5 Axis CNC Router

[wfung]

Hi Everyone,

I thought I might start a lil build log of my 5 axis CNC router. I've been lurking around on these forums for a while, gaining knowledge and inspiration from all the excellent threads around.

This is my first time building something CNC (and my first time building something of this scale too!). Learning how to use my new RF45 clone along the way as well.

About the machine itself, its a moving gantry, 5 axis CNC machine with XYZ, and AB axis (incorporated in a bi-rotating head). Planned travel is 500x600x300 respectively. Ballscrews and linear guides on all linear axis. So far I've been constructing the machine solely out of aluminium, due to the ease of machining, and availability. The price is a bit of a bummer though.

Aim is to be able to route complex shapes out of wood, plastic, and hopefully aluminium. Being able to mill brass and thin stainless steel in 3 axis might be possible as well. As such, I've been designing everything to be as beefy as possible.

Attached are two pics of my half completed Z axis. Travel is 300mm, 5mm pitch ballscrew, 495oz.in stepping motor. My intended design is to create an open 'box' shape, to stiffen up the structure. Not too aesthetically creative, but its cold functionality than I'm after.

I'm aware that this is a rather ambitious design, especially for a first timer. I've seen a lot of threads were people have started off on the 5 axis path, and then promptly vanished. But I do intend to finish building this machine- too much money has been spent on parts and tooling to turn back now.

**I've got a quick question with regards to Mach3. Its installed, and I've restarted the computer before connecting a breakout board from CNC4PC to it. However, when I try jogging the system, there doesn't seem to be any output from ANY of the parallel port pins...I've tried reinstalling the program, as well as trying on a second computer. Even tried Mach2! (I'm sure there is nothing wrong with my wiring)
Both computers were PentiumIII, running WinXP.
Is there something small that I'm missing? Most people on the forums seem to just install it and it functions without any hitches? The parallel port is enabled, and the address in Mach3 is correctly referenced.

Besides that, the build is going smoothly. My rotating head should almost be finished by tomorrow (just making some stepping motor mounting plates and couplings at the moment). I'll post up some pics tomorrow night if I get the opportunity.

-Wilson-
(Anyone here in Sydney btw?)

[blackbeard52]

have you tried checking the pins with a meter to see if you are truly not getting output?

[ger21]

Make sure you're not using a printer cable, they won't work. You need a cable with all the wires going straight thru. Easiest way to check if Mach is working is to check the direction pins at the port while jogging back and forth. Voltage should switch from 0 to 5V, depending on which direction your jogging.

[wfung]

I am using a male to male parallel port cable (not a printer cable)

So far, I've tried 'scoping the step pin, with nothing meaningful.
In the diagnostic tab in Mach3, are the pins in the representative parallel port supposed to light up when you jog the system? Because nothing lights up on mine... >_< (Same on both computers)

(I've almost finished the bi-rotating head. Will post up pics soon!)


Thanks,
Wilson

[blackbeard52]

Gerry is correct. Actually if you are purchasing them they are called parallel cables (used for serial transmission) in the old DB24 serial connectors. Some had a crossover pin configuration for modems (called null modem cables)...this is NOT what you want. Printer cables were centronics which had a funky connector that wouldnt connect to anything but a printer or centonics device. If you already have the cables you can check pin numbers. I have attached a site to reference the pins for the Null modem cable. http://www.nullmodem.com/NullModem.htm.... the correct one the pins will not cross over.

[blackbeard52]

Just a quick check....do you have jog enabled on the run or diag. screen... led must be on

[wfung]

Thanks for the all the replies everyone ^_^
The jog LED is on - the numbers on the DRO are moving as well. I think it might be the cable's fault. After searching through the whole house, I finally found a cable that wasn't parallel-printer...but it had a serial cable branching out from one of the parallel ends.... Since it was all I had at the time, its I tested the system with. If indeed the pinouts have been remapped to suit a modem, then that is the most likely source of all this mess >_<
I shall test it out with a proper cable tomorrow.

Besides that, I've essentially finished the birotating head. It only needs a few finishing touches here and there, and a quick fix to an mechanical interference problem.
It is made from 2 rotary actuator units that I purchased on ebay. Bolted on are 495ozin Nema23 stepping motors. Fabricated some custom couplings to attach the motor shaft to the gears used. (Note to self: Purchase some V-blocks!)
The actuators originally had a servo motor, coupled to a planetary gearhead, and then to the final gear. Since the stepping motor has much more torque, i'm only using the final gearing, which consists of simply a small gear driving a much larger one!

The assembled head will be bolted onto the Z axis with a 500mm long arm of 80-80 extrusion.

A bit worried about the weight of the gantry at the moment. Z axis is 10kg, head is 6kg. The arm will be around 3kg. For the X axis, I have some large NSK, 25mm rails set aside. Bringing the estimated gantry weight close to 40kg. Would a 495ozin Nema23 motor, driving a 20mm, 5mm pitch ballscrew be able to handle the inertia? Or should I consider upgrading to a Nema32?

And some pictures:
(Pic 1: Layout of components used; from the top, disassembled rotary actuator, mounting brace, mounting blocks, motor mounts, stepping motors, custom couplings)
(Pic2: Mock assembly of the 2 actuators - they can't be bolted together yet due to me forgetting to chamfer an edge.)

Enjoy~

-Wilson- (2:48am!)

[High Seas]

Just curious - did you make or buy the adapter(?) for the small gear. When I made my 4th axis using similar drives that was the tough part! I drilled and mounted the small gear. I like your piece better - looks much neater and maybe more dependable. If you purchased - got a part number or source?
Jim

[wfung]

I wanted to avoid having to modify the gear at all costs, because I would have no idea where to get another if I messed it up.

The adaptor is similar in shape to the shaft of the planetary gearhead (9.5mm shaft, with 2 opposing flats). Also turned a 6.4mm diameter on the end to help get a tight fit. 12mm of 16mm dia shaft is left on the end for motor attachment.
Next, the opposing end was bored with a 6.35mm, 22mm deep hole for the stepping motor shaft. The shaft is held in place with a M3 grub screw. The overall length was around 32mm. But thankfully, the offsets from the motor mounting plate still allowed the gear to line up roughly in the same position as the old one.

The gear itself is currently attached onto the shaft using a press fit. Somehow I produced a slight taper on the adaptor (probably from lack of skill whilst sanding >_<). Exploiting this unintended bonus, I pressed the gear in gently using a vice, being careful not to crack it in case it was brittle.
Had I possessed more forsight, I would've made the 6.4mm shaft bit longer, and included a groove for a C spring clamp. Improvised a solution by tapping a M3 hole in the end, in case I need to use a countersunk screw to hold the gear in.

I don't have a CAD program on my computer at the moment, so I hope my lengthy explanation will suffice

-Wilson-

[High Seas]

Nice word picture -- well explained. Seems like that is the toughest part of this "mod." If you'd like to price out a couple of those I'd be interested. Might be a mini market for them considering all the interest in these drives last year or so.
Jim

[wfung]

I'm still experiencing problems with Mach3.
Using the C1 breakout board from CNC4PC.com
+5V is connected to both sides, and the enable pin is hooked up to 5V.
Input side is connected with a male to male parallel cable (not modem or printer cable)
I don't seem to be getting any meaningful output on the pins when I try to jog the system. None of the LED's light up when I jog weight, but the pin2 LED stays on ...

**QUESTION: In Mach 3, under the diagnostics pane, if the system is operating correctly, the squares on the representative pins of the parallel port light up when the system is jogged?? Because on mine, they all remain OFF...

I would be great if anyone could shed some light on this.

Thanks,
Wilson

[blackbeard52]

could you send us a few pics of your hookup. picture sometimes is worth a thousand words. Also what amperage is your 5v power supply?

Bob