CNC router build

ericks · 10-13-2018, 09:40 PM

Originally Posted by skrubol

That's a bit surprising. You should get better results from a mill specifically for aluminum. They're usually 3 flute. Corner radius or chamfer helps surface finish (along with other things) quite a bit as well. A good carbide end mill will last a long time if not abused, though you may lose some life due to chatter.

I was using the timber bit to flatten the mdf board under the workpiece... So i thought i would try it on the aluminium, it really works great.

ericks · 10-17-2018, 02:15 AM

Looks like i might have to mill a slot into the length of the x-axis extrusion. Reason is for the ball screw to fit between the two rails....the design mine is based on uses the ball screw on top of the extrusion.
Hopefully this does not weaken the beam too much??

**skrubol** · 10-17-2018, 10:30 AM

The X is the gantry? Any way you can add spacers for the rails or carriages instead?
Putting a slot in those extrusions or tubing takes away a lot of torsional rigidity and a decent amount of rigidity in the direction perpendicular to the face the slot is in.

**fretman_2** · 10-17-2018, 02:55 PM

Feeds and speeds you were using to mill the aluminum with the wood router bit?

Tnx!!

ericks · 10-18-2018, 01:02 AM

Originally Posted by skrubol

The X is the gantry? Any way you can add spacers for the rails or carriages instead?
Putting a slot in those extrusions or tubing takes away a lot of torsional rigidity and a decent amount of rigidity in the direction perpendicular to the face the slot is in.

Yes the x is the gantry....i already have spacers for the z axis. Don't want to have the spindle motor too far from the gantry beam.

ericks · 10-18-2018, 01:03 AM

Originally Posted by fretman_2

Feeds and speeds you were using to mill the aluminum with the wood router bit?

Tnx!!

I am running my kress router at max speed, on cambam i choose a feed of 800....sorry but with my limited experience i am not sure what the exact feed speed is.

ericks · 10-18-2018, 01:07 AM

Today i managed to mill the gantry beam slot.....the way i did it i don't think it will affect the rigidity. Anyway it's a very solid extrusion....only needed the slot to start 100 mm from the edges, hopefully i drew the cad correctly. The timber router bit worked faultlessly, i only made a couple of mistakes cause i had to do the milling in two sections due to the part size.

CNC router build-bit1-jpg

ericks · 10-18-2018, 03:44 AM

More progress.....it's going to be a heavy x-axis, it already weighs 26 Kg.

CNC router build-xaxis1-jpg

**firepong** · 10-18-2018, 07:05 AM

Originally Posted by ericks

More progress.....it's going to be a heavy x-axis, it already weighs 26 Kg.

CNC router build-xaxis1-jpg

I know how you feel on weight. I'm redoing my whole X axis on my home made router. With everything that is going on it, it will almost weigh 50kg. Using 50mm x 150mm x 1m of 6061-T651 solid Aluminum stock with part of the center being machined out for the Ball-screw. Biggest upgrade on the machine by far.

As for the cutting in the picture, that looks really damn good for a router bit like that being used. Nice work.

ericks · 10-18-2018, 08:34 AM

Originally Posted by firepong

I know how you feel on weight. I'm redoing my whole X axis on my home made router. With everything that is going on it, it will almost weigh 50kg. Using 50mm x 150mm x 1m of 6061-T651 solid Aluminum stock with part of the center being machined out for the Ball-screw. Biggest upgrade on the machine by far.

As for the cutting in the picture, that looks really damn good for a router bit like that being used. Nice work.

I expect around 40 Kg at the end. Mine is under 800 mm. The timber router bit is working great, any bad spots is due to my own inexperience. I find a little bit of wd40 gives it a very smooth finish. Looks like everything lined up very well cause the axis is running very smooth.

Wow 50 Kg that is a lot

**firepong** · 10-18-2018, 09:35 AM

Originally Posted by ericks

I expect around 40 Kg at the end. Mine is under 800 mm. The timber router bit is working great, any bad spots is due to my own inexperience. I find a little bit of wd40 gives it a very smooth finish. Looks like everything lined up very well cause the axis is running very smooth.

Wow 50 Kg that is a lot

Tell me about it. 2.2kw Spindle, 25mm Z-Axis plates, linear rails for both X and Z, Ball-screw, and the 35mm plates for the gantry itself. And that's just the gantry.

The table (base) currently as it is is roughly 75kg. It has a 24mm thick aluminum base plate (36in by 36in) 6061-T651, with 72mm x 24mm x 1m on each side for the Y-Axis rails to mount to and 15mm plates for mounting everything together and aluminum profile under the 6061 plate for stability.

I have honestly got to much in the machine, but it has been a constant work in progress since I got the machine over a year ago. Love working on it when I'm not working on the CNC conversion for the manual mill.

EDIT* It's actually starting to get to heavy for the table it is currently sitting on top of lol.

ericks · 10-18-2018, 09:55 PM

Originally Posted by firepong

Tell me about it. 2.2kw Spindle, 25mm Z-Axis plates, linear rails for both X and Z, Ball-screw, and the 35mm plates for the gantry itself. And that's just the gantry.

The table (base) currently as it is is roughly 75kg. It has a 24mm thick aluminum base plate (36in by 36in) 6061-T651, with 72mm x 24mm x 1m on each side for the Y-Axis rails to mount to and 15mm plates for mounting everything together and aluminum profile under the 6061 plate for stability.

I have honestly got to much in the machine, but it has been a constant work in progress since I got the machine over a year ago. Love working on it when I'm not working on the CNC conversion for the manual mill.

EDIT* It's actually starting to get to heavy for the table it is currently sitting on top of lol.

Sounds very interesting, i would love to see some pictures of your build

ericks · 10-19-2018, 03:05 AM

Currently busy working out where the cables will run from the control panel through the stand to the machine. Made a hole on top of the stand for the cables to exit and will be making a little cable rack out of aluminium.
Able to spend a little time on it while i order and wait for the ball screws to arrive.

I also plan to review the Hertz spindle motor and Chinese VFD for anyone who may be interested. The little 2.2 Kw drive is performing quite well....i did not expect it

ericks · 10-20-2018, 06:10 AM

So....i powered up the control panel to test run the Hertz spindle from the Sako drive. I used mach3 and the 5 axis bob to start the drive...all good. The speed reference via pwm from the bob worked but i found a slight fluctuation in the speed ref, installed a 470uF capacitor to stabilize the analog voltage to the drive....it works perfectly....usually you can filter the analog signal to the VFD drive with the drive parameters but this drive does not have most of the features that high end drives have

Later i will actually use the scope to look at the analog voltage to see if there is actually a fluctuation...For some reason i think its the bob pwm to voltage converter....i tested the drive with 0-10V from a power supply and the drive speed was perfectly stable. So far i am happy with this little Sako drive

ericks · 10-21-2018, 09:09 AM

The Hertz motor is running very close to the 18000 RPM....i measured 17890 RPM, that is not loaded

ericks · 10-22-2018, 12:16 AM

Managed to make up and install a little cable rack. I should order all the cable soon...

CNC router build-crack1-jpg

ericks · 10-23-2018, 06:08 AM

Had a closer look at the pwm signal from Mach3 and the bob. What i found was noise on my 5 V, i did not have time to check the 12 and 24 V....however i am sure it's there too. The noise is caused by the VFD, most likely generating the noise back into the mains then through the power supply. It's unlikely to affect the 5 V digital signals. I should have taken a photo of it

ericks · 10-24-2018, 04:21 AM

Today i confirmed that the noise is coming through the 230/5 volt power supply. Looking at doing the following:

1) Remove the 12 and 5 volt power supplies.
2) Remove the Schneider Zelio plc/smart relay.
3) Make up my own plc/smart relay.....with an on board filtered 5 volt power supply. The microcontroller will do all the machine logic and also do the Mach3 pwm to 0-10V conversion.

I need to think carefully to try and include all the stuff i might need ...i wont make a fancy board only a through hole board with a few surface mount components, will modify one of my old plc board designs.

Any ideas or advise will be much appreciated

ericks · 10-28-2018, 05:13 AM

Its been a while since i programmed a micro. Fortunately i managed to run a pwm signal from the micro.....read it accurately on another pin. All that is left is to build and test the converter circuit to convert my micro output to 0-10 V. It might seem to some as overkill but with the micro i can do a few tricks...one is to have the spindle running with zero variation and have the speed exactly as set by Mach3. At least that is the plan

ericks · 10-29-2018, 11:40 PM

I have just completed making up a pwm to 10 V converter. Using the power supplies that caused the initial issues on the 5 axis board, i am getting excellent control over the spindle from mach3. The noise is not affecting anything re analog signal. Also the speed is linear, without any compensating in the micro code....
I will still make up the noise filtered 5 V dc-dc converter that i use on my microcontroller power supplies. After final testing i will complete the little board, and if anyone has a similar setup with similar issues then i am willing to send them a board for testing/help.

CNC router build-test2-jpg