Stacy E. Apelt - Bladesmith
ilmarinen - MODERATOR
Moderator
Knifemaker / Craftsman / Service Provider
- Joined
- Aug 20, 2004
- Messages
- 38,242
The length of the turnbuckle will determine the hight of the ram above the anvil, which can be adjusted to make a light strike or a hard strike. Hardest strike will be somewhere between 90 and 120 degrees into the stroke, and softest will be at 180 degrees into the stroke.
The position of the connection rod to the helve will allow fine tuning of the helve,too,but you may still need to be able to move the main fulcrum (pillow block) some for tuning the vibrations down.When you move the drive point (connecting rod) at the helve ,you also change the period of the helve, and the vibrations will change,too.The ram is fixed ,and can't be changed, so the two places you can adjust the helve are the fulcrum (pillow block) and the force ( contact point where drive shaft connects). Once these points are balanced, try not to move them.Think of the ram as a pendulum, The swing (stroke) must be even and smooth. the force to keep the pendulum moving at a steady beat is applied by the helve. If it was a solid piece of steel. it would have to be massive, as in a drop forge or old trip hammer.Since it is flexible, it allows some inertia to build up due to the mechanical advantage of the position of the fulcrum. This allows a smaller power input (and an increased force at the ram). But if the arm of the pendulum ( helve) is vibrating out of sync with the period of the pendulum ( stroke cycle of the ram) it starts canceling the transfer of power. Now all that energy tries to go backward, exiting through the fulcrum ( pillow block) or the force source ( drive shaft and eccentric wheel) and they bend/break. If these parts are sturdy enough to absorb the force (vibrations) without destroying themselves, they transfer the energy to the frame, which either shakes horrifically, or jumps all around the place. So, you can see why tuning the helve to quiet things is really important. When tuned properly, the period of the drive wheel will be exactly the same as the period of the ram. If it isn't, you will know it.
The eccentric of the drive wheel (tire) is another place that the stroke is controlled from. It sets the amount of travel that the helve will have at the drive end. This is multiplied by the longer arm, and translated into increased inertia ( and travel) in the ram.It needs to be enough, but no more than necessary. This is where someone who has built a tire hammer can help you .
Stacy
The position of the connection rod to the helve will allow fine tuning of the helve,too,but you may still need to be able to move the main fulcrum (pillow block) some for tuning the vibrations down.When you move the drive point (connecting rod) at the helve ,you also change the period of the helve, and the vibrations will change,too.The ram is fixed ,and can't be changed, so the two places you can adjust the helve are the fulcrum (pillow block) and the force ( contact point where drive shaft connects). Once these points are balanced, try not to move them.Think of the ram as a pendulum, The swing (stroke) must be even and smooth. the force to keep the pendulum moving at a steady beat is applied by the helve. If it was a solid piece of steel. it would have to be massive, as in a drop forge or old trip hammer.Since it is flexible, it allows some inertia to build up due to the mechanical advantage of the position of the fulcrum. This allows a smaller power input (and an increased force at the ram). But if the arm of the pendulum ( helve) is vibrating out of sync with the period of the pendulum ( stroke cycle of the ram) it starts canceling the transfer of power. Now all that energy tries to go backward, exiting through the fulcrum ( pillow block) or the force source ( drive shaft and eccentric wheel) and they bend/break. If these parts are sturdy enough to absorb the force (vibrations) without destroying themselves, they transfer the energy to the frame, which either shakes horrifically, or jumps all around the place. So, you can see why tuning the helve to quiet things is really important. When tuned properly, the period of the drive wheel will be exactly the same as the period of the ram. If it isn't, you will know it.
The eccentric of the drive wheel (tire) is another place that the stroke is controlled from. It sets the amount of travel that the helve will have at the drive end. This is multiplied by the longer arm, and translated into increased inertia ( and travel) in the ram.It needs to be enough, but no more than necessary. This is where someone who has built a tire hammer can help you .
Stacy
. I understand the action of the helve much better, it is amasing the different kinds of forces going on, and how they all work together or tear each other to shreds. Again, thank you very much.