Chinese 300W DC spindle - is the spindle shaft grounded?

**m_c** · 16-06-2013

deletedjustforlee

**Lee Roberts** · 16-06-2013

Thanks for all the info, links and pics guys.

I hope to build a small mill type machine for doing light work, engraving, pcbs and so on at some point so I would like to go with a smaller spindle myself for this unit rather than the bigger units we commonly use for our machines.

My original plan was to build my own spindle like Mark and JB have using an out runner motor, the cost is going to be more then these off the shelf options but I think it may make for a better spindle. After seeing that video of the 2mm run out, I am interested to know if you with these spindles have the same problem with the quality or if or not the guy who made that video just got a duff one?

Here is a video of the kind of thing I’m talking about re going the DIY spindle route:

With a nice link to Raynerds blog post showing the spinde in bits: Brushless Spindle – Part 2 (think he has a link to these forums on his site some place, so not sure if he is a member or not).

Cost will be a bit more but it looks quite easy to do, what do you think?

.Me

**HankMcSpank** · 16-06-2013

Since the 300w spindles are very common on CNC machines, I reckon there'd be internet 'mob outcry' if all these spindles had runout like the video I linked to earlier (so I can only assume his had been dropped or similar)

asbo kindly applied some power to his spindle & videoed the result - for the sake of a bit of balance, I hope he doesn't mind me linking to it here...

I'm actually buying the spindle from asbo, so I'll soon be able to report how these 300w spindle perform wrt fine pcb milling (vs my present proxxon bfw40/e ...which is fine, but only foes up to 7000rpm & the spindle & brackets weigh in at well over 2kg which is mental for a small machine like I'm using!)

**Swarfing** · 17-06-2013

Hank the one in the video as a kit is exactly as the one i bought. I've only run it up at 40v as that is the pwm driver o bought to use for it. Looking at it was a disappointment when it arrived. Powering it up was a different matter. It ran rather smooth with no noticeably run out. i will change some of the parts on the driver so i can run it at a higher voltage when i get round to finishing one of many projects.

**HankMcSpank** · 17-06-2013

Originally Posted by Swarfing

Hank the one in the video as a kit is exactly as the one i bought. I've only run it up at 40v as that is the pwm driver o bought to use for it. Looking at it was a disappointment when it arrived. Powering it up was a different matter. It ran rather smooth with no noticeably run out. i will change some of the parts on the driver so i can run it at a higher voltage when i get round to finishing one of many projects.

Cheers for the feedback.

I'm thinking if the fan is removed, then it ought to run much quieter (& possibly smoother) .....it'll be interesting to see how hot it gets & how fast with the fan removed. (the Zen Toolworks spindle doesn't have a fan on the top)...I typically only use mine for 20 minutes stints max - if it runs too hot with the fan off, then I'll even considering mounting a separate larger low noise DC fan suspended over the spindle somehow or other ...this can spin at far lower RPM vs the spindle's & yet should still keep the spindle cool.

**Swarfing** · 17-06-2013

Hank i think the fans are just air movers rather than cooling if you know what i mean? you could suspend a vacuum unit over the top clearing the mess and cooling at the same time :-)

**HankMcSpank** · 20-06-2013

Well asbo's spindle arrived in the post today...as expected the bracket mount holes didn't align with my machine's Z axis, so an adapter/ bracket was quickly knocked up & it's all mounted now.

First impessions are favourable.

I can confirm that asbo isn't going doolalley.... ie there's no continuity between the chassis/casing & the shaft ....wtf? I'll look at lashing something up as a kludge, because putting a croc clip on the spindle shaft for every tool change is gonna get old very quick!

I've already removed the top fan & spindle is indeed whisper quiet ...like so quiet you have to double take whether the thing is even on! (& I typically only use my spindle for 10 minute sessions & whilst it got warm over 10 mins, it didn't get scorchio).

Changing tools on these things is a ballsache vs my proxxon (which uses a tommy bar to stop the shaft turning)....also, even with the nut loosened, you have to continue loosening a fair bit more just to get the tool to finally release, it feels like you have to be an octopus....need to mull this aspect too!

**m_c** · 24-06-2013

Originally Posted by m_c

A steel ball bearing isn't guaranteed to conduct, as even a thin layer of grease will act as an insulator

**HankMcSpank** · 27-06-2013

As an aside, does anyone know (or can check) if a typical chinese water cooled 800W spindle, has electrical continuity from its outer metal casing to its shaft?

**Kn8** · 28-06-2013

Hi I have just checked my 800W water cooled spindle for continuity between the outer case & the shaft rotating the shaft by hand the resistance measured varies between 2 & 7 ohms