Please take a look over my shoulder – CAD CAM CNC Bench Mill System

[whelen]

I’ve been researching the web for three weeks to figure out how to select the software, electronics, motors, and mechanicals to put together a bench mill system. You have all done this, so you have very valuable experience pertaining to my hypothetical system. What I am looking for is your opinion of the direction I am going in. Please feel free to choose any part of the system to comment on. The more detail the better. My objective is to select products that will result in a system with no software / electronics interoperability problems.
My application is to engrave (pointed cutting tool), and mill (end mill cutting tool) both flat plates up to 4” by 4”, and around the circumference of rings. I realize that I need to add a “4th axis”, which will replace either the x or y axis. I am not sure which one. I wish to machine brass, stainless steel, pewter, and plastic. The “engraving” depth will be from 0.005” to 0.040”.
As far as my capabilities, I am a hobbyist and have no CAD CAM CNC experience. I am a competent machinist, and can operate application software packages in the Windows environment. I really don’t want to get into soldering, transformers, circuits etc. I am very fearful of software / electronics interoperability, reliability, and dependability problems.
My present system contains a MicroLux Milling Machine #82573 purchased from Micro Mark. I also have a MicroLux 7x14 Lathe #82710, so I can do fabrication to mount servo motors, and or build new x, and y axis slides. I’ll start with the lead screws that came with the milling machine. Need information about, do I need to modify the lead screw nuts, as an example. I plan to measure backlash.

Software
For CAD I am considering purchasing Rhino, and outputting .stl files to the CAM software. I choose Rhino because all the jewelry applications use Rhino. I’ll be doing very simple “jewelry” machining / engraving. I am not a jeweler and do not intend to become one. Also Tauseef of www.cuttingedgecnc.com stated that he would definitely choose Rhino as his CAD software. Rhino can be purchased from $600 to $900 roughly. If you are a student you can purchase it for roughly $200 at www.journeyed.com, or www.data-switch.net.
Now do I really need Rhino to do my application? I also want to do the regular rectangular coordinate milling and drilling to maybe make a bench top mill from scratch. I was surprised to see that many, many people are doing just that. Do you know of other CAD software that can do my application?
I found Virtual Sculptor (http://www.minitech.com/software/vir...alsculptor.htm), VSCAM-01 at $2,600 discounted to $950. It seems to be both a CAD and CAM package. The main module is CAM VS3D, and the auxiliary CAD module Vscad3 is a traditional CAD program. This software does engraving.

I guess I want to output .stl files from my CAD software. There is also .dxf, but I don’t understand why I would prefer .stl over .dxf output files.

For the CAM software I found StlWork2 a “low cost” 3D solid/surface tool path development system (www.aztec-net.com/~jdemand/links.html). Price approximately StlWork plus Accutrans, list $395 discounted to $75. Has anyone had any experience with StlWork? The CAD output file must be .stl.
Again what would you suggest for the CAD and CAM software for my application? Where do I specify the .stl mesh size? In the CAD or the CAM software?

Next I guess I need translator software. The CAM output files are G code, I think (what is M code?). I find the translator software confusing. What is it doing? Is it part of the motor drive electronics package, which provides the CNC signals to the motor drivers?

I might want a tool-path simulation software.

Somewhere in all of this is the ability to set up the 0,0,0 coordinates to relate the cutter to the work-piece. Limit switches to control run away programs, and something to turn on coolant. Also something must isolate the PC from feed back from the motor driver circuits and power supply. How do I do all this, and not touch a soldering iron or read a schematic?

Again what would you suggest for each of these softwares to perform these functions, and my application? I hate to admit it, but I don’t have a clue of how the CAM software reads the CAD output file. Or how the translator software reads the CAM output file. I realize that I use a down scale PC to run the CNC software to drive the motors. Again what is the CNC software? Is it the translator software or is it the G code file?

Moving on to the motors, chopper drivers, and power supply. I have my sights on LowCostCNCRetrofits (www.lowcostcncretrofits.com)
“INDUSTRIAL 5 Amp Servo System (Closed Loop) - Budget 5 amp Servo Motion Control Package Deal 021”.
3 Axis Small Milling Machine
**3 Axis Servo Motion controller with 2 internal opto relays**
**RAPID 24vdc / 150W Power Supply**
**Jog Pendant Remote (Ver.2)**
**3 / Hitachi 100oz.in Cont /500ppr. Servor Motors including pre-wired leads**
Price approximately $1,399 US plus shipping. Has anyone purchased their products? Are they in the US or off-shore? How is their support? What happens if “it” stops running, and smoke comes out of the controller box?

I am also aware of IMService SYS-3-4axis complete, ready to bolt on closed loop, servo CNC system with brushed DC servo motors, cables, enclosure, and software. Price approximately $1,424.

Lastly I am aware of Dan Mauch, Camtronics-CNC.com products. I’ll have to e-mail Dan and ask him what his servo system costs. Dan’s site also contains very good information for the beginner. Don’t forget Tauseef of www.cuttingedgecnc.com, he has an unbelievable site for the beginner.

Next the Mill and attaching the servo motors
Will the LowCostCNCRetrofits , Hitachi 100oz.in Cont /500ppr. Servor Motors and chopper driver electronics (motor current and voltage) have enough torque for my MicroLux Milling Machine acme lead screws (#82573 purchased from Micro Mark)?
What will be the approximate maximum inches per minute feed rate, cutting brass, with a 1/8” dia end mill, cutting 0.040” deep? Should I connect the servos directly to the lead screws (with flexible couplings) or should I provide a timing belt reduction? What should the reduction ratio be, and what is the technical reason for the reduction and the ratio (other than more torque)? What do I tell the CAM program about the servo motors, reduction, and encoder frequency? I’ll be measuring the backlash in the acme lead screws. Should I replace the lead screw nuts? Do I loosen up the gibs on the slides? Should I lap the ways? What else should I be doing?

There are pictures on the LowCostCNCRetrofits site of a customer conversion of a bench mill that looks just like mine (SIEG of China makes these bench mills and sells them to Micro Mark, Harbour Freight, Grizley, Smithy etc for branding). The person implemented timing belt reductions between the drive motors and lead screws. He drove the large hand-wheel shaft which moves the z axis.

Well I wish to thank you in advance for any help or suggestions you can provide. The more detail the better.

Whelen

[ger21]

First thing, is that for engraving or general 2-1/2D milling, which I'm pretty sure is what you're talking about, Millwizard is the wrong choice. A much better choice would be SheetCAM. http://www.sheetcam.com Although after re-reading your post, engraving the surface of rings may be a bit tricky. But Millwizrd is not the software to use for engraving.

Millwizard will run just fine in XP.

How to export .stl?
After the drawing is done in Rhino, just choose "Save As" and choose the correct file type, .stl for Millwizard, or .dxf for SheetCAM. Once saved, you just use the "Open command to load the file into the CAM program of your choice. You can set the mesh size in Rhino when saving.

Millwizard creates the toolpaths, and saves them as a g-code file.
Millwizard can simulate the tool path and show what the finish part will look like.

Millwizard can NOT control a machine. I'd recommend Mach2 (soon Mach3) from http://www.artofcnc.ca You load the g-code file from Millwizard into Mach2, and Mach2 will send step and direction signals to your motor drives.

Does ArtCAM MillWizard CAM provide for the specification and positioning of the 0,0,0 relationship between the starting position of the part and tool?

This can be done in Mach2, and might be somewhat dependant on the part location in Rhino relative to the origin in Rhino.

No software can provide isolation protection. It would have to be done by the hardware, and depends on what hardware you'll be using.

I really don't know if that package is right for your machine.

As I said, I don't believe Millwizard to be the right software for you. If you think it is, I would recommend an alternative. MeshCAM, at http://www.grzsoftware.com basically does the same thing as Millwizard, for less money, with more features. The only thing it lacks is the simulation.

[ger21]

ALmost forgot. Spend a LOT of time here reading through the pertinent forums, and ask lot's of questions.

[whelen]

I will have to reread your reply a few times. It looks very helpfull and informative. As you can see I've rewritten the original posting so that it flows smoother. Thank you for your time and help.

Whelen

[ger21]

Now I see you edited your post and asked a lot of differrent questions.

I don't think you really need Rhino to do what you want. Most things can be done with any inexpensive CAD program and SheetCAM, like I mentioned above. Engraving rings could also be done that way, if you know what you're doing, and it's fairly simple engraving. Whether you spend a few hundred $$ or a few thousand on software, imo, the learning curve will be similar.

Try to limit you're questions to 1 or 2 per post, and you'll get a lot more response. Also, try to post in the appropriate forums.

[gtoutounji]

Hi,

I am new to the forum and to CNC. I downloaded a trial version of Meshcam 2 and tried to save a toolpath from a simple STL file I created in Rhino but I get the error message "Filter index error. Save cancelled". Does anyone have any idea why?

Thanks for the help,

Ghazi

[LeeWay]

Originally Posted by gtoutounji Hi, I am new to the forum and to CNC. I downloaded a trial version of Meshcam 2 and tried to save a toolpath from a simple STL file I created in Rhino but I get the error message "Filter index error. Save cancelled". Does anyone have any idea why? Thanks for the help, Ghazi

Meshcam has a forum here at the zone. Robert is pretty good about answering questions posted there. You might also just email him directly.

[gtoutounji]

Thanks Lee,

How do I go to the Meshcam forum? I tried in search forums. I did not see Robert's name.

Thanks,

Ghazi

[LeeWay]

Here is the link.
http://www.cnczone.com/forums/grz_software-_meshcam/

[gtoutounji]

Thanks Lee,

Ghazi

[Fixittt]

My opinion is this, I think you are trying to bite off more then you can chew at the present time. Instead, I would see about finding a small machine as a starting point. use this machine to learn the software and fundamentals on. Get a handle on what does what, and why. Start with some of the free/low cost cad/cam packages that are out there. Start small and work your way up the ladder to get to where you want to be. your not going to be able to machine 4 axis parts if you dont understand 3 axis and so on. I seem to have a favorite saying with people starting off, BABY STEPS.

Alot of times what happens is that people spend ALOT of money on a cnc machine only to find out that its alot harder then they though. Money down the drain and cnc sitting in a garage rusting. Or on Ebay. I suggest starting with a taig, they can handle most materials up to the hard ones like steel. But as for learning the ropes, MDF wood is a great cheap material to learn on.

[philbur]

I have to agree with Fixitt. Also if your Microlux has a spindle speed of only 2500 rpm I think it is the wrong machine for your application.

As Fixitt says if you want a hobby building a CNC mill then follow your current route, it will involve many, many man-hours of research, work and frustration and may not turn out any cheaper, and less competent, than a turn-key mill.

Sell your Microlux and buy a CNC'ed Taig, possibly used off ebay, and start engraving. Then all you need to do is buy/learn the software.

If you stay with the Microlux you really need to up the spindle speed to something like 10,000 rpm +.

Phil

Originally Posted by Fixittt My opinion is this, I think you are trying to bite off more then you can chew at the present time. Instead, I would see about finding a small machine as a starting point. use this machine to learn the software and fundamentals on. Get a handle on what does what, and why. Start with some of the free/low cost cad/cam packages that are out there. Start small and work your way up the ladder to get to where you want to be. your not going to be able to machine 4 axis parts if you dont understand 3 axis and so on. I seem to have a favorite saying with people starting off, BABY STEPS. Alot of times what happens is that people spend ALOT of money on a cnc machine only to find out that its alot harder then they though. Money down the drain and cnc sitting in a garage rusting. Or on Ebay. I suggest starting with a taig, they can handle most materials up to the hard ones like steel. But as for learning the ropes, MDF wood is a great cheap material to learn on.