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=earth+ground+rod&source=lnms&sa=X&ei=FubeUpykJKrJygHy54HYBQ&ved=0CAYQ_AUoAA&biw=1920&bih=977&dpr=1

[roy_shimp]

Thank you.

[Brady Watson]

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?

Yes. Think 'antenna'. You want that bare wire to act as an antenna to wick up the static charge in the dust hose. If you connect it - "the path of least resistance" may very well be one of your prox switch wires or some other low volt wire that a high voltage static charge can 'stand on'.*

*If you have a guy with a 100 watt HAM or CB radio and you only have a 1 watt radio - If you both talk at the same time - Mr. 100 watt will 'stand on' your 1 watt signal and nobody but those in the room you are in will hear you! Same with static - higher voltage trumps lower voltage and false triggers are likely to occur.

-B

[roy_shimp]

... to all of your help. Got it grounded. thanks again.

[SAR Monro]

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

Question for you, our collector is on wheels (a Grizzly 5HP) We're having tool stop issues every time we run it. It's grounded to the chassis of the collector, but that seems pointless since the collector isn't truly grounded (except internally at the 220v outlet). Where else should I be running the collection hose ground? If I run the bot w/o dust collection, it will run all day cutting PVC. Add the dust collector and it will tool stop every time about 20% into the job.

[bleeth]

Matt-Try continuiing the ground at the collector to an earth ground. Could be at the hook-up in the DC or at the wall receptacle, or if you have a commercial wiring setup with grounded galvanized EMT to it or the ground lug inside a wall box.

[SAR Monro]

I have the option of going to the ground in the 220 receptacle or to the earth ground right in front of the bot. It seems to me, if I go to the earth ground at the bot, it could just loop....but I could be wrong (and most likely am).

I didn't want to go to the 220 ground without checking since I am electrically challenged.

[joe]

Some materials seem to create static electricity on their own. For example if I take a hand router with my 1" PVC the waste sticks to everything. I mean everything. I've wet the material down with no success. Can't imagine what this does in a vacuum Pick-up.

With all the static problems it seems to me the Vacuum is the major problem. At one time we wound copper around the vacuum hose and grounded it. On my last SB I grounded everything. Even the 3' copper rod in the ground. Still there was problems. Wish I knew a quick fix but it seems to be the nature of the animal.

[khaos]

Did grounding solve the issue?

[bleeth]

Matt:
It doesn't matter where the earth ground is physically as long as you DON'T ground the DC ground wire from the bot end to it. Since it seems your DC is away from the bot, I would connect the wire in your DC hose at the DC end. Winding a wire around a DC hose cannot solve the issue. The DC ground wire MUST go though the DC hose. THAT is the nature of the beast.

[joe]

Joe

Nope I never found a satisfactory solution.

[SAR Monro]

Did grounding solve the issue?

I haven't had time to work on grounding to the receptacle, for now just running PVC with no collection.

My ground wire is run outside the hose and to the earth ground. I also have one inside the hose grounded to the DC chassis. Could the outside ground be causing the problem arcing back to the bot since the bot also goes to that earth ground?

[Brady Watson]

Ground needs to be INSIDE the hose. Bare copper wire - INSIDE - just a flappin around. Terminate it on the DC side to the chassis. Putting any wire outside of the hose or thinking that the structural wire wrap for support is enough will not be adequate.

Electricity follows the path of least resistance. Bare copper wire (.025 non-flux copper coated MIG wire is fine for this).

-B

[SAR Monro]

I took some time this afternoon and extended the ground (inside the hose) from the chassis of the DC to the ground on the 220 outlet. I also completely removed the outside ground off the hose to make sure it wasn't getting back to the bot at the earth ground.

So far, I've run 3 full PVC jobs with dust collection and no tool stops. It looks like it might be fixed. Now on to the 100,000,000 other things I need to learn about this machine.