To CNC? Or not to CNC?

[phrontist]

Our team has it's own shop complete with a very nice set of tools. However as far as power tools go we are somewhat limited. We have no milling capability whatsoever, save a drill press. This did not hamper us this year, but I'm interested in what it would require to obtain/access a CNC mill (Even a small one.) What does a CNC allow you to do that are impossible to do otherwise. Is it a good investment?

We are in Falls Church, VA (Very close to DC, West Falls Church Metro is literally a stones throw from our building). Any teams nearby have a CNC we could use?

(Could we make one? )

[Gui Cavalcanti]

Wow.. you're talking about flying before you can walk there, man.

First off, a CNC is a huge investment, and one that I think shouldn't be done for a team-only shop. The smallest, bottom-of-the-barrel CNCs would run you between $15,000-20,000 used. Yes, they're fabulous tools (I ran one for our team this year in one of our sponsors' shops), but you have to think really hard before getting one.

Having a CNC is not really a question of what it can do, but rather how fast it can do it. You can do (pretty much) anything a CNC can do on a manual mill with the right attachments, but programming and running a CNC will be much faster and more accurate (Instead of .001" tolerances on a Bridgeport you'll get .0002" on a CNC...) for the same process.

If I were you, in a shop that only currently has a drill press, I'd get a new or used Bridgeport manual milling machine. If I had the funds, I'd also invest heavily in quality cutters, vises, and rotary/indexing tables. It'll run you less than just a out-of-box CNC and still give you much of the versatility, if slower.

[sanddrag]

Well, to have a cnc you would need many thousands of dollars. The absolute cheapest one I have found is this http://www.maxnc.com/page3.html and it is extremely small. You couldn't make very big stuff with it. Plus, there is no automatic tool change or coolant or anything like that. You'd be better off getting yourself a nice set of manual machining tools.

The advantages of CNC are:

Very precise and accurate
Quick
Numerous parts of the same are easy
Can make very complex shapes and large cutouts and bores

Disadvantages of CNC:

Cost
Programming time/expertise needed

For your machining needs, see if there is a college nearby that is willing to help you out. That's what we did and they give us full support of a half dozen manual mills and lathes, 3 CNC mills (one of them is 710 ipm 30 hp vector drive) and a CNC lathe plus several other tools. We only have to pay the class fee of $24 dollars per student per semester.

CNC mills can be made from manual mills but the cost vs. benefit may not be worth it. Here are a couple links of people who have done it.

http://www.bmumford.com/cncmill/
http://www.embeddedtronics.com/metalworking.html

[kacz100]

Well a CNC can be a huge money spender but I used to be on team 40 and we had a great sponsor Intelitek, they make some great machines that are tabletop and are just as good as the other larger counterparts. Well enough of me jabbering; here is the link for all you CNC mill and lathe people

Intelitek website

[indieFan]

Here are just a few comments:

As someone who has a CNC to work with in "my" college lab, I can tell you right now that if you don't have anyone who is experienced in running one, you will find yourself extremely frustrated during the season trying to make parts. I have been coding everything directly into the CNC using straight G-codes and have now broken a number of tools due to incorrect speeds, incorrect feeds, or my personal favorite, incorrect Z-heights. Please do not make the mistake of thinking you will be able to learn to run a CNC quickly the way I thought I would. I read all of the manuals cover to cover before I took a one week training course at the company, and I still had no clue what I was doing while I was there.

There are also people that say there are programs out there to make life easier, such as MasterCAM, but they are only giving you a small part of the story. You still need to understand how that software gets integrated with the hardware of the CNC, esp. when it comes to the Z-axis. Until you gain that understanding, the software is worthless. (Yes, I still have to learn how MasterCAM and/or EdgeCAM is integrated with my lab's CNC.)

Other people have commented in part on the cost of the CNC so I'll only add that the tooling that was set up for the one in my lab cost $15,000 for just toolholders and what were considered the standard tools that we would be using. I do not know what the tooling costs would be like for a smaller CNC.

indieFan

[Jon K.]

This year RAGE was lucky enough to have CNC Software, Inc. The creators of MasterCAM as one of our sponsors. I am lucky enough to be able to use the machine donated to our team and the use of MasterCAM software. It does take a while to learn the basics of the machine, but we have two people working it and between the two of us we know most of what needs to be known. We also have the President of MasterCAM teaching us how to use the software and the CNC machine. We are very lucky this year and are hoping to be able to create aluminum sprockets to sell to FIRST teams in the near future. But we are also helping out a few teams this year by creating sprockets for them as well as our own. I have found the CNC machine to be very easy to use when you get used to it, but like I said we have someone with a large knowledge base in the field to help us.

[Wetzel]

Gui was right, CNC is a great step above where you are.

Team 116 has had a manual mill and lathe for years, and we just this past years got digital readouts for the mill. That makes it alot easier to use then counting revolutions of the handle.

A mill is a very useful tool, if you know how to use it. And if you know how to use it, it is almost as useful as a CNC. Dave has a rotary table that we borrowed (and didn't quite take real good care of ) and used to drop about a pound from our big sprockets fairly quickly.

You are welcome to come by our shop durring most any meeting and look at what we have and I or someone else can show you what we have and if you want, you're welcome to come and use our shop. We have an open shop policy.


Wetzel

[Adam Y.]

Just to add on to the disscussion. There is a book that allows you to build a CNC mill from scratch. Though it really does not ressemble a mill. Also, it looks like it can only be used for woodwork but it is a good lesson in that technology.

[jacob_dilles]

Originally Posted by phrontist

We are in Falls Church, VA (Very close to DC, West Falls Church Metro is literally a stones throw from our building). Any teams nearby have a CNC we could use?

we are in Vienna, Va (22181) James Madison Hs. stop on by we have a 3 axis. but we have no idea how to use it, so we could learn together

[tenfour]

As 'ol sanddrag commented, CNCs are not magic. For most applications that can be found in FIRST, manual machines work fine. Lets face it, very little teams need .0002 accuarcy, esp. considering that a human hair is 10X that distance.

There are a lot of the Bridgeport machines out there that you could buy or have donated. I would them spend your money on some tooling for it that will make it like "a manual machine of steroids." This includes some nice cutters, a digital readout, a good vice, and an indexing head.

I would also venture to say that a lot of the time, work can be done on the Manual faster because you kinda just plug and play. There is little setup when compared to the CNC (requires a lot of initial setup and expertise).

PM me if you need more information or have any questions.

[DanArgent]

Sorry phrontist, as I am a member of your team I can safely say that we do not currently have the funds for a CNC. Besides, I believe Dixie sheet metal has one and they are ussualy more than generous in helping us out.

[cmaccoy]

You guys could take a class for Milling. My uncle owns a business that does all milling. If you guys really wanted to go the whole way, you should get mastercam . We use it right now and it has learning software which isn't hard to learn. Also i'm not too sure but i think because this is kinda a school program you guys could probably get the educational version (a lot cheaper). Enough of me yappin, heres the sight www.mastercam.com. **GOOD LUCK**

[cmaccoy]

If i were you I'd just get a small CNC mill. Like one of those cheap things some schools get for like 4 thousand dollars. The mill I'm thinking of isn't nearly as powerful as regular ones but it'll get the job done. And Bridgeport's can't do all CNC mills can. It would take a CNC mill 10 minutes or less to make a sprocket, with a Bridgeport, I'd say it may take 3 weeks if your good. Good luck to what ever decision you decide upon.

[Cory]

Originally Posted by cmaccoy

If i were you I'd just get a small CNC mill. Like one of those cheap things some schools get for like 4 thousand dollars. The mill I'm thinking of isn't nearly as powerful as regular ones but it'll get the job done. And Bridgeport's can't do all CNC mills can. It would take a CNC mill 10 minutes or less to make a sprocket, with a Bridgeport, I'd say it may take 3 weeks if your good. Good luck to what ever decision you decide upon.

And on the otherside, as said before, it takes tons of time and knowledge to setup a CNC.

I was working with a machinist at a shop that produces structural members for large buildings, and all they do is crank out like 100 of these mounting plates a day. For that, it's great. They program it once, then stick all the raw materials on pallets, and load it into the machine. He had a real good way of looking at it that I really found telling. He told me that it takes $2,000-$3000 to make the first part, then after that it's $.20 each.

Basically, CNC is for mass production, or extremely complex parts that simply arent possible on a manual mill.

My team was looking to develop a shifting transmission based on team 45's design this year (which unfortunately didnt pull together in time) and we did not have access to a CNC mill, which was "required". Working with the same machinist, we managed to make every single part which "required" CNC by hand, with no loss in performance, and perhaps a small loss in precision.

My point is, as others have said before, you can do almost anything on a manual mill if you're good enough.

Cory

[dlavery]

Phrontist and DanArgent -

As you can see, there is a strong consensus recommendation that you skip going to CNC for a while. If you want to bump up your manufacturing capabilities, consider a manual mill and/or lathe first. It will do the vast majority of the type of work you are likely to need for the FIRST competition, and provide a more gentle introduction to heavier fabrication techniques and capabilities.

That said, if you (or any of the other DC-area teams) are seriously interested in picking up a mill or lathe, consider a used production machine. There is a used machine tool auction held down near Fredricksburg late every spring. You can usually pick up a good piece of equipment there for about 10-15 cents on the dollar. Just be sure to take someone with you that knows what to look for, and to make sure that you don't get ripped off.

Also, consider attending a meeting of the Chesapeake Area Metalworking Society (CAMS). CAMS is populated with a bunch of retired machinists and metalworking hobbyists, and they are always happy to talk with new folks. They would be a perfect resource for you to learn about machine tool use, and how to make the best use of a new one that you pick up.

Actually, now that I think about it, it would probably be a good idea for a bunch of the DC-area teams to get together and put on a FIRST demonstration at a CAMS meeting. Let them know what we do, and see how many of their members might become team mentors. (slapping self in forehead) I should have thought about this a LONG time ago!

-dave