Thread: BigG CNC

Hi Rod,

It's looking good. I take it that you will be making some nice labels to cover the power supply voltages? This leads to my next question, what are all the supply's for? I just have the one with the G540 controller package and now you have me thinking that I'm missing something here.

Cheers
Brian

I haven't finished in there yet so yes it will be tidied up and labelled when it is done. The scribble on the enclosure was to remind when wiring which component to connect to as you can't read the manufacturers labels in there.

There are 2 X 12 volt, 1 X 5 volt and 1 X 48 volt DC switching power supplies in the cabinet.

There are eleven 12 volt fans - 4 in the cabinet, 2 in the switchboard, 3 over the drivers, 1 out of the VFD enclosure and 1 over the air pump. The 12 volt DC power supplies are 1 amp so rather than be borderline I fitted two.

The other smaller supply is 5 volt DC for the CNC4PC C10 BOB and as an alternative I could have taken 5 volt out of the computer or from a USB lead for that.

The larger 48 volt DC 10.4 amp supply is for the stepper motors via Gecko G251 drivers.

What I have is quite different to the G540.

I have also put in a RCD with distribution blocks (bottom left) from the main power so it should be safe.

Thanks Rod.

Another month has passed since my last update.

It is still ticking along and I have cut, sandblasted and painted all the steel for the machine base.

I have also assembled the Y and Z axis so once the base is done it is ready to bolt on. I only have the motor plate to make as I have done the spindle mounts. Hopefully it should come together fairly soon as the fiddly machining is all but done.

Different rails on that Y Rod any info on the

Whow... very nice. Did your bearing hole mounts line up with the slots on the gantry? I guess you've given this a lot more thought then I... haha.. but Im just a beginner on my first attempt.

I hadnt noticed this thread before.... CNC .... I like it.

Brad.

Unfortunately the original supported rails did not make the distance between the T slots but were too wide to allow a connection plate. Sean picked up that I had changed the rails and this is the reason I went for the ones in the photo. Mind they are overkill for this machine but they work.

I have done the same as you have with connecting plates except I used 80 by 8mm ally plate so I could counterbore the cap screws to make them flush.

I am not in a hurry to see the machine run so I buiild the controllers, etc as I go so that the machine is complete when it is first switched on.

If you don't mind me asking, where are you getting your aluminium?

Ive been meaning to build one of these for a while, but this forum has pretty much convinced me to get off my bum and do it.

Has anybody thought to have a suppliers sticky? I think it would help a lot of people get started.

Hi Croxly,
Welcome to the forum.

If you look three posts up WillyInBris has a link in his signature to a suppliers list.
It probably needs updating to include Ausxmods but it is all there.

For aluminum plate I go to Smart Aluminum (Capral) in Malaga. They supply cut pieces to your size. For T slot there is a good thread here for suppliers.
https://www.woodworkforums.com/f170/a...ofiles-112585/

Hi Brad,
I might have missed your point about the bearings. If you meant the bearings holding the ballscrew it was close. 46mm centres on the mounts and 45mm on the T slots so as I made my own T nuts I moved the hole half a mm out on each side. It seems to work OK. The T nuts I made for those are about 50mm long and I drilled and tapped two holes on the bearing centres in each nut.

Cool. And I notice your ball screws are the length of your gantry... If I had have done this I wouldnt have required 6mm spacers due to size of the motors. Oh well.... first build... we live and learn.

Brad.

Having to adjust things along the way is what makes it challenging and interesting. I make design errors and mistakes and have to pack or mill away for the perfect fit. It is overcoming the problems that is the difference between finishing a machine or making scrap.

I think you have done a top job on your machine. Keep going and spend time adjusting your axes until you get them running without any binding. I spend a lot of time on alignment and making sure there is no binding. You loose a lot of motor torque if it binds and it increases wear on expensive components. For shim material cut up a soft drink can and use that.

For information the ballscrew bearing blocks need work to make them suitable for our machines. After assembling the ballscrew and support bearings I noticed end float on the ballscrew. ie if you pushed and pulled along the length of the ballscrew it was moving slightly. It was a sort of springy motion that I discovered was caused by the compression of the seals. After reading copious amounts of conflicting information on another forum I decided to to tackle the job and make up my own mind.

I pulled the angular contact bearings and placed both of them together between my fingers and the centres of the bearing moved in and out. Not good as this is where the end float was coming from. The cure was to shim between the centre of the bearing so that it takes up the slack. There is no easy way to measure the end float and it was trial and error placing 2 thou shims at a time, assembling the bearing and testing. In the end it took 8 thou of shim to remove the slack. By doing this I not only removed the end float it also reduced the drag that the rubber seal was creating when I did up the ballscrew nut. I greased the bearing before final assembly and am pleased with the result. The bearings were assembled with the markings on the outside of each bearing.

Originally Posted by rodm

Hi Croxly,
Welcome to the forum.

If you look three posts up WillyInBris has a link in his signature to a suppliers list.
It probably needs updating to include Ausxmods but it is all there.

For aluminum plate I go to Smart Aluminum (Capral) in Malaga. They supply cut pieces to your size. For T slot there is a good thread here for suppliers.
https://www.woodworkforums.com/f170/a...ofiles-112585/

Thanks mate, show signatures was off by default, but its all good now.