forgemaster Posted November 7, 2012 Share Posted November 7, 2012 Never had an opportunity to pull a beche fully apart let alone a Nazel apart, save for pulling the ram out of the one when I was an apprentice (the beche), an alldays only has one rotary valve not 2 and I gave up on trying to fix that long ago, so no I have no idea or should that be yes I have no idea. Our 5cwt massey has slop in the little end (yes John its on my list to fix it this Christmas shutdown, I have a spare 5 so I can do a sort of swop) but the slop in the bearing does not affect the regularity of the blow at all whether on full blow or tappy tappy. Phil Quote Link to comment Share on other sites More sharing options...
monstermetal Posted November 7, 2012 Author Share Posted November 7, 2012 Phil I am aware of several nazel hammers with irregular blows that Mark has repaired by building new bushings/bearings fixing the issue, I think most of the time its the wrist pin and bushing that is the culprit. maybe because of the design of the hammer this is a Nazel specific issue but I am aware of several situations where this was the solution... It might not be my issue but I need to replace the bearing regardless... Mine had pretty excessive wear in the front bearing, I would guess I could get .125 of movement if you pushed with a bar on the end of the crank which I would guess translates to .025-.045 slop in the bearing. This bearing wasnt getting the oil it should because they had used a chain rather than a cast iron ring to loop around the shaft and carry the oil and the chain was broke and laying in the bottom of the bearing... I also think there is a good chance that this bearing was built for the "other" 4B that the outfit I got it from had and when they broke the ram in it they swapped the new bearing into this hammer after the expense of having it made, I think this because the thrust tolerance was very excessive too, I would say as much as .040 that the shaft would move back and forth plus you had the up and down... Overall the bearing just needs replaced... The tap miss is actually the least of my issues at the moment. The greater issue is the lack of the short stroke.... I have been talking to Mark Krause via email and the only thing he has suggested that I haven't tried or fixed is the valve blow by... I have advance and retarded the valve timing, I have tried softer/harder springs in the bypass check... and of course all the mechanical fixes, new wrist pin and bushing, new spur gear to slow down the hammer, new cushion plug, new rings and leather seals... On a side note I did not have the tap miss issue until I replaced all the seals and rings in the front end of the hammer... It is really air tight around the ram now, so much so that the ram sucks up and parks in about 3 or 4 cycles and when the hammer is shutting down even when the flywheel is almost stopped moving it is still picking up the ram and cycling... and the seals are tight enough that when you shut the hammer down it takes quite some time for the ram to fall back to the lower die... I feel really good about the front part of the hammer, I know the air is going to good use once it makes it into the front bore.... To me that is also compelling to think that small variations in the compressor side caused by different loading during diffrent parts of the compression cycle could lead to small variations in the ram stroke, we are only talking a difference of a 1/16 of stroke length to tap or miss and I can see the small amount of play definitely making that much difference in the up VS down compression cycle air production... Hey I got to hope that all this work yields some positive result... John N also suggested checking the con rod length as a small variation could cause issues. the folks I got this hammer from had two 4B's (sequential serial numbers (304 and 305) At some point they had pulled the compressor piston and con rod from the other hammer and put it in this hammer, I know this because the "spare" con rod and piston I got where stamped with "305" which is the serial number for this hammer... I was told by the previous owners that they could not get the other compressor piston to go back in this hammer because of peening on the top from something getting above the piston.... I spent several days hand fitting the correct piston and reinstalling the original and corresponding con rod. I know which rod went with each piston because both had diffrent wrist pin sizes (only .0020 or so but still obvious which went together. Also with the other con rod and piston the compressor side was gettin hot and sticking, which was the issue that resulted in the sale of the hammer to me as they couldn't solve that (simple fix, put the right parts back in the hammer) So I dont know... If the new bearing does not fix the tap miss that is a issue that I'll have to live with, it needs a bearing anyway... The main concern is the lack of the soft short blows as without those there is just to much energy under light treadle to do fine work.... Once its back together with the new bearing the next thing Ill have to look at is rebuilding the valves which sounds like a ugly time consuming project.... Ive had the valves out and there does not seem to be excessive wear but I suppose it doesn't take much for air to get were its not suppose to be, According to Mark there is no real good way to check tolerance in the valves either as feeler gauges and such dont tell much about what is going on down in the belly of the bore... Quote Link to comment Share on other sites More sharing options...
nonjic Posted November 7, 2012 Share Posted November 7, 2012 If you are just looking for a few thou on the valves hard chrome plating works well, and push a bore hone down the tubes.... Is the 'doo dad' that lets air into the top of the compressor piston bore deffinatly letting enough air into the bore when the cranks at BDC ? If there was not enough fresh 'atmposhere' air coming into the 'top' of the system when the pumps at the bottom of its stroke it could get a bit 'vacumme' ( :lol: cant even spell, let alone describe!) - Lower pressure on top of the compressor piston = lower pressure above the ram = higher ram lift. edit - suppose it cant generate to much of a low pressure as the valve is partially open to exhaust (atmosphere) at light treadle.... Ill keep mulling it... Quote Link to comment Share on other sites More sharing options...
Daniel.85 Posted December 23, 2012 Share Posted December 23, 2012 Hows the rebuild going? Have you had time to get it back together with the new bearing? Quote Link to comment Share on other sites More sharing options...
r smith Posted December 24, 2012 Share Posted December 24, 2012 I have had an idea in the back of my head for a few years now about how to soften the blows to do light work without danger of smashing the work by mistake. I have not really thought it out and should talk it over with Krouse. My thought is to de-tune the hammer blows with an adjustable linkage between the two valves, maybe tight fitting pins to be set in a few different positions, similar to an OTC adjustable wrench. I am a little worried that the out of time valves will allow movement of the ram & piston that may damage itself.... Quote Link to comment Share on other sites More sharing options...
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