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I Forge Iron

Little Giant Hula


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I am trial running testing and tuning my newly homebuilt junkyard helve, (the one with the boring picture show with me talking) I will have video footage up here like tomorrow...using a leafspring linkage I have found through various adjustments I can make it hammer tottally perfect on the low end and on the high end it will double tap bounce, on bang tap, (a hit and pause) , or loosen up the spring till it hammers super hard and consistant at high speed, but the low end is wacky, I have done research into this, I know little giant style dupont linkages do this when way out of tune or the spring is shot, I am pretty darn sure Im hitting a lucky resonance when it hammers great fast on the light spring, and assume the other way round its working till the ram overpowers the spring at high speed and then gets out of timing, my next move is going to be to add a 3rd leaf to the stack and test again
I am happy with the build just want to tweek it up to great,
Rather than reinvent every wheel....I know there are a bunch of "rusty" style hammers and spring helves out there, many home built, so if somebody has got a bunch of expirience with this, Ill surely figure out eventually but it could really save me some wasted time,
And if not Ill post the solution when I get to it for others benefeit.

Thanks
Woodsmith

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I have people that I rebuild hammers for call with this problem alot. Most of the time I fix it buy setting the die opening to the correct clearence. Many home built hammer over look this design feature. It is very nessary on mechinical hammers

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Thanks, I have researched these settings as they apply to little giants, and attempted to "calculate" or anticipate how these apply to a helve, there are some smilar dynamic situations. The loose space in the center of a leaf spring flex were the initial preload on the spring is made either up or down is similar to a du pont linkage center were the arms and linkages have almost no leverage against the ram, allowing the "snap" of stored energy from the upstroke to go into the downstke slam of the ram. I have adjusted clearance at the dies intuitivly both up and down (beyoond reason) so Im pretty sure i need to stiffen the leaf springs up tll they can handle the inertia of the helve arm to bring it within normal tuning range.

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2nd heat, trail run, video as promised, no real technique here just seeing if the hammer can move metal, at this point ram performs poorly at at low rpms, but hits consistantly with great force at higher speed, we are turning 1-1/4 square 1045 into 5/8
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You already said it, but I think the dynamics of a long helve require a lot stiffer springs than what you have.
If you look at my helve hammer thread, you will se that mine is sprung up to the eyeballs.
It's my observation that the dynamics on a helve (specifically an unguided helve) are quite different from an upright mechanical hammer.

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Actually, having looked at your video again, you could alter yours to have the pivot point of the helve closer to its middle, and have the driving mechanism at the back.
Basically, it could be more like the design of a "durabo", which is what mine is. It would require more cushioning to protect the helve (i.e. springs) but I think it would almost certainly make the transmission of the drive more succinct and controllable?

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Thanks guys, observation of the "durabo" love the name by the way, as well as the old bradlys hawkeyes etc, heavier springs was my first direction to go, although on the durabo it appears as though the leaves are so overly stiff that they added the little pogostick style mechanism, at end mounting to put a bit of whip back into the arm?, adding a secound spring got me half way there, today I got a third leaf spring mounted in under the arm, same configuration, length and leverage. All 3 spring are 3" wide and run full length up to eye, were they are clamped together. Very happy with this, ram is under control throughout the opperating range, hardest strikes should be adaquite to forge 1" stock.

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