How Would You Upgrade An Old Ox CNC Build Into A Serious Machine?

[Clive S]

surprised me when I read the manual and it clearly says to NOT use a contactor or it could damage the VFD. I’d watched people on YouTube use contactors in their build and would have made a big mistake if I hadn’t looked at the manual.

What you basically must NOT do is put any form of switch between the VFD and the three motor cables going to the spindle or unplug the spindle with the VFD running.

If you do you might hear a big bang.

[Kitwn]

What you basically must NOT do is put any form of switch between the VFD and the three motor cables going to the spindle or unplug the spindle with the VFD running.

If you do you might hear a big bang.

Double up on that several times over!! NOTHING should come between the VFD and the spindle. Only ever use the spindle ON/OFF control wiring to stop the spindle if you ever want it to start again. I wouldn't even cut the mains input to the VFD with the spindle running, though that might be my clinical anxiety kicking in

Kit

[JAZZCNC]

What you basically must NOT do is put any form of switch between the VFD and the three motor cables going to the spindle or unplug the spindle with the VFD running.

If you do you might hear a big bang.

Double up on that several times over!! NOTHING should come between the VFD and the spindle. Only ever use the spindle ON/OFF control wiring to stop the spindle if you ever want it to start again. I wouldn't even cut the mains input to the VFD with the spindle running, though that might be my clinical anxiety kicking in

Kit

While this excellent and sound advice, It isn't exactly correct.? . . . It's true that you shouldn't control the spindle ON/OFF with a Contactor between VFD and Spindle or use anything that will interrupt the connection while running, however, you can safely have a contactor between them provide it is not switched while the VFD is running.
I've done this before to control multiple spindles with single VFD but there must be safety involved and interlocks checking the spindle as stopped spinning and the RUN command isn't active before allowing it to happen.

This said the advice above is good.

[NeoMorph]

What you basically must NOT do is put any form of switch between the VFD and the three motor cables going to the spindle or unplug the spindle with the VFD running.

If you do you might hear a big bang.

Wouldn’t that turn the spindle into a generator with nowhere to send the juice? Plus does the power run a cooling fan?

One thing I didn’t specify in my order was a breaking resisistor. Do I need one?

[NeoMorph]

I said it in other thread : I buy from these guys https://es.aliexpress.com/store/822038 12 and 15 size. Have not bought from them 20 size , but their rails are very good quality and price. Custom size also, contact them. make sure to buy the long carriages.

BST is good for original HIWIN but last time i checked / 2 years ago/ the Chinese rails they were selling were not very good. While the ones from the link above are top notch

Dont rush discarding the C beam. Take a look at my design for a DTG printer base using that C beam and said linear rails+some 3d printed elements:



This is 12 size Hiwin square, which would happily move 0.8kw spindle. I would say even 2kw spindle if 3 blocks.

But this is not my point. Maybe 15 size and use the C beam like a L shaped gantry. I have never tried it but that's the fun of it, you can figure it out for yourself.

One thing I’m thinking of building is an engraver for spherical objects. I bought an Eggbot yonks ago to check out engraving on a sphere but it’s still in its box.

What I need to engrave for a long term project of mine is two hollow hemispheres. They are part of an Apollo navigation system.



The reason the hemispheres are hollow is because there are motors and sensors INSIDE them. There is a central disc with an axle going through the middle of it and a hemisphere on either side giving the appearance of a sphere. The disc then has axle point top and bottom and it then mounted in a C clamp and that is powered too... then the C clamp is rotated to give the third access.

I worked out all the control circuitry but the one thing that is holding me up is engraving the hemispheres. Both of them are half black and half white making it even harder.

Anyhoo, my point is I think a heavier guage Eggbot might do the trick... emphasis on the “mighty.

[JAZZCNC]

Was looking at some HGR20-1000’s in the BST automation store for my side rails... but for the life of me I can’t figure out the differences between the different carriage options.

There is only few differences HGR is the rail followed by the rail width then length. HGR20-L1500
HGH20CA is Narrow carriage
HGW20CA is wide flanged carriage.

Hi-win do offer other types with different heights and preloads etc but most of what you see for sale in China are common preload and carriage heights.

[JAZZCNC]

Give me the dimensions of the machine ie: Profile lengths for X and Y axis and I'll see what I have kicking around that could possibly send your way. I've got several second-hand but in good condition linear rails and also some new 15mm Hi-win bearings floating around. I've also got a few ballscrews floating about.

How is the gantry made up it's hard to see from that picture and I've seen them build these things several ways, plus you said you'd upgraded it. Just trying to determine if it's strong enough and best layout for rails. etc.

Regards the Z axis and C section profile and it sticking out a little far then I wouldn't worry too much because if you change to linear rails then the gantry end plates will probably need changing so you can design them so the gantry is offset back a little to reclaim the lost travel.

Give us better pics of the machine from different angles so can see better how to beef it up.