Building a power hammer
Posted 12 December 2005 - 10:50 AM
I have decided to build a power hammer over here in Korea along the lines of his, but a bit smaller.
I would also like to get the plans from Appalachian Blacksmiths, but they are not replying to my emails--any ideas?
Finally, what suggestions do all of you have once I actually start building this thing?
Thanks a lot,
Posted 12 December 2005 - 11:33 AM
Do a search on "tire hammer" for the best homemade mechanical design out there. The only hard part is doing the welding (for me, anyway) and figureing out the length of the toggle arms and spring strength.
Clay Spencer has been doing some workshops on building these things over here, and is working on plans for it, but until the plans come out emailing him or the inventor of the tire hammer (Ray Klontz, firstname.lastname@example.org) is probably the best way to proceed.
Posted 12 December 2005 - 05:05 PM
Posted 12 December 2005 - 05:35 PM
I built a 20-lb "rusty", and sold it for these reasons. It works and it's simple, but it's not the best.
Posted 12 December 2005 - 07:21 PM
my "krusty" has a 90pound ram, and boy, it's not going to break.
Safety, and stability were two of the main concerns for me...
I weld sword size damascus billets, use a hot cutter and it works smooth.
sure the springs can "weaken" an break... it doesn't matter.
the moment my foot is off the treadle the thing stands still.
besides during the first tests I had a wrong spring installed (too hard... it broke, nothing did happen but the hammer stopped workin).
The wheel-design looks good to me.
honestly, it's more space saving and such.
but the ammount of friction on the wheel, and the loss off power by it are problems I did not want to take care off...
both designs have, from a machinists point of view, drawbacks and advantages....
I have worked with many a commercial hammer, from 20 pounds up to 4000 pounds.... mechanicals of about five different types, air hammers of about 6 different types.
krusty is being used since more than half a year now.
has worked smooth and I needn't even to change the V-Belt or anything else...
The whole thing has more power than my 50 pound commercial hammer did have.
180-195 blows per minute are fast enough.
Well... honestly a bit more wouldn't hurt, and for drawing work be even the better... for a "drawing only" hammer I'd go to 220-240 bpm.
I chose the slower speeds to be able to work with handheld tooling as well...
I bet the "tire-hammers" are just as good.
It all depends on two things imho: craftmanship and right proportions.
Get a heavy enough solid anvil. the most optimal ram-anvil ratio would be 1:18... 1:10 being still considerd very good.
everything lower, sub optimal at best.
speed, anything from 160bpm upwards to 240 should work fine. (more than 240 seems not to be a good idea, unless you are going to build a sheet-metal planshing hammer.
20 pounders are "small hammers", albeit a little giant with 20 pounds already can do a good ammount of work.
for damascus I consider 40-50 pounds quite a "minimum" on industrial hammers... I get more with my 90pounder, but not as much as a commercial 90-100 pounder , well my anvil is a bit on the "sub optimal" side though
Moving parts "arround the head"... hmm... well every powerhammer has a ram, which operates close to your hands, and close to your head....
what i clearly like about the (k)rusty design, is the fact that all rotating stuff is WAY OUT OF REACH of the operator. ... nothing to get cought up in, nothing which, if it gets loose will fly at you. the only thing which maybe can happen are broken springs, broken jack-shaft... none of which wold actualy hurt the operator.
I'm not easy on my hammer... it works hard... maybe harder than it should. but I can say it does so without complaints.
I may will make a different set of dies though... some for faster drawing....
Check these two links:
One other option,... if you have a large compressor.... build an air hammer... it's not much more expensive, neither more difficult... however you gain way more control and if sized accordingly, more power.
and never forget, every powerhammer is a dangerous tool.
Posted 12 December 2005 - 09:35 PM
Posted 13 December 2005 - 04:32 AM
I find it strange that powerhammer sizes are measured by the weight of the tup when the velocity is more important (Kinetic energy = half mass x velocity squared). Perhaps this is a hangover from the days of the drop hammer.
Yes, Velocity plays a big role... but it has a limitation, as too fast a hammer is not usable at all.
imagine this powerfull 600bpm hammer sure ... beats the hell out of things, but you got no control, and forget working with handheld tooling or forming dies... it just is no longer practical...
the fastest hammer I have worked with was indeed a mechanical one, quite similiar in the design to krusty but industrial grade... had approx. 320bpm... which was FAST.
Way too fast for most things... it was a fantastic drawing hammer... but for anything else, no way.
Mass... mass does play, according to the formula you display have a large impact on the whole concept... and it is the only factor we can largely play with, as speed is a bit of a defined factor... slower than 140 is not much, it's actually slow for a hammer... faster than 240 is for most things already quite out of "bounds".... so we got about 100bpm to "play" with... where practical use has shown that most think of the ranger between 170-240 as being most usefull.
so no matter how "important" velocity is, you have not much way to modify it, so that imho. is being the reason why it is most often not mentioned as an important (for the power) factor.
Usually when building or buying a hammer, one does take these things into consideration, but always keeping in mind what the main purpose for the hamme will be.
some airhammers offer control over the speed, which is a great thing.
mechanical hammers have a limit mechanically seen, as the stress on the material will rise with faster speeds.
besides by limiting ram movement (which brings some drawbacks when it comes to the use of tooling or larger dies), and other design factors the overall performance of a hammer can be "tuned".
Another thing to consider is, like with any "normal" anvil, rebounce of energy... the more mass there is, the more work with less force will be acomplished, as there's less "waste" of energy.
so mass is not only important for the ram, it's important for the anvil-block.
as mentioned before... optimal ratio for larger industrial hammers is considered 1:18... and believe me there's more than just a slight difference between a hammer havin 1:12 and one having 1:18. These are "different worlds".
the 4000pound hammer I worked with (not for making damascus, unfortunatly )had approx. 1:14, which was very good... but it was no "drawing hammer" in the common sense... we used it to shape large pieces, to forge rings, drive-shafts, ... whatever large. but the 800pound beche, which was close to 1:18 was a hell of a hammer... used this to make some damascus during the "spare" time... wow... with the right set of dies (we had standard shapes)... this thing was amazing, lots of precision, lots of power, enough speed....
That's one of the differences with airhammers too, velocity of the ram... not directly related to the ammount of "beats per minute" but the ram gains speed while falling, as it is being pushed "harder"... so you got a higher velocity per beat as compared to a mechanically linked system.
here velocity does a good deal of the work.
besides, air hammers strike harder.
For example I believe that these two factors are what enables the 50 pound air hammer to do as much work as the 75 pound mechanical one, both with arround 1:10 ram/anvil ratios.
The whole thing is quite more complex than a simple equation.
A major role as well plays the Ram-Guide, the dies, and more than a dozen other important factors.
it is basically not possible to just look at each factor "isolated"... It's the whole thing, which needs to play along "optimal" to deliver best performance...
for example krusty... whilst it is a good hammer, and does a lot of work, it's far from optimal.
Factors leading to this include a way too sub-optimal ram/anvil-ratio a less than perfect guidance-system (albeit it's a shimmed desin (copper), and greased well), the less than perfect die-shapes, speed is in the lower range (~180), springs are on the stiff-side, etc...
Only by improving ALL of the factors a major difference in final Power and work-load-possibilites would be gained.
But then there's cost...
We're talking homemade hammers, so with most of us, we're talking low-budget hammers too ...
so it's often difficult to get everything into an optimal range.
For me for example, the most difficult thing to find was something for the anvil... no problem I could have ordered one being large enough... but it would have cost a "bit more"...
the whole machine did set me back approx. 500$ which is ok, especially as I had to buy a new motor, as I did not find one used with the right specs at a good price.
I have seen a couple of homemade hammers, and to be honest NOT ONE was comparable to an industrial grade hammer...
Not that it can not be done.... not at all... actually it would be no problem.
but the costs would be ten times higher, and a heavy duty milling machine, a more than avarage good welder, and a good ammount of material would be the absolute minimum shop requirements to build a heavy duty high-performance hammer...
but with all the materials, time of work involved, a "used" industrial "Second hand" hammer will cost you less...
For $3500-$5000 I could get a 140 pound beche air hammer... or something similiar...
sometimes it's more in the 10k Range... but it's available, you know for sure what you spend your money on... and I even know a few lucky ones who got their 200pound air hammers for free (transport not included).
for arround $2400 there can be built a perfectly working forging press... which of course has drawbacks too, but will be a hell of a machine, far less complicated to build than a powerhammer, and more "sophisticated" than most homemmade powerhammers too.
so most tend to stay below the $1000 range for homemade hammer, often you try to get as much "scrapyard leftovers" as possible, I know a few who, besides a lot of work, didn't pay more than $100 for the whole hammer, including the costs for el. arc welding rods, and all the bolts, nuts and washers.
That is what makes the hammer attractive... low cost, lots of fun.
want a drawing hammer? well, make good drawing dies, go with arround 240bpm, get a 40-60 pound ram, and a 400-600 pound anvil...
make a precise ram-guide and a sturdy frame and base....
that will deliver you enough for most of "our" work.
forging / Damascus hammer? go with at least 50 pounds, at least 700pounds for the anvil, arround 200bpm and a perfectly sturdy frame and base.
the two examples above would be in the "close to optimal" range, would deliver good work.
and I'd go with the air hammers... more controle, more precision, less design-problems....
but then again, for such a hammer your compressor got to be large (read expensive).
Posted 16 December 2005 - 05:54 PM
What are you calling Krusty a beefed up Rusty ???
Can you post a picture?
Posted 16 December 2005 - 05:59 PM
I bought the Rusty plans ( I thought there should be more to the plans}
What are you calling Krusty a beefed up Rusty ???
Can you post a picture?
"Krusty" is a beffed up, more sturdy 90 pound hammer, which has the same basic wroking-technique as "rusty" does...
I've drawn up my own set of plans, and neither the dimensions, nor the clutch system has a lot in common with the original krusty...
here's a link to the plans
(btw, these 18pages of CAD Drawings, PDF format, are for free )
here's a picture:
and here's a small gallery page I've put together of the building process:
Posted 24 December 2005 - 09:59 PM
Posted 25 December 2005 - 04:18 AM
that would be the " I-Hammer " (you'd just need to fix some apple logo onto it too). hehe
Another safty thing: go beefy... make all parts a bit more sturdy than they actually would need to be... and you're on the safe side of thing.
Posted 26 December 2005 - 08:43 AM
I think you have the best compromise if you want a powered hammer. The costs to run a compressor that would be effective for a hammer would be large.
I'll bet that if you compared the costs to run your hammer vs. an air hammer you will be ahead.
Posted 04 January 2006 - 08:08 PM
heres the link to the gallery
hope that link works..
Edited by Greg Thomas Obach, 04 January 2006 - 08:10 PM.
Posted 05 January 2006 - 03:49 AM
hehe... I had one quite similiar to the one you posted ....
well, different frame, but same working methode... albeit on the beronious hammer in the pics there's one of the main wheels missing!
would be difficult to fix, without a LARGE Lathe or industrial grade casting...
these hammers work like this:
- the treadle moves the "fork" to the left (towards the frame) thus moves the belt from the free-spinning "idle"-wheel to the next wheel (which is missing)... this drive-wheel is fixed to the shaft and starts to rotate... pushing & pulling the jackshaft up and down....
the farther to the left the belt gets moved the more power is being transmitted, the harder & faster it strikes.
they usually have been operated with a overhead-shaft-drive system... but are easily converted to a motor (as I did for the one I had)....
verry small picture of my old hammer... was german made arround 1948 or so (had the date
the "operator" was a "student"... and the pic has been taken in my first shop quite a few years ago.
Somewhere I must have a larger pic still...
Posted 05 January 2006 - 09:58 AM
not the boronius... haven't seen this one before... but a similiar design can be found at so many different hammers all arround europe...
the design is almost as popular as the little giant type hammer (often copied) in the US...
Interestingly we have only a handful of little giant type hammers here...
I have seen only one in person, but more than a dozen of the mentioned type.
some have more options for adjustments, some have solid-cast frames, other are "constructed", yet others are "hybride" having a free moving ram, similiar to the air hammer with "wild/crazy" mechanics
0 user(s) are reading this topic
0 members, 0 guests, 0 anonymous users