What are common SB failures?

[johnm]

Folks -

The wife and I are thinking of taking the plunge for a 48" SB and spindle. We're looking at everything and the topic of failures came up. Can those of you with some experience here relate what sort of troubles you've had with part or component failures on your SB? If there's some expensive dongle that goes ffffffft! - I'd like to know before we order so we can at least be aware of it. How robust are the motor assemblies, for example? Are there any systemic problems with Columbo Spindles.... like that...

Any feedback would be deeply appreciated.

John

[mikejohn]

John
My experience, and I feel most others are going to say something similar, is the ShopBot is very well built.
I personally had a driver failure after very little use, but we all know chips fail once in a blue moon on any system.
There have been other driver failures reported, but it doesnt seem an overwhelming problem. ShopBot reacted instantly to supply me with the right equipment to get back up running in very short time.
Motors dont seem to be a problem, although dust ingression caused Gerald some difficulties a while back, although he doesnt blame the motor as such.
We router users can not give advice on spindles

My very first impression was how well built and strong the ShopBot is.
You do need to trawl through this Forum to ensure your working methods, and set up methods, avoid potential problems.
You will find differing, and sometimes heated, discussions on how to do things.It appears to me that there are many approaches to working with the ShopBot, often depending on your personal circumstances, preferences, amd what your using the machine for.
Try to spend time reading the Forum. Its a little ShopBot University.
...........Mike

[elcruisr]

After three and a half years of running one and recently two 'bots in a production environment (20,000 to 40,000 parts a year)I can say I've had remarkably few problems. I wore out a 2 z-axis slides on the older style PRT. The new axis is more robust. That was also after around 25,000 parts on that slide. I cooked a driver board once but that was probably due to a lightning strike, we've since taken steps to correct that. I've worn out the occasional pinion gear, easily replaced. I've rebuild the spindle on one and have also purchased a backup as I can't afford any down time when we're really busy. Never had a drive motor problem, had the odd communication issue between computer and controller but that was usually a setup issue not equipment failure. These are fairly simple machines as CNC routers go and hold up very well. I compete against "big iron" in my market and when they break down or have part wear they need the factory techs and big $$$. I just make a call to Shopbot and replace it myself!

Eric

[gerald_d]

John, the guys before me have covered it pretty well. They will probably agree with me if I tell you that you will spend more money on fixing operator errors (ie broken bits and spoiled material) than fixing the machine. Not that we spend a lot on fixing our own mistakes, of course.


PS, John, how are the marijuana leaves and roses doing at your school?

[evan]

John,
I'm in San Rafael, CA and would be happy to let you
take a look at my Bot (an upgraded PRT to Alpha)
if you ever get down this way. Just email me and we'll see about setting alittle time aside.

Evan

[johnm]

Hello All -

Thanks for your remarks - I agree that the SB setup is pretty robust, tho' Eric's remarks about Z axis wear had been something I thought about - for my work, virtually all of the wear would be confined to about a 2" Z path as I'd be working with 3/4" thick material about 99.999% of the time.

I'll be sure to add some $$ for surge supression but that brings me to another question - what do you do for 220V - like with a spindle or 220v router? I've never seen surge supressors for 220 and using a pair of 110's for each leg of the 220 seems klugey..

The production of carved Marijuana leaves has been curtailed - we are in the thick of growing season, so I can only assume that my charges have other priorities during their summer break, um, dude!

The roses are well - but getting the reliefs carved in enough detail to show the aphids is a bit of work, and I guarantee that the SB does NOT like being hosed down with garlic juice, hot pepper powder, hot water and dish soap. The wife used that solution on her roses, but boy do the sparks fly when I give the SB a good soakin' :-)

And Evan - I *WILL* take you up on your offer! I am in Lakeport, about 2 hours North, and 30 years behind San Rafael.

So, for those of you that have had to replace a driver motor, what do they run??

Thanks for all of your remarks!

John

[mikejohn]

John
Go here (http://www.talkshopbot.com/forum/cgi-bin/discus/show.cgi?tpc=26&post=15911#POST15911) to read the saga of blown drivers (not the motors).
You can also read what a wally I am

.............Mike

[dhunt]

Your link to "here" doesn't work any longer but I'll continue with Blown Drivers.
It's my opinion that it's simply too easy to blow a SB driver.
Gotta improve the technology somehow, guys. Gotta!

Today TWO drivers got blown just assembling/setting up a new(2006) Shopbot PRT-96 with fancy new board in the SB 'box' that no longer allows for user-replaceable drivers, it seems. Not good.
We are yet to cut a single thing, and already we're down by 2 drivers.

(In the past too, using another -yr.2001- PRT-96, I've experienced three blown drivers:
it's easy to do, just make a simple mistake and,like the guy above describes it, pffft!)

After the first one blew today,Shopbot Support was very good in setting us right re. using the accessory Channel as a substitute for 1-Red (after tweaking teensty little switches!) - the fix worked and 1-Red was restored so the X-car can now move the way God intended.

Trying the new 'fix' out for the first time. fffft! oops! what was that?
- it was the 2nd. blown driver, on the Y-car this time, just like that!
Are we having fun yet?

Now the board has to go up to Shopbot, from a small Caribbean island not far from S.America,
while we wait 1-2 weeks for TWO drivers to be replaced, hopefully at Shopbot expense!
Support suggested we might want to buy a whole new board from them, at a mere US$500 (cheeaap!)..
..to keep us running, while our blown board goes up to USA for repairs.
At prices like that, we simply can't afford it,sorry. We'll just have to wait it out.

I now live in fear almost, of blowing drivers willy-nilly, given two drivers blown in one day, so to answer you question about an Achilles Heel for the Shopbot, it would be blown drivers at great inconvenience and quite some co$t!

Sorry, I don't mean to sound bitter about this, but I'm getting both weary and wary of co$tly and inconvenient blown drivers.
Other than that, the Shopbot is a fairly bullet-proof machine that may freak you out now and then by jumping the tracks, another minor problem that's FAR less costly and aggravating to fix:
(- you just drop the two X-motors off the racks and two strong guys manhandle the X-car back onto the rails, hook back up the motors, check everything and resume production.)

Buy the Shopbot with confidence: support is excellent,seriously!
Just beware blown drivers.
It may be wise to buy a spare board when buying a new ShopBot,
coz in my opinion, you're going to blow a driver SOME time.
Those of you who've never had That Special Thrill are the lucky ones!

[seana]

David,
Sorry to hear about your problems and the time it will take till you can play with your new toy.

You have me a bit scared i don't want to blow a driver.
Can you fill me (us) in on how yours blew?
Did you give it a bad command?
Was it the same driver both times? (running the same stepper)

Thanks,
Sean

[dhunt]

Oftentimes you're never quite sure just why/how a driver blows.

Warnings are against you pushing either of the cars along their rails with the system up and running, (except VERY slowly)
since the motors generate current running in the other direction,
i.e. back to the driver
- which can(often does?) blow the driver.

No.. it was the channel leading to the far side X-motor (wire lead One-Red),
and the second 'blower' was the channel leading to the single Y-motor
(wire lead Blue)

[phil_o]

I had a problem with my X-driver blowing. It turned out that I ddin't have the wires connecting the motors to the drivers secured properly and when the machine moved back and forth there was a strain on the connection.
I teach high school wood shop. When the driver blew, it happened a few times, I figured that one of my students caused the problem. That's been my only issue and it turned out to be my fault for not properly securing the connections.
The Shopbot is a well built machine. It's been able to hold up to high school students mistakes. I'm buying one for my home shop.

[patricktoomey]

I managed to blow 2 drivers at once with one poorly made (by me) motor cable. I had a short between two wires and took out that driver and somehow another one as well. I will say one thing... although it may be relatively easy to blow a driver on a ShopBot, you do NOT want to see the price of doing that on any other machine! I had the two drivers replaced for $150 and had the board back in my hands 48 hours after I sent it. Do that on a big CNC machine and you are talking mega bucks. For anyone doing production work, I would recommend having a spare controller board. For $500 it makes sense to have it if you're going to lose more than that by being down for a couple of days.

Having said all of this I would like to see the controller separated from the drivers like the Mach/Gecko systems do. If each driver was a discreet box like a Gecko that just plugged in and took power plus step/direction signals we could have spare ones sitting around for maybe $150 each.

[gerald_d]

...less than$150 each, and they are fairly bulletproof. Have made some lovely sparks while "experimenting" with motor cables, but havn't blown one of the little black boxes yet. Actually quite interesting to see how they light up when a gantry is pushed by hand....


The "here" link above goes here (http://www.talkshopbot.com/forum/show.cgi?tpc=26&post=15911#POST15911)

[olecrafty]

If you need to move the carrage by hand turn the drivers off with the (m0) command. This will reduce the chance of a blown driver during manual moves.

Kaiwa
olecrafty@charter.net (mailto:olecrafty@charter.net)

[dhunt]

What about GROUNDING//EARTHING?
How does this affect the likliehood of blowing drivers? Any effect?

How SHOULD one ground/earth a Shopbot?
All sorts of suggestions abound: is there a standard earthing/grounding procedure/rules?

[mikejohn]

David
Look here (http://www.talkshopbot.com/forum/show.cgi?tpc=7&post=37812#POST37812) for a recent explanation about grounding.

..............Mike

[Towersonline]

Sorry to hear about you repeated driver problems. I currently own 2 Bots and have owned 4 of them in the past.
I have not experienced any blown drivers on these machines. I even push the carriages around slowly with the control box off without problems.

I think some of the reason for me not having such problems is the fact that the machines are well grounded and the control box and computer are run off a high quality line surge suppressor. Not to be confused with a UPS they are not the same. I have serviced other machines in my area that were experiencing driver problems. In all cases I found no or limited grounding or ground loops. Could this be your problem? This is only one of many possible solutions. Considering you have had problems on two machines in the past I would look carefully at the grounding and if possible the AC mains into the building. Are the lines noisy? what condition is the service entrance ground in? What is the ground resistance like? Ideally it wants to be less than 25 ohms. In my former career we installed cell phone facilities. The cell phone infrastructure manufactures would not warranty the electronics in the base stations unless we could document less than 25 ohm resistance in the ground system. It was not unusual to pound 15 to 20 ground rods the get there. This might be worth a look. In the US the ground should be near the meter. A word on safety NEVER remove the service entrance ground. This work needs to be done by a qualified electrician.

I don’t know what frequency and voltage your local power utility utilizes. Single phase, 3 phase? I have seen some strange problems when one leg of a three phase line sags in voltage.

Is it the driver that is blowing or the TransZorb’s both types of failures will exhibit the blown driver symptom. One is an expensive fix the other is a 25 cent part that most anyone can diagnose and replace. These TransZorb devices are working right at the edge of their specification. In order to reduce the threat I lowered the power supply voltage by two volts. I noticed no degrediation in performance. I have not seen the newer style control box so, they may not have the TransZorb’s.

If it would help I can e-mail photos of my grounding system.

Sorry if I rambled a bit, just trying to give you some ideas to try.

[dhunt]

No need for an apology.
In fact, Many Thanks for all the helpful hints!!
I'm coming to realize that a cleeean electricity supply wouldn't hurt the beast, would it?!

If your photos are clear(to us!) by all means please do email a few to pcdoctor@sunbeach.net (mailto:pcdoctor@sunbeach.net)

Again, many thanks for your pointers.

[dhunt]

A few more questions..

You spoke about the diode blowing, not the driver.
We're not sure where the diode is: - is it user-replaceable?

I'm posting a pic of our board
to see what 'directions' to the diode you might give us..
(this is not the best picture, but it's all we have for now,sorry)

You said there was an easy way to test it
maybe you can tell us how..

- also, how does one test to see if your electricity supply lines are noisy?
3257

[Towersonline]

David, The TransZorbs are located on the board near the connectors for the motors. Little black devices standing on end. There are 2 for each driver chip. The quick way to test them is to simply clip the lead at the top of the device. Repower the control box. If performance is restored then you have isolated the problem. If not try the same procedure on its twin. If that does not do the trick then the driver is toast. Don't try this if your timid about soldering. I'll post some photos so you can see what I'm talking about.

[gene]

John
If i am not mistaken the alpha's are not as vulnerable to blowing a driver as the older bots are. I have a alpha and as a rule of thumb i Dont move the carriage. the bot does... As compared to the rest of theese guys mine has been a dream not a nightmare. I love my bot I named it pedro. it does EXACTLY what i tell it to and how , all said would i buy it again YES.
Keep in mind you have only heard from a few of us while there are over 4000 sold and its just what my shop needed.
Gene

[dhunt]

Once again, many thanks for all your suggestions,etc.
the only question left to be asked is about the surge suppressor - what type to get?
We are currently using a fairly ordinary store-bought APC powerbar thing which provides six outlets, with a rocker-swith ON/OFF and a green light, and red light indicating site-wiring fault(which we corrected, we found a ground wire broken)- but this US$40-50 unit(cost here on the island) may not be adequate as a "line conditioner".. or is it??

[gene]

David ,
My power co has put a surge suppressor on the lines comming into the shop . i ask if the whole shop is protected and they say yes. that if a spike of lightening strike they will cover the cost of replacement or damages . I pay 9.00 a month for this protection. I dont know if your power co has this . I do recomend some type of protection Gene

[Towersonline]

David, The type we use here is made by Trip-Lite the model is Iso Bar 8 Ultra. I think between the shop and the house I have at least 6 of them. I paid around $80.00 each but, thats 6 years back. The inexpensive ones have a MOV in them for protection. The problem they are a one shot device and when they fail they fail open so you have no way of knowing if your protected or not.

I owe you a photo or two, I'll try to do it tonight.

Bill Thorpe

[dhunt]

Wellll.. we had the Power Co. guys come around to test the existing ground for resistance.
Someone mentioned an ideal of 25 Ohms or less, as a level to hope for/achieve..
PowerCo. guy gets a reading of 225 Ohms, yes that's two hundred and twenty-five Ohms, nine times the allowable level!
And so we are now committed to seriously re-grounding the whole shop,
and then having PowerCo. return to test again, before we hook up and run the Shopbot!

If you've blown a driver or two,
perhaps you should have YOUR ground tested,
as a matter of precaution..

Bear in mind that surge surpressors can only work well if they can conduct that surge safely away TO GROUND..
so if your grounding is pathetic(like ours) the device can't possibly do its job, can it?!

[Towersonline]

David, 225 ohms yikes!!! I would think the power company woudl be responsible for maintaining a reasonable ground. I suppose it all depends where the measurement was taken.

Tell me what your soil conditions are like and perhaps I could suggest a fix.

Bill Thorpe

[dhunt]

AVERAGE topsoil on the Caribbean island of Barbados is 2 ft. - average!
Where the new SB is set up, it's far more likely to be on the order of 9 inches.
Underlying bedrock is limestone(fossilized coral reef,less than 1 million years old)-calcium carbonate,
often quite soft and porous, but sometimes with hard bits here and there, if you're unlucky.

Since 4-6 ft. down seems to be considered a decent ground insert,
it has been suggested to us by local electrical contractors that the best orientation for a ground/earth in our shallow topsoil is to run 4-6ft. of brass rod in a close-to-horizontal orientation, preferably in a wet/damp area for max. conductivity!(local tricks of the trade?)
Paul reckons he has such a damp/wet area identified, and is procuring a suitable length/s of brass stock.
When we're done, the local PowerCo. will be brought back in to test again,
before we resume installation of the SB, bcoz clearly we need to get our electrical act together before we destroy any more diodes,drivers,boards,whatever!

ShopBot service has been superlative,as usual, and we are informed that our repaired Controller board is already en route to us, so we expect to receive it Monday, but before we have another go at it, we have to work on the electrics.

In retrospect, it would seem that, with lousy 225 Ohm "grounding" like we had/have,
that this may have been the cause of our dual-driver-blowout,
or at least one of the causes? Make sense?

[Towersonline]

Wondering why brass? Ground rods are usually copper clad steel. If you’re going to the trouble of opening a trench why not add more! More is better!! Back in my ham radio days we used old automobile radiators. Yes I can hear the laughter now!!

Have you considered a separate ground system for the Bot? My machine is next to an exterior wall so it was easy to run the ground cable thru the wall to the ground rod.

The minimum ground wire size should be #10, my feeder ground wire is #6 but it might be a bit over kill.

I’m trying to figure how to post the grounding photos. With any luck they will be the next post.

Yes Indeeed-- The ShopBot folks are great, they have gone above and beyond for me in the past.

Bill Thorpe

[Towersonline]

3258

3259

3260

[Towersonline]

I was able to post the photos but the text got lost. So, here it is.

The ground wire runs from the Y-Gantry over the wire guide then to the X-Gantry then on to the control box. I bared the metal under the bolts and added external tooth lock washers under the wire lugs.

Note the method I used to tie the motor wires down. Ty-wires on each end of the connectors, hopefully it will prevent a connector separation.

Bill Thorpe

[dhunt]

Bill,
Many thanks for super-clear photos and wiring suggestions!
I LOVE the idea of old automobile radiators for grounding electrics: excellent re-cycling effort!
I'll bet they worked very well.. all that 'mass' underground!

When Paul returns from Saturday Sailing, he'll be the one to get the most from your several suggestions, since he's The Electrical One.

The new (2006) Shopbot comes with those WAGO connectors at/near the motors all beautifully shrinked-wrapped and sealed against dust, in a v.dark grey shroud of sorts: you can't even see what going on under there, but we are confident we'll be having zero dust/connection problems at those points!
- the new connectors under the shrink-wrapping are clearly not your standard bulky WAGO connectors, like those in your pix.

God Bless ShopBot for that(and other) improvements to the design
(the other SB-PRT on the island is a late-2000/early-2001 model PRT,
and the several diffreneces/improvements in design over the course of five years are obvious, and welcome:
- they came as pleasant surprises when we unpacked this new '06 SB!)

[gerald_d]

If you dig a trench to sink a ground rod, a bag of salt will help to form an electrolyte with the moisture that should be there. Also, dishwashing liquid makes the soil more "wettable".

[dhunt]

Funny that you(too) should come with this talk of SALT:
- that's exactly what Paul was told by a local electrical contractor!
Seems to me that it would eventually wash away?

How would you suggest placing the salt?
In a porous bag of some sort?
- or just a great big dollop of it..like 2-3 lbs. of the stuff, just chucked into the hole, around the rod??
In a cloth bag, to help it last a lil longer?

Or does it just bind locally(very locally) with the soil in that immediate area,
and remain forever useful?
Any further explanation as to how salt works to assist a ground rod would be interesting to us all, I'm sure.

Thanks for the tip.
We're on the right track, I'm sure.

[gus]

If you are going to use salt make sure you cadweld all the connections before you salt it down. Salt will shorten the life of your ground rods and interconnecting copper wire or strap. If you need to use salt due to soil conditions then it is something you have to think about. It does have a down side.

This is a good read: http://www.gordon.army.mil/AC/Summer/Summer%2000/ELECGRND.HTM

[dhunt]

Maybe that's why we were advised to use brass, instead of steel?
Brass should last awhile (in a severely saline environment)
- longer than steel would last
maybe we should be going with (expensive) bronze..

Speaking of local soil conditions,
Barbados soils are notoriously alkaline:
- perhaps this factors in to the salt thing...

[gus]

Here is some info on copper alloys and corrosion in various environments:
http://www.hghouston.com/coppers/cu_table2.htm

[dhunt]

Thank you, Ted G.,
for those two interesting links,above!

That military site re. grounding procedures was especially good.

Thanks again.

DH