CNC Mill

[dagronlund]

Our team just recently bought a CNC mill before this year's season (we received it in August) and it worked great for everything we did. Our entire chassis was CNC machined (as seen in this post: http://www.chiefdelphi.com/forums/sh...ighlight=4499). Although they are harder to learn and more expensive, the CNC knee mill is really the way to go for a lot of FIRST teams. We were able to cut not only 1/8" aluminum tubing but also huge blocks of both aluminum and steel, with remarkable precision and speed. We bought our mill used from a local shop for about $4000 and we haven't had any problems. It's an old machine but runs great (it looks just like this: http://www.practicalmachinist.com/vb...ill-mill2.jpg). It was a great investment and has given us returns far in excess of what we paid for it.

[asid61]

Lathes are also nice. Given the choice, I would rather have a small 4-axis CNC rather than a much larger CNC mill. Even a cheap $1000 manual lathe will serve you very well for doing things like hex shaft e-clips and spacers.

[Dunngeon]

Originally Posted by Thad House

Do you already have a lathe? I would say that having one is more important then a manual mill, which is more important to have then a CNC. That would be the order I'd purchase things in. I don't know much about specifics to buy, but I know other people on here will have better answers.

I know the manual lathe is considered above the CNC on Chief Delphi, but depending on how your team builds, a CNC may be more useful.

For example:

This year, we used all hex shaft on our robot, no encoders, hex collars, spacers, and bearings. The robot frame is gusseted 2x1 aluminium extrusion (pop rivets, plates, holes made by cnc). Each end of the extrusion is faced by our mill so that it is square, all the holes for the pop rivets are made by CNC so that everything lines up perfectly. The gussets are made inhouse on the CNC as well. The custom gearboxes we used on the robot.... You guessed it, machined by our CNC mill. We also have a hex broach, so that we can buy circular collars and make it fit onto our .5 inch hex shaft.

Now, this isn't to say that a Lathe is totally useless, because it isn't. As a team, we under-utilize it. However, depending on what direction your team wishes to take fabrication capabilities, will then dictate what tools you buy.

Also know that my perspective is from a team with access to a large machine shop (see below). This is simply the direction our team has decided to take our machining, a lathe may be more useful to many teams who design for a different chassis/design differently.

955 has 3 Manual Mills, 1 CNC, 3 Lathes, 2 Table Saws, 2 Chop Saws, Sheet Metal Equipment, and 2 CNC routers. + Full on Welding Equipment (Through the high school shop)

[Metalcrafters]

Originally Posted by Andy A.

A team new to CNC and still building up 'traditional' resources might be better served by something like a prototrak knee mill. Just a thought.

I will second this option, we have had converted Bridgeports by southwest industries since the beginning of our team. Having a cnc that programs conversationally is a huge advantage as to other options that require extra software. This has the simplest user interface I have seen and used.
We are coming to a end of constructing a new facility with many high end machines. I just ordered prototrax knee mills to square up material and run 3 axis program just as we have since 1999. My students need to turn handles prior to running a Haas.


__________________
Lucas Pacheco
Instructor/Team Manager
Manufacturing Engineer
Hawthorne High
School of Manufacturing and Engineering

[craigboez]

I was not familiar with Prototrak until recently and now I've seen them mentioned a few times. Anyone care to give more details about their setup and experience with this equipment?

[Dunngeon]

Originally Posted by Metalcrafters

I will second this option, we have had converted Bridgeports by southwest industries since the beginning of our team. Having a cnc that programs conversationally is a huge advantage as to other options that require extra software. This has the simplest user interface I have seen and used.
We are coming to a end of constructing a new facility with many high end machines. I just ordered prototrax knee mills to square up material and run 3 axis program just as we have since 1999. My students need to turn handles prior to running a Haas.


__________________
Lucas Pacheco
Instructor/Team Manager
Manufacturing Engineer
Hawthorne High
School of Manufacturing and Engineering

I would also agree with this, students should understand how to operate a mill by hand before using a CNC, or writing conversational code. Otherwise, how will they know when something is going wrong?

Also, once you get the CNC, test programs either in air above the piece or in plastic to see if they will actually work. The number of times plastic has saved me from breaking an endmill or wasting Aluminium plate is too high. (or breaking the mill ) #handwrittencodeprobs

[Metalcrafters]

Originally Posted by craigboez

I was not familiar with Prototrak until recently and now I've seen them mentioned a few times. Anyone care to give more details about their setup and experience with this equipment?

http://www.southwesternindustries.co.../prototrak-emx

This is basically what our Bridgeport conversions are. Prototrak has been around a long time and services the prototype machining sector, one off parts. It allows for manual machining with a DRO digital read out and allows for simple to complex cnc programs. These programs can be programmed at the machine or offline such as mastercam or any other cam software.
SWI offers their base line knee mill with 2 axis cnc for around $18k they work with education, but are not a huge company that can offer huge discounts.
I also like them because they are local to my school and service calls are not outrageous. But in all honesty I have really never need them serviced in over 15 years.
We also have one of their cnc lathes with exact same controls as mill which is nice.
Like I said I am ordering knee mills with Emx controls for 3 axis and bedmills with smx controls 3 axis . The only difference between the two is level of conversational programming. SMX offers direct import of dxf files and on machine programming.

I would like to add the tracking feature. Program your part turn your handle and the program steps through the cycle at the speed you turn the handle, reverse the hand it back steps. Great for proofing your program. No crashing the machine!

[Rob Stehlik]

I looked into a Prototrak bed mill from Southwest industries this fall. They are pretty nice, and I really liked the idea of being able to run a machine in either fully manual or CNC mode. It seems like a great way for students to learn. Unfortunately, the open style guarding raised some safety concerns, and when I priced the machine out with a few options, it was actually more expensive than a Haas TM1-P. You can imagine which one I decided to go with

[Hadi379]

Team 379 purchased a Tormach PCNC 1100 about two years ago. There is definitely a learning curve, but our entire robot was machined in-house this year on our CNC mill. My biggest complaint is the bed size, I don't think you can machine anything larger than 18"x 10", which is decent for FRC.

I also believe you can purchase a lathe attachment that mounts to the bed of the PCNC:

http://www.tormach.com/product_pcnc_lathe.html

Or a rotary/4th Axis attachment as well:

http://www.tormach.com/product_rotaryproducts.html

[Andy A.]

Originally Posted by Metalcrafters

http://www.southwesternindustries.co.../prototrak-emx

It allows for manual machining with a DRO digital read out and allows for simple to complex cnc programs. These programs can be programmed at the machine or offline such as mastercam or any other cam software.

I'll just offer a counterpoint: I don't really like the conversational programming interface, at least as it appears on the machine I have access to (an EMX, I think). It's functional but has a significant learning curve and takes some time to enter anything moderately complex (all the while occupying the mill). It's a lot of data entry with limited visual cues and many ways to make mistakes. Obviously more frequent use would bring greater familiarity and speed, but even after 6 weeks of fairly intense use I feel like I'm digging a hole with a stick.

95 had to jump through quite a few hoops before we finally had access to mastercam and a working post, but it makes the mill far more powerful and pleasant to use. So I recommend the prototrak on the strength of it being both a reasonable manual mill and a fairly large work envelope cnc mill when coupled with dedicated CAM software. The conversational stuff surely has it's place and fans but its never lived up to the promise, in my mind.

[Metalcrafters]

I fully agree that complex parts need offline software, I program almost all of our pocketing with mastercam. But having to post a program to run a few drill points is just as much of a waist of time.
Haas Tm1 is a nice machine we will have two in a few months, I know I will be missing the manual quill that our prototrak has, especially drilling simple patterns.
We all choose to suit our needs, making chips is what it is all about!

[sanddrag]

A knee mill style machine definitely has its place in almost any shop, and while I've never done much with conversational programming, I'm not really a fan of it. If you learn your CAM package well it can get really fast to generate and post code for almost anything. Even if I'm just drilling a couple holes, I've become so fast at CAM and CNC that I can program, set up, and run faster than I can change the belts and clean up the job on a manual mill.

Honestly after the HAAS, the only use our manual mill sees anymore is infrequent by students who haven't yet learned the CNC.

[Rob Greene]

Cost is everything. A good entry level cnc router is a great place to start. We have 6 machines from Probotix CNC. These machines are turn key for $3,200.00 and work well with the abuse of teenagers. Our machines are still running well after three years in a public school. Many options, just one to consider.

[eli2410]

A big thing for us is that we can cut out all of our parts on our CNC. We have a giant Techno LC 4896 (school was new, and they spent a lot). If I was looking for our first CNC machine for our team or any other team, here would be my requirements:

• Minimum Cutting Area: 4'x4' (so you can cut the frame of your robot, as well as other large pieces)
• Easy way to secure material to table We have a vaccum table and screw into sacrifice boards. (Don't want pieces flying)
• Easy to change tools, going from 1/8" bit to 1/4", for example(You want it to be able to change and remember tool lengths so you don't have to re-zero the Z axis, and so you can use bigger bits to cut out parts. The bigger the bit size, the faster you can go)
• Coolant (Makes working with metal much easier)
• Spindle Speed >9000 rpm (The faster the spindle goes, the higher the feed rate can be. The higher the feed rate, the shorter the job)
• Easy to operate (we have a different machine that is a pain in the a** to operate. No one uses it and I've only known one person that likes it even the slightest. On the other hand, the Techno is pretty straight forward for a beginner, but there are advanced features that an experienced user can use.)

Other things that will affect your experience:

• CAM Software (Don't be cheap, get a good one. Autodesk has HSM Express for free, and you can sign up for CAM 360 Beta, which is CAMing in the cloud.)
• Tooling (You want to make sure that you have bits that can cut the materials you want it to, and that you have different sizes and multiples of some of the more popular sizes, such as 1/8" and 1/4". You will break one at some point, and you want to be able to just swap them out quickly, especially during build season.)
• Experience (Just like everything else, the more experience you have, the better you will be.)

If you have any more questions, feel free to private message me.

P.S. On any machine you get, make sure you know where the Emergency Stop is. Another great thing to have is a wireless mouse, so if you are cutting a material for the first time, you can stand a few feet back. That way, if it sparks or something breaks/flies, you have more time to react and you don't have to get closer to it in order to stop the machine. I still stand a couple feet away when I first cut a part out, and I've stopped parts numerous times with the wireless mouse (most of the time, there wasn't a problem, I just wanted to be sure).

[eli2410]

Originally Posted by craigboez

I was not familiar with Prototrak until recently and now I've seen them mentioned a few times. Anyone care to give more details about their setup and experience with this equipment?

We have a Prototrak. Our teacher that was new for this year had a lot of experience with it, and we have use it a lot for smaller parts that would take too long for the Techno, for touching up other parts, and, until recently, accurate cutting of any metal besides aluminum (figured it out on the Techno. Use Torchmate Plasma Torch for not as accurate cutting). Before this year, we didn't use it that much. Now, it's probably the second or third cutting most used machines in our shop (the techno is still number one followed either band saw or the Prototrak).

Once again, if you have any more questions, feel free to private message me.