Looking at older used shopbot - what should I look for?

[aschutsky]

Hi all,

I've been looking for a used bot for a few months now and I've found an older 48x96 model somewhat local to me. I don't yet have the exact model number but the owner believes it to be from 99-2001 timeframe. I'm assuming this is either a PR or PRT (older) model. I'll have more information when chatting with the owner later today but wanted to get some insight from you all first. The machine will be usually basically as a hobby for myself and projects for friends/family.

Questions for the experts:

1) What potential issues should I look out for?
2) If all goes well, what should be my first upgrades in terms of value? What can I expect to spend to get everything to spec? I'm fairly handy in terms of ability and toolset.

Thanks for your time!

Andrew

[jerry_stanek]

What do you plan on doing with it? Ask what control box it has?

[aschutsky]

Mostly carving up some 3/4" and 1/2" ply to make some DIY speaker boxes, cabinets, furniture, signs, etc. Mainly just for fun but would be nice to turn some small profits eventually.

[aschutsky]

Confirmed it is an older PR96 with original electronics from the seller.

[jerry_stanek]

Call Shopbot and see if they still have the 4g upgrade. I had an old pr and did the upgrade and the machine was like a new one to me. I could cut at 4.0 IPS without losing steps. It also was more accurate and I could run the newer software.

[myxpykalix]

You may want to have him take some pictures of the model numbers on the stepper motors, the control box, open up the control software and see what version is running it and post some of that here. The more mechanical technical guys who may have upgraded from similar situations may have good insight as to whether the cost of the unit plus the cost of upgrading would make this a good fit for you.:D

[aschutsky]

Call Shopbot and see if they still have the 4g upgrade. I had an old pr and did the upgrade and the machine was like a new one to me. I could cut at 4.0 IPS without losing steps. It also was more accurate and I could run the newer software.

Thanks you Jerry. I will call and check on the cost for the 4G upgrade.

Is the Z on the original PR a ball screw design as well?


You may want to have him take some pictures of the model numbers on the stepper motors, the control box, open up the control software and see what version is running it and post some of that here. The more mechanical technical guys who may have upgraded from similar situations may have good insight as to whether the cost of the unit plus the cost of upgrading would make this a good fit for you.:D

Great, thank you! Will be chatting soon and will post more info as soon as I receive it.

[jerry_stanek]

Yes the original z is ball and screw. I didn't change that when I had mine. Check out some of some of the stuff Gene Crain does with his PR.

[rb99]

Yes the original z is ball and screw. I didn't change that when I had mine. Check out some of some of the stuff Gene Crain does with his PR.

Gene has a newer Z, not the old ball screw.

[curtiss]

as before...

It would be nice if ShopBot would create a "small history section" of various ShopBot models / with photos as to how the machines have evolved.

[chiloquinruss]

I believe if you call ShopBot and give them the serial number they can answer a lot of your questions. They give great support even on older machines and second or third owners. Russ

[aschutsky]

Was not able to get a serial number but the steppers are PK268-02a orientals.

[Brady Watson]

PK268 motors are Nema23 size - The PRs used these on the Z axis, but Nema34 size - like the newer tools on the X&Y.

Is this a rack & pinion machine on the X&Y - can you see a gear rack stuck on gold utility strut? ...Or do you see cables?

How far from Thornton is this machine? Can you post a few pics?

-B

[aschutsky]

Brady - I'm a good 2.5-3 hours away. Here are the pics I've seen so far - attached. Thanks for the help and for taking a look.

I don't mind spending a little extra to get what I want - a reliable, fairly efficient machine that will be more fun than trouble.

[gc3]

looks to be rp driven with gear boxes...get the 4g board and a prt z, put .125 thick angle iron on the unistrut and you'll be good to go

[Brady Watson]

Yes - that is a rare bird. It is a PR, but they only made them with belt reduction boxes for a short time. In many ways it is better than the PR with Nema34 motors and straight geared gearboxes.

Machine looks good from what I can tell, has factory steel table (option back then) but I would take it off the casters and make sure it is dead level.

Do the upgrades that Gene mentioned and it will work well for you. Just don't expect it to cut as fast as a newer tool since the chassis and gantry aren't stiff enough to handle high speed machining.

-B

[aschutsky]

Thanks very much again guys for the input. I spoke to a tech at shopbot about 2 different options for upgrade:

1) 4G board only upgrade (with drivers of course) $1495
2) RBK complete control box with new aluminum enclosure, which would allow for spindle control as well. $2695

As I understand it, both options would allow me to use USB to control the system vs. parallel. Would my capability for cutting speed and resolution be the same for both options?

[jerry_stanek]

It doesn't have a spindle and the 4G is capable of using a relay board to turn spindle on and off. I had a PR just like that one and with the 4g it was a very good machine. The 4g is the first upgrade that I would do and then the Z. Did they offer a rebate for your old controller card. I know I got one but that was a few years ago.

[aschutsky]

It doesn't have a spindle and the 4G is capable of using a relay board to turn spindle on and off. I had a PR just like that one and with the 4g it was a very good machine. The 4g is the first upgrade that I would do and then the Z. Did they offer a rebate for your old controller card. I know I got one but that was a few years ago.

Didn't mention anything about a rebate, so I would assume not in that case. So the only advantage to the dedicated enclosure in the RBK is relay control and getting a nice shiney new enclosure?

Speaking of spindles - I'd very much like to use a hitachi VFD and a 2.2 Chinese spindle that I had already ordered from another project. Is that possible with this unit? Does SB sell 80mm based tool holders?

[jerry_stanek]

I don't think the spindle control that Shopbot will operate that setup. You will get a new case with the 4g upgrade but it will look like a tower computer case also you will get new connectors and I got a new E stop.

[Brady Watson]

You'll be fine with the 4G setup in an ATX computer case. You'll need the 5&12 volts from the power supply. You'll also want a 48-70v DC power supply for the stepper motors. SB can sell you one of them as well or buy one on Ebay etc.

You can run that spindle on that machine, but you cannot control it from the PC. No big deal - adjust it from the keypad on the VFD.

SB sells mounts for both the PorterCable 7518 & 690. I don't know the diameter, so do some research and find out. 7518 for gantry tools. 690 for Desktop tools. It should be possible to adapt the latter to a gantry tool - or buy an 80mm mount from K2 or something.

-B

[aschutsky]

You'll be fine with the 4G setup in an ATX computer case. You'll need the 5&12 volts from the power supply. You'll also want a 48-70v DC power supply for the stepper motors. SB can sell you one of them as well or buy one on Ebay etc.

You can run that spindle on that machine, but you cannot control it from the PC. No big deal - adjust it from the keypad on the VFD.

SB sells mounts for both the PorterCable 7518 & 690. I don't know the diameter, so do some research and find out. 7518 for gantry tools. 690 for Desktop tools. It should be possible to adapt the latter to a gantry tool - or buy an 80mm mount from K2 or something.

-B

Brady -

Understood with the spindle, I'd be fine with using the VFD for speed control. I'm sure I could find something from K2 or CNCRP that might be able to hold it in place.

For the power supply - It was my understanding the original power supply has adjustable voltage out and with the new board it could be set to somewhere around 48V. Is this not the case? Or is it just easier to use a new PSU?

[Brady Watson]

Some of the PR power supplies were 24-28v. If you have one that can be dialed up to 40+v you'll be fine. Otherwise, a newer power supply would be in order.

-B

[jerry_stanek]

My upgrade came with a new box with everything mounted in it. I just had to replace the Wago connectors at the control box and cut the yellow and I believe white wires and make sure they don't touch each other. Load the new software on my computer and run the firmware. I had to change my values by about 10x

[aschutsky]

Some of the PR power supplies were 24-28v. If you have one that can be dialed up to 40+v you'll be fine. Otherwise, a newer power supply would be in order.

-B

Got it. The power supplier are cheap enough anyway so no big deal.


My upgrade came with a new box with everything mounted in it. I just had to replace the Wago connectors at the control box and cut the yellow and I believe white wires and make sure they don't touch each other. Load the new software on my computer and run the firmware. I had to change my values by about 10x

That would be great, although when I asked they said I would pretty much just get the board.

As of now I will see what I can swing on this machine and go from there. I assume things like bearings in the rails would be a relatively inexpensive fix if it came down to it.

[jerry_stanek]

I would check back with SB and let them know you don't have the case with the power supply for the board.

[steve_g]

I believe it’s the RBK upgrade that comes with a new case…

SG

[Brady Watson]

I believe it’s the RBK upgrade that comes with a new case…

Ed Zachery. No case or PS with 4G upgrade. Only RBK is available with case & power supply installed already.

-B

[aschutsky]

Unfortunately this machine sold before I was able to go check it out in person. Thanks to all for the help and guidance, it will be put to good use during my search.

Cheers!