Increase The Control of your Pneumatic Hammers

[ciladog]

I recently completed building and new forging hammer. It’s in the style of the Bull but with many modifications in the controls that allow for on the fly changing of the length of stroke, intensity of the strike, position of the stroke, and it will even run without touching the treadle at any given stroke. But this post is about increased controllability for all pneumatic hammers (not self contained).

I have a pressure gauge on the supply line just before the hammer and I noticed that each time the tup changed direction; there was a pressure spike of about 10-15% PSI. This happens because at the very instant that the tup changes direction (when the spool in the control valve changes position), the pneumatic cylinder becomes a pump while the inertia of the present tup direction is overcome. The intensity of the spike varies since air can be compressed and it is unpredictable.

I installed a directional air control valve (inline spring type control valve) just ahead of the spool valve as an experiment and although the effect was subtle it was noticeable. The control became more exact.

I got the valve from McMaster-Carr for under $14.00. You may want to see if adding a check valve adds to your hammer’s control. Place it as close to the spool valve as possible.

I know you’ve seen a pic of the paperclip before on the Phoenix hammer website but I just had to try it so I post if for your amusement. I also posted a pic of my hammer, it's control box, and one of the original Bull control box.

Thank you Tom Troszak for designing the Bull. It is the best hammer pound for pound.

[youngdylan]

I recently completed building and new forging hammer. It’s in the style of the Bull but with many modifications in the controls that allow for on the fly changing of the length of stroke, intensity of the strike, position of the stroke, and it will even run without touching the treadle at any given stroke. But this post is about increased controllability for all pneumatic hammers (not self contained).

Hi Ciladog

Welcome on board and thanks for the tip and pictures.

Kinda curious about the valving arrangement on your hammer. You seem to be using top and bottom limit switches; care to tell us more?

I've built a couple of air hammers using essentially Kinyon valving and I've recently posted some info on mod's to the valving that may/may not be of interest to you.

Hope to hear more from you, I've always got open ears for a fellow tinkerer.

[John Larson]

I've used check valves on Iron Kiss Hammers since 1997. They do indeed tend to reduce the spikes. Mine cost about $70 each and have needed durability. Others have used them as well. Congratulations on recognizing that the inertial movements of the tup cause the tup cylinders to be pumps once the shuttle valves have moved. You are exactly correct that the effect is meaningful, though subtle. There are others who have advocated using the check valves, for example Mike Linn of the Alabama Forge Council.

It would be very interesting to hear more about your hammer's conmtrol features and how you achieved them. Thanks. Sounds so far like you've really donme some serious design thinking.

[doc]

Hi Ciladog

Welcome on board and thanks for the tip and pictures.

Kinda curious about the valving arrangement on your hammer. You seem to be using top and bottom limit switches; care to tell us more?

I've built a couple of air hammers using essentially Kinyon valving and I've recently posted some info on mod's to the valving that may/may not be of interest to you.

Hope to hear more from you, I've always got open ears for a fellow tinkerer.

Hello youngdylan,

The picture of the original limit switch valveing is of my hammer. Ciladog and I are friends and when he seemed interested in building a hammer I proposed building a copy of my old bull.

To say the least as Ciladog progressed on his work we learned a lot about limit switch type hammers in a hurry. Since this the only hammer I'm familar with some of what I say be eronious but this what I beleave I've leaned in the process.

Kinyon style hammers Bull and perhaps all limit switch hammers work on the same basic princple. A five way valve with lines to and from the hammers cylinder has it's spool shuttled back and forth by the opening and closeing of the limit swithces. These switches must be timed in someway with the up/down stroking of the tup. On the Kenyon style this is accomplished usually with a virtical control rod with ramp that opens and closes the limit switch as it moves past.As it goes past the upper one it opens it, which pushes the spool in the fiveway so air is admitted to the cylinder in such a way as to cause it to descend. When it strikes the lower switch it does the reverse and the tup goes up.

On the Bull style hammer the only real difference is this control rod is linked to the tup on one end and to the treadle linkage on the other. The switches are positioned one on either side of this rod and as the treadle is stepped on the rod moves back contacting the down switch and opening the main air supply. As the tup descends the telescopeing control rod moves with it ( You will notice in Ciladog's pictures the rod diagonaly between the two swithes ? )it's set in a diagonal configuration and the movement of it's lower end backward and it's upper end forward as the tup descends causees it scribe a polygonal motion between the two swithches.

This motion seems to be the sutble difference that this style hammer has from the others.The two switches can be set to open and close in such a way with such control that one will open at the exact instant that the other has closed. This eliminates any lag time between opening and closeing and thus makes the movement of the tup and it's control very responcive.

As I said I and Ciladog have limited exsperience with this work and I hope I've described this in a way which you can understand.

Doc

[ciladog]

Doc is correct in his explanation. I could not have built my hammer without his knowledge, support, and collaboration. I now have this hammer thanks to Doc.

So let’s take this a step farther. We, Doc and I, talked about the workings of all the hammers we could find and with Doc’s long experience in the art, when he told me that his Bull hammer was so versatile, controllable, and dependable I decided that it was the one I would build. But like a lot of Kinyon style hammer, stroke controllability causes the stroke to shorten when doing hard forging (I think). Could you get a full 11 inch stroke at full power and still control it when you needed it? Could you get a full single blow like a striker, have clamping ability; does controlled chisel or repousse work? Could you build a hammer that could it all without sacrificing any one element? We think we did.

Subtle changes in the control valve positions cause great differences in the ram’s movement. The polygonal motion of the control rod also has great influence on the ram’s movement. So I decided that on this hammer I would be able to adjust the valve position and the control rod position while the hammer was under power (so to speak).

By moving the position of the control rod where it attaches to the ram changes the length of the stroke. If you move it forward, the stroke gets longer and moving it backwards makes the strokes shorter. See the pic of how this is achieved.

The spool control valves are mounted to plates that have arms that extend through the top of the control box so their position and relationship to each other can be adjusted without having to open the control box. See the pic.

Something that we discovered after the hammer was built could help anyone trying to adjust or time a Bull or other hammer is that it is NOT an all or nothing situation with the spool control valves: Meaning that you can have two control valves in the pressure state at the same time. The spool can’t move with equal pressure on both sides. Which ever valve is pressurized first controls until one of the valves goes into the exhaust state.

I hope this further explains the working of this hammer.

[monstermetal]

My dad has a 125lb Bull... the more conventional looking machine. I borrowed it for a year or so and really fell in love with the thing. Its such a universal machine. Ive tried to buy it from him but I guess I am just going to have to build my own.

Thanks for sharing you hammer build and info... Looks like it was a great success!

[ciladog]

My dad has a 125lb Bull... the more conventional looking machine. I borrowed it for a year or so and really fell in love with the thing. Its such a universal machine. Ive tried to buy it from him but I guess I am just going to have to build my own.

Thanks for sharing you hammer build and info... Looks like it was a great success!

Hello monstermetal, Yes, the hammer came out better than I expected. It was not hard to build with minimal skills in machining and welding. It cost me under $1,900.00 in material in the new market. No salvage. It took about 4 ½ weeks to build.

There are several other changes I made on this hammer that is different then the original Bull. First, is that I can move the cylinder up 3 inches and down 2 inches to accommodate different dies or tooling (check the pic). Second, the distance between the column and the anvil is 2 inches not one to allow for larger forgings. Third, the anvil is taller than the original. And the column is made of 2 ½ cold rolled welded into 3 inch X ¼ inch tubing. I think it makes the more ridged. The bearings are made of 3/8 inch HMW oil impregnated polyethylene and should last a long time (see the pic).

The Bull is a controversial looking machine compared to what most think of as a forging hammer. But I like radical especially when it works

[Senft]

Still trying to understand the whole picture of how it works, but would it be similar to this- http://chriscoleman.com/stuff/ , except by making the motion rod pivot rather than moving the lower limit switch down with the throttle movement?

[youngdylan]

Ciladog/Doc

Thanks for the info, you guys know what you're taliking about.

Is it a terminology thing or a different control system with the Bull/Phoenix? I've built two kinyons with a spring/pilot big spool valve and a single pilot switch. In a nutshell the hammer relies on "overshoot" for it's stroke. Ie as it passes the pilot, the air is switched to make it want to turnaround but its momentum keeps it going until "the air wins the fight between air pressure and momentum" and it turns around. From the little I know this is kinda like a steam hammer (not self contained)

In essence the stoke of mine is constant but I lift the pilot for higher work. I have also rigged up a circuit so it acts as a treadle giving one shot full cylinder length blows but thats a seperate subject. This uses a pneumatic monostable valve, ie something that give a single fixed length pilot pulse of air when triggered.

You seem to adjust the pilot height but also use a "control rod". Whats this then? ... despite waffling for England I don't always take word in.

Do your hammers use a pilot/pilot big spool valve with upper and lower pilots? Maybe you could post a back of the envelope diagram schematics. ...... pictures, thousand words and all that .... any sketch gratefully received

PS one good thing I like about the original Kinyon is it's simplicity. In essence the only moving parts are the tup/cylinder rod and the shuttles in the pilot/big valves .... less to go wrong. How robust / resiliant to shock is your control sytstem?

PPS One of the things I like about the Bull/ Phoenix is the cylinder pulling instead of pushing. It gives more equal up/down forces on the tup when it's weight is taken into account ..... = better control. One of my Kinyons is KA75ish with cylinders like this, other is conventional but uses a regulator to even out forces = better control/ less power. I use a regulator bypass circuit that is progressively switched in as the treadle is pressed.

PPPS One thing I don't like about the bull/phoenis is the off centre forces from the cylinder. Your hammer has something going on at the top of the pillar ?????

[ciladog]

Youngdylan/Senft,

I have posted a CAD drawings that might help explain how the controls work. I suggest you print the pic so you can look at it while you read this explanation.

The “control rod” is telescoping. It is made of 16 gauge ½ inch square tubing with a 3/8 inch rod sliding in and out of the tubing as the ram moves.

The red line on the drawing represents the alignment of the control rod when the ram is at its upper most position and the treadle is not depressed. The blue line represents the alignment of the rod when the ram is down and the treadle is depressed all the way. At any given position of the ram and treadle, the line will be somewhere between the red and blue lines.

Let’s start with the ram up and the treadle up. As you depress the treadle the bottom of the rod moves to the right changing its angle and moving it away from the up pilot control valve, on the left of the rod. The rod then begins to contact the down pilot valve and the ram begins to move down. Depending on the treadle position, the rod will move to the left at the top as the ram moves down contacting the up pilot valve and reversing the ram. The further the treadle is depressed, the further the ram has to travel before the up pilot valve is contacted.


Youngdylan, Anyone that has a Bull knows how violent the ram moves to the top of the column when you supply air. Research of available posts on the Bull indicates that if the cylinder is going to break it will do so on the up stroke. So what you see on the top of the column is a shock absorber. The cylinder has air cushions but it’s not enough. Since I can adjust the hammer for a full stoke, I put that up there to save the cylinder. It does nothing during normal hammer operation.

[doc]

Youngdylan,
If you have seen the videos of the Kinyon style hammers with the Coleman controls you can probably understand what I’m trying to say.
The Colman style uses a rod which moves up and down with the tup. On this rod is a contrivance which contacts the limit switches striking them independently to open and close them and tell the pilot valve shuttle to send air to and exhaust one end of the cylinder or the other, these two switches are located one above the other on one side of the rod. Tup stroking is controlled by moving the switches further or closer apart.
Now on the Bull style. Imagine this rod is configured at say an angle of 15*from vertical. The switches are placed, one on the right side and the other on the left of this angled rod. The switches do the same thing as in the Kinyon style they tell the pilot or spool valve in a five way valve which end of the cylinder to exhaust and which end to pressurize. This rod is connected to the treadle, as the treadle is depressed it opens the main air supply and moves the rod bottom rearward at the same time. As the rod moves back it contacts the switch that is for downward motion of the tup. The upper end of the rod is connected to the tup (remember 15* angle) and both ends of this rod can pivot around a bolt. This rod is made of two pieces, a square tube in side of which a 3/8” round rod slides. This means the rod can lengthen and shorten as the tup moves up and down. Simultaneously as the tup comes down the rod is shortened and because of the angle as it is shortened the angle must increase say to 25*. This pulls the rod away from the down motion switch and it now contacts the up motion switch as long as the treadle is held down the rod will oscillate between the two switches and the tup will continue to cycle.
The harder the treadle is pressed the more air is admitted through the main valve and the faster the tup goes up and down.
To try and draw a sketch of this for yourself draw a line slanting from bottom to top to the left at about 15*. Now place dots to the left and right of this line, the one on the right just a bit higher than the one on the left. Place a ruler on edge on this line and twist it to simulate the motion of the rod in the hammer and notice how it will contact one dot and then the other as you twist from the 15* angle down to the 25* and back again.
If this is still unclear ask Ciladog if he can send you his shop drawing or a straight on pic of the inside of the control box
PS I guess Ciladog beat me to the answer so here's a similar explanation
Doc.

[Senft]

Ciladog/Doc


Thanks, the additional explanations really helped. Very neat stuff!!

[youngdylan]

Ciladog/ Doc

Gonna sit down, take it in, and watch the video, meantime I'd just say thanks for posting the info

[youngdylan]

Ciladog/Doc

Just digested your posts; thanks for the info, it now makes sense and appeals to me.

I'd like to get the opinion of two master tinkerers as per yourselfs on another hammer option I'm thinking of. If I ever get time to do it, I'd also like to incorporate some of your control sytems features in it.

I was planning on one day revamping my conventional Kinyon. I really don't like the off centre guide; I had trouble with it breaking off in early days. The cylinder is too small at 63mm. One option is to use a 80mm cylinder but I'm not sure about the unbalanced forces. Currently it uses a regulator and progressive bypass for the down air supply. It works but theres another option I'm thinking about. My KA75ish uses 2 off 50mm cylinders; the bigger area makes a diffrence and the pull instead of pushing means more balanced forces/better control.

I was going to use a similar guide system to the phoenix and although I'm a real fan of "upside down cylinders" my limited engineering sensibilities don't like the off centre forces. One option is to use 2 cylinders as per my KA75ish but "beside" the tup .... see diagram. It also avopids the height problem with normal Kinyons and my my KA75ish has proved quite robust. That said, it does have problem when it tops out on the stroke (as per Bulls ???? ) all the shock absorbing comes from the mounting springs; I could incorporate a top buffer as per yours, though this looses the low height advantage.

My conventional Kinyon will snap rods at the tup junction. A previous thread has discussed this and any misalignments don't help. The KA75 spring/spring mount on the cyliders would help since the cylinder is not rigidly connected. There's also plenty of space for a spring/spring tup connection as per Grant Sarver's suggestion in the thread.

http://www.iforgeiro...tup-connection/

Kinda think a combination of your control system, the Bull/Phoenix and this configuration (if it's viable) could result in low height, fully featured, controllable and powerful hammer. What more could anyone want?

[finn;-)]

I have really enjoyed this thread, Thanks. I really haven't felt comfortable in my understanding of the controls of just how the air hammer opperated. Objectively I know what is going on, but it really hasn't jelled into reality to me. I really like the hollow ram with the pulling cyclinder in the Bull design. I have a Bull 75 new style ( where the ram is actually 75#, but not so new as the pheonix design with the controls on the lower back of the machine...) My problem has been that I have broken the cyclinder once, and the mounting bolt twice, because the tup was SLAMMING up into the frame too hard... So I have been trying to debug a system that I haven't really understood completely ;-( So this thread has really helped. Once I get the new tie rods in for the cyclinder, and get a roof over my new shop... I will hopefully understand things well enough to trouble shoot a bit better.

But as to design ideas, I had thought of using some heavy walled U channel to make a hollow ram with enough rigidity but that would still allow me enough clearance to pin the bottom of the cyclinder through both sides of the frame. This would keep the design balanced and symetrical, and would also overcome the weakness of the mounting of the cyclinder in the original BULL design. I was thinking of using a larger hydraulic cyclinder maybe a 3" cyclinder with the flat plate steel clevis's that would fit inside the U channel. Durability and overengineering are a good thing in my book.

I seem to remember Bob Bergman mentioning to Nathan Robertson that there were sometimes issues with keeping the two cycliders balanced especially in larger versions??? But like I said I love my air hammer, but don't really feel like I understand things well enough, I could easily have misunderstood what Bob was talking about.


Christian
Husband
Father
Blacksmith
Farrier
Farmer
I like problems I can solve with a hammer, I am good with a hammer ;-)

[ciladog]

Finn,

If you have ever watched the demo video by Tom Troxzak on the Pheonix website, there is a subtitle that says, “Always snap foot off treadle to allow cushion at top of stroke when finished.” The reason for this is it closes the throttle down so the last upstroke is slowed down and the ram doesn’t slam up.
Video

The throttle adjustment (connected to the treadle) is critical on the Bull. You want the hammer to start slowly when you first depress the treadle and gradually increase speed as the treadle is depressed further and the throttle opens further. If the throttle isn’t adjusted correctly, the ram will just keep slamming up hard until you get the stroke far enough down the column.

Obviously, the pilot control valves also need to be adjusted correctly. This is a matter of trial and error. You want to start out so the up and down valves are both contacting the control rod when the ram is in the up position and treadle is up. The up valve is pressurized and the down valve is almost pressurized. Be sure that the valve pivot stops are contacted for this first adjustment. Then it’s a matter of tweaking the adjustment until the hammer runs the way you want it to.

They call it a 75# hammer but the ram weighs more than that. It starts as a 6” X 9” ram (72#) add the die and die plate (14#) add the bearing plates and housing (20#). So the 75# ram weights 106#. Mine weights 120# because the housing is larger because of the bearings I’m using.

A 2” cylinder produces 377 pounds of force at 120 PSI. That’s more than enough to overcome gravity and raise the ram at a good speed. For a 12” stroke, the acceleration on the down fall is only about .27 plus the weight of the ram (106.27) feet/sec. x sec. Meaning, the force when the dies hit is about equal to the force the cylinder produces. Inertia is a story for another day.

The 2” X 12”cylinder requires 37.692 cubic inches to fill once. A 3” cylinder will produce 848 pounds of force at 120 PSI but requires 84.816 cubic inches to fill once. Depending on the strokes per minute and the length of the actual strokes once the hammer is running will determine the CFM needed to run the hammer. A Bull should run on 16 CFM but change to a 3” cylinder and you would need more than twice that.

When you get your hammer fixed make sure the bearings are adjusted so the head stays perpendicular to the column but allows for easy movement. Consider stabilizing the cylinder by making a stabilizer to eliminate torque at the top of the cylinder (see the pic).

Good luck and get that Bull running.

[ciladog]

Youngdylan,

I like that KA75ish hammer you made, real nice.

I’m not so sure that I like the spring shock absorbers though. They may help save your tup to cylinder connections but don’t they take away some if not most of the striking force the cylinders produce? There can’t be much acceleration with such a short stroke so it seems to me that you are relying on the weight of the tup for all the force. I’ll have to think about this some more.

I suggest working with the throttle valve so the hammer starts off more slowly and is almost in a closed position when you take your foot of the treadle. That would eliminate some of the slamming. I can’t see all the controls in your pic so I don’t know what kind of spool valve you have. If it is a spring loaded spool with only one pilot valve, you may want to consider going to a 5 port 2 way valve using 2 pilot controls for more control.

When I first considered building the Bull, I too was concerned about what looked like an unbalanced force. I thought there would be too much torque on the connections of the cylinder and would require more force to move the tup. But it turns out that much of that concern was unfounded because of the way the head (tup) slides on the column. The cylinder doesn’t “see” an unbalanced force as long as the bearings are adjusted to keep the head perpendicular to the column. Doc’s Bull has been in production use for 10 years with no cylinder problems at all.

Check out my reply to Finn for some more info on the throttle and using larger cylinders.

[finn;-)]

Thanks for you help, and advice:-)

But I think my hammer is a little different from what you are describing. When I bought mine Tom told me that they had redesigned the 75 to be a true 75# hammer... I will need to measure my ram but I do not think it is 6x9? and my control rod attaches to a plastic arm attached to the side of the ram at the top and a pivot point above the frame of the hammer. I will need to see if I can get some pics as to how mine is plumbed and tigged up. I suspect that there were several things going wrong all at the same time that conspired to make my control problems worse. When I first got the hammer is was a pure dream to use, but as I got it broke in good it got a little sloppy and I tried to tighten up the guides just a bit. First problem;-) At this point I am not sure my pilot valves are functioning correctly and I am not sure my main throttle is exhausting correctly either. There seems to be a fair amount of play in the bracket that fits onto the valve, when I first noticed it I thought at the time that it might have been made that way intentionally??? Now I am not so sure. I know my top limiter is set too high... Right now I would love to get the hammer back up and running even if I don't have a foundation for the hammer yet, or a roof over the shop (the BUll is hiding in a little storage shed, waiting till I have the time to tackle it;-)

I have a 6" diameter axil forging courtesy of ptree, that weighs 454# and have been planning on building either a mechanical hammer or another air hammer on it. I was all hot to build a tire hammer, or a a guided ram helve, but after reading this thread and getting some neat ideas about how to go about it, I'm leaning back toward doing an air hammer. I have more than enough sufficiently heavy structural steel to build one hammer, a hydraulic press, my overhead cranes... But if I want to build a mechanical as well I need to come up with another anvil... Luckily I have a good scrap yard near here, and a discount steel yard only an hour and a half away;-) I'd LOVE to find a 1'x2'x3' H13 drop from a mold shop to use as the anvil;-)


Christian
Husband
Father
Blacksmith
Farrier
Freetime is that like disposable income???

[ciladog]

I have gotten a number of email request asking that I post more info about the control system on my hammer. A picture is worth you know a thousands words. So I have posted a small video about how they work.

[Anderson G. Phillips]

Thanks for the vid!