Old Shopbots

[roy_shimp]

Does anyone else have an old shopbot AND does it seem to run well?

My PRT96 was purchased new in 2000. It has run well, has had upgrades as they became available, had a very picky machinist square and tack weld the y carriage and i have kept up the maintenence (blow off anything with teeth and where dust would gather around spindles and rails).

As i was v carving some copy in marble tile the first name went well as usual, however one of the upper case O's in the next carving took a slant to the left. The image looked good in both the EnRoute previewer and the shopbot previewer. In all six of the 3x12 marble sign plaques, three went well and three each had a single letter slant to the left. The letters that slanted did not have similar xy values. Saw no damaged teeth, all rollers and such seemed good. I don't think the plagues moved during the cutting, i slipped in pieces of business card stock for a tight fit in the screwed down to the table top jig.
Never had this happen before. Have cut many marble plaques, pcd v bit.

So i was just wondering if others had old shopbots that have done anything flukey?
Thanks, Roy

[gc3]

http://www.talkshopbot.com/forum/showthread.php?t=17722

[Brady Watson]

Assuming that you didn't lose steps from pushing too hard or too deep...

It's Winter & dry...static can do some weird things. Make sure your dust collection is grounded using the following EXACT method: Take some .025" MIG welding wire (not flux core) or equivalent BARE copper wire and run it THROUGH your dust hose. Let it poke out of the 4" hose at both ends (just fold it over the end of the hose @ the router end) and connect it to the chassis of your dust collector. This is assuming that you didn't break the grounding lug off of the end of the plug & it is in fact grounded.

-B

[roy_shimp]

Brady
x,y and z = .5 ips
no dust collection on this small job

[Rob Gunn]

Roy, I have the twin to your PRT96 2000 vintage. I have run it for the past 3 years doing 2D and 3D work. Yea its slower than the new machines but its still dependable (and paid for). The only issues I ever have with it is when static builds up. I do need to add a few more grounding cables and run a dedicated earth ground to the frame. ANYTIME I have ANY issue it is always due to static.

[roy_shimp]

Rob - please explain "add a few more grounding cables and run a dedicated earth ground to the frame". What is an earth ground? What would be a step by step? Thanks a million. Roy

[Bob Eustace]

Assuming that you didn't lose steps from pushing too hard or too deep...

It's Winter & dry...static can do some weird things. Make sure your dust collection is grounded using the following EXACT method: Take some .025" MIG welding wire (not flux core) or equivalent BARE copper wire and run it THROUGH your dust hose. Let it poke out of the 4" hose at both ends (just fold it over the end of the hose @ the router end) and connect it to the chassis of your dust collector. This is assuming that you didn't break the grounding lug off of the end of the plug & it is in fact grounded.

-B

Just to clarify Brady. Are you leaving the router end free and not attached to the frame of the Shopbot at all? At the DC end are you connecting to the frame as well as having the DC connected to earth via the mains plug?

[roy_shimp]

think i'm gonna regret asking "what is an earth ground (grin)"

[mark_stief]

Just a copper round driven into the ground When ya don't know ya ask

[Rob Gunn]

Take a look around your power meter, I would assume you will find a copper rod driven into the ground somewhere near. That is a earth ground for your home power supply. Basically what I would recommend is another rod close to your ShopBot that you can run a copper line to and "Ground out" the frame. Attached is a diagram of what it looks like. I would also recommend that you install a copper wire inside your vac hose and then tie this all together. The end result is that any metallic object on you machine has a direct path to the ground rod. When in doubt, add more grounding wire to any joint or connection of the frame. One hidden area that I have found in other equipment is the bearings that travel on the rails, these may not always allow the static to travel through. The oil inside the bearing may act as a insulator. You would assume that a metal to metal contact will always conduct the static but sometimes it can fool you. As I always say "when in doubt, add more".
More info can be found : https://www.google.com/search?q=eart...&bih=977&dpr=1