[samim]

I got my hands on a Dahlgren CNC router for $100. I seem to be very solid and have ball screws for both axes. I am planning to rebuild the third axes so it has full cnc control instead of just on or off (up/down). The motors are Rapidsyn American Precision (Model 23D-6306C, 3.4VDC). As you can see, it runs off Radio Shack TSR-80 and it has a huge controller! The table is 12"x16". It is obsolete and outdate.

My question is can I still use these old motors?

What kind of controller can I use?

Thanks.

[ahren]

Sure, those look to be stepper motors. Read more on this forum -- some Gecko drives (or whatever drives are in the machine may still work) should fix you up. Then, use a computer with Mach 3 to do control. Nice find!

Ahren
www.cncrouterparts.com

[ZipSnipe]

I,m diggin the TRS80 that is amzing that one of those is still functioning. Great find.

[DSL PWR]

You could probably sell that old computer to a collector and pay for the hole retrofit.

[stepinator]

Hey check out this thread. You're in good company. Glad to see someone else has resurrected a Dahlgren from the past

http://www.cnczone.com/forums/showthread.php?t=48718

[Netjams]

Back in the 80's Mike Dell was my neighbor in south Austin. I had a computer just like that and didn't know what to do with it, so I took it to him (at the time he had his little enterprise in his garage with a few employees), he saw the machine and offered me $40 for it. I jumped on that deal because it was given to me.

As for your new (old) cnc machine.. That looks like a very cool machine.

[samim]

I am finally getting around to start my CNC conversion. The old TSR-80 computer does not work. There are so many options for the step motor drives. I want a good quality accurate and smooth drive.

I really like the Gecko G540 because it it all one self contained unit but seems pricy at $300. The preassembled drives from PROBOTIX is a better option at $35 for each axis. I am not really too sure about the $65 3-Axis drive from HobbyCNC.

www.hobbycnc.com

http://www.probotix.com/stepper_motor_drivers/

http://www.geckodrive.com/product.aspx?c=3&i=14469

What does the Gecko or PROBOTIX have that the Hobbycnc version does not?

Is Gecko G540 a really good drive?

What are other good quality drive (less then $300) for controlling the 3-Axis?

[steve323]

I really like the Gecko G540 because it it all one self contained unit but seems pricy at $300. The preassembled drives from PROBOTIX is a better option at $35 for each axis. I am not really too sure about the $65 3-Axis drive from HobbyCNC.

The Gecko is bipolar, giving you about 40% more torque than HobbyCNC from the same motors. It also has speed morphing that allows it to have high precision micro-stepping at low speed that morphs to full stepping at high speed. The Geckos are also fully assembled vs a kit. Supposedly, the Geckos are very fault tollerant. The HobbyCNC drivers can blow themselves up if you remove the motor (or your wiring breaks) while power is applied.

I have the HobbyCNC and it is a great setup. I think the Gecko is a step up at a slightly higher price. I would have bought the Gecko if it was available at the time.

Steve

[samim]

If the Gecko is bipolar, then the drive have to be bipolar too. Correct?

Is the G540 going to provide more "accurate" positioning?

The G540 contains four of our G250 drives. Looks like a single G250 has about four times more components on the board then the single 3-axis HobbyCNC board.

Thanks.

[Santa Fe Al]

Hi Samim,

If you'll look at some of the threads about Geckos, you'll be amazed at their policies.

First time - S**t happens - Fix or replace for free

Thereafter - Free evaluation of driver.

Extremely good customer support.

Always polite and very helpful.

Have a crazy idea that the customer is important.

Al

[steve323]

If the Gecko is bipolar, then the drive have to be bipolar too. Correct?

Is the G540 going to provide more "accurate" positioning?

The G540 contains four of our G250 drives. Looks like a single G250 has about four times more components on the board then the single 3-axis HobbyCNC board.

Thanks.

Unipolar drivers can only drive 6 or 8 wire motors. Bipolar drivers can drive 4, 6, or 8 wire motors.

Both designs will give you similar positioning accuracy. You probably end up with about 0.0001" positioning accuracy in a system with possibly 0.001" or more backlash. You don't really need that much positioning accuracy.

The HobbyCNC driver uses a pre-configured driver chip and adds a few discrete resistors and voltage regulators. Each G250 uses an FPGA with discrete MOSFETs for the driver. It is really tiny. The G540 packages 4 G250s into a space that is about the same size as the HobbyCNC board.

Steve

[samim]

Sound like G540 is way to go.

I will take apart the DB9 connector on my motor to see what type they are.

Can the Gecko G540 drive Unipolar or Bipolar motors or just Bipolar only?

This machine is really old and Rapidsyn is out of business. Do you think the G540 will be able to drive my motors?

This machne has manual adjustment for the Z-Axis. I am planning to ad belt drive with a stepper motor so I will have full CNC axis. Any suggestions on stepper motors?

Thanks.

[steve323]

Sound like G540 is way to go.

Can the Gecko G540 drive Unipolar or Bipolar motors or just Bipolar only?

This machine is really old and Rapidsyn is out of business. Do you think the G540 will be able to drive my motors?

Any bipolar driver can drive a 6 wire unipolar motor. Bipolar has 4 wires that connect to the 4 outside taps of the unipolar motor. The 2 center taps should be left floating (and protected from shorting to anything).

Both the G540 and HobbyCNC boards will drive your existing motors that show 2.9A on the label. G540 supports up to 3.5A motors. HobbyCNC supports up to 3.0A.

Steve

[samim]

It looks like my stepper motor uses 6 wires.

[samim]

How do check the wires on the motors so I can hook them up to the drives?

[BobF]

Samim,
read this first.
http://www.geckodrive.com/upload/Step_motor_basics.pdf
This will show what 6 wire motor connections look like.
With a VOM you can find the 3 wires that go to each set of coils in the motors. Once you have that, you may be able to determine which wire is the the center tap by finding small differences in the ohm reading between pairs.

[arizonavideo]

If your TRS-80 is the 12 model it may be worth around $300 on ebay. That could buy a few drivers.

[samim]

Since the motors are 3.4 VDC / 2.9A, can I use simple 12V Computer Powersupply?

Thanks

[phreephilip]

Our company still uses those old machines. The originals
ran off of the old trash-80's. But the newer version ran off ofany PC with windows 98 or older. You said you still have
the original control unit? Go to engravingsystemsllc.com
and download free superpro software. The control units
can be adjusted using this software for air-driven or z-axis
tables. If your switching over alltogether, I would be
willing to take the old motors off your hands.