Help evaluating a possible Bot purchase

[scoop113]

Hello folks,

I'm a new member considering the purchase of a used Shopbot. The owner has very little information on the machine; I believe it is an early PRT.

He acquired it used for his business, but then found someone with a laser cutter that could do the work more cost effectively, so he never did anything more than fiddle with it.

He says he can't demo because the computer isn't working. I want to propose that I provide a computer for a test drive, but I know nothing about the machine and wouldn't know where to begin.

I know I can download the control software here. But once I get the computer hooked up what should I do to check that everything's working? Or is this too complex a request?

All help is appreciated.

Regards,
Mike

[phd1658]

Mike,

Where (town/state) is the machine located? You might be able to get someone to check it out with you.

[myxpykalix]

depending on how old it is it should plug right into your usb port on your computer.

Download the control software, plug it in but you need to FIRST turn the machine on THEN start up the software. In that order.

[scoop113]

I suspect it is pre-USB, but I didn't examine the computer connections very closely.

Is there a way to determine the machine's vintage? I suspect it's about 10 years old. The copyright date in the manual is 1999-2000.

Also, is there a way to determine whether the board has been upgraded to 4G? It looks like someone's been messing with the box; it has no back cover, just clear packing tape to keep the dust out.

As far as location, no offense, but I don't want to give out too much information lest it be snatched out from under me while I dither about.

[srwtlc]

It most likely uses a serial connection. The back of the older control boxes were wide open (just a computer case). I don't know the motor numbers, but look to see if they are the direct drive ones. My 2000 PRT was direct drive and I later switched to 3.6:1 gear box motors because of the poor cut quality with them.

[mikek]

Mike, the 4G upgrade should look like this. The black drivers are Geckodrive stepper drivers (manufacturer).

http://www.shopbottools.com/PRT_4g_Upgrade.htm

http://www.geckodrive.com/products.aspx?n=540837

[scoop113]

Here's a couple of pictures. It looks like the motors are geared? (If you can't read the label, the model number is Vexta PK296A1A-SG3.6) Is the bottom photo a vacuum pump or dust collector?

Any guesses on how much this machine is worth?


6764

6765

6766

[scoop113]

Also, the connector between the computer and the controller is a serial connection. After looking at Mike Kelly's links, I assume that rules out the 4G board since that has a USB connection?

Sorry for all the newb questions, and thanks for the help.

[zeykr]

The bottom pict is a vac pump. Looks to me like a prt of around 2000 vintage with a steel table built from the plans. The motors are geared.

[scoop113]

Hi again folks,

So I went back out there this morning and hooked up my own computer.

I didn't try to cut anything, because I don't know what I'm doing. But I was able to get the Bot to move in all three axes as well as doing a couple of circles.

When doing the circles, it made a noise that was different then when it was moving in only one axis. Not alarming, just different. Is that normal?

Also, now that I know the controller, motors and router work, are there any other pitfalls I haven't addressed? Or am I safe in assuming this is a working machine?

Thanks again,
Mike

[jerry_stanek]

did you use usb or serial to connect? what version of the SB software did you use?

[scoop113]

It's a serial connection, and I used version 2.39.

[ron brown]

Mike,

That machine will have many hours of practical use still in it! But, what is it worth - and what is it worth to you is getting personal.

It can be upgraded to "4G" for "$X". But, do you need the speed and power?

Most CNC machines will 'sing a song' when cutting. The noises you are hearing are probably normal and most likely it is a working machine.

I'll guarantee you will learn a lot if you buy the machine. You will possibly learn more than by buying a new machine. ShopBot support is great even on 'old iron' and it takes a good while before most are up to speed with any machine.

Good Luck,

Ron

[jerry_stanek]

Ron is right about the learning. I bought an old PR and ran it for 6 months then upgraded to the 4g that made it like a totally new machine for me. I still own that unit and use it but I bought a newer PRS and I am happy with it. I tried cutting the lithophane on each and found the PRS just a little faster but not any better than the PR.

[richards]

Shopbot sells a variety of controller options for those who want/need to upgrade the electronics. You can select a single card that you install in a controller board of your own manufacture or you could go all the way and buy an Alpha controller. In between those two options are several other levels of parts or complete controllers.

If none of those products meet your needs, you could build or buy your own controller.

A machine that is mechanically in good shape (and one that is priced right) could be used for years and years. A vintage Shopbot can be modified to do just about anything that you would expect a newer model Shopbot to do.

My "heavy iron" PRT-Alpha produces parts that are very nearly equal than my good friend Jeff's "lightweight aluminum" PRS-Alpha. I would say that the parts my machine cuts are better. Jeff would say that the parts that his machine cuts are better. The truth is that both of us are nearly blind, so we can hardly see what we've cut, much less know whether it is a quality product.

[jnbish]

However I am quite certain that I would beat you in a foot race!

[gc3]

...Jeff is that a foot race to the EMERGENCY STOP...





Gene Crain
www.plantasymaderas.com (http://www.plantasymaderas.com)

[scott_smith]

Looks like a good machine depending on the price. Only bad thing I can think of is that ShopBot added output protection to the motor drivers around 01 or 02. My Bot’s an 02 and I can replace the protection diodes for $1.50 in 20 minutes rather than sending the board into Shopbot to replace the driver chip. I can give more info on them but searching the forum I couldn't find my old post on the change.

That vacuum pump looks like it may be 3 phase. You may want to ask if you don’t have 3 phase power.

[scoop113]

Well, after all that time, trouble and research, the owner decided to barter the machine to someone else, even though I agreed to his asking price.

After 10 years of fantasizing, this little encounter (plus all the great support here) has really solidified my desire for a Shopbot.

So if anyone knows of an older PRT machine available at a good price, let me know.

Thanks again for the help. skoop113@yahoo.com (mailto:skoop113@yahoo.com)

[myxpykalix]

keep watching the "For Sale" section they come up all the time. Who knows a better deal might come along!

[bcammack]

They've turned up on craigslist from time to time as well. Never hurts to check the listings in your geographic region once or twice a week.

[scoop113]

Brett,

Craigslist is actually where I found this one. Five minutes from my house, no less. Made it seem pre-ordained. Not likely I'll find another so close, but I'm looking.

Mike