Z axis hits counter sunk bolt, which backed out- help!

[nailzscott]

I have a PRS shopbot with probably less than 10 hours on it. While cutting out a 5' sign backer out of MDF in 3 passes, the last cut just finished, apparently tried to z up to safe, but could not and cut a 2' slot right across the finished piece. If that wasn't bad enough, I can't figure out how to get to the bolt. The z axis v tracks have probably 6 countersunk bolts bolted from the inside to aluminum block (that all of the rollers are bolted to). Apparently one of those bolts backed out during the final cut of my sign backer and would not allow the Z to travel up very far. Trouble is, I can't see out to possibly get to it. I moved the z stepper motor back out of the way, but cannot get this thing to move up past the backed out bolt. It's one of the middle bolts. Even if I take the aluminum roller mounting block loose, the backed out bolt would not allow the rollers to move past it. I am supposed to deliver the sign backer Tuesday. Any ideas on how to get to the bolt?

[tparr]

I would e-mail SB support with this note to support@shopbottools.com (mailto:support@shopbottools.com) They keep tuned in the off hours.

[GlenP]

Hey Scott, I just went to the shop and looked at my PRS. If you remove the Z assembly from the gantry and then remove the mounting plate you should be able to get to the bolts. Doesn't look like too long or hard to fix. If you do take it apart make sure you use locktite on the bolts when tightening them back up. Other option is too try and find another botter in your area to maybe cut the file to get your order to your customer by Tuesday. Good luck and keep us posted. I am certainly going to keep an eye on those on my machine.
GLen

[nailzscott]

Attached is a picture showing the problem area -looking down on the right hand z track. One of middle bolts holding the track backed out (you cannot see because it is in the middle), impacting the rollers on either side of it. Movement of about an 1" or so up and down - until the bolt would contact the v-roller. The second picture is how I solved it. I temporarily removed the z stepper, and drilled a 5/16" hole directly over the offending bolt, then reached through with an allen wrench to tighten. I checked all the bolts then and found two others loose. Just posting the pictures in case anyone else has the issue.

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