote in message
...
I have a spare 13 horse Honda engine laying around and a
need for a vibratory compactor. My thought was to use the
engine to drive a shaft attached to two pillow block
bearings. The shaft would have a piece of square tubing or
something else welded to it to create the "off balance"
effect.

Yes I know I can rent one but I need it for several different
things and not all at the same time if that makes sense.

Any ideas on the proper way to build the out of balance
shaft? Such as how much weight and how far from the
centerline of the axle it should be?

Thanks,

============

You could rent one the first time and study its design.

================================================== ========

HarborFreight has a 6.5 hp model,
http://www.harborfreight.com/65-hp-p...tor-69738.html,
they say 5500 beats per minute and a total weight of 176 lbs.
In the manual is an exploded diagram that is probably close
to scale, which makes it look like they step up the engine
speed less than 2:1 with pulleys and two drive belts in
parallel, and the eccentric is pretty small. They list the
bearings for the shaft as a 6308 so that tells you the shaft
size and what strength bearings they felt it needed, the
weight looks to be less than the shaft diameter and tight to
one side of the shaft. They claim 3000 lbs of force. Anyway,
just one place to get some info.

----- Regards, Carl Ijames
Thanks so much. What size would you say those pulleys are?
================================================== ==================


No comment :-). If I had to guess, I would print out that page
and grab some calipers to get the ratio. Look up the 6308
bearing and use the eccentric shaft diameter to get the scale
factor, then you could estimate the pulley diameters. If the
motor runs at 3600 rpm which seems the popular speed for
governed lawn mowers and such, and they get 5500 beats per
minute, the step up ratio has to be 5500/3600=1.53 or just 1.5,
and then just find some pulleys to get that ratio. Read the
rest of the manual to see if they specify the engine speed, in
case my 3600 guess is wrong. It's on sale for $550, and you
could probably sell it for over half that when you are finally
finished ... (Just saying; I know, building is the fun part for
most here. For me it's doing the design work, I think through
lots more designs than I ever try to build.)

----- Regards, Carl Ijames
Looks like a 6308 bearing is about a 1.5 inch shaft. I would have
never guess it to being that big....
================================================== ====================================


They claim 3000 lb impact force, and they do want it to survive a
few impacts. At 5500 per minute, say 1000 hours to wear out
(complete guess on my part), that's 330 million impacts. Also a
great reason not to couple the eccentric directly to the motor
crankshaft :-). If you are going to step up a little, with 16.5
vs 6.5 hp, I'd keep the speed the same and guess the volume and
center of gravity radius on the eccentric, then multiply the
radius times the volume of theirs by 16.5/6.5 to get yours. Yes,
you should convert volume to weight, but then you would just
divide it right back out :-). I'd bump the shaft cross sectional
area by 16.5/6.5 as well, and use a 6300 series bearing as well.
You are going to need some very good vibration isolation mounts
for that motor, too.

----- Regards, Carl Ijames


Usually the plate and eccentric are one item. That is then isolated
from the motor and drive assembly by isolation mounts. The one I
have uses almost the same idea as a sway bar end link. Two rubber
mounts on each end with a tube and bolt holding it together.
Mounted at about a 45 degree angle.

-- Steve W.

Yea. I found some rubber mounts that are sold for MSD ignitions for
racecars. ABout 14 bucks for 4 of them. They are designed to reduce
vibration to the electronic ignition box.

Can any of you tell me how thick typically the plate is? I have some
scrap 1/8 inch laying around, but I don't think any are big enough
for a bottom plate. I may have to buy a sheet of it. (I think it is
expensive. I may have some square tubing laying around I could use
instead to form a flat bottom, but not sure how it would work
compared to sheet steel.

One other question, on that diagram there are a series of discs on
the engine shaft. I assume that is some sort of clutch? I wonder what
I could use for a clutch?

Mine has a 3/8" thick plate.

Most are a simple centrifugal clutch. Belt drive.
http://www.mfgsupply.com/gomini/gomi...lutchbelt.html



--
Steve W.