Planning CNC for RF-45 Clone ZAY7045FG

[sarel.wagner]

I am in the process of planning my CNC upgrade for the ZAY7045 clone mill. Need to order the mill, ex stock locally in South Africa. I do have the option of going a real Rong FU RF45 as well, a bit more dear on the wallet though

Since we do not have a dedicated sub section for the RF's and clones it is a bit difficult to get to all the info, a real pity.... as there are so many paths and options to select from but nothing really easily reachable.

This will be my attempt to document the process of planning and what lead to my decisions as well as what they are and the effects on other parts of the build.

I am in IT as a professional and design Data Centres, Networks and Systems as well as trouble shoot and repair all types of IT equipment. I also design and build Embedded systems, well in the past I did but do not want to spend the time doing so for this project.

The types of things I want to mill are dies and arbours for building other tools, making parts for projects and cars. I restore and build old VW aircooled cars, Beetles and Busse's. I am an Amateur astronomer with a few telescopes and want to make some components for that as well.

I do have a Myford Super 7 lathe, currently being fitted with DROs, waiting for the delivery of the scales. Also have MIG, Plasma cutter, can do some milling in the Lathe, metal cutting band saw, compressor and all manner of drills, bits, hand tools, measuring tools like Mitutoyo Calliper and DTI etc etc. Oxy setup for cutting, heating and welding sheet and Aluminium. Currently building and English wheel and do some metal shaping for me car projects.

The mill type is sorted ZAY7045FG (RF-45 clone) or the RF-45 itself. On a broad level the following items are kind of crystallized as well (I am pragmatic):

1. Enough speed and accuracy (I do not need super fast nor 0.0005mm)
2. Stepper driven
3. Micro stepping via USB or Ethernet desired (I do have and older Compaq Server with Parallel port available but do not want to be reliant on just that)
4. Mach3 or LINUXCNC (EMC)
5. Ball screws
6. VFD (Don't mind changing the Motor to get 3000-5000 top end RPM)
7. Cooling
8. Smooth finish and co-ordinated axis cutting
9. Rhino or Solidedge 3D CAD
10. CAM dependent on the above (Prefer integrated CAM)
11. What else?

I need to make up my mind on these issues and need some help please. Feel free to be critical as I do n ot want to end up second guessing myself nor wast time and money. I prefer to plan, do it once and build it once, then use it until it brakes, or I brake it. This is merely a project to get to make parts, I do not want to keep changing my CNC to correct issues.

Thanking ya all Please fire away.

[kensbey]

will be following your thread with interest. I am also going throught converting a 45 clone, intending to use steppers as well. Most guys on here tend to use servos, but there are a few stepper driven 45's around.

all the best.

[ninefinger]

For the stepper versus servo issue - as you selected steppers AND you want USB or Ethernet that limits you to Mach3 and smooth stepper I believe. I don't think there is an Ethernet or USB driver for Linuxcnc (used to be EMC2).

There are other driver boards out there that include a cnc / g code control software ( I think these guys have an interesting product Dynomotion | Motion Control Boards )

Steppers are perfectly fine for the machine - its just that as you go up in size the cost difference between servos and steppers narrows and you can go either way for the same money with a few benefits for servos such as fault detection and usually higher speeds. AC servos systems have come way down in price and are nearly the same as DC servo now - check out Kregan's build in this forum on his MD001 (a large RF45). From these guys DMM Technology Corp. I like the package they put together and Kregan seems to like it too.

Some food for thought...

Mike

[sarel.wagner]

For the stepper versus servo issue - as you selected steppers AND you want USB or Ethernet that limits you to Mach3 and smooth stepper I believe. I don't think there is an Ethernet or USB driver for Linuxcnc (used to be EMC2).

There are other driver boards out there that include a cnc / g code control software ( I think these guys have an interesting product Dynomotion | Motion Control Boards )

Steppers are perfectly fine for the machine - its just that as you go up in size the cost difference between servos and steppers narrows and you can go either way for the same money with a few benefits for servos such as fault detection and usually higher speeds. AC servos systems have come way down in price and are nearly the same as DC servo now - check out Kregan's build in this forum on his MD001 (a large RF45). From these guys DMM Technology Corp. I like the package they put together and Kregan seems to like it too.

Some food for thought...

Mike

Hi Mike, The USB and Ethernet is so I am not stuck without a parallel port in future as I have only one Server/PC with such a port and new computers as we all know do not have these ports (I like future proofing). While this is still working, I am planning on using it to keep costs reasonable. If it fails I may have to change to USB/Ethernet. Good to know that Mach3 can work with that.

I then think that I may have to go Mach3 so that the system can stay with that software no matter what port I may use.

As this is for my own entertainment and strictly own projects, speed is not that important to me. In South Africa steppers are far less $$$ than Servos and steppers being good enough I will stick to that.

At this point then the Software will most likely be Mach3 with steppers. Then it looks like Gecodrive's G213V drives to get at this:

1. 7A 80VDC Power Ratings
2. Full step, half step, 5 microstep and 10 microstep selectable resolution
3. Mid-band resonance damping
4. Morphs to full step at higher speeds to maximize motor torque
5. Recirculate mode while motor is stopped

The Smooth Stepper Board with BOB C25 would then be the USB interface and connection to the Gecodrives.

The list from the first post, will make this up to date on a regular basis:
1. Enough speed and accuracy (I do not need super fast nor 0.0005mm)
2. Steppers (Still need to select em) driven by (Gecodrive G213V or G203V)
3. Micro stepping via USB or Ethernet desired (Smooth Stepper board USB and C25 BOB)
4. Mach3 or LINUXCNC (EMC) (Mach3)
5. Ball screws
6. VFD (Don't mind changing the Motor to get 3000-5000 top end RPM)
7. Cooling
8. Smooth finish and co-ordinated axis cutting
9. Rhino or Solidedge 3D CAD
10. CAM dependent on the above (Prefer integrated CAM)
11. What else?


Rgrds

[sarel.wagner]

Ok, so on to movement, looking at about 150IPM rapids (63.5mm or 2.5"/sec) as a max. Now if the head & motor weighs 250lbs it means about 70Watts consumed by motor should be enough to to move that head weight at 150IPM Does this seem right?

What size stepper motor (what brand as well please) would work here with Gechodrive G203V or maybe a G540 but the 203's preferred.

The head may gain some weight due to new 3phase motor for the VFD drive, say another 50lbs for a total of 300lbs so abot 85Watts consumed by motor required, making it 15 watts extra for the extra 50lbs.

Rgrds

[ninefinger]

The movement of the head is governed by its weight as well as the friction it exerts on the dovetail ways - its not acting the same as for X and Y. Most of the contact pressure is at the top and bottom of the Z saddle and this creates a lot of friction. I found that my calculations were pretty good for X and Y but when I tried on Z my little servo motor that in theory could handle it just fine was under powered. Use a big factor for friction to be safe (ie 50%) and your calculations will be in the ballpark.

If you want 150ipm don't look at the wattage - check the torque requirements to accelerate the head to the velocity you want, then find the drive and motor that fill the requirement.
Also - you'll notice that steppers really drop off on torque as their stepping frequency increases so keep this in mind. You should be able to get the torque curve of the stepper you're looking at from the vendor.

ie. 150ipm with a typical ballscrew of ~5tpi (or 5mm for metric). Direct drive that is 750 rpm. 200 steps/rev is 2500pps at full stepping - but with micro stepping of 5 you're at 12500pps which drops you off the bottom of the torque curve - see this example http://kelinginc.net/KL23H276-30-8AT.pdf

Some food for thought.

Mike

[SCzEngrgGroup]

"but with micro stepping of 5 you're at 12500pps which drops you off the bottom of the torque curve" - Micro-stepping does NOT change the position on the torque curve. The curve is plotted using FULL steps, and microsteps land between the points plotted in the curves.

Regards,
Ray L.

[sarel.wagner]

Gents, thank you. Point taken on microstepping pps. Am I then correct to say that for this motor: http://kelinginc.net/KL34H295-43-8B.pdf and 5tpi ballscrew @ 150ipm driving it with 70Volts @ 4.3A (Inductance 3.3mH Unipolar) I will get 730RPM for 200step/rev or 2433pps consuming 300Watts

Rotor Inertia for this motor is 1400g/cm^2 and Unipolar holding torq is 640 oz/in
The supplied torq graph gives about 4.7N/m (665oz/in) at 2500pps.

Will this stepper be ok for this mill given the friction of the head with said stepper & ballscrew in direct 1:1 connection?

Rgrds (here is to hoping my math is sound)

[sarel.wagner]

I grabbed the Kollmorgen Motioneering app. I am stumped in a few places. My export attached, just delete the .txt extension.

I think I got the Slide sorted as well as the screw. The rest of the entries load coupling and force, not so sure about them. Maybe explain the function of the Force entries to me?

Any help appreciated.

[sarel.wagner]

Here are my inputs into the Motioneering app only Z-Axis given here, some are guesses and I do not even know if they are close:

Z-Axis created
Load Coupling: Inertia direct entry: 1400 gm-cm2 (Stepper Rotor Inertia, I ignored the actual coupling inertia, but should not I guess)

SCREW: Diameter 20mm, Length 350mm, Lead 5mm/rev, Nut preload 10N-m, Efficiency 90%

FORCE: Thrust and Continuous Force (Unsure what to enter here, please explain)

PART/TOOLING: 10KG for a part (This represents the weight of the tool and stuff clamped to Z-Axiz)

Slide: Weight 150kg (330lbs), Elevation 90degrees, Gib force 20kg, Speed at Thrust Force, 0mm/sec(do not understand this parameter), Speed maximum traverse 65mm/sec (150ipm)

Please comment and give me direction.

Rgrds

[sarel.wagner]

It dawned on me while looking for tooling for the mill, I was going about all this in completely the wrong way! This came about due to the fact that apart from the useless Chinese tools imported as part of the clone mills, I cannot get decent MT3 industrial quality tooling at the few tool suppliers locally. The Clone importer only imports MT3 mills and tooling.

Two other importers import mills with R8 spindles, one being the genuine Rong Fu series but get this, not the RF-45 only up to the RF-40 round column mills :O and boy are they $moking their own socks!

So now I need to get a R8 spindled RF45 clone, a ZX45. Price is reasonable at about $2700 including a stand and a 2HP motor.

So here is my thinking, why am I trying to decide the IPM speeds that I want to get on my mill, if my tooling ACTUALLY will dictate what speeds and feeds are required? From a requirements point of view, select the tooling and run them via a Speeds& Feeds calculator. That will spit out the IPM and RPM and bingo!

What do you think?

Rgrds