The trip hammer perform great. Yes, I have plans and more pictures of
details. The motor speed is controled by a frequency converter.
If you or others are interested, please contact me. ( The hammer is also
This is my new propane forge se pictures at
Arnar Haugedal (Norway)
I thought I would add that there is a lot cheaper, and in my opinion,
better, way to control the motor speed, other than frequency converters. I
set my power hammer up with a variable speed drive using an adjustable
"Hi-Lo" spring tension pulley on the motor. There is a hand crank motor bed
that moves the motor in or out for speed changes. It costs a small
percentage of a variable speed drive, and is more reliable....nothing
electrical to fail, and is just as quickly adjustable as a frequency
converter. Another nice thing about this method is the motor speed stays at
its rated run speed. I describe the construction and operation of the power
supply on my Forge and Foundry Page if interested. Here is a link to an
image of the finished variable speed power supply I built for my power
This is a 1-1/2 hp system, but you
can set one up for just about any horsepower you might need. This system has
an output rate for the hammer of 125-325 hammer cycles per minute, but you
can shift that to whatever range you want by simply changing the fixed
pulley size. Here is a link to an overall picture of the hammer prior to it
being moved into the shop.
This is a 35#
rated Little Giant "Easy Hammer," but it has the striking energy of at least
a 50# hammer due to the helve action.
Golden Age Forge
I don't believe that any variable ratio pulley made of springs and
sliding parts can be as reliable as solid state electronics. That's
the most reliable thing we know how to build. It seems the machinery
manufacturers largely agree, since most have abandoned mechanical
variable speed drives for solid state inverter drives.
On Tue, 05 Aug 2003 19:16:47 GMT, firstname.lastname@example.org wrote:
True, the main one is availability of spare parts. Electronics technology
moves rapidly, so parts don't stay current very long. But the parts themselves
are very reliable, much more so than moving mechanical parts. They don't
wear out, they only fail if overstressed.
BTW, the problem with electrolytics was solved a few years ago. You
can now get large value capacitors with basically indefinite life.
Apparently you have not used variable pulleys. Look at the "Hi-Lo" page,
http://www.hi-lo.com/pages/prod_DCv_2.html , and you will see a device that
is pretty much proof against failure. You only need the part that is shown
in the picture in the center right of the page, and a carrier to move the
motor, http://www.hi-lo.com/pages/prod_motorbases.html . You could get ten of
these for what a frequency converter set-up costs, and it will last as long
Golden Age Forge
I've used, repaired, and replaced more than my share of variable diameter
pulleys. The problem is always the undamped spring allowing the cam followers
to chatter on the cams. That causes excessively rapid and *uneven* wear of
the cams. Then the sheaves start to wobble, and wear accelerates exponentially
until the pulley disintegrates.
There are no moving parts in a VFD to wear. The electromigration problems
of 30 years ago have long been solved. The components won't fail unless
you feed them too large a voltage (lack of proper power conditioning), or
allow component temperature to exceed its rated maximum. A well designed
VFD has spike suppression, over voltage shutdown, and over temperature
shutdown built in. It should perform the same as new for many many years.
I didn't find a price on the variable speed pulley and motor platform you
mentioned, but a 2 hp VFD from Dealer's Electric is $170. I doubt the
Hi-Lo pulleys and platforms cost under $17 each (you said I could get
ten of them for the price of a VFD).
I'll throw in with Gary Coffman on this one. I use a lot of VFD's at
work. Currently, I have 21. I've installed others in the past.
Before that I used DC drives. several decades ago, I used Reeves
(variable pulley) drives. I have not had a vfd failure yet. I did
have a few failures on DC drives, and the Reeves drives required a
quite a bit of periodic maintenance. The variable speed drives were
considered latent mechanical hazards due to the springs employed.
In addition, the vfd's and DC drives give me the precision I need
(variable speed pump drives for precise flow). The Reeves never did
due to belt wear. They drift.
In my home shop, vfd's give me 1 to 3 ph conversion plus the speed
control. I do have several variable pulley drives. The one advantage
of the variable pulley drive (as pointed out to me by Leigh Knudson)
is that they serve as torque multipliers while decreasing speed. This
is useful for manually controlled machine tools. VFD's are constant
torque. However, you shouldn't run them at tremendous turndowns
unless the motor they're driving is designed for it.
I prefer VFD's. My experience is the reliability is second to none,
and the price has come down tremendously. The variable pulleys will
work, too. Just be aware of the maintenance.
On Fri, 15 Aug 2003 11:18:49 +0200, "Arnar Haugedal"
the advantage with a VDF is that you can start and run the motor very slow,
and with full power even if it is just moving. The drawbacks are that it is
very expansive, and also a little complicated to adjust (for me?)
vary the speed from 0 to full rotation and with full power? However,
of cause the construction I think is more rugged and simple, and much
Hmmm, it says that "Everyone knows you can't melt steel with an ordinary
propane burner." Wonder where I have been, because I didn't know that. I
guess I best e-mail Dave in Florida that his tool steel making furnace
can't melt the iron, chromium, tungsten, and other alloying metals, he
uses to make his steels. It is done with nothing more than a blown "Reil
burner." I have pictures posted on my site.
You don't need to spend $$$ on patented technology that doesn't do
anything more than you can already do with the technology freely
available to you on my web site. If you need those kinds of temperatures
they are easily available without messing around with recuperative burners.
I am not taking a shot at you Mr. Duncan, the link is appreciated. I
just hate to see guys spend money for technology that isn't any
improvement over what is available for free.
Golden Age Forge
R. Duncan wrote:
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