My CNC Machine and How to Make One

[webgeek]

I've been playing with robotics for years and didn't even know we had a local robotics group. Since there is a CNC forum, I figured I'd post some details on my machine and how I CNC'd it. Here is exactly what I did and what it took to do it...

1 x Harbor Freight Sieg X2 mini-mill
1 x CNC Fusion conversion kit #5
3 x CNC Fusion Pre-loaded ball nuts
1 x Gecko G540 Stepper Controller
3 x 380 oz Nema 23 Stepper Motor
1 x 48 volt 7.3 amp power supply
3 x 15' Serial extension cables

The next set of things needed is the computer and some software. The computer was just my old desktop machine. As for software, I'm using:

EMC2 for the machine control - really pleased with it - fast, free, and reliable.
CamBam for the CAM operations - Inexpensive and surprisingly powerful. I really like this one too - it has far more capability than I do so it will be enough for me for a long time. It has a lot of useful abilities related to 2.5d parts as well - things like auto holding tabs are pretty cool.
InkScape for creating 2d DXF files. For instance, I drew the claw/leg thing below on paper, photographed it into the computer and used InkScape's pen-tool to trace it then saved it as a DXF file. I could have drawn it directly in InkScape as well but I like to sketch on paper. The file loaded into CamBam perfectly with no issues at all. Another cool ability is "bitmap trace" - basically, InkScape takes a bitmap and using a variety of techniques, it can trace it into a series of vector paths. This would let you take an image from a book for instance and convert it to a DXF file. Best of all, InkScape is free too.

Personally, I used Virtual Box to run InkScape and Cambam from inside Ubuntu which is running EMC2. This might be too geeky for some people so another option is to just "share" the Ubuntu drive on your network so you can copy files. I do this too - means I can use any computer and talk to the milling machine's file system as needed.

Finally, tooling is needed. I don't have the exact list here because I bought some of it long ago. Any newbies reading this should really research this stuff as I'm inexperienced when it comes to actually machining things and my tooling might be dead wrong.

1 x Clamping kit
1 x Vise
1 x Collets
1 x Parallel set
1 x Dial Test Indicator - I think this is invaluable for tramming the mill - the thing needs constant adjustment it seems
1 x Test indicator holder - Makes tramming easier - I think so at least.
? x End mills - Since I'm new and pretty hard on end mills, I've been using cheap imports from Enco. I use mostly 1/8", 3/8", and 1/4". I just do any big stuff yet. I've never tried to surface anything so I'm missing any tooling needed to do that. I also haven't done any engraving so I don't have anything smaller than 1/8". I know the experts frown on cheap import end mills but it's easier to swallow crashing a <$3 end mill than a >$15 end mill.

All the companies I've linked are absolutely great to work with - prompt service and shipping and good prices. I'd gladly purchase from any of them again - and likely will.

I've made a few things with my mill but I'm still very much learning how to use it. I've got it partially torn down now to make it more accurate (my fault during initial assembly) but overall I LOVE IT. It's very cool being able to create something on paper and see it machined before your eyes in metal that same day.

I've attached a couple pictures of things I've done while learning - nothing too exciting. The little spidery leg thing is for a small robot I want to make.

Have fun!

-Mike

[Brian Turner]

Wow. what a detailed post. Great information. I have that same mill and would love to have a CNC mill. I was hesitant to CNC this one because of the accuracy issue that you mentioned. my backlash adjustments are always all over the map. I know how to deal with it manually but not in a CNC environment. I also have the same size of lathe from harbor freight and it seems to be a lot more accurate.

I was hoping to get a larger mill and convert that one to CNC. Or just bite the bullet and buy one already outfitted. But money has not been coming my way lately. The good news is that I have a friend with an awesome machine shop and when I really need something I have him do it.

Brian Turner

[TFrederick]

Mike,

Thanks for the great post.

You've done what a lot of us would like to do.

We try to have presentations by members every meeting to share things we've done and to help others learn. I know your not a member yet, but I'm sure we all would love to hear more about how you did your CNC conversion. Perhaps you would consider giving a presentation at a meeting sometime.

Terry

[webgeek]

Thanks for the nice kudos. Regarding accuracy, the best way to CNC an X2 is to replace the leadscrews with new ones and some pre-loaded ballnuts. Many of the X2 CNC kits include this as an option as it's a very good idea and reduces backlash immensely. This makes a huge difference in your overall machine. In practice, this machine should be down to a couple of thousands in backlash. That amount is easily compensated for in your controller software.

Regarding a larger machine, that's a good possibility. The single biggest problem with the X2 is only 4" of y-axis travel. There are several ways to eek this out to 5", but that it's still very limiting. The x and z axis both have about 8" which is a good amount overall. The next machine up from the X2 is the X3 and there are CNC kits for it, but they are quite expensive as the machine is physically larger. That makes it less viable for me personally. I've got an enclosure for the X2 with flood coolant and it fits nicely in a corner of my garage. With an X3, it would need quite a bit more space. You also need bigger stepper motors, higher current power supply, a different driver mechanism, etc. All of those things raise the price quite a bit.

As for being a member, I plan on joining. To be honest, I wasn't sure the group was still around. It's been several months since the last post in most of the forums. I figured I'd post this because I'd already put the post together for a different forum (for the people that helped me pick components and wire it up at cnczone.com).

Unfortunately, unless someone can give me a ride to the meetings, it's very unlikely I can make them. They are downtown and I'm in south Overland Park and don't have a car available at that meeting time. My wife teaches Zumba and is teaching it on Saturdays at the time and we only have the one car.

Otherwise, if we can work out a travel arrangement, I'd love to talk a bit about how I've set up my CNC and some of the things I've learned. Thanks!

Mike

[Brian Turner]

I don't know of any members in South Overland Park. We sometimes have meeting in the evening during the week.

I did not know that you could replace the lead screw in that mill. Good info. On mine it seems that the backlash changes quite a bit with use. I have been working with the adjustments but I can't tell if it is just getting loose or if that is the amount of flex in the mechanism. A ball screw would probably be a lot better.

Yes we are still around and we exist more in the real world than we do online.

Brian

[TFrederick]

There are three members that I know of that live out south. We've got a couple of weekends to figure this out. Mike send me an email at terryf<at>custom-solutions.com (replace the <at> with @) and let me know where you live and I'll ask around.

Terry

[davidf]

Way nice! I live in Stanley @ about 151st and Metcalf. I would be willing to
take you to the meeting most of the time. My wife works with Blue Valley Rec.
She might know your wife.

David F
faserobotics@gmail.com

Give Me a shout. I would love to see your mill.

[webgeek]

Ha, I'm at 157th and Metcalf - just down the road from you! I live in the neighborhood across the street from the Walmart.

My wife (Jamie) used to teach at the Blue Valley center and now teaches at the Prairie Village YMCA exclusively.

I've attached some pics of my "dense-pack" EasyDriver mount design I'm making on my mill next if anyone is interested. I'd be willing to make some of these for local members if they might be useful to others. I'm just learning CAD so these are a bit crude and probably done the wrong way. I figure I'll start making chips on this in the next week or so. I'll need to use 10 EasyDrivers for my mech warfare bot. The first two pics are of the final design, the last two show the original design but they show it as a whole so I included em.

Both the front and the back pieces are going to be cut from .75" x .25" 6061 aluminum rectangular stock. The parts are a total of 5.5" long - nice and small. They contain some neat features like grooves to hold the chips in place, a design that exposes all pins and controls on the board, and a reasonable heat sink effect from both the front and back of the board. Basically, the boards get sandwiched between the top and bottom mount without allowing anything to short and not interfering with any of the functions of the board. The bottom board's center holes are used to attach the board to the bot directly. The top board's outer holes are used to secure the top and bottom board. This let's you remove the top board and all the driver boards without removing the bottom board from your bot. Seemed pretty useful to me.

Thanks for the interest and kind words!

Mike

[davidf]

Mike,

Send me an email to faserobotics@gmail.com and I will call you and come
over if you are interested.

David F.
faserobotics@gmail.com

[vinito]

I just now ran across this post.
The one thing you missed is actual pictures and movies of your machine!! What's up with that? hehe.

From what you were saying last we talked, it seems you've come a little way since this post. Looks pretty good.

If you want any help, please don't hesitate to ask me. I like helping folks with this kind of stuff when I can.