Wobblycogs CNC Mk2

[njhussey]

I'm just about to press the button on the ballscrews and round rails so would be interested to hear where you got your linear rails from as I might bite the bullet, pay the extra, and get these from the outset. also I'm going to get a PDMX-126 BOB so give me a shout and I'll order one along with you and perhaps we can save some carriage by getting 2?

I keep meaning to have a play with Linux but I've been out of playing with PC's for years now so probably know enough to get me into trouble but not out of it!!

[Wobblycogs]

The rails came from eBay a seller called fa-system. All told they cost £484, the same kit from Zapp would be £683 (not sure if that Zapp price includes postage). As far as I can tell the rails are still in tip top condition. The Z-axis have clearly seen a harder life than the X and Y which look almost brand new, I'd guess they all still have a ton of life left in them though.

I like the idea of buying the BOB's together, I'm pretty sure that's the model I'll end up going with but I want to have a bit more of a read first. I'd guess I would be looking to order late next week if that's ok?

Have you had any thoughts about spindles? There's an eBay seller "happykisssoul" that's shipping 2.2kW from the UK for a good price (even including insane shipping costs). I've seen a couple of guys say they have bought from him without problems.

[njhussey]

End of next week is good with me for the BOB. I've looked at that seller and even bookmarked some of the rails but they would be miss matched sets and the NSK S20 rails that are 1390mm long look like they have a bit of damage to one rail so not 100% happy about getting it. Might just have a look about and see what else is available.

I've made my own spindle which should put out 1.7kW and I've got a 25V 47A PSU to power it....

[Wobblycogs]

I think you are right not to touch those NSK rails, the damage is way to close to the bearings for my liking. There are some HiWin and THK clones over on AliExpress that looked ok and the reviews I've found are generally positive.

Does the power supply really have that written on the top? I can't quite tell if it's been "photoshopped" on. You certainly wouldn't mis-read the spec.

[njhussey]

I got it made from a chap on the heli forum I'm a member of, it was going to power my LIPO battery charger but I've got a bigger supply for that now The writing is vinyl stickers so could be peeled off if so wished...

[njhussey]

Just looked at the rails again and the damage is right at the end of the rail, as it's 1390mm long and I only want 1300mm I could cut that off....

[Wobblycogs]

I've been having a look at the control / motion side of the machine for the last week or so hence the lack of updates. I think I've now settled on a fairly uncontroversial set of components but I'd be grateful if someone more experienced could have a quick look over the shopping list...

• Steppers - 4 * Nema23 3.1Nm, CNC4YOU
• Drivers - 4* AM882, Zapp - Is there a reliable cheaper source?
• BOB - PMDX-126 Rev C - I plan on using the Rev B slave feature for the X-axis.
• Spindle Speed Control - PMDX-107 - Unlikely I'll set this up straight away but might as well get it now
• Step Generator - Ethernet SmoothStepper
• Software - Mach3 - Might wait till Mach4 as it looks like there won't be an upgrade option.
• Stepper Cable - 4 Core CY Cable 1.5mm^2
• Spindle - Spindle 2.2kW with VFD
• Computer - One of several spares kicking around the house, running Win XP probably.
• Power Supply - Currently planning a self build...

Total cost:

I plan on adding limit switches, water cooling pump, radiator, etc but I think this will get me started. I could do with a recommendation on cable for the spindle though

Most of the machine will be bolted together with M4 cap head screws, will this be strong enough? I settled on M4 rather than M5 to get additional threads in to the aluminium box section. My gut feel is that with the number of bolts I'm using either would be fine but I don't want to go buying a million M4's only to find they are the wrong size