The start of a big CNC project...

[UKRobotics]

After nearly a year of debating I have finally bit the bullet and purchased my first CNC milling machine. My original plan was to build one from scratch but I decided that was too complicated, then I considered converting a drill/mill but then figured I’d need the CNC mill to begin with to make the gearboxes & motor mounts so I decided to try and get hold of a second hand CNC mill instead.

This proved to be a lot harder than I thought as they don’t seem to come up for sale very often. As luck would have it a few months ago a Bridgeport interact 1 appeared on eBay which I bid for but then lost at the last minute. Between then and now I had more time to think about what I really wanted to end up with. As nice as a Bridgeport would be it would be stupidly big and would take up all the room in my shed (and that’s if I could get it through the door!) the CNC routers all have nice big tables but cant cut metal which put them out of the equation which only seemed to leave the sherline type things but they were too small for the things I wanted to make.

Despite beginning to think I’d set myself an impossible task, I attended a local machinery and tools auction today and by chance came across just what I needed - a mill/drill size CNC milling machine with enough travel to make the majority of things I had in mind. The machine is 3 axes, ex college and is in immaculate condition & to cut a long story short, I won the auction and am getting it delivered to my house on Friday.

The only problem now is wondering where I should go from here. The company that made the CNC mill has gone out of business and there are no references to this mill anywhere on the net. I haven’t got any of the original software to go with it, and quite frankly even if I did have the software I wouldn’t want to use it as its all nasty dos based stuff that’s over 10 years old.

For those of you out there who are more knowledgeable here is the machine spec as printed in the instruction manual:

Conect Numerical Control Contour Major Twin Column CNC Mill

Table dimensions: 615x150mm with 3 x 10mm Tee slots at 50mm pitch
Axis Travel: X - 380mm Y - 140mm, Z - 310mm
Spindle Speed - 300 - 3000 RPM
Spindle Motor 0.8kw
Maximum Feed Rate 1000mm/min
Rapid Feed Rate 600mm/min

Spindle Motor
Ferrite brushed servo motor
Motor Type: DPM30H4-33
Stall Torque - 2.1Nm 6.8A
Max: 4000RPM 130v 37A
Tacho V/KRPM IP44 IC 400

Stepper Motors - L281-1
Volts - 3
Ohms 1.8
Amps 1.7
Deg 1.3

The CNC mill is enclosed in a metal box with a polycarbonate front. Inside there is a coolant pump and in a separate compartment at the back, all the control electronics which appeared to consist of 3 or 4 driver boards, an interface board and some power supply circuitry. - Until I get the mill delivered on Friday I won’t be able to take a closer look to find out who made the control electronics. On the front panel of the machine there is no screen, just a few jog buttons, key switch and emergency stop button. At the back there is a standard computer type 3pin power connector and a serial connector.

As it is, without any software this thing is nothing more than a very large and expensive paperweight. Does anyone know if I’d be able to find some general purpose software that would be compatible with it, or will I have to replace the controllers for something more modern like geckos if I want to use the more modern software?

Also, I’d be interested to know how good the supplied stepper motors are. As I bought 3 gecko servo drive units a while back, if I found I had to replace the old controllers, if the motors aren’t anything special I'd be tempted to replace them with servo's so I don’t have to buy another set of geckos.

Sorry for the long post ... I seem to be making a habit of it .

As usual, any help, advice, comments or constructive criticisms very welcome!


Regards,


Dom



http://www.ukrobotics.com

[RotarySMP]

Sounds like you got lucky Dom. If the machine is in good mechanical condition and has standard NEMA motor mounts then the worst case you are looking at getting a set of servos to go with your gecko's and an old pentium to run the G code controller.

There is a design for a DC motor speed controller in the electronics forums if you have to replace the spindle drive as well.

1.3 deg/step motors? This is probably 1.8°/step - 200 step/rev which are standard two phase steppers. 3V 1.7A motors are probably pretty weeny If you wanted to you could replace the current drivers with a three axis xylotex board for $145, but the machine wouldn't be the fastest.

Coolant is easy enough to control. Does it have a tool changer? What sort tool interface does it have?

Please post pictures as soon as you get it.

[UKRobotics]

Well, I went back to the warehouse today with one of my dads friends who has a big transit van. 3 hours later it was back home and it was only then I realised the true size of the thing.



Despite looking quite small in the aircraft hangar, getting it into the shed was a different matter and required some slight 'modifications' involving a large hammer, saw and angle grinder to make a hole big enough to get the thing inside.



and here's a close up of the front of the machine:




Between now and my previous post, I spent many hours on the phone trying to find out more about my cnc mill and have had a lot of success.

The machine doesn’t have an automatic tool changer and the tool holder was missing, I have since found out that it uses an 'Easy Change' tool holder made by fockard (http://www.forkardt.com/index.html.en) and I should be able to obtain one for £150-200. Tooling is also readily available.

I also found out that the software I have been using at school for the last 4 years comes in a special version to work with the connect machines and just isn’t mentioned on their website because of the lack of demand. At £500 it seems a little steep but considering its CAD/CAM/NC all in one and I already know how to use it, it seems like a worthwhile investment.

Finally, I also managed to get a phone number for a company who has a lot of employees who used to work for connect. I got through to someone who used to be involved with the design and manufacture of the machines and he was incredibly helpful, answering all of my questions and even offered to try and track down a copy of the original DOS software for me. One of my concerns about the techsoft program was that its only 2.5d but he then told me that the connect machines are only capable of 2.5d anyway so that’s one less thing to worry about. He was also quite amazed at the price I managed to get this thing for. The mill I picked up at the auction was the top of the range Connect model & I got it for £500. Apparently £5,000 of materials went into them when they were built, and they were sold for around £15,000 so it seems that I’ve got a bargain if I can get it running.

When I’d finally got the 300kg machine positioned in my shed I powered it up to see what happens. No smoke - got to be a good sign! and several cooling fans started up. I was hoping that the manual controls buttons on the front of the machine would let me move the axes but it appeared to be dead. At the moment I’m not too concerned as I think (hope!) that it’s just not working because it needs a pc to be connected.


The current plan is to put an old computer out in my shed ASAP, buy the easy change tool holder + an end mill, buy techsoft (they said I can return it within 14days if it doesn’t work) and wire everything up and test it. All going well I should have a complete working system towards the end of next week.

Should there happen to be a problem with the electronics, I'll look into any options of getting it repaired, or failing that I'll do as you suggested and buy some servo motors and run the thing with my geckos.


Either way it will be fun so it’ll just have to keep my fingers crossed for now.

I'll post more photos and info as soon as I’ve made more progress.


Dom

http://www.ukrobotics.com

[nervis1]

That little thing is cool. Be sure and post up pics as you progress. I and many others would love to watch it come alive.

[RotarySMP]

What a great buy. Lucky Barstard

Keep in mind that the mechanics are not limited to 2.5D. If you fit gecko's and use TurboCNC or MAch2 or EMC etc, it will do full three axis coordinated moves, if the machine is dead.

Regards,
Mark

[UKRobotics]

Yep, I realise that. Although if the machine does work as is, i'll probably leave it and then use it to build a bigger better 3D machine

[Graham S]

How does it connect to the PC, parrallel or serial?

If parrallel it will probably be step and direction and you will be able to drive it from TurboCNC or whatever.

If serial then there may well be a board that produces step and direction for the driver amps that you can bipass, the stepper drives may use a very common chipset and be easy to work out.

That's where I would start.

Also by working out the drivers you should be able to test them with just a pulse generator, even just a switch.

Graham

[UKRobotics]

It is serial but my electronics knowledge is somewhat limited so I dont know how much luck i'd have trying to troubleshoot it. I dont have anything like signal generators or oscilloscopes readily available.

[RotarySMP]

If it works and you are familiar with the software anyway then it is a good choice to stick with original.

If an axis's driver dies, or the it is not year 2000 compliant or whatever, your 500 pound would be enough to get it converted to TurboCNC (A lovely program, and V4 is now released).

[xknacx]

Did you get it going?!? Looks awesome!! what a deal!!!

[ynneb]

Did you have to widen the door for the guy in the shed. He he he