CNC Machines

[davidthefat]

How many teams actually have a CNC machine? Are they that useful in the context of the whole competition? I wanted to propose the idea of actually MAKING one, both a great offseason project and beneficial during the build season. What are the components than can possibly be made with a CNC machine? I was thinking of using it to make the intricate parts that can't possibly be made by hand precisely. Is is limited only to Plastics and Wood? Can it possibly be used on aluminium?

[rahilm]

We actually do have a CNC, but the one we have I don't find all to useful. The primary reason is that it is too small...it has a travel of ~10". At that travel, there's not very much to do on it, and most times I'd rather do it by hand (just this Friday, in fact, I made a gearbox plate by hand, after the CNC almost screwed up the first one). Basically, I'd prefer a larger manual mill over a tiny CNC like this.

Also, building a CNC machine is actually a great excercise (another member and I have built 2 now), but you won't get nearly the precision you need, unless you make the parts on a CNC or manual mill.

[davidthefat]

Originally Posted by rahilm

We actually do have a CNC, but the one we have I don't find all to useful. The primary reason is that it is too small...it has a travel of ~10". At that travel, there's not very much to do on it, and most times I'd rather do it by hand (just this Friday, in fact, I made a gearbox plate by hand, after the CNC almost screwed up the first one). Basically, I'd prefer a larger manual mill over a tiny CNC like this.

Also, building a CNC machine is actually a great excercise (another member and I have built 2 now), but you won't get nearly the precision you need, unless you make the parts on a CNC or manual mill.

LOL I thought of the idea of making a CNC machine out of plywood to make the parts for a second CNC machine (stripping the motors and stuff off the old one) and repeating the process as necessary and making the final one out of high quality plastic or something. Well would you say that if it were to be bigger, it would be an essential tool during the build season?

[rahilm]

Originally Posted by davidthefat

LOL I thought of the idea of making a CNC machine out of plywood to make the parts for a second CNC machine (stripping the motors and stuff off the old one) and repeating the process as necessary and making the final one out of high quality plastic or something. Well would you say that if it were to be bigger, it would be an essential tool during the build season?

Yeah, I think a larger Haas or Fadal would be pretty useful and a lathe to go with it would be great. At the same time, though, I think it would be far more effective to go either of these routes:

a)Get a manual mill. It teaches students to actually pay attention to measurements and understand tolerances. Also, it is far more cost effective for FIRST purposes.

b)Get machine shops in the community to provide support. If you can get 3 or 4 shops to give you support, and you can depend on them to deliver parts in a timely manner, this would be far better. You don't have to spend time on fabricating, except small parts. Also, you can expect much more precision.

[Ian Curtis]

David,

What types of parts are you looking to cut? That plays a big factor. My dad built a CNC routing table with a 24"x12" usable table when I was a little kid, which still runs and works great. We use it mostly to make one-off signs & cribbage boards (they make great gifts!). It can cut wood & plastics at 20 inches/minute, which is pretty slow (the sign in the upper right of second link took nearly an hour to cut), but passable. 1276 borrowed our school's ShopBot table (8'x4') to make these handouts in 2007.

www.cnczone.com is a great resource. I was too young to participate in the building of the one we have now, but almost everything he learned in the construction process was from that website. You've got some reading to do!

[sanddrag]

I converted a Sieg X1 micro-mill to CNC with a HobbyCNC stepper kit. It's small, and it's capabilities are very limited, but it's still very fun, and I've really gotten a lot of good use out of it. You just have to respect its capabilities, and have a lot of patience. We're talking probably no more than about .025" DOC at 4 IPM in aluminum with a 1/4" endmill. One thing that I really like using it for is drilling several holes in precise locations in several of the same parts. I manually operate the Z, but just to have the XY position itself is a real time saver over having to dye and scribe it out. For practical application of making quality parts in a reasonable amount of time, look to something larger.

[DonRotolo]

I built a CNC machine a few years ago. It can be used for light milling. Had I used slightly beefier hardware, I could be milling aluminum on it easily enough. Slowly, perhaps...

[Hawiian Cadder]

last season i think my team used the CNC for over 80 hours total, we have an excellent. 48 - 12 - 12 vextrax machine that works like a charm. we intend to use it a lot more the next few seasons because we don't have the budget to get parts cut at the water-jet anymore. a CnC is awesome, if you can get one, it makes life so much better. the primary thing we use it for is bearing holes, and pockets.

[RoboMaster]

We thought about making our own CNC, but didn't think it'd be worth the time, effort, and money. It's a pretty big project (at least for us). We've also thought about buying one, but that also is quite expensive and not worth it for what we do in FIRST.

I would totally agree with rahilm to get a manual mill or talk to local machine shops. One of our parents/mentors co-owns a machine shop and is always very willing to make whatever we can think of (unfortunately, we haven't thought of much for him). A manual mill is also great as rahilm said, if you can afford it. See if you can get a used one.

Most of the time there isn't a ton of use for a CNC. But every once in a while you'll find it would have been really handy. We've asked the machine shop to make a couple brackets and drill holes for gear sprockets. There are teams out there that machine really cool "trick parts" that can be the highlight of their robot or drive system. On a related note, there are a bunch of teams that machine their own wheels. I think that's a little overkill, but to each his own.