CNC Machine

[steve355]

A while back I asked in the CNC forum for some advice etc on building or buying a CNC router. In the end I bought a bunch of Chinese bits from Rattmmotor (eBay) and they turned up today.

The goal of this is to be able to cut out plane blades from tool steel, plus engrave brass for bits for all these planes I’ve been making. Out of the box(es) the CNC machine will not cut tool steel reliably, so it’ll be fun modifying it to try to get it to a spec that can.

I may as well do a build thread in case anyone is interested. (?!). It’ll probably take a few weeks as I understand the parts I don’t have, order them, and wait for them to arrive.

But right now, it’s Christmas

 

[Max Power]

Would definitely like to see this being built

 

[steve355]

I’ve unpacked the boxes, here are the main ingredients for the CNC router.

Clockwise from bottom left…

DDCS V3.1 CNC controller. Rightly or wrongly, I opted for a standalone CNC controller, rather than using a computer. We’ll have to see how it works out. I guess my only complaints is the screen is a little small compared to a computer. It cost around £200.
Various cables.
Height measurement probe
Fan
3 Nema closed loop stepper motors plus controllers (blue). I read that close loop motors are more or less essential for metal cutting, as they keep track of where they are supposed to be and do not “lose steps“. They were a lot more expensive than the open loop controllers, so hopefully they will be worth the money.
Fish tank pump for cooling the spindle
2.2 kW spindle
Collets for the spindle,
Hand controller for the CNC system
VFD for the spindle
Three power supplies, the big one is for the stepper Motors, the two little ones are for driving the CNC controller.
IEC socket, switch etc.

In another box, came the gantry…….

I am really impressed with this. It is extremely solid, I was concerned it was going to be flimsy. I was expecting to have to strengthen it, I now expect that I won’t have to strengthen it, but we will see.

I think there has been a lot of competition between, suppliers of CNC hardware recently, and this version has zero backlash ball screws, and square rails, both design to provide rigidity in a metal cutting situation.

The main base for the CNC machine has not arrived yet, apparently that will be with me soon. But all of the above, including the base, cost approximately £1300. Which I think puts the consumer CNC routers to shame.

So I have the base coming today, plus some wire, some terminal blocks et cetera. I bought some plywood this morning from Wickes to make a console box to put the controller in. So next step will be making the box and then I think running mains wires for the different components. The box is not going to be fancy!

Few more pics of the mechanics.

 

[Phill05]

I like the look of it for £1300 as you say puts some to shame.

 

[steve355]

The bed turned up this afternoon. Again, it seems very solid and well made. I will have to replace the top with a steel plate for reliably cutting metal, but I factored that in. TBH I didn’t expect it to be assembled - I expected a bag of bits. Result then.

I’d better get it out of the living room before SWMBO comes home ….

 

[Ozi]

Now that's a project.

I have a pipe dream which is not likely to happen of building a laser cutter, it would not take much to add a laser to the head of this and have a twin function machine.

 

[Ollie78]

Looking good, I trust you have a dial indicator for getting it spot on.
I certainly think this was a good way to go in a value for money sense. Be interested to see the performance and reliability of the all in one controller.

Will you be building a tank on the bed for coolant for cutting steel ? I see no reason to necesarily make the bed from steel and in fact I suspect you will end up with repeatable fixtures to hold what you are cutting.
Did you get a low rpm high torque spindle ?

Ollie

 

[steve355]

Looking good, I trust you have a dial indicator for getting it spot on.
I certainly think this was a good way to go in a value for money sense. Be interested to see the performance and reliability of the all in one controller.

Will you be building a tank on the bed for coolant for cutting steel ? I see no reason to necesarily make the bed from steel and in fact I suspect you will end up with repeatable fixtures to hold what you are cutting.
Did you get a low rpm high torque spindle ?

Ollie

Dial indicators seem to mate and breed in my shed. The current plan is to get a bed laser-cut in steel to give it some decent rigidity. The current bed is less flimsy than I expected , but still too flimsy. I’m sure I can find a way to level it, but at first at least I’m just wanting to rout brass and steel, so I was planning on using a sacrificial piece of plywood, which would rule out coolant, initially.

I just got a basic spindle to start with. I’ll see how it goes. All my experience of machining says it’ll cook the metal (which for a heat hardening steel is not a useful thing), and I’m fully expecting to end up with a slow spindle, and coolant. But there are plenty of YouTube videos of people cutting metal with the kind of setup I’ve specced. We will see. It’s possible that with light cuts, high feed rates, and a small end mill, it might work.

I’ll see how far I get with the wiring tomorrow. I think there are lots of sockets and things I need to order which will slow it all down - but overall it looks like a pretty easy project. Famous last words…

 

[sploo]

All my experience of machining says it’ll cook the metal (which for a heat hardening steel is not a useful thing), and I’m fully expecting to end up with a slow spindle, and coolant. But there are plenty of YouTube videos of people cutting metal with the kind of setup I’ve specced. We will see. It’s possible that with light cuts, high feed rates, and a small end mill, it might work.

Yea, I would be surprised if it'll work well (for steel) without some form of coolant. I have a ~130kg mill with a low speed (0-2000rpm) spindle that will do fairly light cuts in steel. As you say, a high rpm spindle doing very light cuts may be OK but I'd suspect it would generate quite a lot of heat. Carbide tooling will help (survive heat) but then it's also more brittle.

I have a CNC machine that will do wood/plastic and aluminium but I find galling is a major problem in ally if I'm not generous with a can of WD40. Really it would need some form of lubricant/coolant if I did more, but it's mostly for wood so I've not gone down that route.

Certainly interested to see how this project goes.

 

[steve355]

Progress report… well, I made the box

I knocked it up out of Wickes plywood, which delaminated so much that I decided to wrap it in sticky back plastic (wrapping credit to wife!)

Once done, it looked so much like a piece of audio equipment that I couldn’t resist 3d printing the Marshall logo.

I made and drilled a plate (red) for the numerous connectors, and the part standing up will hold the vfd.

On the internals, the controller comes with a breakout board. I’ve seen several rats nest wiring disasters online with this, so I decided to decouple it with a serial port extender cable (eBay £5). I 3d printed a bracket to hold the breakout board on the floor of the box (the controller is in the lid). This should massively simplify the wiring.

I have a fairly free day today, so hopefully I can make some significant progress with the internal wiring.

 

[steve355]

It lives!

 

[steve355]

Yes, I am definitely building a CNC controller

 

[steve355]

Little video showing all 3 motors now running.

The wiring has all been pretty straightforward. I decided to use aviation plugs, which taught me how long it has been since I did some serious soldering.

It needs tidying up a bit, some shields grounding etc but it’s gonna be okay.

Spindle next.

Various bits and pieces still to turn up for the main router part, but I may have it basically running tomorrow.

 

[niall Y]

Well done! You're already at a more advanced stage than my project. You've certainly motivated me to pull my finger out and start working on it again.
Out of curiosity, don't the heat sinks on the drivers need to be on the outside of the cabinet, where they will be more effective? I spot that you have a fan in there, but will this be enough?

Niall

 

[steve355]

Well done! You're already at a more advanced stage than my project. You've certainly motivated me to pull my finger out and start working on it again.
Out of curiosity, don't the heat sinks on the drivers need to be on the outside of the cabinet, where they will be more effective? I spot that you have a fan in there, but will this be enough?

Niall

I don’t know really, too early to tell. The control boxes that are factory made have the stepper drivers packed tight inside them so it’ll probably be ok. I can always add another fan circulating air through the box.

 

[steve355]

Back to the router itself, a few days ago I found an issue with it in that the carriage on the main ball screw was not correctly seated in the base of the gantry. I asked the supplier for some help and they fobbed me off, telling me it was a design feature and to add some washers. It isn’t, it’s a manufacturing or design defect. Never mind, overall it seems well made, and adding a shim in this kind of position on a machine is fairly normal. Besides, I think they are fed up me, annoying customer spending money with them.

I’ve measured the gap with feeler gauges and ordered some suitable (15 thou) shim stock.

 

[steve355]

Couple of steps forward today….

First, my shim stock came, so I made a shim for the carriage…. If it wasn’t for eBay, I’m not sure I would find 15 thou shim stock. It’s nice and tight now.

Next, I wired the VFD, set it up, and got the spindle going.

So, very nearly there. Unfortunately, I need a few M4 cap head screws, which I’ve ordered from Screwfix and apparently will be in tomorrow. So I can’t finish it off until then.

Looks like first test run in the morning

 

[steve355]

Well, it’s kind of done. All wired up and linked up today. Lots of glitches ironed out, but now all 3 axes, and spindle, the hand controller and the probe are doing what they should. Tomorrow I’ll try running some real Gcode. I might even try cutting out some wood or plastic plane blades.

I still need to get limit switches, proper shielded VFD cable, drag chains, etc.

Then the biggest problem …. Where the heck I’m going to put it. It’s a “6040” but it is way, way bigger than that.

 

[Phill05]

Steve, You have a lot of overhang from gantry to cutter looks like some packers in there? I think you will have problem to cut steel cleanly, I had the same problem when I started and ended up re-making the gantry and Z axis getting it to the minimum overhang I can now use it to cut any metal/wood/stone with no problems at all.

 

[steve355]

Steve, You have a lot of overhang from gantry to cutter looks like some packers in there? I think you will have problem to cut steel cleanly, I had the same problem when I started and ended up re-making the gantry and Z axis getting it to the minimum overhang I can now use it to cut any metal/wood/stone with no problems at all.

That’s a really interesting point Phill, thanks. Yes, there are two packers, both of which could be designed out. Once I’ve got a bit further with it, I’ll look into that as I try to make it more rigid.