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Shaper goes clunk

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Sblack

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#1
I have an atlas 7b. Just got it. Nice shape. When the ram gets to about 3/4 of forward stroke I feel a definite CLUNK and it leaves a line all across the work. Otherwise it works fine. I suspect it is from the ram drive mechanism. Do any of you guys recognize what this might be? I will go in and tear it down, looking for something loose but if anyone can tell me off the bat that they know what it could be that might help. Thanks.
 

francist

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#2
Is the thunk at 3/4 of full-stroke (full stroke being about 7") or is it at 3/4 of forward stroke regardless of what you set the stroke length to?

-frank
 

Sblack

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#3
3/4 regardless of stroke length. So I suspect it happens at the same bullgear position every rotation.
 

francist

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#4
Right. May also be something with the sliding block or the shaft the sliding block runs on. It's really hard to see in there while it's running and sometimes just manipulating the mechanism by hand doesn't make it happen. At least that's my experience.

The 3/4 stroke length is interesting -- I have a thunk in my Peerless but it's closer to the turnaround point. Mine is also not so severe as to leave a noticeable flaw in the cut. Good luck figuring it out, maybe someone else can provide more insight.

-frank
 

benmychree

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#5
Look for a missing gear tooth
 
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f350ca

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#6
Maybe the thunck is a Peerless thing, mine has it intermittently at the back turnaround point.
If the stroke length doesn't affect the thunck (I like that word, even if spell check doesn't) it would seam the problem isn't in the sliding mechanism. Could be in the link to the ram but I'd first look at the bull gear. Might be a bad spot on its shafts bearings. Or as said a bad tooth.

Greg
 

Silverbullet

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#7
Try this again , I posted on this and a banner said waiting moderator ok. Well it isn't here, so my take on the shaper , is the motor turning the correct direction. It could be a tight spot on the ram , gib adjustments. Or a gear tooth or the sliding block ,, bushings ,, shims ,, loose toggle connections or the main shaft bearings or bushings . Pictures or video would help. Do you have a stethoscope hold it on different parts and listen.
 
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