Stepper Advice

[Bumole]

Hi all

I am new to CNC machines and have been reading most posts in the forum for the past few months trying to bring myself up to speed with what is needed for a CNC, the terminology used and a better understanding of how the MechMate is assembled and how it operates.
I have ordered the laser cut parts and hopefully they will arrive before Christmas. Next on the agenda is the motors, drives and power supply. I would like to go with the motors selected by Gerald but as this is just going to be a hobby machine for me I can't justify the expense. I have been looking at a few different sites and have been trying to match motors that are similar to thePK299-01AA (http://catalog.orientalmotor.com/item/stepping-motors--1068/pk-series-stepping-motors/pk299-01aa?&plpver=11&origin=keyword&by=prod&filter=0).
I have read the posts about MotionKing steppers but I have not seen any on the ms-motor (http://www.ms-motor.com/) steppers. I have selected two motor and driver combinations that I think might be suitable.
1. The 34H280-30-8A (http://www.ms-motor.com/HB3418.htm) stepper motor with the H2MD (http://www.ms-motor.com/stepdriver.htm) driver
2. The 34H280-45-8A (http://www.ms-motor.com/HB3418.htm) stepper motor with the 8078 Microstepping Driver
(http://www.ms-motor.com/stepdriver.htm)
If any one has used these motors/drivers or has some advice on my selections your input would be greatly appreciated.

thankyou

Bob

[Richards]

Bob,
Although the specs on the components that you've selected look good, you may easily find that saving money on electronic parts is expensive - if you're the only one using those parts. You may also find that you'll need to stock several spare units for quick replacement, depending on how quickly replacement parts can be shipped to you.

My first test setup (4-Gecko G202s, 4-Oriental Motor PK296B2A-SG3.6, PMDX-122, PMDX-135-8020, Avel toroidal transformer, misc. hardware, Mach 3) cost a little more than $2,200. Those parts and pieces taught me how stepper motors work in the CNC world. All of those parts survived my learning curve and will someday drive a CNC router. My second test setup (4-G203v, 1-G101/G102, 4-PK268-02AA, toroidal transformer, cap and bridge), would have cost about $1,600, but I had those motors left over from other projects. That setup taught me about high-speed motion with steppers. Those parts also survived my learning curve and may find there way into a CNC machine; however, the G101/G102 may never make it off the test bench. My third system was exactly like the 2nd except that I bought a G100 module instead of the G101/G102 combination. It would have cost about $1,800, except I used some other PK268-02AA motors that I had on hand. The purpose of setting up test system three was to see whether it would be practical to build a ready-to-go controller pre-wired with the G100. (I decided against that because expecting the end-user to replace a G100, with its +50 wire connections would be an exercise in futility for most end-users.) Along the way, I also bought other Oriental Motor PK29x size motors and designed a belt-driven gearbox to harness the power of those motors.

The point that I'm trying to make is that a developer accepts the fact that there will be a development cost involved in selecting parts, in testing the parts to see whether they work as expected, and in substituting other parts until a marketable product is developed. My old rule-of-thumb, when I was very active in designing process control computers, was that the sales for the first ten units might cover the cost of developing a simple controller - if I charged at least 4X the cost of materials. As an end-user, you will have to decide whether you want to also be the developer (and pay the price of development), or, whether you want to use electronics that others use (and benefit from their experience).

Personally, I would rather play with electronics than cut wood, but I'm guessing that most CNC owners would rather do just the opposite. However, I draw a solid line between buying test systems from all available suppliers, and sticking with one or two suppliers. (In the process control world, if a developer saw a market for several thousand units, he would contact all of the manufacturers that had compatible parts and ask for evaluation units. Most parts manufacturers would send complete development systems to the designer, along with home phone numbers of their own designers to influence the developer to select their product.)

If you do decide to use the Motion King components, please post your results.

[Bumole]

Thanks Mike for your reply, your input is greatly appreciated. I might do a bit more home work before I make a purchase.:)