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GlennA
User Rank
Gold
Re: Logic, or assumptions?
GlennA   10/14/2013 11:21:23 AM
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taimoortariq;  The engineer had decided the problem was a mechanical adjustment, and was not interesrted in any troubleshooting that I had done - he did not want to be confused by the facts.  As a 'senior' engineer, his job was to give me instructions, not to listen to what I had found.

taimoortariq
User Rank
Gold
Re: Logic, or assumptions?
taimoortariq   10/13/2013 8:35:18 PM
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Sometimes we are really sure of the problem but that is not it.

Also, I guess if you could have explained the senior engineer properly, he might have understood the actual technical problem behind it.

RBedell
User Rank
Gold
Re: Logic, or assumptions?
RBedell   10/12/2013 1:35:12 PM
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Glenn, you made a gauntlet by not being clear to your intent.  Whom ever came up with the title is guilty of throwing it down.  What engineer can refuse a challenge?  :^D

Still, your write-up made us think.  At least I now know what an edge-banding machine is and a little bit about how they work.  Good job.

 

GlennA
User Rank
Gold
Re: Logic, or assumptions?
GlennA   10/11/2013 9:45:44 PM
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Ken E;  With apologies to Rob Spiegel, my original intent was that when the mechanical adjustments are found to be correct, the next step may be to check the sequencing / programming of the machine.  I agree that I did not provide enough information for a reader to diagnose the problem.

GlennA
User Rank
Gold
Re: The missing symptom, maybe.
GlennA   10/11/2013 9:35:54 PM
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RBedell;  That is a good description of the machine function.  The root cause of the roller being damaged, in my opinion, was that the entire assembly was being advanced during initialization, along with the depth-setting cylinder, instead of just the depth-setting cylinder.  I had recently been re-assigned to working on edge-banders.  The senior engineer had given me instructions to adjust the machine.  After I had checked the adjustment, and found it was correct, I then observed the machine functioning to see if I could find the cause of the problem.  I then told the Italian engineer that the adjustment was correct, and the problem was in the machine programming (software).  And some omitted information was that I had previous experiences with Italian engineers telling me "You don't understand" when I found problems that they did not like.

William K.
User Rank
Platinum
Re: Logic, or assumptions?
William K.   10/11/2013 7:13:47 PM
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post vy much lie  case of the "Jm Moore"syndrome, which is that "if I think it is that way, then it IS that way", which often leads to incorrect conclusions. I have had sevice techs describe things to me over the phone and on some occasions my respons is "that can't happen", but since it has been observed, the clearly there is  problem. The assertion tht it can't happen tells the tech tht I believe they have found at least part of the problem, and the statement that there is a problem verifies that we now need to understand why the thing happened. This has been as simple as a damaged limit switch bracket to as complex as a hydraulic control valve that was sometimes sticking because it was full of dir, on a stamping press that would sometimes do a second stroke after the two-hand buttons were released. Just because something can't happen des not mean that it won't happen.

But the best way to diagnose a problem is to be able to understand how the process is supposed to function, and then observe how itis actuallyfunctioning, and then figure out why the two are different. That method is fairly different from thesymptom-look-up-table method of service diagnostics, which can be useful for service people wo have no cncept of what the process should be.

RBedell
User Rank
Gold
The missing symptom, maybe.
RBedell   10/11/2013 2:21:34 PM
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The problem is the pressure cylinder extending during start up.  Searching/watching vids on youtube for Biesse edge-banding machines to grasp how they work provided some ideas.  The description mentions two cylinders  but does not clearly describe their individual functions.  But, 'cylinders' implies air pressure.  The videos show that during operation, the pressure roller moves out prior to the wood edge arriving at the roller.  As the wood contacts the roller, it pushes the roll back and that is the 'pressure'.  But, the wood clamped to a track traveling a straight path, Glenn mentions a cutting wheel to trim the edge.  This sets the depth of the edge of the wood.  The pressure wheel has to be depth adjusted for the thickness of the veneer/edging material.  If the rotational axis of the pressure roller extends past the surface of the edging material then the roller will 'catch' the material cause problems.  The pressure roller is a fixed radius; geometry defines the how much farther the pressure roller can extend pas the surface of the edging material and 'ride' up over the leading edge of the material onto the surface creating pressure.  So, how should the depth be set?  With the pressure roller retracted, the depth slide is extended and set such that the roller is on the edging material.  Next, the depth is fixed using spacers; retraction of the depth slide to lock the spacers pulls the pressure roller slightly away from the edging material.  The design would take this distance into account. Now, when the pressure roller is extended, it is a known distance past the surface of edging and can ride over the leading edge onto the surface, pressing the edging into the wood with some leeway for variations in edging material thickness.

So, what is the problem?  Retracting the depth slide against the spacer(s) only makes sense if the retraction remains during operation.  The first problem appears to be in the description: The paragraph four contains descriptions of what is supposed to happen and what is happening.  This makes it hard to separate what is supposed to occur from the problem.  The machine's problem is that during depth setting the pressure roller was not supposed to extend.  The pressure roller was only supposed to extend during production. 

Why is the roller extending during depth-setting instead of staying retracted?  I dunno know.  But, likely this was Glenn's first or earlier jobs where he was not familiar with the machine's normal operation AND the senior engineer blew off Glenn's description because they (senior) never heard of the problem and Glenn is unfamiliar with the equipment and therefore doesn't know what he (Glenn) is talking about.

Radwan
User Rank
Iron
Its easy as its hard
Radwan   10/11/2013 2:10:30 PM
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See i will give you my opinion in this problem its salution in Technical people

in the field and Michanical adjustment will drive you to the diffeclt result you

can solve many practical thing in Electronics desigen then this Mechanical

adjustment,Better to give to its spaciallist and peace your mind and energy

skyefire
User Rank
Gold
Pics or it didn't happen :)
skyefire   10/11/2013 11:12:22 AM
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This must have been before cellphones with cameras became ubiquitous.  I can't even begin to describe how much easier my life has become thanks to these handy data-gathering tools.

That said, I recall having one of these once, except I was the guy on the other end.  I kept getting field reports that a piece of my robot software kept crashing the robot into a structural member under specific conditions.  I kept going over and over my code, and kept finding that event to be impossible.  The kicker was, I didn't know that no one in the field had ever installed the latest revision patch that fixed that problem, and the person responsible for installing that patch had been let go.  So the code I was looking at was not what was running in the machine.

Lesson learned:  always get the actual running code.

skyefire
User Rank
Gold
Pics or it didn't happen :)
skyefire   10/11/2013 11:12:22 AM
NO RATINGS
This must have been before cellphones with cameras became ubiquitous.  I can't even begin to describe how much easier my life has become thanks to these handy data-gathering tools.

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