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Thread: When is old too old? 2004 Shopbot PRT

  1. #1
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    When is old too old? 2004 Shopbot PRT

    Ever since dabbling with a used CNC shark(and immediately selling it) 10-12 months ago, ive been on the lookout for a 'real' machine at the right price. Even going so far as to sell my restored Powermatic 72 to free up shop space and shop money for such a machine. The saw is out and im living just fine the last two weeks with the Felder saw/shaper as my only table saw. My local CL had a shopbot pop up that is pretty old. A 2004-2006 machine that is a PRT model. I think its listed at $4,500, which isnt exactly a smokin deal, but it made me wonder at what point is this machine worthwhile? $2,000? Less? What are pitfalls with older machines where they become almost value-less? I know controllers are expensive components to keep an eye out for. This specific machine has the updated controller that is a couple years old at this point, and not much of a worry. Is it possible to wear out rails or ball screws/lead screws enough to matter? Im not necessarily pursuing this machine, but it had me wondering and wanting to start this thread about older 4x8 machines. Ive seen a couple over the last year and they appear like 'OK' deals close to my budget, but i dont know enough about CNC routers to appreciate their used value. For example, its hard to wear out a table saw, or for a table saw to become obsolete compared to newer models. Quite the opposite, actually. In the case of this Shopbot, i feel like a new $7,000 Avid CNC kit would smoke the PRT.

    Even though this isnt the greatly improved PRS model, im guessing this steel frame provides enough rigidity for most of the cuts i would want to do. The CNC shark had the structure of a wet noodle. What is disappointing is this PRT has a PC router as a spindle, maybe NEMA 17 or less steppers, and an outdated software package. These are most likely critiques leveled against most mid-level machines that are 10+ years old. With that in mind, is there a specific point where CNC routers became more affordable/better designed etc? Knowing the very little i know, it seems like frame/gantry designs from 2008-2010 are still relevant and potentially still in production today. This is me looking at companies like Shopbot, Camaster, Shopsabre etc.

  2. #2
    Yes you could find worn out bearings, lead screws, etc depending on how much it was used and what kind of maintenance it has had. The gantry and frame should be good but you would probably be spending a decent chunk of change updating all of the electronics. You are probably right about the Avid compared to an old Shopbot. If the tariff wars would ever end with China I would suggest looking at a Chinese machine. I got a 4X8 that is built like a tank and it cost less than the Avid machines. You just have to be careful about buying really old machines because they can seem like a good deal and turn into a money pit fast if you don't know what you are looking for when inspecting them.

  3. #3
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    This brings to mind my first experience with commercial sewing machines. I was on the lookout for something fairly heavy duty to do some automotive upholstery work. After some research, I found an older Singer model with the "kick-foot", which sort of mimics the "walking-foot" functionality. I found a decent machine on Craiglist, the seller demonstrated it, and I ended up buying it for $400. I got it home, attempted to sew some samples, and it kept bunching up the thread and clogging the machine. I fiddled around for weeks attempting to set the timing, make adjustments, and so on. I eventually gave up on this machine and gave it away to a friend. I then did some more research and ended up buying an brand new Seiko (made in Japan) commercial walking foot machine for $1200. What a joy to use! After watching may Youtube videos about using these machines, one of the experts had some good advice. He said, "if you want to learn how to repair a commercial sewing machine, buy a used one. If you want to learn how to sew, then buy a new one" (and he was using and recommended the Seiko model that I ended up buying). I would say the same thing - to a certain extent - about some of the older cnc routers. If you want to learn how to trouble shoot the electronics, replace controllers, upgrade software, etc. then one of these might be for you. Of cousre there are may exceptions - for example purchasing a well cared for older Camaster, etc. In my case, I opted for purchasing a brand new Avid CNC router - and I don't regret it one bit. I think it all boils down to what you think your time is worth.
    David

  4. #4
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    Used machines can be a good value...if they are "more recent". I'd be truly uncomfortable with a CNC machine from 2004. The whole industry has come "leaps and bounds" forward since then. Knowing how a machine was employed and worked is important information...buying a one-owner, more recent machine that's offered because that owner needs to go bigger/heavier or because they are not using the machine as anticipated at least provides more recent history. Most of the used action I've observed on Camheads, for example, (the Camaster forum) has been the former...folks who have a 4x8 and are upgrading to a heavier/bigger machine. I suspect the same is true for ShopSabre, also made in USA like Camaster.

    I will say, however, that AVID has some very nice offerings including for those who need the flexibility of getting a big machine into a space with small openings as long as they don't have heavy production needs where a more industrial machine is indicated. US company, too.
    --

    The most expensive tool is the one you buy "cheaply" and often...

  5. #5
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    For 2 grand I would jump on the ShopBot PRT, especially if it has a controller box is only two years old.

    There is a thread here documenting a rehab I did on our local High Schools ShopBot PRT a few years ago. BTW they use gear rails not ball screws.

  6. #6
    Is it under power where you could run some test parts on it for a bit?

  7. #7
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    This does not sound like a difficult decision. If you are comparing an AVID kit to used, I assume you are up for the challenge of the build. In that case, starting out with a decent steel frame makes sense to me. Maybe the electronics turn out fine, but worst cast scenario you throw away the electronics (or sell), and put in new. The most common problem for end users and old equipment is how you get information to/from the computer, software, and the operating system (windows 7?). Even if you swap out the electronics to what you want I doubt you will be far off the AVID cost (assuming $2k+- price) and you have a decent frame. The router/spindle debate boils down to the runout you can live with as well as the noise. I like my spindle, but tons of hobbyist's use routers. The gears and rack used on the entry level machines are not expensive. You can find much more expensive rack and pinions, but most of the time those are on industrial machines. If it turns out your guiderails are worn out, you can import new HIWIN guides easily from China.

  8. #8
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    Nice, Keith, I will definitely search for that thread and give it a thorough read.

    No, id rather be cutting material and making things than jerking around with a machine. I put up with it as part of the initial purchase because i typically buy low, but after that i dont need a reocurring headache.

    Yes, Jim, exactly. I am curious if there is a point where the industry turned a corner and experienced that 'leaps and bounds' growth? It seems like the last 5-7 years were full of proliferation of different makes/models alongside a steep decline in price. Im not a huge car guy, but its hard not to notice how incredible the last decade has been for performance in vehicles. As an example, i currently drive a mid-size SUV that would beat a mid to late 2000s Aston Martin DB9 or Ferrari F430 in a quarter mile drag race. Thats astonishing to consider. Comparing cut rates etc. I feel like the last 15-20 years of CNC routers are very similar. Its partly why i referenced a 'budget machine' in 2020 as a comparison.

    This guy is asking $4,500. After this brief discussion, i feel like its worth looking at it and throwing him an offer. I doubt he sells this quickly.

  9. #9
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    I missed the almost new controller earlier...so Keith has a good point.

    As to the industry, controller technologies have come a long way, steppers and servos are better and have come down in price a little, there are more choices for spindles even for the hobbyist so the screaming router can go away, etc. And, of course, software really has a lot more capability now than it did a few years ago.
    --

    The most expensive tool is the one you buy "cheaply" and often...

  10. #10
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    Quote Originally Posted by Patrick Kane View Post
    i currently drive a mid-size SUV that would beat a mid to late 2000s Aston Martin DB9 or Ferrari F430 in a quarter mile drag race.
    With the Ferrari F430 weighing in around 3000 lbs with an estimated 500 HP and 6-speed transmission, 0-60 in 3.6 sec, top speed of 196 mph, I am impressed with the performance of your mid-size SUV. Which specific make and model did you say you drive?
    David

  11. #11
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    Quote Originally Posted by David Buchhauser View Post
    With the Ferrari F430 weighing in around 3000 lbs with an estimated 500 HP and 6-speed transmission, 0-60 in 3.6 sec, top speed of 196 mph, I am impressed with the performance of your mid-size SUV. Which specific make and model did you say you drive?
    David

    My bad, it is the F430 Spider that does a quarter mile in 12.3 seconds. Im assuming the convertible version is slower. However, the real point i was making is 10-15 year old supercars and SUVs shouldnt be in the same sentence, but they are now. It seems analogous to the industrial CNCs around the turn of the century to 'hobbyist grade' stuff of today.

    I drive a 2020 X3 m40i.

  12. #12
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    Your analogy is spot on. For example the NEMA34 motors that came on an old PRT had low power, high inductance, and generated a lot of noise and heat, especially in the drive. Modern NEMA23 motors have 3-4, maybe even 5 times the torque, are quieter, smoother and generate much less heat.
    Gary Campbell
    CNC Replacement & Upgrade Controllers
    FabMaster ATC-40 Bridgemill

  13. Nothing wrong with buying used older machines...most are better made anyways and you will save a lot of money...cnc machines can hsve several decades of life and can be easily repaired in the future if needed...ive got several 25yr okd cnc that are better made than anything new and i got for cheap....new is not always better.

  14. Wrong...older machines are way more reliable and will outlast all the cheap china junk made today . The singer sewing machine will last 100yrs or more the chinese seiko sewing will last maybe 1-10yrs if u lucky and stop working due to mechanical or electr failure...which is common in modern made chinese products..

  15. #15
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    Jeremy, the OP isn't comparing to the cheap imports...the ask is about an older ShopBot (which there are acknowledged challenges) vs modern ShopBot, Camaster, ShopSabre, etc, which are all USA-made machines.
    --

    The most expensive tool is the one you buy "cheaply" and often...

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