Looking for opinions (esp from Educators) on good machining tools to begin with.
I’m looking at starting a class that would focus on FRC, and include instruction on CNC or machining as part of the class. What would be good student/beginner friendly CNC/machining machines? It would be ideal if we could utilize existing power infrastructure and not have to upgrade to 3-phase, but would still solicit opinions if you feel strongly about a 3-phase machine.
Our FRC team currently only uses chopsaw/drillpress, and soon hopefully getting a bandsaw. So most things are done manually, and it would be awesome to up our potential with new tooling.
This is a slight derail here, but I don’t know that I’d rush immediately to a CNC of some kind. In my (limited) experience, it might be better to first start with a good quality manual mill and lathe. I know that, for me at least, once I learned to use manual machines, I had better learned the mechanics of how an endmill does its work, and a better intuition for what might be good or bad practice, and the sorts of things a CNC might be able to do better. Then, once I started using CNC, it no longer seemed like a magic put-metal-in-get-parts-out black box. It’s hard to understand how an endmill made of METAL (“They said it was hardened”) might break if you’ve never used a mill before, but once you’ve broken a few, you realize how delicate (and precise) machining can be, and how small a thousandth of an inch really is.
Manual machines can also be operated without depending on students knowing the software, so decoupling software and fabrication at first might more clearly separate the errors due to bad machine setup from the errors due to bad toolpaths.
Their dedicated OS, integration with HSMWorks, effective tooling system, and low cost makes it a wonderful option.
A business that another coach and I own heavily utilizes a Tormach 1100 to make things as precise as neurological implants (not for humans) and as artsy as titanium ear gages.
A fully-loaded turn-key system is on the order of 25k, which is really quite reasonable in my opinion.
Edit: the shop that my team operates out of has a Prototrak, which can be operated manually or by CNC. With the manual option available, none of the normal shop students have learned the CNC process. If the objective is to teach CNC manufacturing (which is a very employable skill) it can be quite difficult to execute if the option for a manual tool is always there. Of course this can be solved with discipline, and I’m not trying to start a discussion on this tangential topic, just presenting my observations.
I would go with a manual machine first. If you do want a cnc though I wouldn’t get a benchtop size, you are going to want something with enough travel in the x-axis to do a piece at least half the total length of the robot so something over 10"
CNC machines, especially small ones are very easy to break.
You can get a grizzly manual machine with digital readouts for less than 2k
Thirding Tormach. We’ve got a PCNC 770, and one of our sponsors has a PCNC 1100. For the scale at which FRC operates, they’re spectacular machines. Service/support has been very good as well. No 220V needed.
Depending on what you’re doing, you might also consider a CNC router. A router won’t cut steel, but aluminum is still a possibility, depending on configuration. A router will have less vertical travel, but significantly more horizontal travel, allowing you to cut larger parts. We’ve got a 4’x4’ ShopBot. Ours is quite large and uses 220V power, but you can get smaller ones, with or without enclosures.
The PLTW machine is not geared towards the machining capabilities of a robotics team. Its more geared towards teaching the basics of CNC. The actual class does very little when it comes to actual machining.
I would echo what others have said that a CNC mill/lathe might be too much to bite off for a team that doesnt have much more than a bandsaw.
Having a shear and brake opens up sheet metal too you which could be very advantageous. Also as another said having a CNC router would be more powerful than a mill/lathe. With a router you can do everything from side panels to sheet metal to bearing holes and bolt holes with perfect dimensions. That ability would open you up considerably more than a small mill and lathe would.
If you want to add CNC into the curriculum, I would look at very small CNC machines that can fit into the shop easily (like benchtop ones). Ideally a 1-on-1 between the student and machine would be possible, and that makes even relatively inexpensive CNCs like a Tormach prohibitively expensive and large.
Desktop manual mills may be your easiest option here purely because of space and cost. It’s also easier to learn manual machining early on to grasp the concepts behind machining IMO.
Slight tangent; I wouldn’t bat an eye at starting a class without a manual mill, and focusing solely on CNC operation from day one. I’ve never bought the argument that you have to learn the basics on a manual machine first. You can learn all the fundamentals on either type of machine. I think there’s a strong element of ‘I learned manual first, so you’re going to learn manual first’. I’ve never gotten a cogent explanation as to why that order is so critical (full disclosure: that’s how I was trained).
I think the irony is that the sorts of things people claim you learn best using a manual mill, like cutter geometry, chipload, climb vs. conventional etc. are all far easier to teach and learn in the CNC space.
Alright, tangent over.
Consider your space, budget, and educational goals (both for students and teachers!). Reading between the lines, you probably don’t have the space, budget or curriculum to make use of something like a Hass TM-1. At the same time there really is a minimum level of size, rigidity and power required from a CNC mill in order to make FRC robot scale parts. Machines with the word ‘benchtop’ in the sales brochure are probably going to let you down.
Additionally, trying to teach the fundamentals of CNC operation on ‘hacky’ conversion bridgeport clones is tough. It kills me trying to get students interested and excited about CNC milling while using a kind of crummy machine. It’s no fun trying to explain how a ‘real’ mill would work, and why ‘our’ machine can’t do all the cool stuff. The retention of manual dials on those sorts of machine really handicaps them and isn’t a positive in my mind.
I’ll second James’ recommendation of a Tormach mill. There have already been some good thoughts posted on why it’s a safe bet, and as a daily operator of one I’d be happy to expand upon those if you’d like. I will add the specific recommendation of, whatever machine you opt to get, it’s important that it includes an enclosure and a powered drawbar. The enclosure is an obvious safety feature. A powered drawbar removes any problems with young adults not being strong enough or tall enough to torque down a traditional draw bar.
Tormach the company is educator friendly. Take a look around their website and give them a call. They can put you in touch with an owner of their mills near you that is willing to give you a tour of one in the wild.
A Tormach 1100 is a nice machine for this. It’s user friendly, not that expensive, and it can basically be bought in pieces for easier budgeting (get the machine one year, an enclosure the next year, etc etc)
It’s not going to have the travel or the horsepower of even an entry level Haas, so if you can get a TM-1P or something that would do much better, but the Tormach is a nice usable machine in itself.
A CNC router is also a popular choice in FRC due to the lower cost and large travel possible. It’s also a lot easier to modify or make your own if you really wanted.
I will second what both individuals before me have said (Andy A & Chris is Me).
I have a benchtop Prolight 1000 that i use with my PLTW CIM class. Great size and scale for CIM class but don’t bother trying to do any real FRC parts on it. Really, please don’t. PLEASE DON’T.
In our Robotics room we have a Bridgeport with a 2 axis Prototrak circa early 1990’s (i’m not kidding, it is a Prototrak II). It was donated to us from Kodak and has been a wonderful piece of equipment to have. Cuts everything you just have to push buttons and work the Z axis. I know newer equipment will do all of that for you but we use it mostly as a DRO to square up stock and some for cutting heavier pieces. I also do not believe in the theory that I learned on knee mill & so will you.
A few years back my school invested in a full 3 Axis machine. I looked at the Tormach fully loaded or a Haas. Shop space is an issue for us so I had to settle (if you consider a $60,000 Mill settling) on the MiniMill2 with 10 tool auto loader, rapid tapping, and the WIPS (wireless intuitive Probing System). I teach CIM (PLTW) and have Inventor HSM so the Haas was great because it comes with the post processor installed. We design the entire robot in Inventor, the kids convert the files to G&M with the HSM, we throw it on a flash drive, pop the parts in the mill and get back to work. (always within earshot of the machine, just in case.)
I must say, all 3 pieces of equipment make me feel spoiled but each has their place. The Prolight is great for your average CIM kid, they are not afraid to run it. The old knee mill is super for work, the limitations are huge (We did just fine with the bridgeport for years) but a 3 axis cnc that is made to handle larger materials is what you want.
So, after that long-winded rant base on your situation I would say you probably want to go with the Tormach. Start with the 3 axis and grow into the 4th + as you progress. Dig through these forums (use the search button) and you will find some great information about how to best setup your machine for FRC needs. If you decide on a Haas let me know. I don’t know how we built robots before we had it.
I would highly recommend the PLTW CIM course for learning to CNC. If you’re just looking to CNC you can skip to unit 2 of the CIM course.
The CIM course covers pretty much everything you need to know to be able to use the CAM strategies tab in Autodesk Inventor. From what I’ve learned in class I’ve been able to apply to robotics with only a week or two of instruction. Hopefully more of our students will be taking CIM next year so we have more students knowledgeable in using our CNC mill.
We use the Tormac PCNC 770 in class but I would not recommend this for FRC use. However, what you learn in PLTW will apply to other CNC mills.
(I’m a software student on my team so if I can learn CAM strategies from CIM just about anyone can)
What makes you say this? We have been using the tormach series (both 770 and 1100) for years now with absolutely nothing to complain about. They have made building our machines much easier and allowed us to make parts we never could have before. I personally would recommend a tormach in a heartbeat.
You are probably more knowledgeable on the Tormach for FRC application then I am. I personally have not used it for FRC and neither is my team but a few of my mentors have expressed concerns with the 115V single phase it uses instead of a 220 3 phase.
Have you used it for aluminum? If so what thickness? I assume you have to run a relatively slow feed rate with aluminum? I also assume it works well at a normal feed rate for nylon and other plastics?
I personally like the Tormach, I’m just not sure how well it would work with aluminum. It’s very user friendly and very easy to use espically if you have the tool changer attachment.
We regularly mill aluminum on our tormach and do it at 40 inches per minute with about 30 thou stepover on a 3/8 -1/2 cutter depending on the job. We used to take much deeper passes (half the diameter of the cutter, so 1/4in on a 1/2in cutter) but we ditched that method because we found dynamic milling toolpaths with the smaller depth cuts better as we could run the machines so much faster. The thickness of the material really doesn’t matter for us so long as it fits in machine. This year the thickest peice we did was 1.5in 6061 aluminum. And yes, nylon and other plastics we go through very quickly.
Tormachs aren’t great machines but .030 is a ridiculously small cut for one. You should be able to slot full depth in 1/4" Al with a 1/4" cutter no problem, provided you have coolant to clear chips.
It sounds like you’re getting good results, but the entire point of “dynamic milling” toolpaths (trochoidal milling/HSM/etc) is large axial depth of cut and narrow radial depth of cut (10-20% cutter diameter), which results in more efficient use of the tool (full flute usage instead of wearing out the bottom 1/4" of the tool), higher feed rates due to some science (radial chip thinning, if interested in learning more), and constant load on the cutter. If you do some digging into HSM cutting strategies you will probably be able to dramatically increase your productivity, especially on thicker parts.
[edit] Just took a look at your video. You guys obviously understand HSM. The way you worded your post was very confusing. I think you meant you take .030" width of cut.
Ya I see now how my post could be misleading. Unfortunately our head mentor (the schools shop teacher) doesn’t believe in coolant so that puts a bit of a bottleneck on our speeds. However all this being said, considering the ease of learning the system and it’s costs, I feel tormachs are a very capable machine for learning and FRC.
Wow. As a production machinist, I have always believed in why take two cuts when you can take one.
I have run $150K CNC mills, and I have to say, the Tormach PCNC 1100 is a unbelievable machine for it’s low cost. You can’t plunge a 1" dia cutter 3" in 4140 and travel at 12" per minute like the big boys, but you can plunge a 1/4" dia solid carbide cutter through 1/4 aluminum plate and travel at 7" per minute. Make sure your endmills are 2 flute if you are machining aluminum, and you must use collant. There are many friendly coolants out there
As a former production manager and cutting tool manufacturer, and now a HS educator, I can easily say the Tormach is you best bet.
We did all of our custom gearboxes, custom drivetrain rails, lightening patterns, etc on my Tormach 770 this year. I was running a 1/4" lakeshore carbide endmill at ~8000 RPM, 20 IPM, 1/4" DOC and 30% WOC doing adaptive clearing strategies with helix entry. A ~7"x7" gearbox plate out of 1/4" Al, with holes drilled worked out to something like 20 minutes of cut time per plate. (with power drawbar)
That being said, I got a sweet deal on the 770 (brand new at 70% of the price), but if I was starting from scratch I’d probably go with the 1100. The 770 is nice that it has a 10K RPM spindle, which is great for being able to clear with smaller cutters, but I’d rather the 30-40% larger work area. I was having to do quite a number of setups and indexing to make my 7"x14" area work. Obviously, even the 1100 area is tiny compared to a real VMC, but it is also a $10K machine for hobby use, not a professional machine for true production. For FRC use, it is more of a machine than I am a machinist, and I found the major limiter was me… not the machine. A bigger machine could do faster work with less setup time, but not necessarily “better” work (for most FRC applications). If you take the time to properly probe/measure, it can easily hold the tolerances needed for things like bearing fits, chain runs without tensioners, etc, even over multiple setups to reach a distance.
Here are a few pictures of some Tormach work (minus the belly pan, done on our gantry mill) Pictures/Video Link
Side note, the faceting of the holes is due to the 2D adaptive strategy settings (not a finish strategy). I finished the bearing holes with a 3/8" end mill contour pass with no faceting, snap fit on the bearings.