Posted 29 May 2012 - 02:43 PM
24" x 24" bottom plate.
70" tall main post.
37" to top of anvil.
18" of travel.
28" deep x 24" wide x 74" overall size.
Posted 29 May 2012 - 04:49 PM
Posted 03 June 2012 - 10:14 AM
Posted 03 June 2012 - 02:24 PM
That looks like an excellent start to something I have been lightly experimenting with also.
Now that you are on the job, I can rest and let you figure the rest out!
I wish you the very best as you find a well thought out solution to add power and appropriate linkage for a smooth operating hammer!
Posted 13 June 2012 - 07:35 PM
I've recently been thinking of building an inline treadle hammer. I had plans from the grasshopper treadle from several years ago. Then I started searching on straight line 4 bar linkages and found the Hoeken's linkage which looks similar to what you have drawn. I'm wondering if you have any comments of types of bearings and size of shafts for treadle hammers? Is 1/2" large enough for the shafts using bronze sleeve bearings? Is steel on steel with plenty of grease good enough?
Posted 14 August 2012 - 01:36 AM
I'm new on the forum, but very interested in blacksmithing and treadle hammers. My name is Niels, from the Netherlands. At the moment I'm building an inline treadle hammer too, so I'd like to share and hear your ideas on the subject too. Josef, I used bronze bushings too, the shafts in them are 16mm (0.63 inch) which seem more than enough wrt strength. I 'sandwiched' the mechanism between two plates with the holes lasercut in them, so that they are all perfectly positioned. I soon try to post some pic here, the hammer should be finished this weekend. If any new progress on other hammers I'd be happy to hear about it (also for example things that maybe you'd do differently if you would build it again
Posted 14 August 2012 - 05:52 PM
Posted 14 August 2012 - 08:34 PM
There are a number of inline systems to use for treadle hammers and the like. You can search "Watt Linkages" for a number of them. I'll be very interested to see what you're doing. I have one of my own on the drawing board and some steel cut but on a back burner.
Frosty The Lucky.
Be yourself. Everybody else is taken.
Posted 22 August 2012 - 04:44 AM
Posted 13 January 2013 - 02:04 AM
I saw this post about 3 weeks ago and just had to go digging around in my files for some of my old drawings as I had worked on this design some years ago but never did anything beyond a bunch of sketches and calculations (too many distractions). For your benefit, and that of others interested in straight-line linkages, I shall share here some of my findings and suggestions regarding adoption of a Hoecken's mechanism to the a treadle hammer. By no means do I consider myself the final word on this mechanism, nor should anyone else, as there are many more experienced smiths here, and probably more than a few engineers, on this forums that could share a great deal more knowledge regarding these mechanisms and treadle hammers in general. If you're interested in greater detail or further explanation of my my calculations I shall gladly present them (I've got about 20 pages of notes and calculations on this design and about again that many pages of free-body diagrams showing forces at all the pivots under various conditions). I've learned a lot from others on this, and other, sites and believe in sharing information if it helps further the craft and saves someone from having to reinvent the wheel.
Now, first off I need to state that this design might not produce the same or a greater amount of impact force as some other treadle hammer designs, say the late Grant Sarver's hammer with “whip,” but all designs are a trade off of sorts. Where Grant's might have had a the advantage of energy stored in the spring added to the force of gravity, its space requirements in the smithy were significant, whereas this design will yield a very compact foot print and still offer a very potent impact force. In my opinion if you're looking for a treadle hammer for drawing out quantities of metal, get a power hammer. IMO treadle hammers are great for limited forging elements, shaping, punching etc when you need a bit more oomph than a hand hammer can provide or a third hand, but for long draws or production work, a power hammer is hard to beat.
For the general audience: The Hoecken's mechanism is unique in the category of the straight-line linkages due to the fact that it deviates off true straight line by less than 1% over the portion that is “straight-line” (approximately 60% of the travel of the wheel or rotation of link “A” in the drawings). Additionally the linear velocity of travel of point “C” (see drawings) is relatively constant over this duration of travel. No other straight-line linkage mechanism, that I know of, can boast to this claim – if someone knows of one please enlighten me, as in my research I have not found another. Now to maintain these characteristics of travel it is very important to adhere to the linkage ratios. As you increase or decrease the ratios of the arm lengths relative to “a” you cause “C” to travel in an increasingly divergent and oscillating motion having a backwards “s” curve or forward “s” curve, respectively. Depending on the mass of your ram, overall weight of the entire assembly and construction quality this could prove harmful to your linkage or downright dangerous to the operator.
hoecken's - pic3 reduced 320x414 - optimized.jpg 25.35KB 178 downloads
Now, Jason, as for your posted “design” (using your start and stop limits considering the 3 o-clock position as zero degrees and the 9 o-clock position as 180 degrees and your use of a wheel for your drive geometry, the ram will experience, not accounting for initial start acceleration of your foot placing the mechanism in motion, an 11% acceleration over the first 30 degrees of rotation and then the ram velocity will be constant (of course considering that your foot is descending on the treadle at a constant speed – which it likely will not be) over the next 120 degrees and will decelerate 9% over the last 30 degrees of your 180 degree wheel arc. I will suggest an improvement to this in a bit. I believe you mentioned that you were thinking of using roller chain and sprockets to the drive the mechanism. May I offer a cause of pause regarding this plan. The additional mass of a roller link chain will cause you to have to work harder to over come its inertia without any appreciable benefit – you may find a cable and sheave (pulley wheel) a better option (far less expensive and lower mass). Now before someone starts mouthing off about cable stretch relative to the roller link deformation under load – park it! Under the forces that any “normal human can directly exert on a short length of 3/16 inch diameter, or better, 7x19 cable will never amount to anything worthy of mention. Next, may I suggest that you reduce the face area of your ram (6x6 to something on the order of 3x3 or 3in round) to concentrate the ram energy. Next, to improve the overall efficiency of each strike in deforming metal, increase the mass ratio of anvil to ram (absolute minimum should be 10:1, though many would state that a minimum of 15:1 or 20:1 as a more desirable ratio – again simple physics will demonstrate the rationale for this). I mention this only because of your use of equal size masses on both ram and anvil in your earlier design (the linkage of which I would consider absolutely ingenious – It appears to be a mashup of a parallelogram and a contorted Peauclleier mechanism – why people keep comparing it to a Watts mechanism is not understood by me – but I'm a little on the slow side). The physics of deforming (smashing) metal between ram or hammer and anvil is neither a purely elastic nor inelastic interaction, but somewhere in between, and if you want to have the greatest effect on the work piece at the anvil, under the power of ram or hammer, you want, among other things, the mass and strength of your anvil to be such that it is able to easily counter and reflect any force that you impart on the metal to be deformed. Otherwise considering the modulus of the steel you are trying to deform (yes, temperature does have a function in the deformation, as does interface friction, etc) you will just be trying to put the anvil into motion instead of squishing your work piece. If someone needs empirical evidence to this concept, just find yourself a 1 foot length of the largest size railroad rail you can find (120 or140 lbs/yard) (I choose railroad steel as it is very strong steel – makes great dies - and readily available) anchor it to a stump of comfortable height, and heat up a 1” square piece of A36 steel to 1400 deg F, take your 3 lb hammer and strike the steel over the rail bead as hard as you can (one blow), quench it, and now take the other end of that same piece of A36, again at 1400 deg F and strike it the same on a 300 lb anvil mounted on a similar stump. If that doesn't convince anyone to the importance of a large mass ratio between anvil and hammer don't bother reading any further in my post as you'd be wasting your time.
Now to improving on the posted design. May I suggest the use of a spiral instead of a wheel of constant radius to rotate moment arm “a” through its path. The rationale for this is such: Given the unique nature of this mechanism having near constant velocity at “C” relative to rotation of “A” (for the arc segment that you have selected to use - IMO approximately the best segment of the arc for this purpose), use of a circular path to drive “A” will result in kinetic energy in the ram dictated by the speed of your foot and approximated by the equation KE=(m*v^2)/2 (I'm not going to get into discussing impact forces, thermal energy losses, internal elastic energy losses or any other losses here – they are not important to the discussion at hand). (gravity will not enter into the impact force as the force of gravity on the ram is more than countered by the mechanism's return spring (more on this later). So, though it has been several decades since I took any college math or physics course (no I am not a teacher of either, nor am I an engineer), it is easy to see that the element of the equation that you want to maximize is the impact velocity (since velocity gets squared) - any incremental increase over the constant velocity achievable by a circle will result in a greater impact force, and we know this translates to more metal squishing. So in my drawings I have shown a spiral (equation shown in polar coordinates) that will result in pivot “A” traveling at near twice the velocity at the end of the 180 degree arc as compared to the beginning. There are many different spiral to choose from but the equiangular is in my opinion the best for this application. To add further to the acceleration, and therefore the terminal velocity of the ram, you could also add a toggle linkage to the treadle linkage to cause acceleration. I will not go into treadle linkages here as optimum selection would generally be dependent on the strength of the smith and size of the treadle hammer assembly. I would also suggest the use of alloy steel socket shoulder screws with bushings or bearings for pivots (don't even consider common grade 5 or 8 hardware as dimensional tolerances are suboptimal and the wear at the pivots and slop in ram travel will show in very short order – you could get away with that stuff in the treadle linkage but not in the ram linkage or mechanism). Remember that due to the number of pivot joints each thousandths of slop at a pivot is magnified at the ram proportionally by the length of the linkage arm.
Treadle mechanism - pic2 - optimized.jpg 20.15KB 213 downloads
treadle mechanism - dual sprials - pic1 - optimized.jpg 19.61KB 262 downloads
Now I'm going to simplify a lot in this next example, so for anyone who's a stickler for nth degree accuracy and inclusion of all the variables that could be included, forget it – there's not enough space nor time here to account for all the variables, nor is it warranted. Lets just show the difference in the terminal KE between using a circular drive versus the spiral that I suggest in the drawings. First I have to figure out how fast I can drive the ram down from the uppermost position to the lowest position (anvil face). Well I can't do that without having the treadle hammer build – and as I stated above I haven't done that (except for a wooded ½ scale prototype). But, though I feel fairly comfortable that I can stomp down 10 inches with my foot a good deal faster and harder than with my fist, I'll just use the downward speed (velocity) that I can swing my 2-1/2lb hammer over a 22+ inch arc. This ended up being a velocity of 3.65m/s (though not perfectly accurate, this was number was calculated from the number of hits on a flat piece of steel on my anvil over a 1 minute period – now at 45 seconds I could definitely feel a slowing in my pace but we'll go with the final 1 minute average anyway). So using that speed as a datum for our treadle speed I'll calculate the difference between between a 25lb ram using the constant velocity of the standard Hoecken's mechanism with a circular drive vs a spiral drive path to give a measure of comparison.
If we take the KE equation I mentioned above to calculate the energy at the ram face just before it strikes the anvil after traveling from the top most point or zero degrees of rotation of the linkage (in this example lets just use the 180 deg rotation as the impact point). The height doesn't matter as the force potential from gravity is more than canceled by the force of the return spring. I could add potential energy (PE) but in this scenario it would not be a significant contributing force. So lets just go with KE, yes a simplification, but highly demonstrative. Now I have to remove the force of gravity from the ram's weight to find its mass for use in the equation. (I use metric units in all my calculations as the calculations and conversions are simpler – I don't like working with slugs, but I'll give the resultant to the equation in both metric and US common system of units.) First I convert the 25lb force to Slugs to kg mass, this yields: 11.36kg. Now using the velocity that I stated above for my ram velocity (though it would probably be faster if I were to use my foot on a treadle over a 10inch stroke), 3.65m/s, plug all this into the equation KE = (m * v^2)/2, yields 75.69 kg-m^2/s^2 (N-m) or 55.82 lbs-ft force. Nice mechanical gain but not really impressive. Now if I consider the use of the spiral where the terminal velocity will be twice (7.3m/s) that of that of the circular drive wheel then the resultants are: 302.7 N-m or 223.3 lbs-ft. That is a significant difference – one that will move some hot metal.
I've gotten a bit too wordy already but I still need to share my thoughts on the return spring force. Though none of the springs that will be used on a treadle hammer will be Hookian (comply with Hooke's law, F=-kd) the spring constant concept still applies to this application. As the return spring stretches (ram moving downward toward the anvil) the force generated by the spring increases and is not just opposing the force of gravity but also the force you are generating by your foot on the treadle. To attempt at reducing this opposing force I would suggest the use of a spiral at the Hoecken's mechanism pivot for return. This spiral would need to be configured with the larger radius tangent to the return cable with the ram in the “parked” position and the small radius tangent to the return cable with the ram at the anvil (see drawings). It is a matter of moment arm length. Such as the force of the spring increases with displacement you want it acting on a shorter moment arm to reduce the torque generated. How short or what rate of spiral will be dependent on the “k” factor of the selected spring. I've tested the seven garage door type springs I've collected for these types of projects and they each have slightly different “k” factors (none of them is Hookian so you have to evaluate the spring over the range of travel you plan based on the size of linkage you are considering, to figure the torque needed to slightly better than balance gravity with the ram is “parked” and then figure the rate of spiral for when the ram is deployed).
Img_3943 - CG at tradle - optimized.jpg 41.24KB 302 downloads Img_3948 - closeup of spirals - optimized.jpg 30.28KB 307 downloads Img_3951 - retracted - optimized.jpg 29.38KB 282 downloads Img_3952 - partial deploy - closeup - optimized.jpg 32.37KB 221 downloads
Well this is far longer winded than I had planned but this is the just the basics. I reduced the size of my images to below 300KB, after reading some posters stating that this was necessary for the inclusion of images. I wish I could've embeded the images in the text but, I'm new to all this forum stuff and maybe in time I'll figure it all out. I've included a few pics of the 1/2 scale wood prototype that was built to better show some of the geometry. If these aren't clear on the forum i imagine that I could email them directly if someone wants. I hope that these ramblings help you or others in some way in your consideration of this mechanism for use in a treadle hammer or provided things to think about for other designs – just remember they are all trade-offs, each having unique strengths and one or more weak points – only end application can determine what is “best.”
Posted 20 January 2013 - 03:31 PM
Charlie, wonderful analysis and optimization of this hammer...and perfect timing, as we are just now in the process of starting our build of a hammer based on the original threads ideas...
Thank you for your thoughtful advice.
We shall look more closely at your advise and implement what we can.
Will start a new thread on the build after we have the hammer functional.
Very Best Regards,
Posted 23 January 2013 - 06:03 PM
Charlie, that was simply wonderful and I appreciate you taking the time to post it. I don't understand what you said, but I've never been one for the higher concepts of mathematics so it's not any fault with your writings.
Do you think a complicated mechanism like you built, with all the various linkages, would be strong enough to motorize?
Posted 29 January 2013 - 02:28 PM
Awsome design i am working on making the straight line linkage #2 . For the treadle design you need to look at the way a train uses its piston to turn the wheels you could easley use the same linkage and conect the sprocket to a secondary double sprocket one going to a motor/foot pedal and the other going back up to the first sprocket.u can also use different size drive sprocket to have a faster speed with a shorter stroke if your first gear spins 1 revolution and the end sprocket spins three times you can achive three strokes from the hammer with 1 stroke of the pedal and it will be more efficent. i will post a video of the gearing to further under stand how to achive this 3 to 1 ratio.
Posted 30 January 2013 - 05:24 PM
Posted 31 January 2013 - 08:01 AM
Hello Vaugh T, I am just entertaining the idea . Just a little of my back round I worked in a machine shop doing tig welding and and fabricating and operating cnc machines. I also was a steam fitter for a few years .For the past ten years I have been an elevator mechanic . I like a good challenge I however have the sam reserves about the strength of the linkage my linkage is 3/8"x 1 "flat stock with a 3/8 pivot I have all of the mechanical devices to make this apperatus so I wont have to shell out anything but time and just brain storming ideas . My concern is also with the travel of the ram with a rigid linkage your ram will always travel lets say 17 inches so if the space between your dies is lets say 1/2 to a 1/4 " your hammer will want to travel the full stroke , so lets say you are hammering on a 3/4" bar you will bottom out before your full stroke and put enormous strain on your pivots most likley breaking them . I like the design of the sraight line treadle better as you can have rebound and a return via springs or a counterweight . You also mentiond about the impact all the linkage will be taking and the chain and sprocket as well because this will all be conected and rigid and no chance of spring back with a continous motion so as I said I have my reserves about this design. The train drive linkage will only go to the motor and then the double drive pulley one side would be the offset pivot the other would be the chain sprocket so that point would remain the same all the time so in theroy that linkage should work. The down side is the impact this would take I believe would destroy the mechanical linkage rather fast . Now if you used the sam machine in the top of this page and did not try to go with a continuous motion and stoped when the ram hit the die, you could use a countrweight or spring to return the hammer I think it could still work . The hunk of steel I have for for my hammer weighs 25 lbs. and I plan on welding a peice of 1"3/4 chromolly solid round bar to the top of the hammer and it's polished to a mirror finish and above the hammer will be a arm with a 360 degree ball bering so this will act as my guide so I will not be relying on my linkage to guide the hammer the bar will be my guide. The chromolly round stock weighs 25 lbs and the rest of the linkage is about 25 so the weight of my ram will roughly be 75 lbs. I will also have my counter weight on an assembly attached to a similar roller bering and the cable on the weight frame will have a spring between the cable and carriage so it will isolate the impact deliverd to the counter weight. I was looking at doing a motor but think I might stick with the treadle design so I will not need power . I am looking at a counterweight so I dont have to worry about the springs streching and needing to be replaced and I can balance out the hamer better. I have the ram with the linkage already configured I havent drilled the pivots to the main post yet still looking this system over . My pivots clamp on the bar stock so I can adjust them in and out till I get them set then I will weld them in place they also are independent of each other so i have room to have a gusset go through the middle of the arms to support my arm with the bering the ram will travel up through . I have no idea the length all of these arms need to be but I can slide the pivot up and down the arm so I can move it around to get the motion I desire I will post some pictures tomorrow all of this linkage. All of this linkage is off some old elevator door closers it's really handy to work on all this mechanical stuff. But hopefully we will be able to build a system that the home mechanic can build and use and repair himself that is my end goal.
Posted 01 February 2013 - 05:34 AM
Posted 01 February 2013 - 07:17 AM
Also tagged with one or more of these keywords: Treadle hammer, Inline, Straight line
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