Let's Make Robots!

Getting started with machining

About four years ago I came close to taking a job at Honeybee Robotics, a company that makes robots and parts for things like the Mars rovers. One of their robots, W.I.S.O.R., even had a really cheesy movie made about it. It would have been a pretty cool job, except that what they wanted was someone to machine parts for their robots, and I didn't know a single thing about machining. I ended up deciding not to pursue the job because I didn't feel qualified, but ever since then I've been really wanting to learn metalworking. It happens so often, as I'm reading some guy's robotics website, that he'll casually mention how he threw such-and-such part on the mill and made a slot so he could bolt it to his robot, or whatever. It sounded like such a useful ability to have.

A few months ago I decided to buy a milling machine, and so began a lot of research, trips to the library, renting instructional videos, etc (not to mention saving up cash). Finally I felt comfortable enough to make an informed decision about what to buy, and I ordered a "mini-mill" a week or two ago. As I waited for it to arrive, I worked on building a workbench to bolt it to. I've finally got it all set up and made my first chips, so I just thought I'd post some pictures of the process :) The full selection of bench-building and milling-machine-unpacking pics are at my website, but here's a selection.


Materials for the workbench brought home (man it's handy having a trailer)



Most of the bench frame assembled (those three 2x6's in the back will become cross-supports for the upper surface, just like the three 1x2's in the lower shelf).



Picking up the milling machine at the freight terminal (did I mention how handy it is having a trailer?)



Mill uncrated. It comes covered in red packing grease to prevent rust -- time for an hour with a rag and a gallon of kerosene.



Bench surface (two layers of 3/4" plywood) attached.



Getting the 150 lb milling machine up onto the workbench. Having an engine hoist is also very handy.



Damn, that's something I didn't think to account for in my bench design. Can't get the hoist in place to bring the mill over the bench.



Bring the mountain to Mohammed!



Mill bolted down securely, tooling and metal stock arrived.


Some of the fun toys:


Clamping kit



A simple starter set of 4-flute end mills



Aptly-named "1-2-3 blocks", a precise 1" x 2" x 3", used for measurin, marking out, and clamping.



Dial indicator and dial test indicator, accurate to .001" and .0005" respectively



A set of 6" parallels, pairs of precisely parallel plates, also used for measuring, marking, and clamping



The UHMW plastic I ordered shows up before the aluminum, so my first milled piece isn't actually metalworking. It's... an ashtray?



The metal arrives



After milling the upper face flat, I practice drilling accurate holes



My second milled piece! It's... a spice rack?


So now that I'm more or less all set up, it's time to actually get to work and start making interesting things. Or trying to, anyway :) This has the potential to make robot building way easier, being able to fabricate my own brackets etc. But I'll have to figure out how to translate all the machining techniques I've been reading about into actual ability :)


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Yeah, it sounded like a pretty interesting project. I rented the movie from NetFlix, and while it WAS pretty cheesy (they added a computerized voice where the robot would "talk" sometimes, hehe), it was an interesting look at the process of designing, building, and testing a robot in an environment where you don't have lots of leeway for mistakes. The guy I would have been working for is featured in that movie -- at one point he goes off on a random diatribe about religion and god and stuff. Would have been an interesting work environment :)


Thanks for the kind words. Yeah, it's exciting having access to a mill finally -- feels like I there's so many possibilities open to me now :) Of course now I keep thinking of things I want to make and realizing that I need a lathe for them... Time to start saving again, sigh :)


I was curious, what was the deciding factor between getting a mill before a lathe?

Looks really cool, I'd love to start machining parts some year too. Had thought about classes somewhere, but it looks like most hobbiest learn on their own, with videos, books and such. Hope you have fun!

That was a big conundrum for me. I did a lot of reading and forum searching while trying to decide between a lathe and a mill. It sounds like the lathe is a little more useful/capable, and the 'standard' approach is to start with a lathe and then later get a mill if you find that you need it. There's some overlap in their capabilities, but for the most part, the two machines are more or less complementary -- the things you can't do on a lathe, you can do on a mill, and vice versa. But I get the impression that probably 60-75% of typical machining tasks can be done on a lathe, whereas only like 40-50% can be done on a mill, which is why the lathe is the better place to start.

I ended up deciding on a mill because I definitely want to have the ability to make things like mounting brackets for servos, and things like that, and that's definitely a mill-type part. But already there's a bunch of things I keep thinking of that I'd like to make, but I'll realize that you need a lathe for that. So even as I was ordering the mill, I was pretty much accepting the fact that I'd be buying a lathe before long as well, and I designed my workbench to fit both machines side-by-side :)

And yeah, I looked for classes at the local vocational schools etc, but couldn't find anything about machining. Looking at the forums, it did sound like most people learn on their own, which I'm up for, but I felt like I didn't even know enough to be able to decide what machine I needed. So before buying anything, I checked out the only machining book the library had, rented some instructional videos, etc. One great, free resource is MIT's TechTV series of videos on machine shop practices. Go to http://techtv.mit.edu/ and search for 'machine shop', you should find a series of ten one-hour videos available for download (about 100 MB each) which do a great job of explaining everything from basics and shop safety up to operation of bandsaws, sanders, mills, and lathes. After watching the whole series, I felt I had a much better idea about what I needed in a machine, and could make a much more informed decision.

Of course, now that I've got the mini-mill home and am starting to work with it, I'm already finding myself feeling limited by its small work envelope :) I'm trying to work with a 1.5 x 3 x 7.5" block, and it seems to be just about at the limits of the capabilities of the machine, requiring me to get pretty creative with my clamping in order to be able to work on it, and having to use the full range of travel to barely get the cutting tool around the sides of the part. Maybe the idea of a bigger machine isn't as unnecessary as I decided it would be :) Ah well, obviously for a good while now I'll just have to make do with this. Most robot parts shouldn't be as big as what I'm trying to work on, so I think it'll do just fine for the vast majority of my work.


man those videos are great! is there only the flv format ?

Hmm, when I discovered it a week or two ago, there was a link you could click on each video page which provided you the URL for the original WMV file to download, but now I don't see them. I wonder what changed.


He definitely did some research before buying what he actually needed, but when it comes to building robots you can’t buy just any milling machine accessories but only the best ones that are going to last in time and, of course, respond to your needs in matters of productivity and safety. What’s quite interesting is that he decided to build a workbench for the milling machine instead of buying one.

Gonna be stuck on that site for a while, much info to take in.

Very cool!  I actually went the 3-in-1 route, and got a machine that does everything.  A mill/lathe/drillpress in one.  Here's a good example of one: http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=46199 The one I purchased does have certain limitations.  You can't pay 600-700 for a metalworking machine, and expect it to have the precision of a $1000.00 machine that just does one of those jobs.  But I've found that for my projects, it's good enough.  I'm not working with micron precision parts anyways.  One complaint I do have with it is that the units to move in the x-y-z axes is very strange (0.1mm/tic, 0.06mm/tic, and 1.4mm/tic) so I have to do a little math in order to make sure I move the right distance, but other than that, the machine's great. 

One thing I do recommend you do if you want do get a lot of practice in but don't want to pay too much for stock metal, is practice on acrylic. I looked at the price of stock metal, and it's very expensive.  There's a plastics place near my house, so I buy acrylic sheets that are 1 or 2" thick, and I do all my practicing on that.  Of course the properties of acrylic are different from metal, but they did allow me to make some really cool parts for my projects.


How does that little mill weigh more than me?!