Mechanical Engraver

[Kathy Madan]

I posted this in the CNC forum as well, but perhaps we have someone who can help me solve this problem. On some letters the cutter is overshooting. I thought it was a dragging cutter, but it is not. I thought it was a bad cutter, but we have replaced it. The only thing left that I can think of is that is is within the engraving head (bad connection) or the screws (slipping). I am using an APEX controller from Newing Hall. Anyone? Thanks

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[Kev Williams]

Notice how the bad spots are always at the right side of the letter? What's happening is your spindle head is moving toward the next letter before the tool has fully lifted out of the way.

Is this an air or stepper motor operated spindle?

If it's air, the spindle is hanging before lifting, probably just need to clean up and lube the spindle, housing and any slides.

If stepper operated, try running the same or similar job with at least .125" of spindle lift. If the 'overshoot' stops, then look at the spindle- it may be loose within the housing and 'floating', or have an internal problem, like a missing clip, etc...

[Mark Sipes]

If the cutter is not lifting fully before it moves to next character you need to increase the up dwell time. If the spindle is hanging. you need to unscrew the silver rotary spindle from the head and clean the bore and spindle. do not oil these surfaces ( it will just gum up ) You might just try to add a few drops of paint thinner on the silver spindle to break the muck up and manually move up and down. Make sure the air plunger nut. on underside is aligned and not binding...... Make sure=the needle valve is not turned in to much. this will hang the air release valve (brass thingy on the top where the air goes in Marked with LCE E= exhaust. make sure it is not installed backwards.... it happens.

[Kathy Madan]

Thanks for all the ideas. I had already checked dwell time, spindle sticking but finally found the problem. The serial cable came into contact with the rotary spindle bands and essentially sliced thru it. All the data was not going over to the machine. (Apparently someone did not tie up all the cables last time we came back from a show ) New cable, tests running, looking good so far.

It is the one thing I do not like about the machine, all the cables are susceptible to this problem. The spindle arm and pulleys are too close to everything else.

[Mark Sipes]

That's one of the reasons a guard was added to the design to encase the drive belts. If yours is an Apex I or II then the belts are exposed. The HPGL received the guard in the third year of production....along with led lighting on the carriage bar.....

[Kathy Madan]

Mark,
That goes to show you just how old my poor machine is, but it keeps plugging along turning out work year after year.