Lathes in FRC

Hey everyone,

My team’s school recently purchased a CNC lathe for their machine shop and we were wondering what uses it may have besides adding retaining ring slots for hex shaft. How does your team use your lathe if you have one?

A lathe can have a lot of value to a FRC team.
A CNC lathe is likely overkill for an FRC team, although with enough experience it may allow for quickly repeating operations.

Some tasks I’ve done on lathes for FRC over the years:
*Cutting retaining ring slots ( :wink: )
*Cutting shoulders in shafts (although this was more common in the era of round shafts as opposed to hex bore gears everywhere)
*Center drilling (also less common now that things like Thunderhex/Rounded hex come with pre-drilled center holes)
*Sanding down hex or thunderhex shaft
*Cutting spacers (far less common now that 3D printers are a thing and COTS spacers are also a thing)

(I guess this process has also made me realize that a lot of lathe operations have been phased out by COTS parts)

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Spindles for winches, custom pulleys for polyurethane belts, V-belt pulleys, wheels, rollers, spacers, flywheels, precision bores, axles that have multiple diameters for different sized bearings, custom fasteners, the list goes on

The fun part is now opening your brain to the new possibilities when designing robot parts. Now you can make precision round parts

What kind of lathe is it?

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We don’t currently have one, but here’s some uses that I’ve seen in the past:
-Converting hex shaft to round shaft at the ends
-Quickly parting out spacers
-Any sort of round belt pulley–you could even do a single-piece shaft though that would be quite heavy
-Turning down the end of a shaft to connect to the shaft of an encoder more easily
-Using the lathe to line you up properly for doing the shaft-end drill/tap maneuver
-Winch drum manufacturing–start with tube, end with flanged tube
-Light-weighting steel sprockets (in certain configurations)
-Precision shortening of shafts

If you want a fun challenge: Make a cube with it. It CAN be done, or so I hear (never done it myself, haven’t had access to a 4-jaw chuck).

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Fabricating flywheels, among other things.

I believe it’s the Tormach 15L Slant Pro. Not sure which config
https://tormach.com/machines/lathes/15l-slant-pro-lathe.html

I see nobody has mentioned latheing down Colson wheels. I’m not sure why you would do this, but I was the designated machinist for LAR once and a team needed 6 lathed down Colson wheels.
Tips: your lathe is not fast enough, and the tool is not sharp enough: wear a face shield.

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We’ve done this but took a file to the wheel while its on the lathe.

Also I’m jealous, this is on our wish list for our summer fundraising :smiley:

Probably not the same approach to lathing, but we’ve lathed flat a side of 6x2 Colson wheels to fit two of them tightly together for shooters. The rigid plastic hub was easy. Taking off a bit of the rubber wheel was harder, but we were able to do it with a cutter and not a file. We were prepared to “file” lathe the crowns off the wheels if the slight crowns caused ball centering problems, but that didn’t happen. I don’t think we could find Fairlanes with hex bore in 6", so we resorted to this alternative. Performance and durability was excellent.

That’s a nice machine. Tormachs are very nice because they’re well documented and there great tutorial videos out there

My dream is to get the team an older Haas TL1 that still has the manual hand wheels and can do CNC

The other is to fix drivetrain center drop issues by adjusting wheel diameters on the fly …

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We at 4909 made knockoff “thriftybot 2 Inch Vectored Intake Wheel”. We buy this stock from McMaster-Carr and made a CAM program that faces them and chamfers the corners. This would be impractical on a manual lathe but works well on CNC. We had to reverse engineer the 3d printed parts but it really isn’t more than an afternoon of work. It makes this centering mechanism work really well, but you can see how it would take a long time to make 22 of these wheels with 7 rollers per wheel. image

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Pretty sweet - I get a bunch of robot parts done with my little 12" Atlas (pic below is just some rando pic and not mine - that is a pretty old school setup with the lantern post and all).

“It’s two priests!”

“In a Ferrari?”

“They’re doing the Lord’s work.”

“In a Ferrari?”

“Maybe they’re just doing it faster.”

– Dom DeLuis and Burt Reynolds in “Cannonball Run”

You’ll just be doing FRC stuff - just faster - and bigger.

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I don’t need to state how important lathes are… because it is documented here.

But for FRC usage, the lathe is not the most important tool, but it can be helpful.

Our lathe work this past year mainly consisted of lots of custom length hex shafts with tapped ends as well as spacers and standoffs for custom gearboxes (custom gearboxes made using CNC mills and various cots gears).

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We’ve had the Tormach 15L Slant Pro since 2015 and we’re pretty happy with it. We also have a manual lathe that we use regularly as well. For FRC related work, we mainly use the CNC lathe for:

  • Cutting axles and spacer stock to length
  • Retaining ring grooves in our rounded hex stock. We use a 0.040" Thinbit grooving tool insert for the our 1/2" retaining rings.
  • Tapping. We mainly use tube stock, but we sometimes drill and tap solid stock as well. REV’s rounded hex has a 0.160" hole which ready to be tapped for 10-32.
  • Rounding the ends of 1/2" or 3/8" hex stock down for bearings

We have a turret for our profile/facing, parting and grooving tools. We also use a small 3 hole gang plate for our center drill and drills/taps for various sizes (6-32,8-32,10-32, 1/4-20). We just swap in the drill and matching tap when needed. For FRC work, we mainly just use collets with a pneumatic collet closer. We have used the boring bar and internal grooving tool, but usually for projects outside of FRC.

All of this programming can be done conversationally at the machine. If it’s a program that you’re running a lot, you can significantly decrease the operation time by writing the g-code using your preferred CAM software.

While all of the work we do for FRC can be done on a manual lathe, the CNC does save us a bit of time. Congratulations on the machine and I hope your team gets some great use from it.

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We used our lathe to make a hub/plug for our Fairlane shooter wheel last year, that’s it if I recall. Much less than what we would have used it for 10 years ago.

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If you have a full CAD model of your robot, and a large enough pair of calipers, a lathe can be awesome for making precise shafts. You can also use it to precisely face off tubes if you’re more of a welded frame persuasion.

  1. cut the shaft a little longer than the desired dimension
  2. face it off lightly on the lathe
  3. measure the length with your giant calpiers
  4. determine the difference between the cuttent length and your nominal length
  5. chuck the work piece up again, set your zero and take off the remaining material.

You can also add shoulders and other features to retain the shaft, or components on the shaft in an assembly with fewer / zero collars

Requires an ability to hold rectangular stock in the lathe chuck, unless you build your frame with round tube… normally I use a mill for this job.

I’m guessing this implies machining the ends of a long shaft, say the width of the bot or so. Maybe up to 30-ish inches?
This PSA is mostly for those with manual lathes, but also applies to CNCs. Do NOT extend the shaft out the back of the lathe head (to the far left). Yes, the size of the lathe will now determine the maximum length of shaft you can safely hold.

I have witnessed a long shaft sticking out of the back of the head, get spun fast, whipped around, then pulled out of the collet, and stick into a plywood ceiling. It was just dumb luck that the shaft went up, rather than another direction and hurt somebody.

Having said that, I will extend shafts out of the head a little bit ( 10x the diameter, or so). I’ll also spin it much slower than I’d prefer for machining efficiency. I’ve also been a machinist for 30 years and have a fairly good idea of what I can control.

Don’t think you can “cheat” by extend some amount out the back/left and the remainder on the working side. Not only is that still not safe, but the extra material on the machining side will deflect with cutting pressure and you’ll make out of tolerance parts. Yes, I’m aware of tail stock centers, steady rests, etc.
Remember, for the most accurate parts, you want the most rigid setup.

With a CNC lathe, there is a device called a Bar Feeder. It can hold full lengths of matherial (8’ or longer). After each widget made is parted off, a “grabber” in the turret station pulls the bar stock into the lathe for the next widget to be made. The bar feeder prevents the long length from whipping around. It is for production work.

PLEASE use a LOT of caution if you plan to turn long lengths of material in a lathe. Better yet, don’t do it!