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Striker power hammer Questions

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  Hi  I have been a lurker for years now and absorbing the mass of wisdom on this sight . I have found that most of my questions have been answered many times over the years by many people.                                      I recently traded a press for an 88lb striker power hammer and have a problem that I have not seen addressed previously .                                                                                                                                                                 The machine has seen very little use ( maybe I am now finding out why )  it sounds good idling but when the treadle is depressed the tup will go all the way to the top of the cylinder being stopped by the air cushion under the head and the machine will schudder and shake lightly.  When the treadle is pushed further the tup will start to cycle . This occurs right before of the lower rotary valve arm hits the stop pin on the lower valve retainer cap.  It will cycle but has very little control at this point .  I have read all the information on "Beautiful Iron" and done hours of internet searches to no avail .  I have replaced the belts and they are not slipping , I have opened all the ports and removed the valves and  both cylinder caps looking for obvious problems but everything looks good .  If you have any insight or recomendations please repond . Thanks

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5 hours ago, Metalflea said:

This occurs right before of the lower rotary valve arm hits the stop pin on the lower valve retainer cap. 

What occurs? Is the lower rotary valve part of the mechanism that makes it cycle? 

What level of control do you expect? What isn't it doing and how is it not doing it? 

About all I gather from your post is it isn't working like you feel it should but I don't know just what is or isn't happening. 

My experience on self contained power hammer is with a Kuhn40 and later a couple sizes of Nazels and later a Chambersburg. I don't have a lot of hours on one in total but I can describe the action. 

The Kuhn's tup rested on the bottom die until you pressed the treadle. If you pressed it very slowly or felt for the spot you could get it to tap at the top of the stroke at cycle speed and shake the hammer. This was a valve position and operator error. 

If your hammer does this in more than a very narrow treadle position then I'd look at the valves.

It has spindle valves Yes? Did it sit idle long enough the seals started to degrade? Is the sleeve clean and smooth? 

Do you have blue prints or dimensioned drawings? 

I'd refer you to Bob Bergman but he retired, sold his shop lock stock and barrel some years ago so I don't know of a go to guy for self contained power hammers.

Frosty The Lucky.

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Frosty,  thank you for your response                                                                                                          Per your questions:                                                                                                                 

There are upper and lower rotary valves with arms that are linked together by a bar of fixed length.  The treadle connects to the lower valve arm.  When the treadle is depressed the valves rotate in unison, opening the air ports connecting the crank driven rear cylinder with the front cylinder housing the air pressure driven tup . ( a very simplistic explanation )                                                                             I have briefly run 2 other striker hammers and one anyang and they all began a controlled cycling with the upper die progressively descending toward the anvil as the treadle is pressed down.  That is the control I am looking for .                                                                                   

The striker and other c41 power hammers ( Chinese designation ) the tup raises to almost the full height of the stroke and cycles slightly up & down ready to work.  It does not sit on the lower die .     

 I absolutely agree with you that it is a valve problem. There are no valve seals to go bad ,the rotary valves ride in very nicely machined iron sleeves  with pre machined air ports . The sleeves are secured in the frame with set screws at the end and are not adjustable . The only seals involved are "o rings" on the shafts connected to the control arms and I have replaced them .                            

The only blueprints I have found are generic Chinese drawings that give no direction and are of no value in this situation.                                                                                                                                         I have removed all port covers and both the heads and the valves and have run a bore scope through all openings , air ports and air bi-pass holes looking for anything that might have been overlooked during manufacturing or debris left inside by accident. I have inspected both front and rear cylinders for scoring or binding  and have found nothing obviously wrong .                                       Overall I am reasonably impressed by the casting and machining, while it may not be on par with the older American or European machinery I have worked on and repaired there is no obvious reason  it should not work and yet it doesn't . I am sure it is something simple that I have overlooked                                                                                                                                               Again,  thank you for taking the time to respond and you are lucky to live in Alaska                         Gerry

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Okay, I lost rotary valve thinking about the symptoms you described. 

In your first post you say the tup raises all the way to the air cushion when you depress the treadle. In your post just now you say it does NOT rest on the anvil at idle. 

In what position is the tup at idle, no pressure on the treadle at all? 

It BEGINS to cycle just BEFORE the bottom rotary valve hits the limit pin? :huh:

The problem SEEMS (do NOT quote me on this!) obvious to me, your valves are mis aligned. Call it mistimed.

Counter to popular opinion and the turn of the last century patents and drawings claim a self contained power hammer is as simple as a teeter totter. Literally. The driven piston, I call it the "Master' piston and the Tup piston, "Slave" are connected top to top, bottom to bottom with air lines. When the master moves the slave moves in unison, just like a teeter totter. Make sense?

If you were crushing rock all the control you need is a clutch to the master cylinder's crank. Being pneumatic this type hammer has a built in cushion so it won't tear itself to pieces if the tup stops short. Yes?

How you control this basic system is by putting a bypass line between the two pneumatic lines with a 1 way rotary valve in the bypass line.

At idle the control (1 way rotary valve) is open so air from the master simply cycles back and forth from it's top and bottom sides through the bypass and the tup just lays on the anvil. With  me so far? I'll get to the 1 way valve once I've described the basic operation. 

When you depress the treadle or the hammer driver moves the lever the rotary valves begins to close the bypass causing more air pressure to be directed to the slave piston and it begins to move in unison with it's master.

Close the control valve all the way and the slave is locked to the master's motion. PERIOD.

The 1 way valve is also a relief valve that only holds enough pressure to support the tup at the top of it's travel.

In the earliest versions the control valve was pretty simple and the tup rested on the anvil until the valve was closed.

You can model this with: toilet paper tubes, cotton balls, popsicle sticks and soda straws, close the ends of the toilet paper tubes with Saran Wrap and you can watch the action. 

Using two rotary valves is more efficient than a single valve in the bypass but the two valves MUST be in sync like your rotor cap and flywheel. (For those of you who know what and how a distributor cap works. Yes I'm THAT old.;)

When you turn your hammer on the tup should begin to partially cycle and slowly raise to the top where it remains. The gradual raise is the result of the need to build enough pressure on the lift side of the slave piston to support the tup. It pulses on the way up because the pressure being supplied is pulsing. It would be easy to make it raise in one stroke but there's no good reason to stress machinery more than necessary. 

The two rotary valves are closed preventing air from reaching the slave piston except just enough to the retract side to hold it at the top. 

The top rotary valve supplies the air that drives the top into the work and at idle the 1 way valve allows air to flow FROM the slave to the Master because there's no such thing as perfect seals and pressurized air WILL leak from the retract side to the drive side of the slave piston.

When you depress the treadle the rotary valves close the bypass air channels progressively and the tup cycles with progressive speed and power.

The last sentence sound like what you're expecting?

I've only ever seen a self contained power hammer opened up a couple times, two were at Bob Bergman's "Postville Blacksmith Shop" when Deb and I were visiting friends in the area. One other time it'd been taken apart by a guy who thought he could figure it out by scattering the components on the floor.

Living in Alaska means blacksmithing tools can be REALLY hard to come by and I was looking into making my own. Doing patent searches I discovered self contained "fluid drive" power hammers are WAY simpler than the simplest mechanical. I must've collected hundreds of patents for "Improved" fluid drive power hammers. 

Anyway. In my inexpert opinion, the mechanical linkage between your top and bottom rotary valves is out of position. No way either one should be against the stop before the hammer is going full tilt boogy. That's Max for those of you who don't know who the Fabulous Furry Freak Brothers were.

Where are you in S. Cal. Gerry? I grew up a Valley Boy, moved from Sylmar to the Simi Valley 11 days after the Feb 9 Sylmar quake, then to Alaska in July 72.

I just hope I haven't confused things worse. 

Frosty The Lucky.

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Good Morning,

I fixed a perplexing Anyang, last year. Similar thoughts and sequences.

We found a 6mm set screw in the bottom of the Base. We couldn't find where it had come from. Under close inspection of the piston, there was/is a threaded hole in the piston. Obviously now, Anyang was trying something and had drilled a hole through the piston and later plugged it up with a tiny set screw. The set screw had vibrated out. This caused compressed air to push through the hole in both directions, upsetting the valving. We put the set screw back in with Loc-Tite and a little peening the threaded hole. Magic, it works fine now.


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 Irondragon,  I will reserve the  Mark Krause card until I have explored all other options. I met Mark at  a CBA conference years ago.   He was demonstrating a self contained power hammer that he built from hydraulic cylinders and valves as I recall it was amazing , my wife still talks about it .                                                                                                                                                                                       Frosty, once the hammer starts the tup will raise and stay at in the top of the cylinder at idle with no pressure on the treadle.  The limit pin on the lower spool valve cap keeps the valves from turning too far . The valves may be mistimed and I have made an temporary adjustable link from a turnbuckle but will have to wait until I make new gaskets and reassemble the hammer to try adjusting the timing.  Your description of the operating principles seems spot on, and yes the last sentence is what i am expecting .  All parts have been carefully cleaned , wrapped and marked with location and index marks , not scattered on the floor . I still have all the issues of the furry freak brothers in a drawer somewhere .  You can see the border from the top of the hill behind my house , I was in southern Alaska for a month in the early 70s loved it.  Will be back someday.                                                           Swedlefiddle,   I was out in the shop with a flashlight 2 minutes after reading your post , no extra hole in the piston , that would have been too easy                                                                                   Benona, I made an adjustable link from a turnbuckle and will test it when the hammer is reassembled.  

Thanks you all for taking the time to respond ,  I will post the results of the re-timing of the valves .


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Give a shout when you head up this way, maybe we can hook up.

I'll see if I can find where the patent download files are. If I can I'll let you know, you can decide if you want to delve into some of the thinking behind these things.

One last bit about the thinking behind these things, they are ALL more complicated than necessary or there'd be nothing to claim as an "improvement" to file a new patent. Some of the spool valve designs look like they were designed in an ant farm on LSD.

Frosty The Lucky.

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  It's alive !!!   While the cylinder head was off, I marked the location of the top air passage and jacked the tup out just enough to check the ring gap locations. The top ring gap was about 1/4" from the air passage opening and the lower ring gap was partially in the air passage .  I was amazed that the lower ring had not caught in the air passage opening and snapped off . There was no scoring or any obvious damage to the tup or cylinder walls . I rotated the rings to the front of the cylinder with the ends about 1 1/2" apart and reassembled the hammer . The hammer now runs way quieter and with much better control and there is way less oil mist coming from the hammer.  I have not removed the rear piston to check the rings but I may. The cylinder walls still had some honing marks so the rings may seat in . The hammer had never been opened up or worked on after leaving the factory as  none of the paint or filler was disturbed.   I have not tried the adjustable link connecting the valves, but I will.                                                                                                 

Thanks to everyone for taking the time to respond.  Gerry

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  • 2 weeks later...

Metalflea,  I have owned/run a Striker 88-lb hammer for about 20 years now...it is very controllable until it gets hot after about an hour of steady use - then it will start doing the bam, BAM, bam, BAM, bam, cycle, but by then I'm usually ready to go lift the lid on an IPA.  I don't know where your oil mist is coming from...there's no mist from my hammer - you may be feeding too much oil.  The oil line going to the rear cylinder on my hammer will occasionally develop an air bubble, meaning no oil is feeding to that cylinder...use the oil pump handle to get rid of the air bubble and slightly increase oil feed to that cylinder.

Pay attention to the shims/wedges in the top and bottom dies - the shims slowly peen out of shape/position and need to be replaced periodically.  I keep some shim stock in .015 and .020...I have found that using several pieces of thinner shim results in loose dies fairly quickly.  If the top die is "loose" you will hear it rattle as the ram tups in front of your face.  The wedge for the bottom die is easily visible...I keep a "wedge driver" and a BFH handy to reset the wedge.

I did have the top die get loose, broke the locater pin that's up inside the piston/top die space...the top die, wedge and shim worked their way off to the side and needed repairs.  A machinist I know made up several locator pins for me, some reassembly and I was back in business.

Some folks get into huge concrete bases...my hammer sets on a 4" concrete shop floor.  I built a steel base on a piece of 1" steel plate (800 lb empty), filled with sand, setting on a "cow mattress" from Tractor Supply...3/4" plywood between hammer and steel base.  Drill some locator pins down into the concrete to keep the hammer from "creeping"

If you need a copy of the original Striker manuals/prints, get in touch with me and I'll send copies.    Best of luck to you!   Swedge 


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Swedgemon,   I think the oil mist was a result of the ring gaps being almost in line with each other creating exterme blow by . I may be over oiling at this point as the oilier adjustment is either on or off I will address this next. I am using 10 wt hydraulic oil.   What wt oil do you recommend?                      

There were no shims between the die and tup / anvil when I received the hammer and I did not know that they were needed.  Do the shims go on the sides of the die or on each side of the locator pin ?    When I built the shop I poured an 8" slab with extra rebar and fiberglass chop , it didn't cost that much more ( it's a small shop ) .                                                                                                               

The hammer came with a 1/2" steel box base with no bottom plate.  I added a base plate and filled the base with concrete . Like yours, it has 3/4 ply between the hammer and base with a cow mat below.                                                                                                                                                               I would be very interested in a copy of the striker manual thank you .                                                   Benona , I installed an adjustable link as you suggested but it seemed to run best at the factory setting but it was worth a try. Thanks for the suggestion .                                                                          Frosty, until i get the hammer sorted out all I am making are toothpicks , it whacks the heck out of  wood .  Gerry

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If your dies are tight enough without shims - good for you!  The shims on mine are about 1/2" high and maybe 4" wide (the width of your dies)...on mine the bottom die shim is a piece of water heater shell (the white sheet metal) about .020 thick, top die shim is .015" steel shim stock.  A shim is placed in one side of the dovetail when installing the die, with the locator pin in place, then drive the wedge until it is fully seated.  If the wedge goes too deep, remove the wedge and start cutting shims.  Make a wedge driver so you don't miss the drift and hit your hand (cuts your hammer adventures short for the day).

Some of your oil mist might becoming from using 10-weight (ISO VG 32)...the manual recommends ISO VG 220, industrial circulation-type oil.  Some folks use chainsaw bar oil but having worked in the industrial lubes business for 35 years, I can tell you that bar oil can be a mix of almost anything, with a dose of Paratac (the sticky stuff) thrown in.  Paratac is temp-sensitive and starts breaking down around 120F, leaving a dark brown deposit on cylinder walls, valves, etc.  I use Mobil DTE BB, available from most industrial supply places, lubes distributors - Chevron, Shell, Texaco and other major lubes suppliers all have a VG (viscosity grade) 220 - take your pick.  If oil is pouring out the work piston seal area and dripping almost non-stop down on your dies, you are feeding too much oil...excess oil into the power cylinder will end up in the crankcase...neither piston requires all that much oil to be lubed sufficiently.  My lube valves are barely cracked open once the hammer starts running.  Open both valves up a good twist or two and work the handle a few times before starting, then close both valves and crack them open maybe 1/8 turn, then adjust as needed...watch for an air bubble to form in the oil lines, as mentioned previously.

Send your mail address to me at swedgemon@gmail.com and I'll shortly get around to finding the manual and copying it for you...you can buy me a beer if you get to the Des Moines, IA, area.   Swedge

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