CNC #2 - Aluminium Framed

[mikie]

Well its been a long time coming and I have started my second machine. Having taken everything i learned from the 1st build, thrown all this in the garbage I have started.

The base measures 1200mm X 1000mm. Not huge but should suffice for what I want to do with it.

Now the aluminium extrusion comes from (traded) a friend of mine who owns a division of Robotunits, here in Australia. These come from Austria and what i love about the system is that it all bolts together and can be moved around if needed. No need to bore any holes, anywhere. It also knocks up in hours.

I have opted for 4:1 reduction on the X and Y axis.
I will belt drive the X-Axis and screw for the Y and Z.

The Z-axis is an Ebay item from Thailand.

Will also be using a G540 which i won and smooth stepper.

I have included lots of pictures, which show the frame and how the Gantry bolts to the pillow blocks. All rails are 20mm and this is due to the the loads and the gaps in the extrusions.

[tumutbound]

Hi Mike,

Looks good.

How does the price of the Robotunit extrusion compare to say 80/20?

[mikie]

Hi Geoff

Great question, but i have no idea.
As mentioned, i did a deal and there is a LOT of mates rates in the supply.

[Lee Roberts]

Nice build log mate, i'm also looking to make Machine 2 from ali framing.

I share the same views of it being a good way to build somthing with maybe less boring needed and so on.

Ill be keeping any eye on this log and hope to see your machine make it to its first cuts.

Also thinking of going down the fully supported rail system as well over unsupported round rail.

[abomb55076]

Looks great, I built a few parts of my machine out of similar material, alot easier to work with than raw material, mainly the fact that you can easily bolt it together. Good Luck!

[mikie]

It has been a while, but i have been hard at it.

I have a new frame which now has the CNC router sitting on top. I still need to attach this to the frame with bolts and a glue.

I have fitted the x-axis and re-fited it again with upgraded cross-rods as i was finding flex in the rods caused the belt to run off the pulley. I knew i should have gone the 20mm from the beginning.

I have also fitted the Y axis to the ball screw. I made a new connector plate which attaches to the nut. This seems to work quite well.

The Z- axis has been mounted to the Y-axis and I still need to connect the wires to the motor, just as I have with the X and Y axis. I tried to make it all neat by housing them in little gray boxes.

Along with the mechanics, i have hooked the G540 unit to the smooth stepper. I have configured my laptop to drive it. I mounted all of this into the box situated at the base of the router, with the 48Vdc power supply. I added some connectors to the front plate which will allow me to hook up each of the axis and i also added a DB25 which will be used for homing switches and limit switch connection back to the G540.

I re-fitted the DC fans in the box to AC fans which i had lying around. This will keep the hottest unit cool. I will add some filtration pads when i get a chance to limit ingestion of foreign matter. The air is drawn from right to left, so i housed the power supply on the left, close to the fans as i thought it would generate most heat.

I am now in the process of setting up each axis in Mach 3 so it runs smooth and accurate. Once I get my X and Y axis sorted i will go back and finish the Z-axis by connecting in the motor and making a mount for the router.

In the interim i will machine some end caps for the belt pulleys to make sure the belt does not come off.

/M

[rjfurness@bigpo]

Hi Mikie,
I am building, (or trying to get the concept right first) a very similar machine. Can you tell me where you got the belts and pulleys from as well as the ratios?

You used a ball screw for the Y-Axis. Did you consider using belts for that also? Any specific reason you went with the ball screw and reduction pulley?

Thanks

Jason

[rjfurness@bigpo]

Hi Mike,
reading your thread properly I saw the 4:1 pulley ratio. I am on the robotunits website and I am wondering if you used the 40*80 series or the 50*100 series extrusion?

At least the robotunits website will price things for you.8020 won't give you a per unit price, you have to send them a design and they quote it.

Thanks

Jason

[mikie]

Hi Jason,

I am biased to robotunits as my friend owns the business.
I used 50x100 for all rails except the back plate which is 200x50.
This came about as it was offcuts and thus the size of my machine.

4:1 ratio was used for the X, which at the time I thought would give me a good speed with ample accuracy. In hind site it may have been better to run ball screws or rack and pinion with this ratio, instead of belt. I have had issues with the belt and not until Wed night did I actually get this resolved. See picture which shows the new idlers and drive system which makes use of some acrylic sheet I have.

I was lucky with the Y axis in that the screw cost me $20. From a friend. I cleaned it up and modified the nut connection and it works a treat.

If you like belt I bought mine from PowerGrip. They are getting a little expensive now. They are next to linear motion in Rowville Melbourne.

If you want to go screw, I would spend my money and buy from LinearMotion2008 on Ebay (Chai) as some guys I know have used his screws and they are fine and don't cost much even with freight. He will also grind the ends to suit your needs.

Yell out if you want more info

/M

[mikie]

Finally getting there,

I have the HF spindle mounted and the Corian cut for the table base. Just got myself some counter sunk screws and will hopefully be able to fix the sheets to the table tonight.

Progress pic's:

[rjfurness@bigpo]

Thanks for the info Mikie, I will post the price comparison between the 8020 and the Robotunits when I get the pricing back.

Jason