Drawbar down switch has not closed

[Todd Anderson]

I went out to run some dovetail drawers yesterday and when the router tried to do a tool change I got "Drawbar down switch has not closed. Check to make sure the manual/program switch is set to program..."

I was all geared up to call tech support today, but I tried it before calling and it worked fine this time. I didn't do anything to make it work. I've seen this error flash on the screen during program execution before, but it never stayed long enough for me to read it. Has anyone ever experienced this before? What causes it, and how do I avoid it? Thanks in advance for any help.

[Joe Soto]

Todd, Sounds like an air pressure drop. Be sure your air pressure is not too low or a kink in the line.
Joe

[Todd Anderson]

Thanks, Joe.

I did check that yesterday, and all guages showed normal. 100psi at the machine, and 58psi on the guage when the collet tries to open. Incidentally, I ran the machine for a couple of hours today, and no indication of a problem. I guess that's a good thing, but I always like it when there's a reason!

-Todd

[Pete Riddle]

Todd, Joe,

When you get a drawer bar switch error like that it means the router may have picked up the tool but it didn't pull it up into the spindle taper far enough to make the switch. There is a very small window of time allowed for this to happen, so if the toolholder failed to seat properly right away you can get this error.

I recommend that you clean the taper of the toolholder as well as the taper of the spindle with a *dry* 3M Scotschbrite pad. Do not use cleaners or lubricants as they will only attract more debri.

If you would have had a low air pressure problem the machine would have went into E-Stop and displayed a "Low air pressure/ VSD Fault" error message and it would have shown up on the PLC message screen.

I hope this helps.

Thanks,

[Joe Soto]

Todd, Joe,

If you would have had a low air pressure problem the machine would have went into E-Stop and displayed a "Low air pressure/ VSD Fault" error message and it would have shown up on the PLC message screen.

I hope this helps.

Thanks,

Thanks Pete, I would say you are correct about needing to clean the tool holder and taper, but I turn off my air every night and sometimes forget to turn it back on. The machine will go over the tool bar, plunge, sit a few seconds then the blue screen Todd spoke of but no E-Stop. I just flip the air back on and she continues the tool change. I have the bar style changer so it may be different for the other type of changers.
Joe

[Todd Anderson]

Thanks, Pete. That would explain it. I'll do as you suggest.

-Todd

[Pete Riddle]

Thanks Pete, I would say you are correct about needing to clean the tool holder and taper, but I turn off my air every night and sometimes forget to turn it back on. The machine will go over the tool bar, plunge, sit a few seconds then the blue screen Todd spoke of but no E-Stop. I just flip the air back on and she continues the tool change. I have the bar style changer so it may be different for the other type of changers.
Joe

Joe,

It depends on which model machine you have, the air pressure switch may not be wired through the machines E-Stop circuit. You are defintely on the right track now though.

Good luck to both of you!

[Todd Anderson]

I'm curious, Pete. Why did it work the next day? Is there a time out value for it to reset, or something. I guess I'm wondering why it worked when nothing changed to make it work.

Thanks,
Todd

[Pete Riddle]

Todd,

The drawbar sensors are electromagnetic switches, not mechanical switches. It entirely possible that, even with the dirty tool holder and taper, the toolholder was still drawn up to the bottom edge of the switch window allowing a sufficient signal to pass to the system. This is not uncommon, but the overall problem is almost always rectified by keeping the toolholders and tapers clean.

Thanks,