DIY spindle design

[Jeremy]

I've started this new thread here, rather than continue on the collet discussion thread.

Prompted by the discussion on collet types in the other thread, I purchased an ER16 collet chuck, with a straight 20mm shank 100mm long, from Arc Euro, together with a couple of collets. My intention is to build a relatively high speed spindle for my CNC router project.

First off, full marks to Arc Euro - less than 24 hours from order to delivery.

I've just ordered a suitable motor, but have reduced my maximum speed requirement a bit to make bearing choice more affordable. The motor and speed controller I've opted for is rated at 550 watts, but my power will be limited to about 360 watts by the 12V, 30A power supply I already have.

The motor is a three phase brushless one, with a Kv of 1400, giving me a maximum rpm of about 16,800 at 12V. Total cost for the motor and speed controller, including postage, was just under £33.

I've also just ordered some deep groove bearings, that are rated at 20,000rpm, so should be OK in this application (I hope).

I'm hoping to be able to build a fairly high speed spindle, suitable for light duty routing with small diameter tools and a high degree of accuracy. The ER16 chuck is pretty good as far as I can tell. I can't see a difference on a DTI between the run out on the shaft OD (due to the innacuracy of my 3 jaw lathe chuck that I stuck it in to test) and the run out of a 1/4" bit of tool steel in the collet. My guess is that it's better than about 1/2 thou TIR, which should be OK for fine work like PCB milling.

Next job is turning up a bit of 2 1/2" diameter alloy bar to make the housing, then milling a mounting flat on it to allow it to fit to the Z axis plate. The motor will be directly coupled to the top of the spindle. I'm hoping that the combination of direct drive and a three phase brushless motor should make for a quiet spindle.

I'll post pictures as soon as I get something machined up.

Jeremy

[Jeremy]

I'm hoping it'll be fun, although until I read the collet thread I hadn't thought of doing this - I was just going to buy a small router or die grinder to use, so this is yet more work!

Robin wrote (in the other thread I was clogging up with this stuff)
Hi Jeremy

What is a suitable coupling for 500 revs/second?

Balance probably isn't a prime consideration, but no bending parts obviously.

I'd probably go for a rod though one shaft engaging a pair of driving dogs on the other, then spend half an hour adjusting it 'till it ran quiet

best

Robin

Good question. I've been looking at the small Huco and Lovejoy couplings and think I might be able to adapt one of the ones that uses an elastomer spider. Hopefully this will reduce any noise and allow for a small degree of misalignment. Now that I'm being less ambitious with my speed expectations (due to the difficulty in getting affordable bearings) the problem sould be simpler.

I may revert to driving the spindle with a small belt drive, as although this would be more bulky, it might well end up simpler to build.

Jeremy

[Jeremy]

Thanks for the link to that eBay seller. I've already ordered bearings, but the Lovejoy couplings they stock look to be a good deal, so I've ordered some. The 050 size should be OK for my steppers and the 035 size look like they'll work OK for the spindle couplings, as they are rated to 31,000 rpm.

The next challenge is to work out an easy way to connect the chuck shaft to the coupling.

Jeremy

[Jeremy]

That's a good price for the chuck, cheaper than the one I purchased from Arc Euro, even allowing for the shipping charges.

I think I've worked out a way to couple the chuck shaft to the motor, using a small Lovejoy coupling. The only problem I can foresee is vibration if I can't get everything perfectly aligned.

BTW, the motor I have ordered is this one: http://tinyurl.com/5dcho4, which was $30.16.

The speed controller is this one: http://tinyurl.com/5l8ols, which was $11.30.

I've used these RC electric motors in other projects and found them to be quite amazing, they will deliver lots of power with an excellent overall efficiency. Best of all, they are cheap and have no brushes etc to wear out.

Having seen those collet prices on that CTC eBay shop, I'm now tempted to do what I originally planned and replace my clunky old Clarkson with an ER25 set-up.

Jeremy

[Jeremy]

Well, I now have all the bits to build the spindle, so shall; have to crack on and see if I can get it to work.

The motor and controller arrived from China pretty quickly, as did the bearings and lovejoy couplings bought via Bearing Boys and ebay. The motor and controller are tiny, it's quite amazing to think that the motor is rated at 550 watts. This is a real advantage though, as it means that the complete spindle assembly will be a cylinder with an overall diameter of about 1.5". I'm toying with the idea of fitting the Z axis in between the Y axis rails, primarily so that I can (hopefully) gain some added stiffness by minimising offset loads from the cutter. The narrow diameter of this spindle is ideal for this, although it will mean offsetting the Y axis leadscrew to one side (although I can't see this being an issue).

I'm going to try and machine up a small spigot to fit into the end of the chuck shaft (it's internally threaded 10mm) to couple to the lovejoy connector, as I need to get the shaft size down to something similar to that of the motor (the motor shaft is 4mm). Luckily there is a small counterbore in the chuck shaft, just above the start of the threaded section, that seems to be very concentric to the shaft OD (I can't measure any run-out with a DTI). I'm hoping that I can use this to align my shaft adapter, although if it's a thou or two out it won't really matter, as the coupling will cope with up to about 15 thou of misalignment.

It looks like this evening will be spent boring lumps of alloy bar and machining up the shaft adapter. I'll post pictures as soon as it's done.

Jeremy

[Jeremy]

I've made a start on the spindle today. Spent a couple of hours turning a bit of 1.5" 6082-T6 bar into swarf...............

All told it's turned out OK. I turned a bit of bar up to fit as an end cap to hold the 550 watt motor (yes, I know it doesn't look like a 550 watt motor, but it's very efficient at around 85 to 90%). I turned up a small adapter to fit into the M10 threaded hole in the end of the collet chuck to fit to the lovejoy coupling. I am reasonably happy with the way it turned out, the runout at the coupling is around 3 thou, well within the 15 thou coupling limit.

The big bar has been bored out to take a pair of bearings, one at the end and another just below the cutout (the cutout is to allow the coupling to be assembled).

I just need to make a spacer to fit to the nose bearing and space the chuck out about 10mm from the bearing (to allow spanner access) and make up a clamp ring to fit at the top of the collet chuck 20mm shaft and allow the bearing pre-load to be set.

The thing with the wires poking out is the 40 amp speed controller. It's a bit of an overkill, as my power supply is only rated to 30 amps, but it should do the job. The current plan is to fit it into a small die cast alloy box next to the spindle and build a servo tester to drive it. This will give me a manual speed control, which I may seek to change to auto at a later date.

Hopefully I should end up with something much more robust and accurate than a Dremel, with a fair bit more power. The motor may need a fan fitted to the top for extra cooling, I'll see how it goes.

http://farm4.static.flickr.com/3008/3071642290_a436168637.jpg

Jeremy

[Lee Roberts]

Looking very nice Jeremy, how much would you say it has cost you so far to make this ? Would you be looking to make some more?

[Jeremy]

Total cost to date is about £60, not including the 12V 30A power supply that I already had. Similar power supplies cost about £25 to £30 via ebay.

This is strictly a one-off for my router build. I'm after something that will spin at a reasonably high speed so that I can use small diameter tools, but don't really needs lots of power, as it'll only be cutting light stuff. Mind you, I suspect that the few hundred watts that this little unit will deliver should make it pretty powerful for it's size. If anyone want more power, the place I purchased this little 550 watt motor also sells some nice 2800 watt model motors for around £30 each. I have a few for another project, the snag being that they draw around 80 amps each, so need fairly hefty power supplies.

I also wanted a fair degree of accuracy, without the fairly horrid run-out that Dremel-like tools have, as I'd like to try using it for milling PCB's as well. So far I think I'm on-track to have a fairly solid little spindle with relatively good accuracy, probably better than a thou TIR.

Jeremy

[philbur]

Small cutters really need much better than a thou TIR. Better than a tenth would be much more suitable. Otherwise the necessary low chip load per tooth will leave you cutting on one flute only. A decent level of precision in the bearings is called for, together with good adjustment for preload. No-name deep grove bearings of unknown class may not get you there. The other killer will be the concentricity of the spindle taper with the bearings seats.

Get these two points right and you are on a winner. Get them wrong an it's going to be a so-so spindle.

Just some thoughts
PHil

PS: I haven't read the whole thread so if I missed something sorry.


So far I think I'm on-track to have a fairly solid little spindle with relatively good accuracy, probably better than a thou TIR.

Jeremy

[Jeremy]

All good points, Phil, if this were for a precision machine cutting a hard material like steel.

It's going on to a table top router type machine though, intended to cut moulds for composite parts, from mainly EPS foam and MDF. The idea was to make something with a power similar to a small trim router or the larger Dremel type machines, but smaller in diameter, with more robust bearings, a better level of spindle accuracy and, most importantly, a much lower noise level.

If the whole machine turns out to be sufficiently accurate, I may use it for milling/drilling PCBs, although I suspect that the spindle speed will be too low for that task, so I may need to build another, faster, one.

If I get a spindle that is compact, quiet and comparable in accuracy and overall cost to a trim router then it will certainly meet my requirements.

Jeremy

[philbur]

Sorry I must have misunderstood what you meant by:

"I also wanted a fair degree of accuracy, without the fairly horrid run-out that Dremel-like tools have, as I'd like to try using it for milling PCB's as well."

Phil

[Jeremy]

Quite a few PCB routers have been built that work fine with small tools like the Dremel, so my aim was to make something that would be a bit better than this, a bit quieter and hopefully have bearings that would last a bit longer, for around the same price.

I've got a couple of Dremels and the newer one seems to have around 2 thou or so of combined run out and play in the spindle, the older one is quite a bit worse. Their real problem seems to be the eccentricity in the collets, as the tool run out is significantly worse than the spindle - to get the best out of them means re-seating the collet several times to true up the tool. Despite this poor accuracy, many people have shown that they work fine for modest PCB milling, such as the homebrew stuff I'll want to do.

The very best I could hope for using ER type collets is about 1/4 thou TIR, assuming no other error sources, as that's their spec. A 1/10 thou TIR would be totally unachievable using this type of collet chuck, I'd have needed to go for something far more costly if that was my aim.

It's debatable as to whether better than a thou is needed for such an application as DIY PCB milling anyway. Minimum track width is unlikely to be less than about 15 thou and assymetric cutter tip loading isn't an issue for a single flute vee tip PCB milling tool. Given that so many people are very successfuly milling out boards with spindles that are far worse than mine is likely to be I really can't see me having a real problem, apart from the slow speed .

This spindle might be a bit too slow for PCB work with small diameter tools, as it will be limited to around 16,000 rpm. It will be ideal for the bigger mould making requirements I have, using tools up to around 6mm or so, so I may just try it for a while with that task, see how it goes, then look at making a faster spindle for PCB work if I need it.

I've found a source for an ER25 chuck with a 1/2" shaft that looks promising for a future higher speed version. Reducing the shaft size from 20mm to 1/2" gives the possibility of using bearings with a higher speed rating, which will allow me to get up to the 25,000 to 30,000 rpm (or higher) that would be best for the PCB task.

It's good fun experimenting anyway, even if I do get one or two failures along the way.

Jeremy

[Jeremy]

I finished the mechanical part of the spindle today and gave it a test run. All went well, but I need to pull it apart and take a tiny skim from the lower bearing housing, as the lower bearing gets a bit warm after a few minutes running. I noticed that the spindle was a little tight after I assembled it. I hadn't realised how a tiny bit of "pinch" from a bearing pressed into a housing that was very slightly undersized would make such a difference, but it's easy enough to fix.

The good news is that the spindle is reasonably quiet and seems to work well off load. The RC motor didn't even get slightly warm, but the speed controller may need mounting on an additional heatsink, as it was a bit warm after a few minutes running. The motor was drawing around 10 amps from a 12V supply when running flat out, which is a bit high and almost certainly to do with the overly tight lower bearing.

I may also need to adjust the bearing pre-load. I've used a couple of belleville washers under the upper shaft retainer, abutting the top bearing inner race. Pre-load was set by clamping the shaft to compress the bellevilles a small amount, then tightening the shaft collar at the lower end. This wasn't very "scientific", so may also be a contributing factor to the warm running lower bearing.

Here's a picture of the completed spindle:

http://farm4.static.flickr.com/3007/3107033319_58ff1e2872.jpg

The body is 1.5" in diameter and the overall length is 8.75". The motor outer can at the top (the black bit with the writing on) rotates, so probably needs some sort of guard. The small lovejoy coupling seems to work fine, there's no real vibration at all with it spinning at full chat whilst just being hand-held. Overall it seems to vibrate a lot less than a Dremel and is certainly a lot quieter.

I've done a crude run-out check using a DTI, with it clamped in vee blocks on the surface table. A 3mm carbide cutter shank didn't seem to deflect the DTI at all, which seems pretty good. My DTI isn't really sensitive enough to show anything under about 1/4 thou though, plus the lower bearing is still a bit too tight, so the true run out might be a bit worse.

Nevertheless, if I can fix the lower bearing problem I think I shall be well pleased with this little experiment. Let's hope that the motor turns out to be reliable!

Jeremy

[Lee Roberts]

Really nice job mate, have you got any pics or movies of it working ?

[Jeremy]

Thanks, Lee. I'll try and see if I can take some video of it running after I've fixed the lower bearing problem, as long as I can work out how to get the camera to shoot video! (I know it can do it, but will have to sort out how to get Quicktime changed to avi or mpg, I think!).

Jeremy

[Jeremy]

No videos yet, but I do have an update. During bench testing I found that the motor electronic speed controller was getting pretty warm at mid-range speeds. It was fine when flat out, but would get too hot to touch after 20 to 30 seconds at mid-range. I tried fitting a heatsink to it, but there was clearly something not quite right.

After enquiring on an electric vehicle forum (my interest in CNC is to build EV parts) a couple of the more experienced RC model motor guys suggested I needed to derate the controller to a greater degree if it was to deliver higher power at mid-speed. This makes sense, as a model aircraft propeller absorbs power in proportion to the cube of it's rpm, so the controller wouldn't be optimised for running at high currents at part throttle.

I thought I'd been conservative in buying a 40 amp controller when the most my power supply can put out is 30 amps, but it seems that I was wrong. I've switched to a spare 120 amp controller I have for another project and the performance has been transformed. Not only does the controller not get warm, but the speed control is very smooth indeed and the motor starts from a standstill very well. The other plus point is that the motor no-load current has reduced by about 50%, which goes to show how inefficient the original controller was.

Although the motor whines a bit at max speed (around 16,000 rpm) it's not excessively loud. I've been testing it in my study and have so far not elicited any complaints from SWMBO, which would not be the case if I fired up a router in here!

I've still got a bit of fettling to do, including reducing the drag on the bottom bearing, but all told I'm exceptionally pleased with the outcome so far. It looks like it will meet my design goals of being compact, relatively quiet, affordable and fairly accurate.

Jeremy

[Jeremy]

Hi Kip,

Thanks for the kind words, I just need to crack on with the rest of it now!

The cut out in the housing is to allow the Lovejoy coupling to be connected and also to allow the top collar, that retains the spindle in the housing, to be secured. These both have screws that are inserted from the side to lock them in place, with those for the spindle collar being threaded into the spindle itself.

You can buy some brushless motors from UK model shops, but they are much more expensive than direct from Hobby City in China. My experience with using some of these motors is that the really cheap ones are under-rated and not very efficient, but the mid-range ones are surprisingly good, often not much less efficient or less well made than the really expensive ones.

The key is knowing what to buy. The motors are rated in terms of maximum power (in watts) and also Kv, which is the rpm per volt. This latter figure is important, as it allows the use of a motor that will run at the right sort of speed for the application. In general, it seems that using a high Kv motor and then gearing it down with a reduction belt drive is probably a better way to go, as it reduces the low speed torque requirement from the motor. One of the regular contributors on the Ev forum I frequent has converted his Taig Mill to run on an RC brushless motor (his name is Matt Schumaker and he has a web site here: http://www.recumbents.com/WISIL/shumaker/default.htm with some details of his mill conversion, towards the bottom of the page). Matt gave me some advice on motors and controllers recently, quote:

"Jeremy,

I am running a small outrunner on my CNC too. I have over 100 hours on it so far without any issues. I am running a Castle Creations Phoenix35 ESC on it from a 24 volt, 20 amp power supply.

The issue I think you are having is more a matter of the controller than the motor. Also, I am running a belt drive rather than direct drive. For aluminum cutting, I run it 3 to 1 reduction. For carbon fiber cutting I am running 1 to 1.3 overdrive. This gives me 13,000 RPM at the spindle. My Taig spindle uses huge bearings (maybe 1 and 1/2 inch OD). Yet, my ESC runs fine even driving those huge bearings at such a high speed.

You may be having problems partly because of the low motor RPM as well.

A Castle Creations 35 or 45 amp ESC is relatively innexpensive. I would go that route.

Matt"

A look around the Hobby City site will soon give you an idea as to what's available. The controller that didn't work well for me was one of their very cheap 40A SuperSimple series ( see here: http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=6461&Product_Name=SuperSimple_40A_ESC ). Maybe I shouldn't be surprised that it didn't work well, as it cost less than $12.....

The controller I have that works well is a complete over kill, as it's rated at 120 amps continuous, 130 amps peak. It's also less than ideal as it is a relatively high voltage unit (30 volts max) and so doesn't have a built in 5 volt regulator to drive the servo tester needed as a speed control. I will probably go for a higher rated SuperSimple controller for the spindle, I think. The 70 amp version looks as if it might well be better, but again it has no BEC (battery eliminator circuit) so would need a separate 5 volt regulator. This won't be a problem if I put the speed controller in the main box, though, as I already have a 5 volt supply available there.

If you want to do some price comparisons, then probably one of the cheaper UK model shop sites is this one: http://www.budget-rc.co.uk .

Jeremy

[Jeremy]

Another update. I took the spindle apart this afternoon and was a bit surprised at what I found. The lower bearing inner bore was stuck fairly tightly to the shaft, and when I got it free there was brown staining on both the shaft and the bearing inner face. It cleaned off OK, but it's clear that the bearing was running much hotter internally than I thought - I think the staining was burnt oil.

Luckily I had a spare bearing, so I managed to bore a naffigravit off the inside of the bearing housing and reassemble the spindle. This has completely transformed it, as it now spins much more freely than it did before. It also runs more quietly and will reach a much higher off-load maximum rpm (it sounds like a jet when flat out!).

So far building this has taught me a few useful lessons:

1) Don't buy really cheap Chinese speed controllers unless you derate them a great deal.

2) Ball bearing fits are far more critical than I would have thought and make a significant difference to the way the spindle runs.

3) The 550 watt rated motor has more than enough power, even when derated by running it at 12V and 30 amps.

4) My machining skills are gradually getting good enough for precision work, even when using my extensively tweaked and modified Chinese mini-lathe.

Jeremy

[Thomasdj]

Hi Jeremy,

The only reasonable priced spindles I've seen are the Kress spindles..
I find your spindle very interesting! ..I am new to motors in generel and search information about building my own spindle.

I am curious about how your spindle perform, what its limitation is and if these (rc)motors will match my needs. I am building a CNC router with a moving gantry and would like to be able to cut wood, aluminium and mild steel sheet.

[bogflap]

Hi Jeremy

My interest in your thread is for a high speed spindle for isolation routing of printed circuit boards. This as far as I can see will only require bearings that will need to cope with very small axial and radial forces. So the question is has anybody tried attaching say an ER16 collet holder straight to the type of motor that you are using i.e. an r/c model outrunner/inrunner. I assume that these motors are intended to attach straight to a aero prop and so the motors will have fairly robust bearings in the first place. I assume they will be thrust bearings (axial loads) mainly because an aero prop 'pulls' itself through the air. However I assume that there must be some radial loading, which is the issue that plays on my mind at the moment. Has anyone tried this or has anyone any knowledge of what kind of bearings these motors contain.

[templecorran]

Forgive me if this question is off topic.

Jeremy, that is a great piece of work.
You mentioned that you used the Shumaker suggested servo tester to get the pulses needed to get the motor going.

My question is: Does anyone have experience of driving this type of motor control from the MACH3 software suite?
I know from reading the MACH3 manual that PWM speed control is covered on page 5-7 & 5-17, but has anyone actually done it with a DC brushless motor?

Here's hoping!!

John

[templecorran]

Sorry, I just thought to ask you if you have had any machine time with this new spindle yet?

Most important to me is: how noisy is it?

cheers
John

[ChrisG]

Hi Jeremy,

I've just set up an X1 mill with DIYCNC gear. I'm now looking at building a 1mtr x 0.75mtr router. It's been sometime since you made your brushless spindle, I wonder how it's performing? I wondered about using a watercooled esc if heat was a problem.

Very useful thread.
Chris

[miopicman]

I finished the mechanical part of the spindle today and gave it a test run. All went well, but I need to pull it apart and take a tiny skim from the lower bearing housing, as the lower bearing gets a bit warm after a few minutes running. I noticed that the spindle was a little tight after I assembled it. I hadn't realised how a tiny bit of "pinch" from a bearing pressed into a housing that was very slightly undersized would make such a difference, but it's easy enough to fix.

The good news is that the spindle is reasonably quiet and seems to work well off load. The RC motor didn't even get slightly warm, but the speed controller may need mounting on an additional heatsink, as it was a bit warm after a few minutes running. The motor was drawing around 10 amps from a 12V supply when running flat out, which is a bit high and almost certainly to do with the overly tight lower bearing.

I may also need to adjust the bearing pre-load. I've used a couple of belleville washers under the upper shaft retainer, abutting the top bearing inner race. Pre-load was set by clamping the shaft to compress the bellevilles a small amount, then tightening the shaft collar at the lower end. This wasn't very "scientific", so may also be a contributing factor to the warm running lower bearing.

Here's a picture of the completed spindle:

http://farm4.static.flickr.com/3007/3107033319_58ff1e2872.jpg

The body is 1.5" in diameter and the overall length is 8.75". The motor outer can at the top (the black bit with the writing on) rotates, so probably needs some sort of guard. The small lovejoy coupling seems to work fine, there's no real vibration at all with it spinning at full chat whilst just being hand-held. Overall it seems to vibrate a lot less than a Dremel and is certainly a lot quieter.

I've done a crude run-out check using a DTI, with it clamped in vee blocks on the surface table. A 3mm carbide cutter shank didn't seem to deflect the DTI at all, which seems pretty good. My DTI isn't really sensitive enough to show anything under about 1/4 thou though, plus the lower bearing is still a bit too tight, so the true run out might be a bit worse.

Nevertheless, if I can fix the lower bearing problem I think I shall be well pleased with this little experiment. Let's hope that the motor turns out to be reliable!

Jeremy

This is very interesting. I've already constructed a gantry type mill and am using a Kress router to mill non-metals. I'm now looking at ways of milling non-ferrous metals and manufacturing a spindle motor for this purpose. One component of the spindle I'm having difficulty sourcing is the actual spindle/collet holder - from where did you get yours please. I've sourced a suitable motor and have decided upon a step-pulley belt drive system in order to achieve good torque at low speeds.

[ChrisG]

Hi miopicman , has Jeremy used an air die-grinder as a base for his spindle?


http://www.screwfix.com/prods/38706/Power-Tools/Air-Tools/Air-Die-Grinder

Chris

[blackburn mark]

ER11 C8 100mm straight shaft ebay... 8mm shaft (good for mounting straight through a sutable brushless motor)
C10 10mm shafts are like rocking horse s**t
C12 12mm shafts are more common

[miopicman]

Hi miopicman , has Jeremy used an air die-grinder as a base for his spindle?


http://www.screwfix.com/prods/38706/Power-Tools/Air-Tools/Air-Die-Grinder

Chris

I don't think so; have a look at this: http://www.screwfix.com/sfd/i/cat/pdfs/89/p4764389.pdf

[Scott]

anyone have videos of these diy spindles cutting aluminum ??

[blackburn mark]

anyone have videos of these diy spindles cutting aluminum ??

http://vimeo.com/23725581

[HankMcSpank]

http://vimeo.com/23725581


Hey Mark.....a very slick video - well done! I'm assuming that due to the amount of Bokeh you've played, that you used a DSLR?

Which editing package did you use?

[Scott]

http://vimeo.com/23725581


thanks Mark just what i was looking for !!!! ( love the video ) WD40 mmmm lol

i have a 3040 router mill (chinese thing) thinking of upgrade the spindle its only got a 200w servomotor as a spindle could do with more grunt

[blackburn mark]

Hey Mark.....a very slick video - well done! I'm assuming that due to the amount of Bokeh you've played, that you used a DSLR?

Which editing package did you use?

7D (Boken city... got to love it)
Prem CS4 (bit twitchy but gets you there in the end)

[ChrisG]

Super video Mark,

[blackburn mark]

thanks Mark just what i was looking for !!!! ( love the video ) WD40 mmmm lol

i have a 3040 router mill (chinese thing) thinking of upgrade the spindle its only got a 200w servomotor as a spindle could do with more grunt

my large diy spindle motor will take 2000W, however, i run it on a 12v 350W power supply and have no issues with heat in the windings or speed controller getting silly.
with it being an outrunner it has good tourque compared with inrunner type spindles

[ChrisG]

Found this spindle design suitable for smaller cutter sizes, replace the Brushless Motor Shaft with an ER11 spindle which will hold up to 7mm.



http://www.rcgroups.com/forums/showthread.php?t=1175772&page=5




http://static.rcgroups.net/forums/attachments/1/5/2/0/9/1/a3285272-153-Spindle.jpg


http://www.giantshark.co.uk/xyh5045-890kv-outrunnner-p-404603.html

http://www.giantshark.co.uk/images/XYH%2050-45%20with%20attachments.jpg

[sgcharrisoh]

Have you determined how to pulse the electronic driver for the DC brushless motor?
It should be possible using a 555 timer chip.
SH

[blackburn mark]

Have you determined how to pulse the electronic driver for the DC brushless motor?
It should be possible using a 555 timer chip.
SH

servo tester... £2 ish... ebay

[Jonathan]

Have you determined how to pulse the electronic driver for the DC brushless motor?
It should be possible using a 555 timer chip.
SH


servo tester... £2 ish... ebay


Connected to parallel port via PIC development board (http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1406&dDocName=en535806) ... free ish...'acquired' from university.

When I get round to it I'll stick the code on a smaller PIC on a PCB as it's very simple to do and will cost <£1.

[baccus61]

You can get 10mm straight shaft ER chucks here.
Results for Tool & Work Holding:ER Collet Chucks (http://www.ctctools.biz/servlet/the-Tool-%26-Work-Holding-cln-ER-Collet-Chucks/Categories)
Very cheap tools to be had here.
All (3) the electronic brush-less motor driver testers I have used startup in the midband when first plugged in. I have never found a site or a way to control these things where you can have them start at zero volts and then get ramped up from there using a computer.
Mind you, it's been 4 years since I looked so there may be stuff out there that I don't know about. :-)
It would be good if someone had a way of doing this.
There are sites out there that show you how to make your own outrunner motor but the ones I have found are in German or Swedish and Google translator or babelfish don't do a very good job of converting technical lingo.
You could make your own for whatever revs you need for your power supply. That would be nice for a small machine.

If you do make your own spindles for your outrunner motors then you could use the round tool steel blanks from the same site here.
http://www.ctctools.biz/servlet/the-472/HSS-HIGH-SPEED-STEEL/Detail
Lots of different sizes to choose from.
The hardness/brittleness shouldn't be a problem for the power of these small motors.

[Art99]

Hi All

I'm a newbie with a 7x10 lathe that I'm very slowly outfitting and converting to CNC. I am planning on building a tool post spindle to enable me to easily cut key-ways on shafts in my lathe. This thread has been a fantastic eye-opener.

I have purchased a 200KV outrunner motor with an 8mm shaft. It has a power rating of 2450 watts. IS THIS REAL?? At 50% efficiency this would be over 1 HORSEPOWER for a motor that I could hold in my hand.

Indeed if it is real, it is more powerful than the motor which drives my lathe!!

Puzzled,

Art99


You can get 10mm straight shaft ER chucks here.
Results for Tool & Work Holding:ER Collet Chucks (http://www.ctctools.biz/servlet/the-Tool-%26-Work-Holding-cln-ER-Collet-Chucks/Categories)
Very cheap tools to be had here.
All (3) the electronic brush-less motor driver testers I have used startup in the midband when first plugged in. I have never found a site or a way to control these things where you can have them start at zero volts and then get ramped up from there using a computer.
Mind you, it's been 4 years since I looked so there may be stuff out there that I don't know about. :-)
It would be good if someone had a way of doing this.
There are sites out there that show you how to make your own outrunner motor but the ones I have found are in German or Swedish and Google translator or babelfish don't do a very good job of converting technical lingo.
You could make your own for whatever revs you need for your power supply. That would be nice for a small machine.

If you do make your own spindles for your outrunner motors then you could use the round tool steel blanks from the same site here.
HSS TOOL BIT - ROUND STOCK - LENGTH 100MM (5 PCS) #H28 (http://www.ctctools.biz/servlet/the-472/HSS-HIGH-SPEED-STEEL/Detail)
Lots of different sizes to choose from.
The hardness/brittleness shouldn't be a problem for the power of these small motors.

[Jonathan]

I have purchased a 200KV outrunner motor with an 8mm shaft. It has a power rating of 2450 watts. IS THIS REAL?? At 50% efficiency this would be over 1 HORSEPOWER for a motor that I could hold in my hand.

You can expect much better than 50% efficiency from this type of motor - more like 80-90%
At best it's the peak power rating, but how they define peak power is anyone's guess. Take it with a pinch of salt - I just go by the mass of the motor and dimensions of the stator. Bear in mind in their intended application these motors have a big propeller on the front blowing plenty of air through them which is clearly going to allow higher power than in our application which has barely any cooling by comparison. Ultimately the power rating is just a thermal limit, so if you can cool it well then you can get more power without the insulation breaking down prematurely. Either way it's plenty for what you need so I wouldn't worry too much...

[asbo]

Hi

Would anyone be able to make/sell me one of these spindles? If so how much would it cost?

Thanks.

[Jonathan]

Would anyone be able to make/sell me one of these spindles? If so how much would it cost?

I should think so...what specification do you require, or what materials and size tools do you need to use with it?

[asbo]

For fairly light usage cutting plastic, aluminium and maybe MDF. Also possibly wood. Probably 6mm flute bits max.
Would a spindle like the ones in this thread be suitable for that?

Thanks for the quick response.

[Jayman84]

OK so I've purchased everything to make the mechanics work, but I'm still a little confused as to how to control this wit the pmw controller output on the breakout board. I'm running linuxcnc, and the motor I've ordered is a 2000w 700kv motor rated at 60 amps. I have not ordered an esc because I was unsure of the type. Any help is greatly appreciated