monstermetal Posted October 9, 2012 Author Share Posted October 9, 2012 I find it amazing how mysterious hammers are. I have been into enough of them to have a basic understanding and know basic principals but when there is a issue like this I am out of my league. I have read through Mark Krause's book several times, studied the Nazel literature thats available and spent more than a few days trying to get my head around what diverts the air to provide the cushion to keep the ram from stroking from limit to limit under light treadle and cant seem to grasp it. It seems to me that the hammer should do just what its doing, making long strokes in time with the compressor piston. However that's not what happens normally in a correctly running hammer, you get that sweet short tap tap tap stroke which is what I lack Quote Link to comment Share on other sites More sharing options...
monstermetal Posted October 9, 2012 Author Share Posted October 9, 2012 Dave are you chasing similar issues with your 3B? Quote Link to comment Share on other sites More sharing options...
nonjic Posted October 9, 2012 Share Posted October 9, 2012 any valve assembly drawings you could post up ? edit, larry, its my understanding (ie, might not be correct!) that to get light, short blows you do not have any air providing a cushion. What you are doing is diverting a % of the air that is generated by the pump piston to atmosphere, not to the ram bore. Quote Link to comment Share on other sites More sharing options...
Dave Hammer Posted October 10, 2012 Share Posted October 10, 2012 Larry... Yes, I am having short stroke problems also. I’m sorry I haven’t made that obvious. I have great control with my 3B (I believe I could crack an egg without breaking it), but has been with long heavy strokes. As I posted yesterday, I made some progress by making the hole in the top of my tower smaller (my full strokes are now about ¾ strokes). That’s why I said I believe the back pressure on the exhaust is significant (it would literally be pushing air down through the cushion bushing and help keep the ram lower). That is why I’m looking for a factory cone and tower. If I can’t find a factory cone and tower, I need the measurements I asked for so I can fabricate something that is functionally equivalent. It's also why I want to get the hammer moved to the 180 BPM (factory spec). When I got my hammer running, a couple years ago, I noticed, via youtube, that some hammers had that short stroke (there is not much nazel video out there though). I made some inquires, but didn't get answers that supported it being a feature, so I thought it might just be a problem from wear. Evidently, I didn't ask the questions effectively. Anyway... When you posted a few weeks ago... my interest was renewed. I have to believe we can solve the problems we have. The answer may be different for each hammer though. I’ve been studying Mark’s information also. I’m getting close to understanding most of it (still some areas I'm working to get my head around). I can see that the short strokes should be possible…. On full treadle down, all the air compressed by the piston (as well as the suction on the lower end is used to push/suck the ram down. The opposite is true when the ram is raised. That is… all the air compressed below the piston and vacuum created on the top end (input from the ram cylinder and tower) is used to move the ram up. Those actions would produce full power (with full stroke). When the treadle is just part way down, and the piston is on the rise, only part of of the compressed air is used to move the ram down. Some of the air is (as noted by John N. above) sent to the exhaust tower (air is divided between power and exhaust). Mark's (treadle half down) diagram illustrates this. If the use of the air is carefully balanced, with a slight favor to the down side (after consideration of the ram weight), the ram could move down a little at a time while taking short strokes. The amount of air given to push the ram down would determine the length of the stroke. Any excessive air leakage would definitely cause problems and is most likely the problem if everything is factory equipment and all is present, and the leakage could be from more than one source (damaged valves, seals and rings). It should be easy to validate that the valves sleeves haven’t slipped (I checked my visually and have 100% belief they are in the correct positions). It should also be easy to check the clearances of the valves (measurements). Other leakage would be around the piston and ram in various places, which are not so easy to check. Clearances can be checked, but effectiveness of rings and seals are more troublesome to determine. I think.... even the oil viscosity could have impact on operation. We'll find it... Quote Link to comment Share on other sites More sharing options...
Dave Hammer Posted October 10, 2012 Share Posted October 10, 2012 John N. Both Larry and I have diagrams in a commercially available phamplet that Mark Krouse created and sells. It has copywrite protection, so we shouldn't post pictures of the diagrams. The pamphlet can be purchased from Bob Bergman (Postville Blacksmiths). Quote Link to comment Share on other sites More sharing options...
bionicarm Posted October 10, 2012 Share Posted October 10, 2012 Monstermetal, sorry to hear about your air hammer, as is looks like you can beat the tar out of whatever you put in there, but I know you're looking for more control. I was thinking this thread could be used to describe to people who know very little about Air Hammers how exactly they work because only by troubleshooting and correctly fixing (not just "gettin by") does real understanding of a machine come about, and though you guys are stumped, you certainly are very knowledgeable in this area. I've read what you all have said here and am trying to put together the picture...Rotational motion from the motor turns a piston which creates air pressure. This amount of pressure is always the same no matter what the throttle is at because the motor just keeps driving the piston at a constant rate. Variation in ram movement is caused by manipulation of valves that direct available air to the top of the ram, bottom of the ram, or vented off into the atmosphere. This means that at full throttle, potentially all air driven by the piston is directed to the top of the ram and none vented off or used as an air cushion. If that's the case I would say that the issue is in the valves leading to the bottom of the ram that allow for an air cushion and decrease stroke length. Air must be leaking from somewhere in that pathway and not forming that air cushion. The big PSHHT! noise on every stroke is the excess air being vented off into the atmosphere correct? The above makes sense and would work, or I may be on the completely wrong track. Either way any info you all have would be appreciated. Also, I mean no disrespect, Sorry I don't have anything helpful to add, I only want to understand how these machines work. Quote Link to comment Share on other sites More sharing options...
bionicarm Posted October 10, 2012 Share Posted October 10, 2012 Edit, It would work but makes no allowances for ram return...Don't know how that happens. I guess that means I'm on the wrong track :/ Quote Link to comment Share on other sites More sharing options...
lupiphile Posted October 10, 2012 Share Posted October 10, 2012 Hey Larry, After having reviewed Mr.Krause's book and then double checking my 2b ( she's conveniently all opened up right now), I think I can at least answer the stroke limit question. The compressor side displaces nearly twice as much air as the ram requires to do it's stroking. This means that the compressor side starts acting on the ram faster than you might be thinking..... Though at that point it is like a see saw, its like a see saw made of a very flexible board and a fat kid with really strong legs on one side. you see if the fat kid pushed hard enough, and gravity overtook his upward momentum fast enough the skinny kid wouldn't be moving from ground to sky every cycle. He would be moving at the same beats per minute as it were, but his upward or downward momentum would always be being controlled. The valves, in this horrendously articulated metaphor, would be controlling the springyness of the board. Full treadle = concrete board, 1/8th treadle= willow board. All that being said, It looks to me ( and really, you're much, much better qualified than I) like air leak city. I'm sure you've checked all the gaskets, rings ect. how 'bout that silly leather ring that helps pressurize the cavity under the ram. also you checked the ball spring arrangement in the bypass? No air leaks? Druthers be mine I would temporarily block that off in some manner to eliminate it from your trouble shooting. Another good indicator is it's clamping ability. Does it clamp? For the valves, If you're seriously thinking that they are the problem you could always go the turnbuckle route, that way you could feel out how much pressure is going where, by carefully adjusting each one while the hammer is at Idle. Oh I've just thought of a modification to the see saw analogy, The reason the "willow board" still allows the ram to come down from the work is the weight of the ram it self, it causes the the whole elasitc system to shift incrementally downward with just the slightest stiffening of the board because the ram always wants to go down.A Gravitational Differential. I think I'll name my next band that...... I sure hope this helps, I wish I had a better analogy but I'm only on my 3rd cup of coffee today. Take care, Larry, were pulling for ya'. Matt Quote Link to comment Share on other sites More sharing options...
monstermetal Posted October 10, 2012 Author Share Posted October 10, 2012 I'm on my phone so I can reply to your post... Just wanted to say I discovered a likely culprit for my issues. I went to measuring ring gaps and found the cushion tower ring is ridiculously worn. I would estimate the gap at .150 and it should be something like .010. I'm calling to order one but I am guessing it will be weeks if not months before I see the replacement to verify this is the cause ( I would bet $100 it is though) Quote Link to comment Share on other sites More sharing options...
Dave Hammer Posted October 10, 2012 Share Posted October 10, 2012 Larry.... I'm glad you found something that is likely the cause of your issues. Let us know when you have confirmed it. My next efforts (beyond further study of the documentation I have) will be 1. Replace the muffler with something that works like orginal equipment. 2. Replace the leather seals on the ram guide. 3. Reduce the size of the pulley on the motor to get down to 180 BPM. Quote Link to comment Share on other sites More sharing options...
plain ol Bill Posted October 15, 2012 Share Posted October 15, 2012 I have been avidly reading this thread and could not help but think if Grant were still with us he would have been deeply involved in this discussion. I really miss his post's on a lot of forums. Hope you have your problem figured out Larry. Quote Link to comment Share on other sites More sharing options...
monstermetal Posted November 5, 2012 Author Share Posted November 5, 2012 Hey Bill... Yep Grant helped me tear down this hammer before he left us... I wish he was around to help too.. Well.... New ring in place, new cushion plug bushing, new wrist pin and bushing and new seals and I still have the same issues... I also rebuilt all the linkage today to get the loose rods tightened up... The only outstanding issue that I am aware of on this hammer is excessive play in the front main bearing... Still no short stroke... now that everything is tighter I have a tap miss tap miss which is probably a result of the sloppy bearing..... I am getting frustrated, I have been chasing things for almost two years now and still have yet to forge some steel and its now important to get this thing up since I sold the 3B Quote Link to comment Share on other sites More sharing options...
Daniel.85 Posted November 5, 2012 Share Posted November 5, 2012 Thats a bummer that all that didn't fix the problems... Ive never even seen a nazel in person unfortunately so I am of no help. I couldn't imagine there could even be that many more possibilities for things that could be causing it.. Quote Link to comment Share on other sites More sharing options...
r smith Posted November 5, 2012 Share Posted November 5, 2012 Is the tap-miss something inherent with these hammers? My 2b does that as well and someone long ago said it was the rebound of the first hit that caused the second to miss. I am not convinced that is true but it is what I was told. It may be my imagination but I think I am getting 3 different hits in a repeating pattern, all at very light blows, tap-light tap-miss repeat...... Quote Link to comment Share on other sites More sharing options...
monstermetal Posted November 5, 2012 Author Share Posted November 5, 2012 Talking with Mark Krause I think the tap miss tap miss is almost always a worn out bushing issue.. Here is some video, you can see the obvious tap miss towards the end of the video..http://www.youtube.com/watch?v=nLg992q_C78&feature=plcp Quote Link to comment Share on other sites More sharing options...
monstermetal Posted November 5, 2012 Author Share Posted November 5, 2012 This mornings damage... Quote Link to comment Share on other sites More sharing options...
lupiphile Posted November 5, 2012 Share Posted November 5, 2012 Larry, Your wherewithal is , truly, an awe inspiring source of wonderment..... I hope this is the last thing you ever have to do to it. Best of luck, Matt Quote Link to comment Share on other sites More sharing options...
Daniel.85 Posted November 6, 2012 Share Posted November 6, 2012 Awesome looking teardown! hope it fixes it Quote Link to comment Share on other sites More sharing options...
Glenn Gilmore Posted November 6, 2012 Share Posted November 6, 2012 So Larry, are you saying the tap and miss is caused by the crank shaft bearing being worn? Quote Link to comment Share on other sites More sharing options...
r smith Posted November 6, 2012 Share Posted November 6, 2012 Larry, thanks for posting about the crank bearing. While you have the shaft out do you see any way to drain the oil in the bearing pockets? I have nightmares about dirt and grit getting in there with no way to ever get it out. I guess also I will be getting into the lower bearing on 2b soon :( Quote Link to comment Share on other sites More sharing options...
monstermetal Posted November 6, 2012 Author Share Posted November 6, 2012 Yep.... I would bet a $100 the tap miss issue is slop in the rotating bits ( I would have lost the last $100 bet but what the heck, I am a betting guy) I got the bronze ordered for the bearing this morning... If anyone ever needs to buy bushing stock I highly recommend National Bronze, talk to Chris... I paid $80 for the chunk for the wrist pin and cushion plug (I got both from the same chunk) and the bit for the main bearing was $255 shipped Enco was $495 and my local outfit was $750 so $255 shipped I think is a great price (the slug was 45 pounds so about $5.60/lb shipped) Quote Link to comment Share on other sites More sharing options...
monstermetal Posted November 6, 2012 Author Share Posted November 6, 2012 I dont think there is a way to get the oil out, mine where full of gunk and grime but it did not seem to damage or be an issue... The front one had a chain instead of a ring to fling the oil around and at some point the chain broke and was laying in chunks in the bottom of the bearing... still the shaft looks beautiful.... Quote Link to comment Share on other sites More sharing options...
forgemaster Posted November 6, 2012 Share Posted November 6, 2012 When I was an apprentice we had a beche that used to do the same thing, our 1cwt massey will do the sameat times on light strokes, also our 2cwt alldays will do it sometimes, we just decided to live with it If you do succeed in fixing it I will be interested to hear your remedy. I for one don't think fixing the bearings will help fix your problem, so thats my bet in. Phil Quote Link to comment Share on other sites More sharing options...
nonjic Posted November 6, 2012 Share Posted November 6, 2012 Unless the sloppy bearing is making the compressor piston cycle a slightly different stroke length every reciprocation, through the crank bouncing, I dont see how it can affect the tap TAP tap issue.... Quote Link to comment Share on other sites More sharing options...
r smith Posted November 6, 2012 Share Posted November 6, 2012 Phil, John, Any thoughts on what the cause may be if not the slop in the bearings? Quote Link to comment Share on other sites More sharing options...
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