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Andre Muchalak

Low bpm problem on air hammer ( kynion style)

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Hello everyone! My name is Andre, I’m naturally from Brazil.

  I am finishing my kynion style pneumatic hammer but I’m having a low bpm problem and I don’t know what is the main cause, since I have a 250L compressor running with 15bar.. this is the compressor.1DE198A6-EC4C-47D7-BF92-2D7302C096AD.jpeg

My piston is kinda big, but I don’t think that it would be a problem to this compressor... it have 115mm on its base, and the arm diameter is 45mm ( don’t know if this is the right word). The length of the closed piston is 85cm and opened is 145cm.292910CB-48C4-40F7-93DE-BE35271B7D10.jpeg

to create the air circuit I’ve based myself on crickets air hammer plans, but I’ve dove with only one roller valve and I’m starting to think that this might be the problem

57108566-346A-49F6-A66E-C1D81668A075.png

This picture shows the basic scheme that I’ve used, but I’ve removed the venting valve.. the pilot valve is not the one in the picture, I’m using a 1/2” 5/2 spring pilot valve. All the main connections are 1/2”, only the roller valve and its connections are 1/4”

15F463CC-3E68-4427-BD51-DFECA8A3669C.jpeg

And finally, this is the video of the air hammer running... I think you might be able to see the air circuit and tell if the problem is in it... 

Just remembering that this air hammer was made entirely from scraps... that’s why it’s a little bit ugly, hahahaha. 

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Got sound but no visual ??

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41 minutes ago, Jeremy Blohm said:

I am collecting all the things i need to build a very large air hammer. And these are the valves im goimg to use.

airdraw.jpg

http://www.hotanvil-forge.com/id30.html

That’s basically what I did.. the video I’ve posted shows how it’s aranged, I don’t know if you can see now, here it seems to be ok.. the only thing that is different is the port 1 connections.. I’ve added a check valve before connecting to the pilot valve.  The ball valve at the end of the circuit is exactly like this but I forgot to record it

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Im trying to download the video again. It didnt work earlier but i had crap service.

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6 hours ago, Andre Muchalak said:



Same thing  !!??

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Works okay for me. I just don’t know anything about power hammers.

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I got it to wotk but it took forever. 

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On 7/28/2018 at 2:33 PM, Andre Muchalak said:

Hello everyone! My name is Andre, I’m naturally from Brazil.

  I am finishing my kynion style pneumatic hammer but I’m having a low bpm problem and I don’t know what is the main cause, since I have a 250L compressor running with 15bar.. this is the com....

I don't post often (actually hardly at all - lack of time mostly)... but I've been running a 110pound air hammer that I had built while back, very successfully... so I thought I might be able to provide some help...

 

First, your cylinder looks like the hydraulic rather than the pneumatic type...  this itself can be the main issue ..

whilst functionality wise both are similar in what they have to do and how they achieve it, the air (pneumatic) cylinders are optimised for low friction gaskets and the piston moves very very easily (even by hand), where a hydraulic cylinder doesn't have any problems overcoming high-friction inertia by VERY TIGHT gaskets and fits...   after all oil can not really be compressed... where air on the other hand is easy to compress......

I know that there are a number of builds out there successfully utilising hydraulic cylinders in pneumatic systems - but I figure there's some modding to be done, or at least a serious amount of piston-gaket lubrification to be added...  

So one of the factors you could easily and "affordably" change is to use a proper air cylinder...

 

now Speed on an "tool-Air" power hammer is usually down to these factors from what I understand:

air-pressure & volume being moved into the cylinder at speed...  so a "slow" fill  will result in a slow move of the cylinder,.... a slow move will also cause the return valve to be triggered in a slow cycle  and then you get a slow move over all... as seen in your video.

so with that in mind, the actual cylinder's bore has a rather big impact on the speed of the hammer. bigger bore -> more air needs to be cycled...

also try to find areas which can generally reduce the volume of air being moved at speed: small hoses, small diameter reductions, small joints, etc... essentially beef up all the connecting hoses etc... also the inlet needs to be as large as it can be.. you want fast movement of air volume.

and again, the cylinder... a pneumatic cylinder with the ports unplugged, can be moved VERY easily by hand... add friction and the entire system will slow down (this is my suspicion in regards to your hammer's issues)... so the standard hydraulic cylinder is most likely the main cuprit here ... pneumatic systems aren't great at overcoming friction inertia... the cylinder's rod needs to be able to be moved VERY easily and freely...  otherwise it'll cause a number of issues.

again, I myself use a pneumatic cylinder  and have only seen a few adaptions of the design using hydraulic cylinders in an air-system.... I can only guess what can be done to get it running smoothly, like changing the gaskets for something with less fritction, adding more oil / lubrification... but again, that's just guesswork.

 

Adding to that, the guides for the ram on your hammer:  how tight a fit are they?  if you look at most of the TOOL-AIR (external compressor) air hammers out there, the ram-guides are always a rather loose / sloppy fit (check out the videos from the bigblu power hammer and their gib adjustments on youtoube)... same as with the actual piston friction, adding friction by using too tight or not well lubricated guide systems to the ram will increase the drag and slow down the entire system because the pneumatics will have to overcome a lot more resistance to get moving.
also from the looks of it, your guides are Steel  with the steel ram inside...  at least add some bearing bronze or HDPE plastics.. anything that provides better gliding abilities than steel on steel...  at the very least add a LOT of grease...   but again, steel on steel isn't optimal for an air hammer of that make.... it's quite ok on a mechanical spring hammer like the tyre hammer etc... but not on an air hammer. you want the least amount of friction on the moving components without having a wobbly fit....

My hammer uses a fully adjustable guide system made from self lubricating bronze  and has a central lubrification system as well to easily and quickly lube all the guide-ways...  If I adjust it too tight, the hammer will loose a lot of impact force and speed.. 

20171023_152214.jpg

20180124_165216.jpg

I find it quite crucial to carefully adjust the guides to have just a little bit of play - clamp them onto the ram, and the hammer just will not work proper.

too loose and it won't be ideal either...

 

 

hope that helps...

 

here's my hammer and  the video on youtube shows it doing some work:

Build Photos: https://photos.app.goo.gl/2819hrkWQXS5l0n92

20180328_171326.jpg20180328_171319-3.jpg

 

Videos

 

 

 

Edited by DGentile

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11 hours ago, DGentile said:

I don't post often (actually hardly at all - lack of time mostly)... but I've been running a 110pound air hammer that I had built while back, very successfully... so I thought I might be able to provide some help...

 

First, your cylinder looks like the hydraulic rather than the pneumatic type...  this itself can be the main issue ..

whilst functionality wise both are similar in what they have to do and how they achieve it, the air (pneumatic) cylinders are optimised for low friction gaskets and the piston moves very very easily (even by hand), where a hydraulic cylinder doesn't have any problems overcoming high-friction inertia by VERY TIGHT gaskets and fits...   after all oil can not really be compressed... where air on the other hand is easy to compress......

I know that there are a number of builds out there successfully utilising hydraulic cylinders in pneumatic systems - but I figure there's some modding to be done, or at least a serious amount of piston-gaket lubrification to be added...  

So one of the factors you could easily and "affordably" change is to use a proper air cylinder...

 

now Speed on an "tool-Air" power hammer is usually down to these factors from what I understand:

air-pressure & volume being moved into the cylinder at speed...  so a "slow" fill  will result in a slow move of the cylinder,.... a slow move will also cause the return valve to be triggered in a slow cycle  and then you get a slow move over all... as seen in your video.

so with that in mind, the actual cylinder's bore has a rather big impact on the speed of the hammer. bigger bore -> more air needs to be cycled...

also try to find areas which can generally reduce the volume of air being moved at speed: small hoses, small diameter reductions, small joints, etc... essentially beef up all the connecting hoses etc... also the inlet needs to be as large as it can be.. you want fast movement of air volume.

and again, the cylinder... a pneumatic cylinder with the ports unplugged, can be moved VERY easily by hand... add friction and the entire system will slow down (this is my suspicion in regards to your hammer's issues)... so the standard hydraulic cylinder is most likely the main cuprit here ... pneumatic systems aren't great at overcoming friction inertia... the cylinder's rod needs to be able to be moved VERY easily and freely...  otherwise it'll cause a number of issues.

again, I myself use a pneumatic cylinder  and have only seen a few adaptions of the design using hydraulic cylinders in an air-system.... I can only guess what can be done to get it running smoothly, like changing the gaskets for something with less fritction, adding more oil / lubrification... but again, that's just guesswork.

 

Adding to that, the guides for the ram on your hammer:  how tight a fit are they?  if you look at most of the TOOL-AIR (external compressor) air hammers out there, the ram-guides are always a rather loose / sloppy fit (check out the videos from the bigblu power hammer and their gib adjustments on youtoube)... same as with the actual piston friction, adding friction by using too tight or not well lubricated guide systems to the ram will increase the drag and slow down the entire system because the pneumatics will have to overcome a lot more resistance to get moving.
also from the looks of it, your guides are Steel  with the steel ram inside...  at least add some bearing bronze or HDPE plastics.. anything that provides better gliding abilities than steel on steel...  at the very least add a LOT of grease...   but again, steel on steel isn't optimal for an air hammer of that make.... it's quite ok on a mechanical spring hammer like the tyre hammer etc... but not on an air hammer. you want the least amount of friction on the moving components without having a wobbly fit....

My hammer uses a fully adjustable guide system made from self lubricating bronze  and has a central lubrification system as well to easily and quickly lube all the guide-ways...  If I adjust it too tight, the hammer will loose a lot of impact force and speed.. 

20171023_152214.jpg

20180124_165216.jpg

I find it quite crucial to carefully adjust the guides to have just a little bit of play - clamp them onto the ram, and the hammer just will not work proper.

too loose and it won't be ideal either...

 

 

hope that helps...

 

here's my hammer and  the video on youtube shows it doing some work:

Build Photos: https://photos.app.goo.gl/2819hrkWQXS5l0n92

20180328_171326.jpg20180328_171319-3.jpg

 

Videos

 

 

 

In fact my cilinder is quite hard to move by hand,  but I opened to clean, because it is very old,  and it didn’t had any sign of oil inside, so I assume it is pneumatic.. 

about the ram, I’ve mande a nylon bushing inside a steel tube, to work as guide.. the ram runs easily inside the guide, I’ve made it with 0,1cm difference and added a lot of solid Vaseline to lubricate the ram..A98E5448-2786-4569-82B2-66CA88298E57.jpeg

6F8B9435-B7D3-42B4-900F-1163B8DF3BDC.jpeg

CC4AF43C-B522-4A8C-AD8F-DB734AE80FFF.jpeg

FD61EDD1-1D3E-4BE2-9245-150F8134A33C.jpeg

 

one thing that may be slowing it down is in the air inlet.. Im using a 1/4” hose connected to a 1/4” air outlet, because it’s the only one that is long enough to reach the hammer... i have in my workshop another outlet with 1/2” and I think I’ll be using it later, but I don’t know if that will affect the speed..

5343D225-EC7E-487C-A3C2-0B659D9AFDE2.jpeg

This is the air inlet hose (1/4”), the ball valve is 1/2”, followed by 1/2” check valve 

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Andre,

Good choice on the nylon for the ram guide.  

 

On the cylinder:

if it feels sticky or hard to move about, you have probably found your main issue already.
again, as mentioned - whatever cylinder type you use - it needs to be moving very very easily, as pneumatic systems don't like to overcome friction if you want speed.
For most cylinders you can buy rebuild kits that include a new set of gaskets, often the piston sliders and the rod bushings...   you can get away with *some* DIY fixing if it's sticky... have you disassembled the cylinder yet and checked the insides?  if it's air (I looked at the photos again, it's difficult to say, but it could be... I might have been wrong on my assumption of it being hydraulic) - you should really be able to move it almost freely if none of the ports is blocked.

Also yes, the 1/4" line is certainly not idea, but I'd say it's not the main issue.

Another thing that comes to mind:
HOW do you operate the hammer - I mean what sort of ball-valve or other valve do you have installed to let the air out and get the hammer to move with I assume a foot-treadle or something?
here's the thing, those hammers operate on "constant" pressure systems, not unlike old steam hammers, they start to move, once you let air escape and get the system to cycle - but air needs to be able to escape... if your EXIT-Valve (the foot-treadle, ball valve etc) is too small, or doesn't let the air pass QUICKLY  the entire system will slow down..

here's my system:

20180115_184337.jpg

20180115_171124.jpg
(with the support bracket removed)

I use a 1/2" Ball valve and 1/2 pipe fittings  - and most important the filter / muffler (I use a different one now, that has an oil-catch & drain...they are expensive, but last far far longer as the filter doesn't get clogged with excess oil from the oiled-air)...  the muffler - if you have one (and I do recommend one for noise and because of the air pollution the oiled air would potentially cause in an indoor-shop) - needs to be rated for really large volumes of air being passed through.
Again, anything that prevents the "trapped" air from exiting quickly will actually stop the hammer from being fast.

 

My design uses a sprocket and chain to operate the ball valve - the entire thing is supported also by a ball-bearing live center (made from an old unused lathe live center tool)....
Chain and sprocket allows for a fast, yet very precise control over the ball valve.

 

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Daniel...has anyone ever considered/implemented a closed loop type system where exhausted air returns to the inlet side? Is this even possible?

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10 hours ago, SteveShimanek said:

Daniel...has anyone ever considered/implemented a closed loop type system where exhausted air returns to the inlet side? Is this even possible?

Steve,

 

I don't know whether anyone has ever attempted that, but at least to my knowledge this would be very difficult to implement in a pneumatic tool air system.

The problem would be  to use some sort of uni-directional valve on the inlet and outlet of the cyinder, then needing some sort of expansion tank on the outlet to handle the compressed air and prevent it from being over-compressed... you´d then need an overpressure safety valve in line... and that yet you’d need to feed in more air to the inlet... and that means some sort of exhaust at some point.

I bet you could get it to be more “conservative” in its air consumption by trying to collect / feed exhausted air back into the system. but I doubt you’d add a lot of improvement whilst adding serious complexity and potential problems and cost  to the system.,

Again, I have not tinkered with this.

I briefly pondered building a self contained system, but gave up on it due to the complexity of the actual parts....
pefectly do-able but at the required time and tooling to get it done right, you might as well (or rather) buy an anyang new.

So I believe the tool air operated hammers should be designed with a certain simplicity and all I’ve seen (my own included) are essentially based on the principals applied in constant pressure steam hammers..., old tech, newly implemented.

 

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Thanks Daniel...it was an idea that i had been kicking around prior to committing to buy a larger air compressor, with the idea of being able to run an air hammer with a smaller compressor. it seemed likely that it was an impractical idea, or someone would have done it already. I am currently trying to figure out how to run controls for a guided helve style air hammer; I am making the parts for the top currently. I will post some photos on my own thread when i can take them.

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