Re: Stepper cnc retrofit ? For Tape-O-Matic

Wally K writes:

Allen & Marsha, (this post has been cleaned up again for readability)

To summerize the details of your Tape-O-Matic and make it easier for
others to follow i have condensed the previous posts.

You want to use a like new (mechanically) 1967 Pratt & Whitney
Tape-O-Matic 2 axis machine for drilling with peck and some 2D
milling.

The Tape-O-Matic was primarly designed for drilling but is capable of
light duty milling.

You want to use a Tape-O-Matic for drilling with peck and some 2D
milling.

1) Machine has zero backlash ballscrews .2" pitch on X and Y axis.

2) The steppers are 400 in. oz. 5 wire unipolar steppers mounted
with a 1-1 belt ratio.

3) Spindle has a 3HP motor turning it.

4) You want to use your existing quill feed powered by a DC motor
through an electric clutch, this drives a Bridgeport style quill
feed. The depth originally was controlled by several adjustable limit
switch pairs, long since gone. It is not zero backlash. You would
consider powering the Z axis with a stepper. And the quill does have
a handle for manual operation.

5) Machine originally had a speed of 10 in./min. max. But you would
like to see 30" to 60"/min.



From studing the information on this list for several months and
asking alot of questions pertaining to bridgport retrofits. I can
offer the following advice.

1) CNC Pro and Ace Converter are highly recommended. URL as follows.

http://www.yeagerautomation.com/index.html


2) I would use the Gecko G210 not the G201. As i understand it the
201 is a 10 micro step drive. meaning you have to give it 10 micro
steps for 1 full step. This would limit your high end speed by a
factor of 10 because software based controllers can not put pulses
out fast enough.

The G210 accepts full or half step and converts that input to
microstep for smooth motor control. The URL for Gecko is.

http://www.geckodrive.com/

3) To save some money it would be ok to start with the steppers you
have.

4) Your steppers are a little underpowered. You should be running
at least a 2-1 belt ratio and maybe even 3-1. As the ratio goes up
your top speed goes down.

You can gain some top speed by using a stepper power supply closer to
80VDC. The more voltage the more speed you get.

If you know the mfg of your steppers and part number as well as any
info like amps, volts, and coil resistance, ect. Maybe we can find
the motor curves for you and give you an idea of torque and speed.


Wally K.

> --- In CAD_CAM_EDM_DRO@egroups.com, Robert Allen & Marsha Camp

<mcamp@t...> wrote:

> the controller is garbage.
> Based on the info I have that I can buy (2) 720 in. oz. motors
> ($250 ea.), (3) drives (gecko), and CNC Pro software ($550 for
> software and drives) for $1050 and estimate $300 for power
> supply.
>
> My questions are:
> 1. Can/should I keep the motors?
> 2. Is steppers the best way to go for lowest cost when
> performance
> isn't critical?
> 3. Any suggestions for lowering cost?
> 4. Any experience with any of this equipment/software?
> Thanks in advance
> Bob