So now that our season is over, we are in the process if planning for next year and the summer. We are looking to get so new tools and equipment for our shop, and I was wondering if you guys might be able to provide some guidance.
We currently have:
Chop Saws (One set up for aluminum, one set up for steel)
Sheet Metal Break
Woodworking Shop (Planers, Routers etc.)
We also have access to a full metal working shop two hours away, but I don’t want to rely on that for all of our fabrication needs.
I would really like to get a Mill (Used Bridgeport?), a Lathe, a 3D Printer, and some welding equipment.
What order should we buy these in, and what specific models would suit our needs? Any input is appreciated.
First question: Space. What kind of space do you have available, and what kind of power that is reasonably close to that space?
Second question: Budget. Some of those items can be rather expensive for an FRC team to buy new or refurbish from used.
If I had to pick one item from that list, I’d go with the welder, IFF you have people that can use one, or get people trained to use one. Otherwise, the mill/lathe is a pretty close tie–some prefer one, some another–and the 3D printer would be close to last unless you’d be working with a classroom setting as well, in which case it’d be ahead of the mill and lather.
In eleven years of FRC, my teams have welded two things:
In 2004, 1293 welded up the robot frame. (This was the last season of the “Uh, here’s some 2x4 box tubing and some super-fragile drill motors” kitbot before they switched to the sheetmetal JVN/Copioli kitbot in 2005.)
In 2014, 4901 welded an axle to two ball intake wings.
Two applications, one of which is obsolete and one we probably could’ve worked around with more time.
I’d give strong thought to the lathe or mill first. My personal pick list would have the lathe first; the ability to knock out shafts and rollers is universal, since you can plunk some bronze bushings in a piece of hardware store aluminum square tubing and be rolling. I’m sure someone will state the case for the mill.
3D printing seems to be getting more and more common in the pits, but I don’t know if it’s quite there yet. CD has a couple threads on applications here; know the limitations before you drop big money here.
OTOH, I’ve been around FRC for a similar length of time, and my teams have welded an awful lot of things. Drive frames come to mind right away (both 330 and 1197 prefer custom drive frames); arms or towers for arms, shooter structures, ramp frames… This last season, 1197 welded intakes and the ball carrier/shooter structure as well as the drivebase. (A couple of other teams, however, did not have welding resources. Enter the bolts and other creative methods of holding metal together.)
The students of 192 have been welding the frame and other parts for most of the team’s life. Before you buy determine what you can use. If nobody can teach welding then that would not be a good purchase at this time. The same goes for the mill and lathe. Having said that I feel the lathe and then the mill would be the route that I would recommend. Most of the welding could be replaced with rivets but our students take great pride in the fact that they weld the robot. We are starting to have more success with the 3D printer and should make some more use of it next year.
The thing with picking a first choice for a new machine really depends on the methods your team use (or plan to use) for construction.
Speaking from the perspective of a team that has all 4 of the items you’re looking at, in my experience, I would estimate our team utilizes mills (and occasionally 2-axis CNC mills) for roughly 80% of the custom part construction for our robots. Our entire chassis frame is cut using our mills and assembled with machine screws, as are most of the mechanisms on our robots.
Having a lathe can also be very useful though in our case it’s not utilized nearly as much, particularly due to the ease of getting “off the shelf” shafts (though when you do actually need it to make something, a lathe is indispensable).
As far as welding goes, until this year we hadn’t had a weld on a robot since 2003, partially due to a lack of anyone who knew how to use a welder, but mostly due to a lack of need to use it.
We got our 3D printer this year and struggled to find good applications for it on our robot, we found it useful for making several non-critical parts but decided against using it for any higher-stress applications. Mostly we use it as a time saver (having it make simple parts while we do something else) instead of for its ability to make complex objects.
Again, this just our experience, the usefulness of any of these tools comes down to how a team utilizes them for their build process and what type of robot you build.
I agree with Sand Drag. If you use a lot of pop rivets like many teams once you have a pneumatic riveter you’ll wonder how you managed without it.
As far as more expensive tools a lathe and/or a mill would be at the top of my list.
A welder would be at the bottom of my list, there are much better ways for an FRC team to join metal. You need someone with good skills to get good welds and fixing a poor weld that breaks at a competition may not be possible at all venues and even if there is a machine shop with a welder how long will it take. What if you’ve got a welded frame and one of the members gets bent? Drilling out a dozen or so rivets, putting the new piece(s) riveted back in will be much quicker and something that can be done just about anywhere.
Don’t get me wrong, welding is certainly a valid method of robot construction. My point was that it’s possible to get around it with alternatives (bolts, rivets, etc), where it’s harder to get the results of a lathe’s output with something other than a lathe (ditto mills).
I’d also second sanddrag’s suggestion on an arbor press and broaches. 4901 didn’t have to broach anything I can think of this year, but 2815 used the heck out of a 1/2" hex broach in years past. Very easy to make roller assemblies with one–broach your rollers, then round the hex off the ends and tuck it into bronze bushings. (Or leave the hex on and put hex bearings in, but the bushings are usually cheaper and more compact if you can live with a little more friction. And generally, I’ve found you can.)
If you do get a pneumatic riveter, don’t chuck your handheld ones. The one 2815 had was a little…portly at times, making it harder to reach into certain areas of the robot.
That’s kind of what I what I was thinking about the welder. I feel silly saying this, but I have literally no experience with pop rivets at all, although I do know that they can be very useful. Can you recommend some learning resources and/or some specific gear to get started?
Of course you should make sure before purchasing you have people who know how to use them. The welder we have would be next to useless to us if not for a few parents who know how to weld.
I put the mill first because once fabrication starts in our build season you would be hard pressed to find it idle between us and the team we share a shop with. The extra precision it gives us is invaluable in my opinion.
I don’t know that there’s been a definitive tutorial in rivet usage, but I can share a few examples from my past:
4901 (2014) Everything you see on the wings and the shooter arm is just 1" square tubing from our local sponsor Metal Supermarkets (#plug). Some of the gussets holding it together are VexPro Versaframe gussets, some of it is their pattern cut and drilled in-house on a bandsaw and drill press. These were 5/32" rivets, since that’s what VexPro uses and we didn’t have any other standardized size before.
1618 (2009) Crazy simple design, with each piece of angle just riveted together. Zero issues (with that anyway) all season. I’m guessing those were 3/16" from the photos.
2815 (2012) This time, it was square tubing and some angle aluminum to hold it together. Despite a couple of faceplants (it was rather butt-heavy), I don’t think we ever had to tap the box of black rivets I bought as a fail-safe (all the OE rivets were standard ones painted black). These were all 1/8" rivets far as I remember.
2815/1398 (2010) This is a good up-close look at the way-too-idle Stephen Kowski’s work in action. You’ll note that the rivets are holding the entire chassis together (think those were 3/16"), and the kicker foot, and the kicker to the chassis…
2815 (2009) There weren’t as many rivets on this one compared to others, but the upper and lower halves of the ball conveyor were joined by that angled flange down towards the bottom. Each side just had a bunch of rivets sunk into it, and it’s probably still together in 3976’s shop. (We used shoulder bolts into the bearing holes to keep the two sides together, some threaded inserts too. The idea was to keep it so we could get in there for maintenance if needed.) The rivets we used there were 1/8".
For practical hands-on testing at your facility? I’d say build something like an arm frame (use PVC pipe or a 2x4 for the arm and a bolt for the axle, just keep the unsupported length relatively short), strap it to a furniture dolly, and run it through some tests to see how they hold up. It isn’t a substitute for full-on engineering analysis, but for the cost (around $50-60 if you had no extra aluminum lying around and with leftover rivets and riveter) it’s pretty cheap to dive in.
Your local hardware store will have most of the stuff you’d need: a riveter, a couple boxes of rivets (aluminum is fine), a drill bit to match those rivets (the rivet box will tell you the drill size–5/32" is a 20), and some square and angle aluminum (1/16" wall is probably what’s there, and that’s fine).
I will note that McMaster-Carr’s prices are significantly cheaper for rivets than any hardware store around here. Buy in bulk or with other robot stuff, and you’ll save significant money over the course of a season. Riveters themselves are about a wash; at $20 or so for a manual one, I view them as a consumable since they usually last about .75-1.25 seasons. If you’ve got shop air or a compressor for tools, Harbor Freight sells an eminently decent pneumatic riveter too.
tl;dr Rivets are simple enough that a guy with a business degree can’t even screw them up.
If you’re talking this much money, you could get into the realm of a decent CNC router. There have been various other threads on the subject you can search for. Also, do you have a good way to cut solid bar stock, such as a horizontal bandsaw?
If your team uses a lot of rivets, I STRONGLY suggest a pneumatic rivet gun as others have mentioned. I also recommend a large set of clecos and cleco pliers. I was introduced to these when I got back into FRC and they’re amazing. They’re essentially temporary rivets that you can freely put in and take out. Very handy for assembly work.
4607 members seemed to use my welders more than any other tool (maybe the plasma cutter). I don’t think that they are always on task, but they are welding.
I don’t know if you were able to get a look at our robot at the MSHSL, but our winch was all welded together in my lab - as was the throwing mechanism (the catapult), and the mechanical stop.
You already have much of what you need to complement a welder - outside of a bench grinder. If you are in the market, contact a local gas wholesaler (Oxygen Service Co. out of St Paul…) and they will get you set up for around $450 for a Miller 140 Autoset and the initial tank and the cart.
If you have any other questions on purchasing a welder or would need help, just PM me.