Most Recommended USB Controller

[ThomasCB21]

HI folks,

I am a total, total noob here.  I am a definite hobbyist when it comes to wood working, but I'm pretty good with computers and CAD (AutoCAD)and I have lots of ideas that I would like to see become reality.  So I decided I would put two and two together and jump into CNC routing/milling.  I've hit a bunch of forums and read a lot of threads and it always seems that people come to Mach3 as the control software of choice.  I don't have any computers in my house the have the p-port and as a matter of fact my printer doesn't even have one, it's wireless/usb.  They all run Win 7 (64-bit).  

I would like to start out simple with a 3-axis machine to get my feet wet, but I don't want to have to shell out more money for controls when I eventually move to 4 and 5-axis.

So my question would be, "Who can point me to a reliable (somewhat inexpensive  ) external motion controller, either USB or Ethernet?"

[Hood]

Smoothstepper and KFlop are really the only two USB ones that are known quantities. There are a few Chinese made ones being advertised but  no one seems to have one or if they do are not sharing their results here.
Ethernet then at this time its the DSPMC or Galil.
There is also the Centipede which is a PCI card.

Prices range from $150ish for SmoothStepper to probably a few thousand for a Galil.

Hood

[ThomasCB21]

Thanks for the quick reply.  I wil look more into Smooth Stepper and Kflop.

CBT

[HimyKabibble]

Keep in mind, you can buy a PC WITH a parallel port for less than the cost of a SmoothStepper.  My last two (2.4GHz, 1Gbyte, etc., one HP, one Dell) each cost me under $100.  A SmoothStepper is about $150, and does not fully support backlash compensation, which you will probably want if you're building a machine on a budget.

Regards,
ray L.

[Hood]

Backlash works well for me Ray, whats the issue with it?
Hood

[ERP]

I believe currently backlash compensation doesn't work correctly on a smoothstepper if the commanded move is less than the backlash setting.
Probably not an issue for most people.

[Hood]

Not sure how that would be an issue, if the move is less than the backlash its not going to move anyway. Only way I would see it being an issue is if the SS then does the backlash on the reversal, does it do that?
Hood

[ERP]

Just basing it off what I saw on the smooth stepper site (see below), guessing purely by how I would implement the feature, that he assumes that you see maximum backlash in any single move, so if not all of it gets taken up when the move isn't big enough to accomodate it, you'll have incorrect state for the compensation and end up off by the difference between the backlash value and the small move. But I'm guessing.

"Backlash compensation has been added. This version works great as long as you do not enter moves that are shorter than the amount of backlash you have. In particular, you will notice this if you use MDI or Step Jogs and you inch towards something and then back off. I am working on a version that will make that work properly."

[RICH]

I would like to start out simple with a 3-axis machine to get my feet wet, but I don't want to have to shell out more money for controls when I eventually move to 4 and 5-axis.

Consider building your owne controller. Think hard about what you may want to do in the future and decide if you want to go with
steppers or servos as that determines what kind of drives you will purchase. You can just add drives over time if the power supply is adequate thus investing more as time goes on, but, the basic stuff is in place and no need to repurchase or start from scratch.

just something to think about,
RICH

[RICH]

works great as long as you do not enter moves that are shorter than the amount of backlash you have

Suggest you post on the Warp9 site and have the above clarified as i would interpret  it only applies to a commanded move via the MDI
or using the jog buttom. If true, then on reversal with Gcode lines in a program it would not be an issue. If false then the backlash as implemented is ...well... rather useless and don't think Greg would put it out that way.

 
RICH