Advice/recommendations about new equipment for our machine shop

[pipsqueaker]

next year our team is looking to expand our machining capabilities by buying/making, in order of priority

1. A 3-axis mill
2. A laser cutter
3. A lathe

We don't need anything hugely expensive or fancy- just enough to be able to accurately machine things like, for example, swerve drive gearboxes, which we've never been able to do before (tools in our shop right now: belt sanders, a band saw, 3 drill presses, and some hand drills)

Here's the catch- we need this stuff cheap. For all 3 (or two, we could probably do without a lathe), we'd like to only spend 2-3k, max. While we're not broke, this is just about as much money as we can afford to spend.

I can give some more details as needed, thanks for your help!

[MrForbes]

Interesting...if I were in your situation, the lathe is the first thing I'd buy.

[Mark McLeod]

I also think a lathe is the first tool to be buying.

Remember too, that a mill for example is only half the required cost, the other half is the tooling.

[MrRoboSteve]

Most threads like this have historically recommended the lathe.

[sanddrag]

I don't own one yet, and it's a bit over your budget (and all will be), but for a laser, you may want to look into https://www.bosslaser.com/

[Rachel Lim]

I know a student on our team who bought this lathe: http://www.harborfreight.com/7-inch-...the-93799.html
Hopefully she sees this thread and can share her experience with it, but from what I've heard, it works really well on everything she's tried except for long shafts.

I have another friend (not in FRC) who bought this mill: http://www.harborfreight.com/two-spe...ine-44991.html
He said he chose that one mainly because of the price and because he didn't have room for a larger one. I'm not sure how accurate it is (the last time I talked to him, he was working with wood and waiting for aluminum to be delivered) but he seemed happy with it.

I'm not sure if either/both are accurate enough for what you need to do, but I'm sure someone else who will see this thread will. If you have any questions about the mill or lathe, general or specific, let me know and I'll see if they're willing to share more about them.

[Joe G.]

The lathe and mill will be signifigantly more useful to you than a laser cutter, especially in that price range.

I completely agree with other posters in this thread: lathe should be first priority. Getting a lathe revolutionized our team's build capabilities more than any other tool we own.

The used market is your friend. Look on craigslist, you should be able to find a decent sized lathe, and a bridgeport knee mill, for about 2 or 3 thousand quite easily. These kinds of tools last a long, long time when maintained correctly.

[DonRotolo]

The advantage of a lathe is that no other machine can do what it does, such as manufacturing a shaft. It can also do light milling and slotting with a milling attachment. Just for making spacers - very precisely - it is worth it's weight in steel. And wierd threads can be cut as well. A nice manual lathe from Grizzly about $1k, add up to $400 for basic tooling.

If you want precision drilling capabilities, then get yourself a decent X-Y vise. Or, as we do, just learn how to really precisely lay out and mark a piece for hand-drilling. It isn't difficult just requires some care and understanding of the tools and techniquest to be used.

You can get a used knee mill for maybe $1k, it might need to be disassembled, cleaned and re-adjusted. Tooling and workholding gets expensive, so budget another $1000 for that. You can end up with a very capable machine though, even if it is from WWII. Budget for moving the thing too, they can weigh a ton.

I don't think you'll be as happy with a laser cutter as you think. Only mid-power units can cut aluminum. Most of the lower-priced (<$10k) units are only good for wood, paper and maybe some plastics. For that and that, a CNC plasma cutter may be a good choice. The cuts are not as finished, but 3/8" aluminum and some steel are no problem.

Good luck, and search the threads already discussing the topic.

[sanddrag]

On plasma vs. laser, I own a small 30W laser and we're looking at getting a higher powered laser and also a plasma. As Don mentioned, a plasma has no problem cutting aluminum plate, but it may require some finishing work, and does need an industrial "shop" type environment to operate. A plasma can be had for around $10,000. Lasers are nice and precise and clean, but I have not seen one that can cut aluminum for under $50,000. If it is out there, I sure would like to know about it. The smaller lasers can be operated in a more office/classroom type environment, with an air filtration unit.

A small laser is useful for cutting plastics and plywood, but not metal. 1/8" Delrin is about the max on our 30W. We use it for mini-sumo robot projects and things like encoder mounts, but not too many other FRC robot parts.

Boss Laser makes some relatively affordable machines that will cut up to 20ga steel quite nicely, but I can't find the application for steel sheet in FRC.

On your indicated budget, you're looking at a small imported lathe, a small imported mill or larger used mill, and a modest amount of tooling and workholding.

Also, don't understimate the value of a nice toolbox. The Harbor Freight industrial glossy red ones are the best out there for the money. You can put a small lathe on top of the 44" 13-drawer one.

[pipsqueaker]

Thanks for the replies everybody! People have been saying that the laser cutter's out of budget so let's throw that away, i knew it was a luxury anyways.

On the other hand, I'm interested in why you guys recommend the lathe so strongly? My understanding of lathes is that they're good for making shafts and things, but why does that give more utility than a 3-axis mill? I might not have mentioned this but we want to manufacture custom parts with these new machines, and it seems like a 3 axis mill would be much more useful/versatile than a lathe, which seems sort of limited in what it can do

[sanddrag]

Another relevant question here is, what do you currently have in the way of saws?

[Joe G.]

Originally Posted by pipsqueaker

Thanks for the replies everybody! People have been saying that the laser cutter's out of budget so let's throw that away, i knew it was a luxury anyways.

On the other hand, I'm interested in why you guys recommend the lathe so strongly? My understanding of lathes is that they're good for making shafts and things, but why does that give more utility than a 3-axis mill? I might not have mentioned this but we want to manufacture custom parts with these new machines, and it seems like a 3 axis mill would be much more useful/versatile than a lathe, which seems sort of limited in what it can do

To put it simply, a lathe gives you freedom, moreso than a mill. It singlehandedly took our team away from being held at the mercy of what's available COTs, and gave us the ability to make custom parts and mechanisms tailored to our robots. Sometimes it's things that we flat out couldn't have done before, other times it lets us to something in a cheaper, or faster, or more space or weight efficient manner, which pays dividends elsewhere on the robot. Some specific examples:

-Spacers, standoffs, etc. We make every single spacer we use on our lathe out of raw delrin (occasionally aluminum). We can make them to any length, diameter, and center bore that we want, and save tons of money over COTs spacers like the vexpro hex ones. Our students can hold tolerances within a few thousandths of an inch on our small machine, a more rigid one will give you .001" or better. Being able to make a precision spacer any length we want allow other shaft parts to dictate the exact length of the spacer, and makes designing custom gearboxes, drivetrains, and other mechanisms much easier. The spacers tend to end up ugly lengths, but that's okay, you only have to make them once. And the precision really helps solidify our robots, and allows us to use axial-sensitive parts that we wouldn't have attempted in custom systems before, like small pitch chain and belting. It doesn't seem like that big a deal until you've done it, this alone has dramatically improved our robot quality.

-Custom shafting. The lathe made widespread use of hex shafting practical for us, a huge improvement over poorly retained keys causing failures at the worst possible times. Turn down each end of a half inch hex to half inch round, save a few bucks on hex bearings (which REALLY add up, and are a pain to align), and get foolproof axle retention in the process. Like spacers, you can get it cut to precision length on the lathe, and allow other components to dictate shaft length rather than trying to design around a COTs part. We can also add a 1/4" round to the end of any shaft for encoder mounting, and cut our own retaining ring grooves, which save tons of weight and space over shaft collars. Even for dead axles, it's helpful. We ordered about 30 feet of 3/8" aluminum round for dead axle applications, all of which turned out to be a few thousandths oversize and too big to fit our bearings. We shaved it all down on the lathe, rather than giving it to some poor freshman with a file. We've also made oversized shafts for some extremely high stress applications, in sizes you typically just can't get from andymark and the like.

-Custom boring. Need a bearing bore in a gear that doesn't have it? Chuck it in the lathe and bore it out! We've also pocketed out nearly the entire body of a few gears on the lathe, sometimes for weight savings, other times to nest the mounting of an adjacent part in in space critical spots.

-Custom pulleys. 1687's winch based catapult last year would not have been possible to fit in the robot the way it did without the ability to turn a custom winch and two pulley wheels on the lathe. We've also done polycord grooves cut right into ABS or PVC for conveyors.

-Stepped diameter shafting, allowing what would previously have been a pile of loosely connected parts to become one rigid piece.

-Knurled inserts. Before VexPro, we made press-fit inserts for Colson wheels.

And so on. Being able to carve anything roughly round out to precision measurements just changes the way you think about robot design, it opens up so many doors. I strongly recommend that all teams get one as their very first "serious" equipment purchase beyond the very basics.

A few other specific examples of parts made for this year's robot, which I couldn't imagine doing without a lathe:

• Dozens of spacers and hex shafts cut to precision lengths
• Custom standoffs which allowed us to nest elevator bearings inside of slots in our box frame lift system
• A hexagonal sleeve coupler, which enabled super-quick removal and replacement of our drive gearbox.
• A hex/round hybrid shaft which enabled a reverted gearing system for our elevator tilt mechanism, a HUGE space saver.
• A stepped pin used to lock up our elevator.
• Shaving down the outer diameter of dozens of bolts in our elevator ever so slightly, allowing them to press into bearings.
  

A lot of these systems incorporated milled parts as well, but we could have done a whole lot better at reproducing these without the mill. We couldn't have come close to these turned parts without our lathe. In addition, we've found that parts for these custom systems which absolutely demand a mill are generally few in number, very complex, form the big "obvious" parts of an assembly, and as a result, tend to be very well planned out. The turned parts, by comparison, quickly add up in a huge backlog, are generally individually pretty simple despite the precision demanded, and are occasionally forgotten until assembly time. The former lends itself very well to being produced by a manufacturing sponsor, the latter demands an inhouse machine.

I would also argue that a pretty minimalist lathe would adequately serve for most of the jobs above, whereas with a mill, you need a pretty signifigant chunk of machinery to make many of the parts you likely have in mind with a high level of precision. For three years now, nearly every one of our turned parts has been made on an old Atlas Craftsman 618 benchtop lathe, which has performed like a champ for us.