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

[HankMcSpank]

Looking at importing one of these...

Shop Promotions FREE 1pcs ER11 chuck DC 12 48 CNC 300W Spindle Motor Mount Bracket 24V 36V for PCB Engraving-in Machine Tool Spindle from Industry & Business on Aliexpress.com (http://www.aliexpress.com/item/DC-12-48-CNC-300W-Spindle-Motor-Mount-Bracket-24V-36V-For-Engraving-Carving/677456541.html) (these 300w air cooled spindles are common as they are supplied with heaps of Ebay CNC 3040 & 3020 machines etc, therefore I'm figuring there must be a fair splattering of these across the UK)

but for my situation, it's essential that the shaft is earthed (or can be eartheded), so that I can autoprobe FR4 copper clad board with the tool tip.

Anyone know if it is?

Also does anyone have one they'd like to sell?

[Clive S]

Regarding the shaft earth you could just put a temporary ground to it with a crock clip as it will not be spinning when probing.. C.

[HankMcSpank]

Regarding the shaft earth you could just put a temporary ground to it with a crock clip as it will not be spinning when probing.. C.

yes I realise that....the point is I want to avoid putting a temporary croc clip on it! It's how I used to do it, but it's a chore & I used to forget to either put the croc clip on (tool breaks when descending) or forget to remove it ....(croc clip gets thrown off!)

I've a feeling that these Chinese 300w spindles are pretty much the same as the Zen Toolworks spindle...and I know that the shaft is not grounded those (necessitating their owners to put in a workaround suck as spring steel pressing on the top of the exposed shaft ...Zen Toolworks LLC • View topic - Auto Zero your tool bit (http://forums.zentoolworks.com/viewtopic.php?f=11&t=1968#p5038))

[Lee Roberts]

Nice find Hank,

I thought the same as Clive last night, not seen one of them opened up so not sure about the earth...

I have asked Mark and Jonathan to have a look at this thread as i know they have worked with outrunner motors quite abit and as i think that is basically what these spindles are (i could be wrong), could be intrested in buying one as well if you do go ahead Hank bet we could get them down on price if we try !

Let me know.

.Me

[blackburn mark]

The way I see it, the only way the shaft wont be earthed is if they have ceramic bearings and I cant see them having those unless they are the cheaper ceramic coated balls but again, they would be bragging "ceramic bearings" if they did have even those so its a safe bet that they will be fine............. if not you may have to change bearings for some nice cheap ones :)


Edit: just had a though.... if that mount is anodised, that may isolate the earth as aluminium oxide is none conductive (or very poor) so you may have to leapfrog the gaps twixt your motor body and mount
Your mount and Z plate should be fine (via the fixings)
I would guess that those people having problems with the model you mention are suffering this slightly elusive isolator.

[asbo]

I have one I'd like to sell, never been used, still in its original packaging.
I just stuck the multimeter on it and there is 100% resistance between the shaft and the body. There is no earth wire, just Red and Black. The top of the shaft has the cooling fan(?) attached to it, but its level and I'm not sure how you'd attach an earth to it. Would you like some photos?

[HankMcSpank]

asbo: PM sent.

The thing is I want a new spindle for PCBs.....my main requirement is actually low noise (I've cordoned off a downstairs room in our house & deemed it "man cave")...I've neighbours to consider & of course my wife will surely get more than a little p1ssed with the sound of a CNC spindle constantly whirring if its too loud....since I'm only milling FR4 & the odd bit of acrylic, a water cooled spindle seems excessive (& just adds a lot of weight to the Z axis)

the zen toolworks spindle is stupidly quiet.


http://www.youtube.com/watch?v=HGKFMDce78Y]

(& in this video it actually sounds a bit louder than it typically does in other videos I've seen with the zen spindle)

Edit: ok, found it - Here's the video that first caught my attention about how ludicruously quiet the Zen spindle is...


http://www.youtube.com/watch?v=48a5O2vT3Kk

(you have to do a double take to actually suss the spindle is on!)

[blackburn mark]

I have one I'd like to sell, never been used, still in its original packaging.
I just stuck the multimeter on it and there is 100% resistance between the shaft and the body. There is no earth wire, just Red and Black. The top of the shaft has the cooling fan(?) attached to it, but its level and I'm not sure how you'd attach an earth to it. Would you like some photos?

that is odd?
I would love to know where the break is... there must be one between the shaft bearing and body and I just cant see it being ceramic bearings?
maybe there is more plastic in there than you would have thought?

[Swarfing]

I have just checked mine and i have continuity between spindle and body. Does that answer the question?

[Lee Roberts]

The way I see it, the only way the shaft wont be earthed is if they have ceramic bearings

Yea was going to say ceramic...


Would you like some photos?

If you dont mind that would be great, i'm guessing Hank has offered to buy this off you now but photo's of it here would still be nice, as i bet there isn't any online and would serve us well for other people to come (archive kind of thing).


I would love to know where the break is... there must be one between the shaft bearing and body and I just cant see it being ceramic bearings?

Agreed, photo's me think's!

.Me

[Clive S]

I have just checked mine and i have continuity between spindle and body. Does that answer the question?

But is this the same type as spindle? ...Clive

[Swarfing]

300W 12V-48V DC High-speed air-cooled Spindle Motor for Engraving Milling | eBay (http://www.ebay.co.uk/itm/300W-12V-48V-DC-High-speed-air-cooled-Spindle-Motor-for-Engraving-Milling-/380659888849?pt=UK_Computing_Other_Computing_Netwo rking&hash=item58a118f2d1)

this is the same type as the one i have.

[HankMcSpank]

I have just checked mine and i have continuity between spindle and body. Does that answer the question?

yes & no...it goes to show that there are some Chinese 300W spindles out there that have continuity & others that don't - thanks for checking though!

These ones on ali express (which seems to be a tad cheaper place to buy vs. ebay) all look much of a muchness, this one looks like yours...

http://www.aliexpress.com/item/Free-shipping-for-air-cooled-300W-Spindle-Motor-12-48V-DC-ER11-collect-52mm-Mount-bracket/666996832.html

another variant (quite similar)...

http://www.aliexpress.com/item/DC-12-48-CNC-300W-Spindle-Motor-Mount-Bracket-24V-36V-For-Engraving-Carving/677456541.html


Speaking of importing, I'm probably gonna buy this CNC machine (just the machine & steppers only - no drivers, spindle or VFD etc)....

http://www.alibaba.com/product-gs/827192866/Redsail_Mini_Router_CNC_for_wood.html

....as I prefer a moving table machine (quieter...the moving gantry machines seemed to be designed like an acoustic guitar - i.e. a big 'soundbox' below the table to amplify the vibrations!) & nobody seems to sell moving table CNC machines anywhere in the UK (Premiersigns did have a similar model - one of which fivetide bought - but even they don't show one on their site now). The Chinese supplier is quoting $1000 delivered by sea which is about £650 + taxes, which for a 3020 ballscrew/ballnut machine constructed from Aloominum(!) seems reasonable.

[asbo]

OK here are some pics of mine.
I've checked again and there is still no continuity between the body and shaft. Although maybe I've lost a few more marbles :highly_amused:
There are two screws under the plastic fan thingy on top which presumably would allow it to be disasembled, but I'm not sure you'd get the plastic thingy off without breaking it.
Here is the listing I bought mine from CNC Spindle 300W Motor ER11 collect & Mount bracket Set-in Machine Tool Spindle from Industry & Business on Aliexpress.com (http://www.aliexpress.com/item/CNC-Spindle-300W-Motor-ER11-collect-Mount-bracket-Set/608111898.html)
907190729073907490759076

[HankMcSpank]

I've already PM'ed asbo the video, but I'll post it here to so other can have a laugh...


http://www.youtube.com/watch?v=PPfNpjhmsJY

should be ideal for milling 0.5mm pitch pcb packages!

Swarfing - do you use yours? (or have you used it?)

[m_c]

deletedjustforlee

[Lee Roberts]

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:


http://youtu.be/eZ3BzL82qNg

With a nice link to Raynerds blog post showing the spinde in bits: Brushless Spindle – Part 2 (http://www.raynerd.co.uk/?p=1566) (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]

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...


http://www.youtube.com/watch?feature=player_embedded&v=4IoQ_1sComM

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]

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]

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.

[GEOFFREY]

Hi, I was at premier in Nottingham a month or so ago and saw what I think was a used small fixed gantry hiding in the corner. I think it may have needed some work to get it going, but I would suggest it would be worth a call to Collin (forum member) to see if he wants to sell it. G.

[HankMcSpank]

Thanks I'll follow that up

[richie00boy]

I have one of those spindles on my 3020 and it works fine for PCBs. I just measured between the thread the collet nut screws onto and the silver top end of the motor and got 2.4 ohms.

My spindle has had less than 5 hours use and I'm looking to sell it soon. I can confirm they are fairly quiet.

http://www.readresearch.co.uk/personal/mycncuk/spindle.jpg

[Swarfing]

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]

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!

[Swarfing]

Bugger about the continuity Hank, why not just add another bearing to the top to connect off? Got me wondering what the differences are between all these spindle. Might pop mine ope over the weekend and have a look inside.

[HankMcSpank]

Bugger about the continuity Hank, why not just add another bearing to the top to connect off?.

That'd be the best way - but I don't have any bearing & it'd need to be a press (firm) fit - heaven knows where I'd get one of those ...in the meantime, I fashioned a heath robinson arrangement...

http://hostmypicture.com/images/bracketsma.jpg

....yes that green material is acrylic! - I don't have a strong enough machine to mill aluminium ...and besides, there ain't gonna much stress on this particular part. It was quite an ordeal to get right, there are only two screws at the top of the spindle (they run the whole length down through the spindle, so I had to piggy back that makeshift bracket off those two screw holes, which for the record, on this spindle are 41mm between centres!!)

& which will ultimately hold a spring loaded test probey/pointy thing (which I have in abundance), & look a bit like this....

http://hostmypicture.com/images/tp.jpg

& hopefully press down on the centre of the spindle shaft! (thereby allowing me to attach ground to the tool tip)

[Swarfing]

Whats the shaft diameter at the top? i might have a bearing or two knocking about that should fit.

[HankMcSpank]

My digital calipers are playing up (pah, that's LIDL for you ....must get a new one asap!), but I reckon the shaft protuding out the top is about 8mm dia. (eg I have an oldham coupler that's got an 8mm bore & that fitted onto the top shaft very snugly).

So how does this normally work? .....presumably a bog standard 8mm ID bearing will fit over the shaft, but it won't be a press fit (whereas the original fan that came fitted was a press fit & actually took some prizing off!)...& presumably I'll need a press fit here? (at this point, I'm hoping 'press fit' is the right term......ie were the bearing doesn't just slide on, but needs to be coaxed on with some pressure) ...I therefore probably need a bearing a tad less than 8mm?!!!

[Swarfing]

A couple of grubbed screw collars would hold it in place (8mm drill bit stops)

[HankMcSpank]

So I had a look in my bearing drawer, which was totally empty bar one 8mm ID bearing - result......except there's no electrical continuity between this particular bearing's inner & the bearing's outer casing....

http://hostmypicture.com/images/bearing.jpg

('scuse the crud - it's been a drawer for a couple of years!)


....and it ain't a ceramic type either! (i dunno you just can't get the bearings nowadays!).

Therefore I guess we can consider this case closed....clearly some bearings (even non ceramic ones) are open circuit whereas others seem fine (which could make sourcing ones that do have electrical continuity a bit of a lottery!)

Edit: Oh, BTW (as suspected) whilst 'neat', an 8mm ID bearing isn't a tight push fit....do you reckon a 5/16" (7.94mm) ID bearing fit ?

[WandrinAndy]

How about bodging some electric carbon brushes around the shaft, like those used in electric motors, to give you the electrical continuity ?

Off eBay a pair of these costs about £1.50.

[Lee Roberts]

For anyone intrested the new spindle Hank has ordered is for sale on ebay: ER11 Spindle for Sable-2015 / SPD-ER11 / ENGRAVER-mill,PCB's,engraving (http://www.ebay.com/itm/ER11-Spindle-for-Sable-2015-SPD-ER11-ENGRAVER-mill-PCBs-engraving-/200935958440?pt=LH_DefaultDomain_0&hash=item2ec8b767a8)

Thanks for the updates Hank, look forward to seeing how the new spindle dose.

.Me

[HankMcSpank]

For anyone intrested the new spindle Hank has ordered is for sale on ebay

The advert doesn't show the P&P to the UK...it's $23 & is a 10 day postal service.

(for all the spindle's back bracket is an exact fit for the sable 2015 - which I have - I'm sure it's an easy enough job to either change the backplate or knock up some form of adapter plate....the sable 2015 Z axis has M5 holes 71mm between centres & two rows spaced 27mm between centres)


How about bodging some electric carbon brushes around the shaft, like those used in electric motors, to give you the electrical continuity ?

Off eBay a pair of these costs about £1.50.

Bodge 'A' is my present attack (a spring loaded test probe, pressing down in the middle if the top shaft)

Bodge 'B' ...could be what you've suggested

...fortunately, I excel at bodging.

A better option would be to either source some bearings that are electrically conductive between inner & outer casing or buy a spindle that has these fitted!

[Swarfing]

Hank i just did a little experiment. It appears that mine is not kosher in the continuity stakes. What it looks like it is intermittent. So checked my mill and that is, the 2.2kw on the router is also. It could be a question of the grease breaking that connection? So i fired the 300w spindle up and let it run for 10 mins to get the grease going, guess what....connection all the way.

[HankMcSpank]

Thanks for the info ...problem is unless it's 100% all the time, then there's gonna be a lot of tool breakages ...and I can't really spin the spindle prior to every session just to warm up the grease (my cnc sessions only last about 5-10 minutes as it is!)

As an aside, this 300W spindle has claimed its first victim - a 0.8mm drill -I forgot to put the grounding croc clip on the *%~+'ing spindle shaft (I never had to do this with my proxxon) ...this is now an emergency issue for me! lol

In the light of your results, it's now looking like bodge 'A' or bodge 'B' (or bodge 'C' which is have some spring steel press down on top of the shaft - which is what some Zen toolworks spindle owners have done)

[Swarfing]

The answer has to be a slip ring then with carbon contacts. Use something like this mounted on a disc over the top. A little spring to keep in place and your away. You can make the parts on the router easy enough :-)

DEWALT DRILL CARBON BRUSHES DC981 DC984 DC988 DW988 | eBay (http://www.ebay.co.uk/itm/DEWALT-DRILL-CARBON-BRUSHES-DC981-DC984-DC988-DW988-/190590728600?pt=UK_Home_Garden_PowerTools_SM&hash=item2c6017b998)

or find something like this?

http://www.ebay.co.uk/itm/MILWAUKEE-18V-C18PD-4000431188-Carbon-Brush-Assembly-/321146703365?pt=UK_Home_Garden_PowerTools_SM&hash=item4ac5d5ce05

[Swarfing]

Something a bit simpler to adapt

DEWALT N012060 CORDLESS DRILL CARBON BRUSHES DCD940 DCD945 DCD980 DCD985 | eBay (http://www.ebay.co.uk/itm/DEWALT-N012060-CORDLESS-DRILL-CARBON-BRUSHES-DCD940-DCD945-DCD980-DCD985-/190674085894?pt=UK_Home_Garden_PowerTools_SM&hash=item2c650fa806)

[HankMcSpank]

Thanks, they're good options - many thanks for the heads up.

In the meantime, I've lashed up a bodge (like I say, bodges I can do!)...

Bodge 'A' ...aka 'spring loaded test probe pushing down on the centre of the spindle shaft'....

http://hostmypicture.com/images/3lvl.jpg

http://hostmypicture.com/images/2lpl.jpg

(there should be 4 screws holding that top piece up....but I only have 3 screws long enough to hand (it'll probably never see a fourth!)

...it works :-)

[Swarfing]

Nice one! :triumphant:

[m_c]

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

:rolleyes:

[HankMcSpank]

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]

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

[HankMcSpank]

If anyone else has a spare 300W spindle & associated mount (perhaps you've upgraded to water cooled spindle etc), then please shoot me a PM cos I need one more :-)

[fifa]

Spinle can be easy grounded also during operation. Add the axial brush in the top...

kr