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Jonathan
08-09-2013, 12:02 AM
It was so long ago I can't remember, or find, if I posted a build log for the initial CNC conversion of my milling machine. All I did was made some quick stepper motor mounts for the existing ACME screws and quill feed. It works, but clearly it's not ideal and has plenty of backlash, so time to add some ballscrews and eliminate the backlash using the usual system of two nuts and disc springs.

I've done Y, should get a bit more travel than the original 145mm (or actually 141mm because the original was assembled incorrectly):

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That's the old motor mount - I need to replace it with something stronger that doesn't look like a grandfather clock. I've left it like that for now so I can use the Y-axis, as it's tricky to make parts with only one axis working...

I've machined the ballscrew for the X-axis, threads on both ends so I can tension it between angular contact bearings. Long bit for the pulley and room for a dial so I can still use it manually. Annoyingly I accidentally dug the tool where the bearing goes, but it's a good fit so it's only aesthetic damage.

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Here's the ballnut mount for X, which is the same system as Y, so two nuts and a belleville washer to preload one of them against the other and eliminate the backlash:

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Things to do:
Acquire and machine Y ballscrew so it's the right length.
Mill a bit more off the X ballnut mount to get it closer to clearing the table.
Decide how to take 1-2mm off the underside of the ends of the table to clear the ballnut mount. CNC router might do it, if not I guess I need to get an angle grinder.
Make bearing and motor mounts for X.
Make everything for Z.

Here's some pictures of the quill:
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The front face is machined, albeit roughly, so looks like I'll be able to use that to mount the Z-ballscrew...

Clive S
08-09-2013, 12:13 AM
If you want an angle grinder give me a shout ..Clive

John S
08-09-2013, 12:41 AM
Aldi have some in 18 each, picked a couple up today.

Mind you if you want it milling off give me a shout.

Jonathan
21-09-2013, 04:43 PM
Thanks for the offers. Turns out my CNC Router is happy enough cutting cast iron so I'm just using that now. I'm using a 6mm single flute cutter, as they take about 5 mins to regrind if it's damaged. I've set it to 1mm doc, 70% stepover, 250mm/min at 4000rpm and it seems fine. Going to take an hour to take 3mm off both ends of the bed, which isn't too bad.

I've made the motor and bearing mounts for the X-axis, so once this bed is milled it should all fit together...

Jonathan
21-09-2013, 06:40 PM
Getting there...

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Jonathan
27-09-2013, 05:51 PM
I've assembled the X-axis now:
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Unfortunately I'm still waiting for the pulleys to arrive, so I've temporarily put some spare XL pulleys I had lying around on it. Since using the pulleys I had means the bigger pulley had to go on the motor, it's currently 30:14 ratio so it'll currently go silly fast - over 10m/min!

Oddly there's still 0.02mm (0.0008") of backlash... not sure what's causing it yet, I'm hoping it's just the pulleys so I'll look into it further when I've got the new ones.

natec
30-04-2017, 12:57 PM
I know this is an old thread but I was just given one of these and thinking about converting it mostly for machining aluminum. Do you still have the machine? Any thoughts about it?

Jonathan
04-05-2017, 12:29 PM
I still use it most weekends. It's a surprisingly good machine for the size, I think due to having substantial bed slides then for example an X3. If you're looking for a machine to fit on a workbench, I'd certainly recommend it.

Here it is milling a keyway in a titanium shaft:
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About the only change I've made to the machine recently is to add a spacer block of steel under the column, to drill the end of this shaft:
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Some general milling of aluminium:
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natec
04-05-2017, 01:57 PM
Thanks, I'm definitely going ahead with it. What kind of feeds and speeds are you running for aluminum? Looks like you're taking a pretty healthy cut in the last photo.

Jonathan
07-05-2017, 04:42 PM
Thanks, I'm definitely going ahead with it. What kind of feeds and speeds are you running for aluminum? Looks like you're taking a pretty healthy cut in the last photo.

From memory, 2150rpm (spindle max), 5-6mm DOC, 400-600mm/min with a 4fl HSS-co roughing endmill in the last photo. That's a bit of an exception though - standard, not roughing, endmills are quite a lot slower.