Hello all,
My name is Jeff and I'm a foamyholic.
I've jumped in head first,and pre-ordered the MKII. I know practically nothing about cnc machining, and have some questions (hopefully not too dumb) about operating the MKII. I have been reading the forums, and have learned more about cnc (and computers) in the last 2 weeks than I had in the last 20 yrs.
I have read that most laptops are incompatable with the Phlatprinter because there is no paralell port on them. I've also read that something called the ''Smoothstepper'' might be a possible solution. My take on the Smoothstepper is that it has saved some butts, but would still be a limited solution for the MKII, because of the speed of the MKII.
I would like to use my laptop for design, and dedicate a cheap desktop to running the MKII. Is this a good plan, or am I way out in left field here.
Hopefully my questions (and spulling) are bearable.
Thanks in advance

Jeff

 

Yeah, laptops don't put the voltage out thru a usb adapter, i use my main pc to do the design work and share a folder on my network to transfer over to the cutting pc.
A smoothstepper will prob cost you more than a cheap used pc anyways so i would find a used pc and give her a go.

P.S. I am jealous, you got a MKII coming

 

If cash is no object, the smooth stepper is the way to go whether it be a desktop or a laptop! If you need to, you can also power it with an external 5V source.

The smooth stepper generates the pulses independantly of the PC. I watched one of these puppies running a mill from a laptop a couple weeks ago and was quite impressed. I just ordered one for myself earlier today.

Even though I have a dedicated 2.8 mhz computer, it sometimes cannot keep up with a 1200 IPM machine. It does not take too many wasted sheets of $10 foam to convince me to spend a few dollars more to eliminate issues that I can. 17 sheets of bummed foam would pay for the smooth stepper. I have already toasted 2 so I decided it was time to make the investment now before I ruin any more foam.

By the way, I don't have an MKII. I have a modified MK1 (282 oz/in steppers) with the belt drive and I am able to achieve unbelieveable speeds. Moving foam at 1200 ipm requires a lot of step pulses and the smooth stepper is perfect for this.

 

Wow !! 1200 ipm !!

I am going with the stock gear for now. The vids of the MKII at 400 ipm impressed the heck right out of me, but 1200, holy moly, I just woke up and my brain can barely wrap it'self around typing. Does the cut quality suffer at all at 1200 ipm ?

Thanks

Jeff

P.S. Jeff Has the golf dome in Columbus been rebuilt yet ?

 

1200 ipm is the rapid move speed to move from part to part. I slow the feed rate down to 250 ipm for FFF actual cutting and I set it to 80 if I am cutting Depron just to make sure I have nice clean cuts.

 

Yes, it is rebuilt although i never got a chance to fly in it since it was, there were only a couple weeks before all them dang golfers showed up wanting it for themselves.

 

Jeff - I think I'm the only person here using a SmoothStepper to drive my PP, so I can give you some personal knowledge.
For the most part, the fact the SmoothStepper is inline with your controller board is invisible, with the one exception of the "Motor Tuning" screen in Mach3. With the SmoothStepper inline, it disables the up / down arrows when you are in that screen, so you can't "slide" the motor speed up or down and witness the effect "live". You must make a change to an axis, save it, edit any other axis if you wish, then save and exit the "Motor Tuning" screen. Then the arrow keys and "Page up" & "Page Down" keys work like normal so you can test the settings you just made. If everything is okay, go through the whole process again with increased numbers, then save, exit the screen and try the new settings. It's a bother of which Greg at http://www.warp9td.com has been aware since the beginning, and maybe one day he'll fix it.
The SmoothStepper is capable of supporting higher frequencies than your CPU will be able to supply, up to 1GHz, so that won't be a limiting factor, either. The limiting factor is the frequency your CPU can output, which is often limited to 25KHz. So, if you have your controller board set to 1/8 steps, or 1600 steps per revolution, 25,000 cycles per second / 1600 steps per rev = 15.625 revs per second. Multiply that by 60 seconds in a minute and you get 15.625 X 60 seconds / minute = 937.5 revs per minute as the maximum possible RPM of your stepper at 25KHz, independent of the supplied voltage or amperage.
So, on the MKI, using the original 1/4-20 allthread drive system, we must divide the RPM by the "turns per inch", or 20 - which says the absolute "perfect-world" limit for the Y-axis motion of a stock MKI is 937.5 / 20 = 46.875 inches per minute. I believe the best anybody has achieved is around 40 or 42 IPM, so you can see the toll that friction takes.
Some have modified their MKI by replacing the allthread with ACME drive screws, with proportional increases in speed depending on the number of turns per inch.
With the MKII (since I don't have one or know the dimensions of the running parts) let's assume the belt-drive sprocket is 2.00 inches in circumference. That means the belt and the gantry will move 2 inches per single revolution of the stepper. Now we can see that 937.5 RPM times 2 inches per rev = 1875 inches per minute as theoretically possible.
This is assuming an absolutely friction-free, mass-less system, so reality will DEFINITELY affect the actual performance, but 1000 IPM is easily within the scope of any CPU on the MKII system.

Whether you use a SmoothStepper will (and should) be driven by your situational needs. For me, there is no room to put a standard CPU, keyboard and monitor in my garage, so I am driven to run my PP from a laptop. Laptop parallel ports are neutered so badly they can only be trusted to run a paper printer, so my next option was to buy a good PCMCIA-to-Parallel card (read that as $120 and up)(yes, I've seen the ones on eBay and they will not do the job) and hope it did the job, or get a SmoothStepper that is specifically designed to allow Mach3 or a similar program to run a parallel-port controller card, via the USB port, for $155. It wasn't a tough decision for me to spend the additional $35 to do it right the first time, and I have absolutely no regrets.

 

That was a great writeup Dorsal! It confirms exactly what I have experienced, 42 ipm on the Z axis is best I can do now that I have a stepper that has the capability to drive it. That was about optimum on my Y axis before the belt drive mod as well.

The one thing you did not mention, which is the main reason for me buying one, is that the PC CPU is not dedicated to supplying pulses. It is a multitasking operating system and gets demands from many sources including network interrupts which often take priority over all other tasks.

What I have found is that background tasks sometimes do things that take priority for lengths of time that result in the CPU being unable to supply step pulses fast enough to satisfy the controller board.

At least that is what I suspect is going on based on my trial and error testing. By eliminating every background task that was not absolutely necessary I was able to reduce but not completely eliminate a situation in which the X axis under continueous driven motion hangs up.

I suspect McAfee may be the culprit as it is one of the tasks that I have not been able to disable without completely uninstalling it and I refuse to allow any of my PC's to go naked.

If I run the X axis continueously at full speed for a long period of time, it will eventually hang. I can power off the controller and let it set for any period of time (with Mach 3 still trying to send the pulse stream) and power the controller back up and it remains hung, so that tells me it is either Mach 3 itself, or the CPU was unable to keep up. It could be a combination of both Mach 3 and a CPU issue. Before I started killing unneeded CPU tasks, the problem occured more frequently, but since I have started removing unused programs, the problem has diminished to where it is hard to make it happen now, but given enough tries, I can eventually hang it up.

I am hoping the smooth stepper will eliminate the PC CPU from the equation. Its a gamble. But if you are correct in the math, I should be able to expect to achieve even higher IPM readings on my Z axis with the smooth stepper in place and may be able to bump up my rapid feed rates as well.

I should find out sometime next week... I'll post my results after my smooth stepper arrives.

 

Wow thanks for the info guys. For some reason, I had it in my head that the smooth stepper was a crutch, but now I know it is an upgrade regardless of the cpu you are running.

Thanks

Jeff

 

Quote from the manual...

By taking over the task of producing step and direction signals, the SmoothStepper relieves the host computer of most of the CPU load normally involved in running Mach3. The dedicated hardware in the SmoothStepper produces pulse streams up to 80 times faster, and with more precise timing than Mach3 using the printer port.

 

Ok, A couple more questions.

The drawer in the stand of the MKII, is it for dust collection or tool storage ?
What types and how much glue will we need to assemble the MKII ?
Is a cooling fan included in the kit ?

I hope these are'nt too redundant, I'm sure there are more important questions,and as soon as my used desktop arrives I will have gojillions of questions about what software goes where and how to make 2 computers talk to each other and all that other stuff that makes my eyes cross.

Thanks
Jeff

 

At fault ?? You guys are doing a great job. juggling jobs, families, suppliers, web sites, budgets, and answering dumb questions from the computer illitarate ( me ). Right after I posted my last questions I found the tech specs for the MKII, yep the drawer is for dust collection, and yep the fan is included

Thanks
Jeff

 

Ok another question

I am drawing up a foamy for 9mm EPP. The foam is 24''x36''. On the MKII, how much foam gets wasted at the ends ? Will my safe cutting area be 22''x30'' ? I can't quite get this foamy into a 22''x30'' area.

Jeff

 

I cannot speak for the MKII, but for the MKI, I always add a strip of 3 or 4" scrap by taping it to the foam so that I can get a little extra travel if things are tight.

For instance, I use a lot of Depron which is 39" long. In order to get the full use of my foam, I simply tape a 4" piece of scrap to make it 43" long and then I can cut right up to the edge of my 39" piece.

You just need the 3 or 4 inches of extra foam to allow the rollers something to grab onto when the X axis is traversing to its limits. You typically do not need to put scrap on both ends, only the one furthest from you as you face the machine.

Hope this helps.

 

Thanks guys, I'm going to try 23''x35'' it should fit now.

Jeff