Mill or Lathe...

[Chris is me]

I would figure out what you can get done around you, via other teams or otherwise, before making a decision. Maybe your sister team or friend down the street has a lathe which will make the decision easy.

Given one or the other, I would rather have a lathe. I've had stuff made on a lathe a lot more than on a mill. When you consider how many standoffs, spacers, shafts, and other turned parts you have on your robot, it's pretty clear the lathe gets a ton of use. How else do you put in your snap rings anyway?

Stuff like lightening patterns that you'd mill can be done (albeit less efficiently) with a drill press and round holes. I don't think I milled anything in 2009 (we had our ball tower routed with a laser cut guide, though, which would have been much harder and more time consuming with a drill press). This year, Shaker had its chassis CNC milled, but if we didn't have access to mills we could have gotten away with C-Channel or something.

[DonRotolo]

Lathe.

We've used our lathe every year since we started.
We have access to a mill, and have never used it.

[Jay H 237]

Tough decision but I am leaning torwards the lathe slightly. 237 normally has 2 lathes running every build night plus 1 Bridgeport mill, and even two at times. We custom build alot of our parts though.

If you use the kit bot parts mostly then the mill isn't likely to be in as much demand.

Originally Posted by Don Rotolo

Lathe.

We've used our lathe every year since we started.
We have access to a mill, and have never used it.

Don, how does your team handle making custom brackets and such? Bandsaw and file/grind? I'm just curious as this is the first time I've heard of a team having the ability to mill and not taking advantage of it.

[JamesCH95]

That seems to be the opposite of what I've experienced. For several years we had 4 mills and 4 lathes, generally the mills were all full and the lathes were left open. Even this year we used a lathe for two parts. I've found that virtually all spacers/shafts/standoffs can be had as OTS parts or simply sliced-up round stock. McMaster FTW.

[MrForbes]

Like Don, we've had a manual mill in the fab shop we use for a few years, and have not touched it the past two years. We've use the lathe more each year.

The way you get around not having a mill, is to actually design the parts. Instead of whittling a piece of some weird shape out of a rectangular block, you design the part to be made with a minimum of cutting, using stock that is readily available (such as using angle, channel, strap, flat sheet) and do a few simple operations such as cutting, drilling, and bending.

[JamesCH95]

Originally Posted by squirrel

The way you get around not having a mill, is to actually design the parts to be made with what capabilities you have.

Fixed that for you

We would use milling for a couple important functions: boring holes for press-fit bearings, slotting mounting holes to tension chains, cutting key-ways in motor shafts on motors (that are no longer in the KOP), making custom gearboxes/transmissions in the days before they were available OTS, etc.

[MrForbes]

You didn't really fix it, because as I said, we have a mill available, it's sitting right there in the shop next to the brake, over from the Rotex punch. We just can find more efficient ways of making parts using the other equipment.

If you need to make gearboxes, and you're not very good at laying out and drilling the holes with a drill press or punch, then a mill can be very helpful. Boring holes for press fit bearings can be done with a lathe, in fact you can more easily control the size of the hole. A better solution might be to figure out how to design the gearbox so it can use looser fits, like AM does.

[Lowfategg]

Originally Posted by squirrel

If you need to make gearboxes, and you're not very good at laying out and drilling the holes with a drill press or punch, then a mill can be very helpful. Boring holes for press fit bearings can be done with a lathe, in fact you can more easily control the size of the hole.

But it is also far harder to setup and hold a gearbox plate in a lathe with a faceplate or a 4 jaw (unless your skilled, and you have the right tooling). If you don't have either of those, your screwed. With a boring bar and a mill you can make holes of any size (within .0005) on any piece you can get on the bed.

Originally Posted by squirrel

A better solution might be to figure out how to design the gearbox so it can use looser fits, like AM does.

More like poor machining that can causes gears to wear and fail quicker. Also it adds a ton more friction.

The best answer to this thread: Just get both.

Btw, this was quite a good thread also on a similar subject: http://www.chiefdelphi.com/forums/sh...ad.php?t=85568

[J93Wagner]

Look at your own team needs, I know what I would get, but then again, I don't have a clue how your team does a lot of machining or whether the need really goes toward the lathe or the mill. So rather I will outline the pros of each and let you decide which might be the better choice.

Lathe:

Pros:

• If you have the patience, any cylindrical part (and some square) can be worked with to great precision.
• Speeds up the process of working with cylindrical parts enormously. There have been times when all six of our lathes have been used at once. (Curse CAD and their complicated parts... Oh, wait, I am CAD... I guess I'll have to remedy that...)
• Lathes also allow for custom taps on parts. Example: Oops, a screw for the gearbox got lost and the replacements won't get around for a few days. An hour later, "Look! a new screw! Now we can finish the robot!"

Cons:

• Bits, without them, all the pros vanish, especially if you can't sharpen them if they're dull. HAVE AN APPROPRIATE GRINDER TO SHARPEN AND SHAPE THE BITS TO AVOID THIS.

Mill:

Pros:

• Drilling all those holes with a drill dress just got a LOT easier. No longer do you need to worry about placing a center punch exactly where you need to because you don't even need them.
• If you need aslots in a shaft for a key, you also need a mill. Nothing else will do a quality job.
• If CNC capable, round cuts can be made, however, This depends on the machines capabilties.

Cons:

• Many of the things mills excel at can be divvied up between other machines to achieve the same result although using the mill would still be best.

Wow, what a long post. Anyways, I only listed a few of the reasons you should pick one or the other. So read other's posts and decide for yourself.

[CENTURION]

Our team just ordered a 4-axis CNC mill, which really has the best of both worlds, it's a CNC Mill, with a CNC controlled rotating grip that basically works like a lathe.

http://www.youtube.com/watch?v=EH4ZQ...eature=related

[Cory]

Originally Posted by CENTURION

Our team just ordered a 4-axis CNC mill, which really has the best of both worlds, it's a CNC Mill, with a CNC controlled rotating grip that basically works like a lathe.

http://www.youtube.com/watch?v=EH4ZQ...eature=related

What did you get? I'm guessing the Tormach?

[jblay]

If you dont have access to a waterjet i think that a mill is the way to go. a lot of the things that you do with the lathe can be done without one but with many designs having the precision of a mill is absolutely necessary.

Not having access to a mill can really limit your flexibility in design choice.

As 330 has shown you don't really need a lathe you just need a mentor with the patience to do it: http://www.youtube.com/watch?v=GwDFD-TjDFU

[EricH]

Originally Posted by jblay

As 330 has shown you don't really need a lathe you just need a mentor with the patience to do it: http://www.youtube.com/watch?v=GwDFD-TjDFU

After that year, 330 got a new lathe: http://www.youtube.com/watch?v=icWuYQ6m8js

Note that while the drill sped up the process, using a drill in a side-load application is NOT recommended.

It really depends on what you need to do. Drill a lot of holes? Make round parts? Make pockets or patterns? What you need to do will drive your decision more than any other factor.

[artdutra04]

Lathe.

It's a much more useful machine, and will have a greater positive impact in your team than a mill would. Pretty much anything "simple" that you'd need a mill for can now be bought from AndyMark, and those are gearboxes. But what you can't buy from AndyMark are all those shafts and spacers you need to transmit all that motion to where you need it, as those are all largely dependent on how you design and build your various mechanisms.

Originally Posted by jblay

As 330 has shown you don't really need a lathe you just need a mentor with the patience to do it:
http://www.youtube.com/watch?v=GwDFD-TjDFU

Notice the end of the video: "3 Hours, 3 Parts, 1 Tired Mentor".

Spending an hour to make a single shaft is MUCH worse than spending ten minutes drilling some holes on a drill press.

[Joe Ross]

You should look at the thread $1500 Machine Shop. The 10K Machine Shop is good too, depending on your budget.