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Kinyon Air Hammer

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Hello all, I'm getting ready to build a Kinyon style air hammer from the ABANA plans, I have aquired most of the material required, my air cylinder and valves are on order. My question is, of those who have built this style of hammer or any other style, would you change anything ? Thanks Mike

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Mr. Kinyon has made some fairly major modifications to his "latest" hammer. He had one of them at the ABANA conference and the latest issue of ABANA's Hammers Blow has quite a few pictures. You might want to check out the photos and read the article. The article says that the new design takes care of some of the shortcomings of the previous design(s) and that you should be able to operate the new hammer with a 5hp compressor--the new design uses less air...


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The new one also looks to be alot easier to make. less precision needed for the ram and the hammer guides

The ram is attached to the underside of a leaf spring, which is at one end attached to the main upright hammer tube via a shackle and to the hammer head at the other end. kinda like helve hammer.

heres a bad picture I took from the article...my scanner isn't hooked up right now :( so I used my camera

Edit: the hammer head is hollow tube... 60lbs 4x4 thickwalled tube with no added weight. slid into a 5"x5" tube with uhmw-pe guides.


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Hey all,
I've had the frame material sitting around for a kinyon (read as: lots of scrap I beam, sheet piling, heavy angle, and H? beam) and now am finally getting around to working on it... well planning on getting around to work on it anyways:)

Q: What is the optimal size air cylinder for them?? I've the opportunity to get a (barely) used 2" bore x 12" stroke with 3/8 " ports. It is a tie rod style, dual action. Will this be big enough for a 25-30 pound hammer, or should I go bigger (if possible).

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I build an air hammer with a light weight ram of about 20 lb and used a 2-1/2 x 12 inch air cylinder. I thought that I would go for lower mass and higher velocity, but it failed miserably.

The valve I used was too small and would not let the cylinder "exhale" fast enough, trapping a lot of air in the bottom and acting like a cushion. I tied about 15 lb of rail to the ram, adding mass and preventing the piston from going as far down in the cylinder (less back pressure) and it worked a bit better.

Some of the hammers in the 40 lb range use 1-1/2 x 10 air cylinders so that they can run on smaller compressors. 2 inch diameter cylinders are popular in the 60 lb designs and 2-1/2 in the 100 lb plus designs.

I scrapped my odd-ball design and am going with the new Kinyon design, aiming for about 50 lb. using a 3/8 inch wall on the ram instead of what appears to be a 1/2 inch wall for the 60 lb Kinyon design. The new design is descibed in the current issue of the Anvil's Ring. It uses a 2 x 8 inch air cylinder, but the stroke is a bit longer than 8 inches because the ram is cantilevered out a few inches.

I have all the material for the new design except the spring and the pneumatics, so it will be a while before I can scrounge up the rest of it.

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I built a pneumatic hammer using a 2" by 12" cylinder driving a 65# tup. It works fine, but if I had a 7-1/2hp compressor instead of a 5hp, I'd definitely use a 2-1/2" cylinder. The stroke length of the cylinder can be longer with no problems, but don't ever try to economize on a shorter stroke. If you do, you won't be able to use top tools under the hammer. You want at least 8", and preferrably 9 or 10" of opening between the dies. That usually translates to a 12" stroke cylinder but, as I said, you can use a longer cylinder without problems. The valving on the hammer will just use less than the full stroke of the cylinder, so you won't be "wasting" air; you only use the volume that is swept by the piston and unused stroke costs you nothing.

The real killer on homemade hammers is undersied valves and lines. Use a cylinder, air lines and valves with 1/2" ports, nothing less. Make sure your 5-way valve has a sufficient c.v. factor to handle the volume of air you'll be moving. You can calculate it by simple arithmetic; radius of cylinder squared times pi time the stroke equals swept volume of the head side. (The same formula, but minus the volume of the rod gives you the swept volume of the rod side of the cylinder.) The higher the c.v. of your vlaves, the better they will move air and the harder and faster your hammer will hit. Many a good design has been crippled by crappy, undersized valving.

Multiply the volume of the cylinder times the number of strokes per minute times two to get the total cubic inches per minute needed to supply the hammer. (Divide by 1728 to get cfm so you can relate it to compressor size.)

When amassing the necvessary parts to build a hammer, don't neglect a good, high-volume air filter and micro-mist oiler. I like Norgren brand, myself. Again, get ones with 1/2" minimum ports.

Keep your air piping funs as short as possible, avoid tight corners and use copper tubing wherever possible rather than rubber hose. With the copper, use flared fittings, NOT compression collars. Or sweat-soldered fittings, if you can make good joints. It is better to use a mechanical linkage from the treadle to the exhaust valve than it is to have a long hose running down to a foot-poedal valve like the plans show. That long hose has lots of backpressure, resulting in sluggish performance and treadle-response.

Lastly, put a filter/muffler on your exhaust port so you're not blowing oil-laden air into the shop to breathe. Pipe the exhaust outdoors too, if you can.

Hope this helps.

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  • 4 years later...

Great info Rich.

I built an air hammer with a tube in a tube for a guide system before the LaCrosse conference where I showed my ideas to Ron Kinyon over an ice cream at Lunch one day. He took the two tube idea and made a spring lever the air piston hooks to and saves a lot of air for those with smaller compressors. I went to an in line straight ram/guide system with an 18" stroke piston...........this trapped air in opposing cylinders has made for more control than I ever imagined. I also end up with 11 inches of open die space to stack tools or forge large pipe in. Cutting the pressure on this hammer allows it to be used as a power treadle hammer - and that's no exageration.



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  • 8 months later...

I just built myself a New Style Kinyon Hammer, it is fun to run and runs great. I bought the plans from Paul Branch for $35. I made a few minor modifications. When building one you definitely want to use the 1/2" ball valve over a small port foot valve. I tried it both ways. Also on the uhmwpe and shims, get them in as tight as you can around the 4"x4" hammer head, even if you have to tap them in whith a hammer.

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