PRS Alpha shudders

[fredtoo]

My SB is just few months old and now doing well (no comm errors) except for what I would describe as a shudder when I turn the spindle relay control key to the off position. This doesn't happen all of the time but most of the time to some degree. I can't tell if the shudder is in the X, Y, or Z direction and I can't reproduce it by merely moving or jogging around, I need to do an actual cut and then turn off the key for a bit change or whatever. Any ideas what to look for?

[Gary Campbell]

Greg...
Can you explain what you mean by "turn the spindle relay control key to the off position."?
Give the key strokes or mouse moves that you do to accomplish this. Sorry I am not familiar with that particular term.

If you mean the safety lockout on the RBK control box, can you clarify if you deactivated the lockout when the machine was active?

[adrianm]

I have one of the newer PRS Alphas with the spindle safety lockout key and nothing happens to any of the drive motors when I turn it off. The VFD powers down and that's it.

Whatever is happening it doesn't sound right as I probably do upwards of twenty bit changes a day and I've never seen that behaviour.

[fredtoo]

Gary,

I am referring to the safety lockout key on the SB control box. I believe this is a relatively new safety feature which physically attaches the safety lockout key to the collet wrench with a short cable forcing one to turn the key off to use the collet wrench. The shudder (or clunk) typically occurs when I turn off the key to do a bit change. The shudder is sometimes very pronounced and can't be good!

I may need to give Frank at SB a call.

[Gary Campbell]

Greg...
I have seen that in the past, but cant remember the exact situation or cure. I think you are correct, a call to SB tech supt is in order.

[lcolburn]

Greg,

I'd be interested to hear what ShopBot tells you. You're not the only one experiencing this- I get the same thing when I turn off the spindle interlock while the machine is on. Sometimes it's a big shudder, sometimes nothing happens, but I agree it can't be good. Fairly new PRSAlpha, 48x48 w/spindle. Thanks!

[fredtoo]

Unfortunately (or fortunately) I've been flat out and haven't found the time to call SB. Next week doesn't look good either so if someone else wants to call SB support and report in please do.

[plemon]

I get the same violent shutdown when I use the interlock switch but not when I just turn off the main switch. In fact, when I turn off the main switch everything powers down nice and smooth (so I do that all the time now).

Mind you, I'm only new to this game.:D

Phil

[fredtoo]

I'm reviving this thread because I still have the problem and have lived with it due to other priorities. Does anyone have any ideas or should I check in with Shopbot support when I get the chance?

[Brady Watson]

Send an email with your contact information & issue to ShopBot Support (http://www.shopbottools.com/mSupport/req_techsupport.htm)- Do it now...don't let another week go by.

-B

[lcolburn]

I called SB about this problem some time ago- apparently it's a somewhat known problem. The fix was a capacitor installed on the inside of the interlock switch- I think it eases the on-off transition (pardon my lack of specifics here).

They shipped me the capacitor and talked me through the installation- essentially just installing it into two screw terminals on the inside of the interlock. I haven't had the issue since. The folks at SB should be able to take care of you pretty quickly.

[fredtoo]

Thanks, that's great information. I'll check in with SB when I get back off the road.

[fredtoo]

ShopBot Corp sent me a capacitor that mounts on the back side of the key switch and my SB and I no longer shudder when I turn the key off!

Thanks SB!