CNC Millers

[marmon]

Hello,
we are again currently looking to upgrade some machinery and get from conventional machines into CNC. We do not have much experience in the CNC market except for what the salesmen offer. (It is also impossible to talk to a factory rep, seems everything is 3rd party). We seem to be between Milltronics and HAAS. Does anyone have any experience with either? or ideas on what to compare or look for? The one thing we noticed is when comparing similar models the HAAS is alomost 100% heavier, but also 50% more expensive. As for the HAAS we are considering the VF6-40 or comparible in other makes. We also do not do much repeat work, with many of our jobs being one of or two of.
Thanks

 

[BusaJames]

At school we use exclusively Miltronics. They have worked very very well for us but I'm not sure if they were purcased because they're less expensive or because they are just as good. We have not had any problems with them in the 2 years i was there and that's with students hammering...i mean using them.

 

[jelmerra]

You could do a milling trial on both machines and compare the tool life. For most operations tool costs exceed the machine costs substantially.

 

[mullins]

I have been using as HAAS shop to do all of my project work and when I was in school we used HAAS machines. I have not had any problems with either set up. Really either machine brand will function, it is just a decision based upon economics. See if you can get the MTBF of the different parts (table actuators, CPU, and spindle) before you make your decision.

 

[tripleZ]

I've used the Haas machines and have found them to be good for doing the basic conventional work. The machine was not as robust on the three-dimensional contour milling as some of the more expensive brands out there, but you get what you pay for. I have no experience with Milltronics.

Get the factory to do a test cut of one of your more difficult jobs, then give you the part back along with the machine time data. If you're located near one of their centers (e.g. outside Chicago), you should be able to go down for a runoff. They can and will do this if you're salesman pushes for it. That will also give you an idea if the machine is capable of what you need it to do. You'll be out some time and material, but it's well worth the cost.

 

[Heckler]

One more thing to think about is upgrade paths for the controller and other electronics that affect the function.

Heckler
Sr. Mechanical Engineer
SWx 2007 SP 3.0 & Pro/E 2001
XP Pro SP2.0 P4 3.6 GHz, 1GB RAM
NVIDIA Quadro FX 1400
o
_`\(,_
(_)/ (_)

"First they ignore you, then they ridicule you, then they fight you, then you win." - Mahatma Gandhi

 

[marmon]

thanks

i assume the cad/cam interface is generally the same with most new machines? Using an outside 3D based program for the drawing then a CAM program, then download to the machine? Both machines offer many operator interfaces but would it be more useful to do the programming at a remote station?

 

[MikeHalloran]

A CNC mill only pays for itself when it's cutting. Programming on the machine is possible, but it's not a good use of the machine, the environment is not usually conducive to clear thought, and you don't want to leave your books out there.

I broke a few tools on a Milltronics 3-axis mill. It came with a PC based simulator that faithfully mimicked the software built into the machine, and could be used to generate programs to send to the mill. It's good enough to get you started, and to teach you what you don't like.

If you've done any computer programming, you'll find that working with the G codes directly is much like machine language programming. I don't mean like assembly; I mean a level below that. The cool part is that _all_ CNC machines speak it, so it's not a big deal to move a program from one machine to another, even if they're from different manufacturers. A few codes differ, but you'll figure them out quickly enough.

The program built into the machine works at a slightly higher level, and the third party programs like MasterCam and Virtual Gibbs work at a still higher level, but they are not free. Machinists seem to grok them quickly, and like to use them.

Most CNC programs are so small that hundreds will fit on a single floppy, but you will soon tire of carrying floppies around and keeping track of them. Plan to run data wires to the mill from the programming station. You don't need Ethernet; RS232 is fast enough. Use a completely opto-isolated interface at the mill to avoid ground- related problems. (See blackbox.com.) Attach a cheap dot-matrix printer to the mill for recording changes to programs and making markups of stuff to add or change later. Power it only from the socket provided in the mill control box to avoid expensive grounding problems.

BE SURE TO GET COMPLETE WARRANTY COVERAGE WITH ONSITE SERVICE ON THE MILL CONTROLS. My experience says a new mill will kill at least one motherboard. My current record is seven in the first year.

The shop where I learned still has the Milltronics mill, off in a corner. I think they use it for testing new hires and for training. They've bought a bunch of HAAS machines since I left. The extra weight could be just useless concrete, but it usually indicates that you can take heavier cuts and/or maintain closer tolerances.



Mike Halloran
Pembroke Pines, FL, USA

 

[marmon]

Thanks everyone and to MikeHalloran.
I would have never thought that the motherboards could go that quickly!
I like what you said about the programming being more easily done in a better environment. From my reading it seems the Milltronics may be better suited to doing small runs of many different parts, and the HAAS more suited to larger runs. I would like to make the move to 3D CAD anyways so i hope to use CAD then CAM then to the machine. It just seems like i'd have more control and fewer mistakes, also doing a "test run" would be an awesome feature. I looked at the sales sheets again, and it seems that the salesman compared a rigid head mill, to a vertical machining center, so the previous weight comparisons no longer add up.

Thanks again

 

[Heckler]

The controller and other electronics are the heart and soul of any CNC machine. We bought a no-name brand made in asia CNC mill for our R&D shop. The mechanics works like every other machine but what we found limiting is the controller and electronics. We see these limits when we do surface contours. Needless to say the tech guy has made several visits in the last two years. I'm glad we bought the extended onsite warranty.

For production work, programming at the mill is a waste of time and money. G-Code is easy to learn but the real value of MasterCAM or Teksoft is doing advanced surface contours something that would be near impossible manually programming.

Heckler
Sr. Mechanical Engineer
SWx 2007 SP 3.0 & Pro/E 2001
XP Pro SP2.0 P4 3.6 GHz, 1GB RAM
NVIDIA Quadro FX 1400
o
_`\(,_
(_)/ (_)

"First they ignore you, then they ridicule you, then they fight you, then you win." - Mahatma Gandhi