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nnfuller 13-06-2010 09:57

Mill or Lathe...
 
Well my team has sets it's fundraising goals, and one of them is to increase the functionality of our small machine shop. Right now our shop contains:

-Benchtop Drillpress
-Freestanding Drillpress
-Miter saw
-Bench Grinder
-Bandsaw
-Files... Many Files

So my question is if we have to decide between a mill or a lathe, which do you feel is better for a robotics team. I am not an educated enough machinist to know the full capabilities of either machine so i would love to hear people's reasoning.

548swimmer 13-06-2010 11:40

Re: Mill or Lathe...
 
Quote:

Originally Posted by nnfuller (Post 966408)
Well my team has sets it's fundraising goals, and one of them is to increase the functionality of our small machine shop. Right now our shop contains:

-Benchtop Drillpress
-Freestanding Drillpress
-Miter saw
-Bench Grinder
-Bandsaw
-Files... Many Files

So my question is if we have to decide between a mill or a lathe, which do you feel is better for a robotics team. I am not an educated enough machinist to know the full capabilities of either machine so i would love to hear people's reasoning.

Do you have access to any other machines such as a water-jet? If you do, that plays a large role in this decision.

Jee 13-06-2010 11:45

Re: Mill or Lathe...
 
If your team has way too much money, I would suggest a CNC Machine. It uses a computer to control servos and motors and mills according to the CAD drawing you give it. This is how teams go about getting their delicious chasis.

If you don't feel like spending $30,000 go with a combo mill/lathe.
Our team uses a Smithy 3-in-1. It works extremely well and is good for almost every job (custom shafts, rings for clips, milling swerve drive modules).

MrForbes 13-06-2010 11:57

Re: Mill or Lathe...
 
Nothing beats a lathe for all around usefulness. Something with 9-12" swing and at least 20" between centers is plenty big.

sgreco 13-06-2010 12:05

Re: Mill or Lathe...
 
It depends on how precise you want to be. Right now you can't do anything with cylindrical objects. Your shop right now can drill holes. If you need slots, holes drilled with precision, counter bores etc more than working with cylinders, get a mill. If you are happy with being able to drill holes and such with your drill press and don't need the extra functions of a mill, then get a lathe.

If you really want a complete shop, you should see if you can find a way to get both. Maybe just get some smaller cheaper stuff for starters, or you can see if you can get discounts or possibly something for free.

Look around for companies that switched to CNC's not long ago. My team went to a company that had a lot of old manual machines that they weren't using and we got a mill and a lathe for free. (of course it wasn't quite that easy, but take a look around, a lot of companies are probably willing to help).

JamesCH95 13-06-2010 13:09

Re: Mill or Lathe...
 
Go with a mill. I have seen machinists put round stock in a collet (not the same collet used for mill tooling) and put a lathe tool in a vice and essentially turn a mill into a lathe. One can also take a boring bar, flip the tool around, and do outside turning on a mill, in addition to simply using a boring bar to bore out round pieces. Sure a lathe will do any of these better, but a lathe cannot slot, cut angles, chamfer square edges, etc.

Lowfategg 13-06-2010 13:27

Re: Mill or Lathe...
 
Why not both?

Big One http://www.harborfreight.com/garage-...eed-44142.html

Small One http://www.harborfreight.com/garage-...hine-5980.html

Do note, depending on what your going to do with the machine this might not be a very good option. Your mostly limited to smaller workpieces and some what limited functionality (like you can't use both functions at the same time). Yet, it does come at a very nice price and fits in a much smaller space than separate machines. Yes I know the quality is somewhat poor and its not the most ridgid machine in the world, but for most robotics applications it will work fine.

So if your looking to machine small brackets, shafts, hubs, bolt circles, gearbox plates, and etc, this would do a fine job (given you have the right tooling).

Cory 13-06-2010 13:29

Re: Mill or Lathe...
 
I would highly recommend against the 3 in 1 machines. You get one machine that does 3 things poorly, instead of 1 machine that does 1 thing pretty well.

I'd recommend a lathe. I think we use ours more than our manual mill and our experience in the past has been that it's very easy to find machine shops to donate time to manufacture milled parts.

CraigHickman 13-06-2010 14:06

Re: Mill or Lathe...
 
Quote:

Originally Posted by Cory (Post 966423)
I would highly recommend against the 3 in 1 machines. You get one machine that does 3 things poorly, instead of 1 machine that does 1 thing pretty well.

I'd recommend a lathe. I think we use ours more than our manual mill and our experience in the past has been that it's very easy to find machine shops to donate time to manufacture milled parts.

I would echo this. Specialized tools have been refined for a reason, and combining them only cripples each function.

Agreed on the lathe as well. If you have the ability to make holes (drills), making things to go in the holes (shafts, etc) is the next step.

Lowfategg 13-06-2010 14:30

Re: Mill or Lathe...
 
Quote:

Originally Posted by Cory (Post 966423)
I would highly recommend against the 3 in 1 machines. You get one machine that does 3 things poorly, instead of 1 machine that does 1 thing pretty well.

I'd recommend a lathe. I think we use ours more than our manual mill and our experience in the past has been that it's very easy to find machine shops to donate time to manufacture milled parts.

I completely agree that its not ideal and that separate machines would do a much better job.

But if the question is only having one or the other (budget reasons), I much rather have the capability of doing simple mill operations along with simple turning operations, since its a whole lot better than not begin able to do anything.

Some teams aren't so lucky to find such machine shops because of location or other reasons.

Anyway, if I could only have one, I would get a good sized lathe first and then a mill after that (don't dis the usefulness of a milling machine, its a whole load better than a drill press). If you take the time to look around on craigslist or ebay you can sometimes find older machinery that will be well suited for robotics at pretty cheap prices. I got an older J-head Bridgeport for $500 along with a vise, beats any import machine that you could ever get for the money.

AdamHeard 13-06-2010 14:36

Re: Mill or Lathe...
 
Quote:

Originally Posted by Lowfategg (Post 966425)
I completely agree that its not ideal and that separate machines would do a much better job.

But if the question is only having one or the other (budget reasons), I much rather have the capability of doing simple mill operations along with simple turning operations, since its a whole lot better than not begin able to do anything.

Some teams aren't so lucky to find such machine shops because of location or other reasons.

Anyway, if I could only have one, I would get a good sized lathe first and then a mill after that (don't dis the usefulness of a milling machine, its a whole load better than a drill press).

I agree here.

I personally love milling much more than lathing; but if we had to choose one or the other, we'd have a nice lathe.

548swimmer 13-06-2010 14:50

Re: Mill or Lathe...
 
After thinking about this issue for a while, I realized that I almost never use our mill. For this reason alone, I'd say get a lathe. You can currently print out a hole pattern sheet and glue it on to your metal to make your chassis with a drill press or even a hand drill. With a lathe, you'd be able to make so much more.

BEEKMAN 13-06-2010 15:42

Re: Mill or Lathe...
 
I'd say it really depends on the type of team you are, and how you guys usually make your bots. If you find yourself doing complex cuts a lot, then get a milling machine, if you make custom drive trains, axles, or round things, lathe.

Chris is me 13-06-2010 17:24

Re: Mill or Lathe...
 
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 13-06-2010 17:31

Re: Mill or Lathe...
 
Lathe.

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

Akash Rastogi 13-06-2010 17:41

Re: Mill or Lathe...
 
Quote:

Originally Posted by Chris is me (Post 966442)
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 mill gets a ton of use. How else do you put in your snap rings anyway?

Lathe.

.

:p

Jay H 237 13-06-2010 19:51

Re: Mill or Lathe...
 
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.



Quote:

Originally Posted by Don Rotolo (Post 966443)
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.

CENTURION 13-06-2010 20:40

Re: Mill or Lathe...
 
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 13-06-2010 21:03

Re: Mill or Lathe...
 
Quote:

Originally Posted by CENTURION (Post 966488)
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?

JamesCH95 13-06-2010 22:36

Re: Mill or Lathe...
 
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 13-06-2010 22:39

Re: Mill or Lathe...
 
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.

jblay 13-06-2010 23:29

Re: Mill or Lathe...
 
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 14-06-2010 01:58

Re: Mill or Lathe...
 
Quote:

Originally Posted by jblay (Post 966516)
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 14-06-2010 02:00

Re: Mill or Lathe...
 
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.

Quote:

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.

JamesCH95 14-06-2010 09:12

Re: Mill or Lathe...
 
Quote:

Originally Posted by squirrel (Post 966515)
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 :p

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 14-06-2010 09:34

Re: Mill or Lathe...
 
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.

Rob Stehlik 14-06-2010 09:44

Re: Mill or Lathe...
 
Unlike most people here, I would recommend a mill. It's just such a versatile machine. On our lathe we make spacers and the occasional round part, and on our mill, we make everything else. Get a good one with a digital readout, and you can make an amazing range of parts. If you are at all interested making gearboxes and custom drive trains, a milling machine is indispensable. We are fortunate enough to have both machines, and our milling machine gets *way* more use. This might be because I am much more experienced on a mill and I encourage it's use :) But we also encourage the students to work from drawings, and the digital readout on the mill really helps make the connection between the dimensions on the drawing and the dimensions of the part they are making. Our lathe currently only has dials to go by, so it it a lot less user friendly. I guess whether you decide to go with a lathe or a mill, I would recommend spending the extra to get one with a digital readout, and the machine will be much easier to use.
Rob

Lowfategg 14-06-2010 10:33

Re: Mill or Lathe...
 
Quote:

Originally Posted by squirrel (Post 966545)
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.

Quote:

Originally Posted by squirrel (Post 966545)
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 14-06-2010 12:54

Re: Mill or Lathe...
 
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.

Joe Ross 14-06-2010 15:16

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

Dick Linn 14-06-2010 15:30

Re: Mill or Lathe...
 
I would say it depends on the parts you intend to make.

I would also consider the budget. A relatively inexpensive lathe with minimal tooling will allow you to make parts if you learn to hand grind bits. A mill can require more expensive tooling to make it useful (collets, rotary table, boring head...). And don't expect to be taking big hogging cuts on a $400. mini-mill.

A lathe is a good place to start learning, IMHO.

Not2B 14-06-2010 22:29

Re: Mill or Lathe...
 
Without knowing if you have specific projects you want to work on, I'd have to say the lathe is more useful.

I have a small lathe and (CNC) mill in my home workshop, and I use the lathe about 10 times as much.

I'd recommend making a list of all the tasks you would like to do and can't, and see what fills up that list better.

(Besides, lathes are awesome!)

DonRotolo 16-06-2010 22:16

Re: Mill or Lathe...
 
Quote:

Originally Posted by Jay H 237 (Post 966477)
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.

Quote:

Originally Posted by squirrel (Post 966515)
The way you get around not having a mill, is to actually design the parts.

squirrel answered for me; set up on the mill is a pain, and it's off site. We just design parts that use what we have or can get. Custom brackets are generally from extruded angle, or flat plate marked and bent. Our drivetrain doesn't use any brackets (but it uses a lot of axles and spacers...), and mechanisms just don't need milled parts.
Quote:

Originally Posted by JamesCH95 (Post 966544)
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.

Boring holes: If we don't have the right reamer, we don't use that size bearing.
Slotting holes: Drill and hacksaw, followed by a file.
Keyways: In shafts, buy slotted shaft. In sprockets, use broaches. On Motors: use a D flat instead (precision dremel usage)
Custom gearboxes: Andymark, 100%.


On my lathe (a 60+ year old Atlas 618) I have a milling attachment that mounts to the cross slide; 2" holding capacity, about 4" movement up and down. That covers 98% of my milling needs.

Also, note that I do not advocate DRO or CNC machines for FIRST. Digital readOuts are evil, kids rely on them and assume they are as accurate as there are digits, never losing calibration. CNC doesn't teach anything about how to machine stuff. Not that I don't lust after a CNC X-Y Plasma cutter for up to 5/16" aluminum sheet, but just like knowing how to Add, Subtract, Multiply & Divide the "hard" way before getting to use a calculator.

Chattering a lathe bit by cutting too hard, using the wrong speed, or just using the wrong bit grind, teaches something. You (should) never see that in CNC, teachable moment lost.

But that's just me.


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