Kinyon pneumatics questions

[Ferguson]

I have a few general questions. I had asked these questions in another thread, but I think the questions got buried.

If you use a 2 inch cylinder, how large are the ports? 3/8"? Where can you buy cylinders with large ports? How much? I noticed that most 2 inch standard air cylinders have smallish ports, maybe 1/4 NPT. Sounds like cushions are a good idea for the cylinder, maybe even adjustable cushions.

If you go with two limit switches, do you then buy a three position valve? I think that you can buy two position valves with two pilots and no spring, or three position valves with two pilots and a spring center return. The three position valves might have all ports blocked in the center position, is that an advantage? Why? Would that conserve air? If you only had a two position valve, what is the advantage of the two pilots with two switches vs. a single switch and a spring return?

I can see that two limit switches provides a bit more flexibility, especially in adjusting the head travel. In the standard setup with one microswitch and a spool valve with a spring return, what determines the travel of the head? Having the limit switch position tied to the treadle in some way adds complexity, but some advantages as well.

No matter what arrangement you use, you might still need to manually adjust the limit switch position if you wanted to use taller tooling, at least if you wanted full power with taller tooling.

Focusing on the new design, the advantage of the new Kinyon design is mostly lower height and fewer alignment problems with the cylinder, right? I know that the spring adds some "whip", but only if it is tuned correctly.

If you want to understand how to "tune" the spring of the hammer, take a look at this article, addresses mechanically driven helve hammers but applies to this design as well, due to the spring.

Hammer tuning

Richard

[Spears]

Hello Ferguson,

I constructed an air hammer from the plans available from David Robertson. I posted pictures and descriptions of the project on the Metal Artists forum. Only because Iforgeiron already had some similar posts. Here is the link.

http://www.metalartistforum.com/maf/index.php?/topic/5010-power-hammer-build-photos/

I used a Hydraulic cylinder with a 2.5" bore and a 1.25" shaft. Very heavy built and cost ~$220 from Grainger. With the two switch system it never bottoms out in the upward. However, before I had my switches vented properly my hammer piston bottomed out upward quite a few times and still works just fine. That cylinder came with 1/2" NPT adapter fittings that screw into the 3/4-16 SAE ports and was rather easy to plumb to. Once I cured the switch venting on my hammer I have had zero problems with it. Sure, there are inefficiencies with my self made hammer. But when you compare an air cylinder three times as expensive having a 3/4" shaft to a hydraulic cylinder having an 1.25" shaft... Well, let's just say I can beat the living daylights out of it and it never even groans.

My hammer build is posted over there (if you haven't already read it) as an aid in helping people with there own choices and ideas. Good luck! Spears.

[Nakedanvil - Grant Sarver]

I have a few general questions. I had asked these questions in another thread, but I think the questions got buried.

If you use a 2 inch cylinder, how large are the ports? 3/8"? Where can you buy cylinders with large ports? How much? I noticed that most 2 inch standard air cylinders have smallish ports, maybe 1/4 NPT. Sounds like cushions are a good idea for the cylinder, maybe even adjustable cushions.

3/8 is pretty small, actually the 2" cylinder is kinda small. Especially with the leverage of new-style Kinyon. Standard cushion air cylinders are almost no good at all. They are not designed for the speed and high inertia we are working with.

If you go with two limit switches, do you then buy a three position valve? I think that you can buy two position valves with two pilots and no spring, or three position valves with two pilots and a spring center return. The three position valves might have all ports blocked in the center position, is that an advantage? Why? Would that conserve air? If you only had a two position valve, what is the advantage of the two pilots with two switches vs. a single switch and a spring return?

I can see that two limit switches provides a bit more flexibility, especially in adjusting the head travel. In the standard setup with one microswitch and a spool valve with a spring return, what determines the travel of the head? Having the limit switch position tied to the treadle in some way adds complexity, but some advantages as well.

I'm not sure how you would use two switches. Seems like there are only two conditions, up and down. I have often wanted to try a "quick exhaust" valve mounted on the down port. These open to the atmosphere when there is no pressure on the line rather than forcing all of the exhaust air to go through the 4-way valve. If a second switch was used, it could operate a valve on the exhaust from that and create a great cushion. The reason this would be better is that you are trapping a small volume of air which is easier to compress rather than trying to compress all the air in a long line.

No matter what arrangement you use, you might still need to manually adjust the limit switch position if you wanted to use taller tooling, at least if you wanted full power with taller tooling.

Focusing on the new design, the advantage of the new Kinyon design is mostly lower height and fewer alignment problems with the cylinder, right? I know that the spring adds some "whip", but only if it is tuned correctly.

And that it requires a larger bore and less stroke means a cylinder with (probably) larger ports.