PRSalpha vs. PRSstandard

[beacon14]

A pragmatic attitude and having the spirit of adventure takes care of the rest.

Well said, two characteristics of successful ShopBotters and successful people in general.

[dana_swift]

Mike- you really struck a chord with your discussion of your electronics bench. When I was working as an EE, I occasionally worked with new graduates, currently one of the hot things is "spice", a tool for modeling analog circuts.

The trouble I have with the new EE's is they cant just visualize what a circuit will do in their heads. The dependency on sophisticated tools hides the real world problems like RF interference, ground loops, and poor connections. The ability to imagine the real world a system will run in helps make an appropriate design and then figure out what sub-rule of Murphy's law is in control at the moment.

Murphy's law for spice would read something like: "No real component works the way the model does".

Pragmatic attitude and experience beat a lot of modeling tools. I love the wonderful wizbang stuff we have now, but its just as important to remember that the world got along before it came along.

Now you are making me embarrassed that I actually know math and own one of those fancy calculators too..

I think it all has its place.

Thanks for the thought fodder-

D

[dauntless]

I bought a PRSStandard9648 last year, forgoing the Alpha for cost reasons, and now regret my decision. Mind you, I am carving 3D foam blocks for mold patterns, so I am not straining the machine at all. Still, tool paths are often 20+ hours long and the non-feedback steppers inevitably lose X or Z positioning in spite of slow cut speeds (typically 2 ips), and I end up having to repair and rerun.

In fact, I am cooling off right now in the office after discovering that the bot had lost x-position slightly, and it will complicate finishing this pattern.

And now I want a 12" z-axis, too... ;)

[erik_f]

Is it possible you are having a computer issue or connection issue more than a stepper issue? Just putting it out there. I've only run a couple 3d files and have had what looks like a shift in the model. This I'm pretty sure was due to a somewhat poor connection speed between the bot and the puter.

[dauntless]

Thanks Erik. I can't say for certain that it is not a computer or connection issue, though my installation is very "by the book". How would I go about confirming those factors are up to snuff? Stan

[erik_f]

You may already know these things, so I hope I'm not wasting your time. However, there is a usb connection speed test in the utilities of the control software. This will let you see not only the speed of your connection, but what your actual bandwidth is. I am not an expert on this at all, but I have seen people with as good as an 83% connection, mine so far I can't get above a 75%. 70% is the minimum that SB wants. Also I remember reading there is a file line limitation per how much ram you have. I included a link that helps fine tune your computers resources also. I would hunt around for more info on how to improve your computer/control box connection and also how to make sure your computer isn't getting distracted around hour 10 of a 20 hour file


http://www.talkshopbot.com/forum/mes...312/32195.html

http://www.talkshopbot.com/forum/mes...tml?1215604790

[cnc_works]

Stan, I can't be very much help in why you are having step loss, but I would be very surprised if it had anything to do with your stepper motors capability. I have an old PRT96 and often run it for many hours cutting 3d molds with never a loss in steps. Sometimes I have to flip the MDF over and cut the other side and I am continually amazed and thrilled to see the accuracy and repeatability of my CNC.

So, like Erik, I would be thinking your PRS has other issues causing your loss of position.

Good luck,
Donn

[dauntless]

Thanks for the tips, guys.

Erik, I have completed the steps Joe calls out in his thread, and also unloaded a bunch of unused programs. I also cleaned up the programs that were automatically starting up and running in the background (on startup). My USB efficiency is 73.9%.

I currently have only one ground wire, and will upgrade my bot's grounding today.

I did get a chuckle about the "100,000 lines of code". My current program has 758,000 lines.

[erik_f]

I don't remember the number...was it 100K lines per 256K of memory? I hope this clears up your problem...I know how frustrating it can be when things don't work out after waiting for hours!

[dauntless]

Thanks Erik...that makes more sense. My computer has 1.5 gb of ram, which according to that standard should support 600,000 lines of code. The computer has an unfilled memory slot, so I'll add another gb as insurance.