Where the heck? What the he11? HUNH?

[metal-chip]

Well, I picked up this old Bridgeport Series 1 CNC Rigid Ram.... and I gutted the logic cabinet... actually, I saved the cards and tossed the cabinet... lets put it that way. Why? because I want to run it with Mach 3 and Gecko Drives.

However, I'm a little squrmish now at the size of this project. Where do I start, what drives do I need etc etc.

So, lets start it this way. I'm using a 7.5 HP 3 phase motor as a rotary phase converter. I plan to use the existing stepper motors and the original 3 phase transformer for the power for the stepper motors.

Everything else, from limit switches, relays controls etc, its all going to be new, in fact I have just about everything I need with exception of the appropiate type of Gecko Drive and purchasing the Mach 3 software.

I tend to tinker, tinker and tinker some more. I'm afraid that when I'm tinkering that I would move the table in one axis or more when the drives are not turned on and the voltage produced by the steppers will blow out the drives. Does the Gecko Drives have some sort of protection for such an event?

Also, I could use some insite on what Gecko Drive I should pick for this machine. Its for a home workshop, not to heavily into production, mostly one offs or limited runs in aluminum, plastic and probably from time to time some steel work.

So, if someone could get me out of this rut of wondering what do I do now ... help me pick the right drives please!

Thanks

Dave in Kewaskum, WI

[Timvmax]

Hi Dave,
If you haven't ripped too much of the guts out of it, you could have a simple conversion.
We recently converted a series 2 Bridgeport with a board from Hillbilly, you can contact them here ashburn@icx.net
Ours also had stepper drives and this conversion has transformed the machine
for $79 for the board and $175 for Mach 3

[gschoep]

I am in the process of doing the same thing. I have the gecko drives working, a Automation Direct GS2 VFD, and a power supply built with T1 (the 240 v to 120v transformer tapped at 40v). I already had Gecko 201s but the 203s would be better because of the auto short circuit protection circuitry.

Just remember that "common" on the Gecko 201s is 5 volts to power the opto-isolator LED. Also just wire 2 windings of 4 of the stepper motors because the windings are in bifilar (which means that 2 windings are wound together). There are jumpers on the motors that show which terminals are the ends of the windings and then wire to the other side. I have 1 sigma and 2 superior and the geckos work fine so far.

I used a C11G breakout board from CNC4PC which has some extras AC relays for coolant etc and is set up for direct wiring to a Gecko drive with opto isolators.

I am using the original limit switches and wired both NC and NO contacts for a separate e-stop and enable circuits. X and Y are set up as "both limits" in EMC2 and the Z has an upper, lower and a home switch. You can actually move the deceleration switch past the upper limit if you loosen the bracket screws and use it as upper limit. Then the screw adjustable switch can be a home switch.

All this fits in the back cabinet on the mill. Mine had no side cabinet.

For software I am using EMC2. It was probably the easiest part of the project. It has a nice wizard for setting up your mill which lets you check feed rates/limits/etc. They only problem that I had was a non compatible graphics card. Otherwise it was pretty straight forward to install on a empty HDD on a Dell GX240 computer (pent 4, 512 MB RAM, NVIDIA graphics card).

I got most of this information from this forum except for explicit directions on modifying the transformer which I just figured out after reading the suggestion on this forum.

I also had an hour long talk with Mariss at Gecko tech support who has probably forgotten more about Boss retrofits than I will ever know.

Basically my costs were:
Gecko drives free (came with the mill)
Stepper power supply parts
transformer free came with mill
bridge rectifier - 5$ at digikey
6800 uF capacitor - Free (I had one)
VFD from Automation Direct - $260 with shipping
C11G - ~$100 from CNC4PC
EMC2 - Free
Computer (GX240 MB on ebay $40 to put in old case I got surplus)

It is really not that big of a deal to do a retrofit using the original steppers once you get your head around it.