[Cube3]

Hi Guys,
I have been lurking on the forum for a few days trying to get an idea for suitable donor machines, parts, costs etc. Having looked at what is available in the UK I intend to buy new a Warco GH Universal and convert to 3 axis CNC(Mach3/VisualMill). I think, due to the size and especially the Z axis load I will go for servos over steppers. With that in mind I like the look of the Gecko kit G320 or G340 (have'nt sussed the differences yet).
The main reason for the post is to see if anyone has converted this machine that I can share information with, I believe that this machine goes under quite a few other names and I think it is the one Industrial Hobbies use.
I will obviously require quite a few other parts and would be interested in finding UK suppliers of Ball Screws, Servos, PSU's, Toothed belt drives etc.
Looking forward to participating in the forum and once I have a clear plan and taken delivery of the GH Universal I will start a build log.

Thanks
Simon

[LongRat]

Nice machine, I would consider one myself if I was looking in that size range. I don't think it is necessarily out of stepper territory though.
As for supplies of screws etc, UK sourced is going to cost you big time. I wouldn't bother, hit Ebay or one of the US vendors. Even with the current exchange rate you'll probably save money. I got a load of stuff from homeshopcnc.com and was very happy with it. Plus its pretty much a 1-stop shop.

[irving2008]

Hi Guys,
I have been lurking on the forum for a few days trying to get an idea for suitable donor machines, parts, costs etc. Having looked at what is available in the UK I intend to buy new a Warco GH Universal and convert to 3 axis CNC(Mach3/VisualMill). I think, due to the size and especially the Z axis load I will go for servos over steppers. With that in mind I like the look of the Gecko kit G320 or G340 (have'nt sussed the differences yet).
The main reason for the post is to see if anyone has converted this machine that I can share information with, I believe that this machine goes under quite a few other names and I think it is the one Industrial Hobbies use.
I will obviously require quite a few other parts and would be interested in finding UK suppliers of Ball Screws, Servos, PSU's, Toothed belt drives etc.
Looking forward to participating in the forum and once I have a clear plan and taken delivery of the GH Universal I will start a build log.

Thanks
Simon

Simon, have a look for member Robin Hewitt on here or on www.mycncuk.com (and come join us there too). He has CNC'd an older Warco (about 20y old!). may be able to give you some pointers.....

[Cube3]

Thanks guys,

With regards to the stepper/servo options I notice that steppers are rated in holding torque and servo's in torque. What’s the difference when trying to compare steppers to servo's. I am going to try and work out how much torque I need for the Z axis. The head assembly is probably 40lbs on a dovetail slide with maybe 12" overhang! Going to try and source the ballscrew and ask Warco for weights, then I can do a few sums. Fingers crossed, maths is not my strongest subject. Anyone got any data on ballscrew efficiencies?
What are the build/electronics pro's and cons for stepper and servo's?
Simon

[LongRat]

The major advantage with servos is that their torque doesn't rapidly fall off with speed, as steppers do. Steppers have massive holding torque (torque at zero RPM) but the rapidly decreases as you rev them up. Check the torque-vs-RPM curves for the motors of interest to see. If you want to go fast, you should look towards servos. A properly specified stepper system will have all the holding torque you need and never lose steps either. There are plenty of well-informed people on here to give you more in-depth info in this area.

[Kipper]

I converted mine (Round column version=slightly older) using 1.8nm motors on all axis.....Plenty fast enough and strong...Although powering the head (as opposed to the spindle on mine) will require more "oomph" a 12nm motor should cope.

I'm using steppers and in 18mths it hasn't missed a single step, I'll be having the same machine as you're contemplating in a few months.....I need the extra table travel and in the confines of my shed the powered head will be a godsend!

I'm wondering when you get yours if you'll measure the table for me...It may save me some time making patterns if the table is the same as my existing machine as I have the original patterns from when I converted mine..

Mine uses 16mmX2.5mm pitch ballscrews (Isel Bought from Marchantdice and I can't fault them) with a 2:1 5mm pitch X10mm wide belts....Zero backlash from day1.

Stepper drivers and 12nm motor kit from Zapp Automation...Can't fault those either...Although I haven't needed the 12nm motors....YET

The RPM is the only fault I'll be fixing on the next one! Inverter drive and 2800RPM motor next...so as to be able to actually speed up the cutting rate.

The X axis casting I need to modify so as to mount the 4th axis on it (takes up precious bed space)

Have fun.

[Cube3]

Thanks LongRat, I'll have to do a little more research before I decide Stepper/servo.

Kipper, where are you based? As soon as I get my machine, for sure I'll measure anything you need. I run a design consultancy and use SolidWorks all day long so I expect to CAD up most of the machine and produce CAD/drawings for the conversion.
Your right about the motor speed, the machine comes with 1600rpm which I feel is not enough. Once I have got the CNC side of things sorted that will be the first thing I upgrade, just need to look at how the head gearbox is arranged to make sure it can cope with much greater rpm's
Getting excited now, placing order for the GH soon
Simon

[Kipper]

I'm in Leeds West Yorkshire Simon, Once you realise that the speed quoted is for 60hz and that we have 50...it's even less

If you do a google for RF45 Conversion you'll see one with the stepper motor at the rear of the column....Out of the way a little, I didn't care much for the conversion in question as it placed (imho) too much axial load on the ballscrew when cutting forces were factored in and brought the motor back in the firing line of coolant.

I'm going to redesign the motor mounts to use the nema34 units once the size of the table is discovered.

I think you'll enjoy the machine matey!

[Cube3]

Hi Kipper,
Leeds, a long way from me...Im SE Essex!

Could you expand on your note about the axial load for the Z axis and how you see to reduce it. I see that most stepper motors are 1.8 deg per step, what linear travel would you expect to see per step and does the differ between X,Y and Z. Does Mach3 allow you to adjust this ratio to suit your particular setup? Gees the more I learn the more questions I ve got :drowning:
Cheers Simon

[Kipper]

Not the Z...I saw no Z axis modification, The Y axis has a modified mount for the ballnut like the image I've attached....Too long between the mounting point and the ballscrew.....Looking at it I may have made it too short

I've never bothered to try and figure the travel per step....It has 1600 steps per revolution and that travels 1.25mm....So that makes 0.00078125 or.....near enough

Mach is a beautiful piece of software and you only have to tell it how many steps per unit (1mm) and then it all works beautifully.

[LongRat]

Cube, although most motors physically are 200 steps/rev (1.8 degree) the true number of steps per revolution is dictated by your motor drivers. I'm running Gecko G201s on mine which are 10-microstepping. 200 step/rev motors then become 2000 step/rev. Kipper is clearly running 8-microstep drives to get 1600 step/rev. Smaller microstepping gives you more resolution and low speed torque, but limits the top speed you get hit.

[Kipper]

Cube, although most motors physically are 200 steps/rev (1.8 degree) the true number of steps per revolution is dictated by your motor drivers. I'm running Gecko G201s on mine which are 10-microstepping. 200 step/rev motors then become 2000 step/rev. Kipper is clearly running 8-microstep drives to get 1600 step/rev. Smaller microstepping gives you more resolution and low speed torque, but limits the top speed you get hit.

Not that clear...I clearly have them set at 1600 steps per rev....The drives actually go to 10.000 steps per rev, 7.8A units running from a 110V PSU MSD2278 models from Motion Control Products.

[LongRat]

?? Sorry I don't understand. If you are using 200 physical step/rev motors (my assumption) your drivers must be set to 8-microstepping to give you 1600 steps per rev. That's not to say you couldn't set them to something else (1,2,4,...10 microstep etc), as I see the MSD2278 has 16 selectable microstep settings.

[Kipper]

?? Sorry I don't understand. If you are using 200 physical step/rev motors (my assumption) your drivers must be set to 8-microstepping to give you 1600 steps per rev. That's not to say you couldn't set them to something else (1,2,4,...10 microstep etc), as I see the MSD2278 has 16 selectable microstep settings.

I think you do get it, My previous post was clearly indicating that I don't have 8 microstepping drives and your quoted post states now that I have have my drives set to 8 microstepping....which is clearly the case...just clears things up