[hub]

Here are some pictures and info on my new version:
(The previous version is here: http://www.cnczone.com/forums/cnc-wo...build-log.html)

Specs:
- Travel (approx.): X 700mm, Y 1075mm, Z 245mm
- Rapids 12.000mm/min
- Theoretical max precision: 0.002mm
- 3 ax servo drive
- Mach3 control
- AL frame, steel stands, some wood parts (will be replaced)


Making square stock out of birch wood logs,16mm tool: (A band saw would be great to do it, my next project....)
Attachment 275110

Attachment 275112

Attachment 275114

Some electrical connections (with some messy temporary wiring)
Attachment 275116

Z axis:
Attachment 275118

Z axis servo connection:
Attachment 275120

Y axis:
Attachment 275122

Current "T-table":
Attachment 275124


Attachment 275126

[hub]

My old break out board decided to die.. So I bypassed it and wired everything directly to the LPT port.
After that, got some random E-Stops to Mach3 when drives enabled, so I put a 24V optocoupler btw. E-Stop signal and LPT port as I thought it might filter some noice, and it did. Works great now. (I did first try the debounce setting in Mach to 1000 to 5000, but it didn't help).

So, now I lost the control of the VFD from Mach. The BOB converted the PWM signal to 0-10V to the inverter to set the RPM. Is there a simple way of converting the PWM to 0-10V? A capacitor or something maybe, I haven't done any research yet. (0-5V would also work but I would prefer the 10V).

I also made & installed two "sync discs" on the Y screws since they are connected with belts and run by one servo, the ensure that the machine will e-stop if they go out of sync. If a belt breaks etc.

Next, limit switches, it's scary without...

[ger21]

Is there a simple way of converting the PWM to 0-10V? A capacitor or something maybe, I haven't done any research yet. (0-5V would also work but I would prefer the 10V).

I built this circuit for a few dollars.
http://www.cnczone.com/forums/spindl...tml#post853530

[hub]

I built this circuit for a few dollars.
http://www.cnczone.com/forums/spindl...tml#post853530

Thanks That's maybe too much/complicated for my simple need, I only need to convert the PWM to voltage (or actually current is also an option on my VFD).
Maybe I will de-solder the BOB and use its components...
Hub

[hub]

Machined some aluminium today.. (New bearing blocks for the machine as I'm going from hand made temporary wooden ones to AL)
I went too aggressive first, just too much for the machine (it's not near rigid enough yet). But got good results with small depth of cuts (0.25mm).
Lost 2 endmills. The first was my mistake, I didn't set the machine coordinates correctly (forgot), and the endmill crashed into my piece an snapped..
The second broke a bit when Z crashed down on my part with spindle not running. This is a puzzling problem, if I reset (E-Stop) from Mach3 the Z will go down 3-4mm for some reason I don't know. This doesn't happen every time with e-stop. And X & Y are fine. I'll have a look at the servo drive settings...

I also got a few random e-stops, so I connected the PC chassis to the common ground for other components, after that no problems so far. It was grounded through the mains cable to the same ground but that wasn't enough I guess.

I changed VFD settings and re-wired so that the spindle will start/stop. But still have to manually select the freq. (RPM).

SO MUCH to do still, but slowly getting there....

[ger21]

That's maybe too much/complicated for my simple need, I only need to convert the PWM to voltage

That's what that circuit does. I get a 0-5V signal from the PWM.

[hub]

That's what that circuit does. I get a 0-5V signal from the PWM.

I did some searching, to get a 0-5V from a PWM all that's needed is a resistor and a capacitor. To get 0-10V, a few more components are needed. I'd rather have the 0-10V, if possible easily.

[hub]

Made a few more AL blocks, the right side of Y axis blocks are now all machined and finished.
It takes almost 2 hours to machine each part, because I have to cut very small depths.
I'll make the Z axis much more rigid some day soon I hope..

I ordered new angular contact bearing for the spindle. It has currently tapered roller bearings, they work fine but are very noisy...
Will replace as soon as I get the new ones.

I did some wiring too; I noticed at PC power on it turned on the servo packs (even with E-Stop), so I re-wired E-Stop so the the servo packs are always disabled when E-Stop is activated.

[hub]

I made and connected an Z zeroing plate, speeds up thing a lot..
Still have to Z axis servo sometimes rotating down a little after E-stop. It's annoying, but I can live with it. I think it's the servopack, the manual says if the servo isn't moving or is moving very slowly it will coast to a stop. Strange though that the other two don't do it...

Here is a CAD version, maybe clearer than the photos. Some things missing & some extra in the CAD..

Attachment 275866

[TTalma]

Could you post a little more about your spindle? here did you get the head? what speeds are you getting? etc. And maybe a few pics?

[hub]

Could you post a little more about your spindle? here did you get the head? what speeds are you getting? etc. And maybe a few pics?

Sure, (pics later),
The spindle assy is just a 1.1 kW 3 ph AC motor driven by a 1.5 kW VFD. It's connected 1:1 by most rigid rubber tubing I could find to the spindle head which has a MT3 taper. The red bearing block is from Germany, but I'm pretty sure it's the exact same as this except for color : https://littlemachineshop.com/produc...ProductID=1487

Spindle is max 7200RPM. The machine move max 12.000mm/min.

[hub]

Installed the new AL parts on the right ball screw to replace the wooden ones, I'm very happy with how accurate & rigid they are
The machine is getting better and better part by part..

Also as promised, here is the Z axis head assy: From CAD.. Its missing a spindle nut to set the bearing preload, which I have intalled on the machine, but otherwise correct:
EDIT: Also 6 screws aren't in the PIC...

[hub]

Made this project today, as a gift and to test the machine.
Roughing at 5000mm/min & finishing @ 1000mm/min

Attachment 276408
Attachment 276410
Attachment 276412
Attachment 276414
After some sanding:
Attachment 276416
A thick layer of clear coat, needs to be sanded:
Attachment 276418

[hub]

I needed/need a probe to find hole centers, so I just used a precision 5mm pin in the spindle and did a metal-metal touch until trigger. Not very precise, +- 0.015mm but it will have to do for now..
Do you know a DIY electronic probe design (easy to make without a lathe)? Just added it to my endless list of projects

[hub]

Today I installed a temporary 4th axis, I will change it when I have the chance, I have a chuck & parts for it, just need the time to do it properly..
So it's now a fully functional 4 axis

A few photos:

Aligning the the 4th with a dial indicator, (took over an hour, had to shim it with thin AL plates):
Attachment 276658

From the back, It's just simply a small 400W servo driving the spindle with a belt and an adjustable roller to set the tension. Reduction is 1:2.5. It moves pretty slowly, but it has an accuracy of ~0.004deg/step.
Attachment 276660

Also some pics of the new AL parts I recently machined and installed to replace the wooden ones:
Attachment 276664
Attachment 276668
Attachment 276666

And the "sync disk" on one screw:

[hub]

The new angular contact bearings arrived today, so I disassembled the head and removed the tapered roller bearings. Installed the new bearings. Took a couple of hours, it's a tight fit..
Assembled everything and re-installed the head and aligned it. Wow, so much less noise and run-out is also better as a bonus

The 4th axis is barely usable at the moment. The small 400W servo connected directly with a belt struggles to keep position when cutting.
I have a cyclo gearbox with a 2.2kW servo fitted, but no driver for it, so I think I'll fit the gearbox to the current servo as a temporary solution V2. It will effectively lock the position of the 4th axis + offer a lot more torque.

[hub]

As I've been doing 3ax CAM, I couldn't get the CAM to output 4ax.. Steep learing curve, but now I have it figured out.
Just need to update the 4th hardware..
AND install the limit switches which are still waiting to be installed

[hub]

The 4th I'm going to install: (Cyclo gearbox & 2.2kW DC servo)

Attachment 276910

For now, only the gear box to the small 400W servo as a compromise, until I get a PSU & driver & encoder for the DC servo (it has only tach).

[hub]

And to that I have a heavy duty 350mm chuck I'm hoping to install. It's maybe a bit too big,.. Weighs almost as much as me.. at around 70kg... But at least I can grab large diameter parts with it.

[pippin88]

Why do you need a 70kg chuck???

You can make a much lighter chuck. If you are turning large diameters, you'll be turning them slowly.

Your machine is not suitable for such a heavy chuck. That is the sort of chuck used on a 2 tonne lathe!