Diy Brushless Spindle

[njhussey]

Basically a car radiator with fan and motor, like this:

[blackburn mark]

Basically a car radiator with fan and motor, like this:

now that is POSH!
splendid :)

[Point25]

Hello folks,

Many thanks for sharing all this info, it has inspired me to build a spindle based on a 5045 motor & ER11 8mm spindle :-) I have a couple of questions though which I hope arn't too simple !!

- The bearing arrangement is along the lines of: for the chuck/housing interface a pair of Angular Contact (AC) bearings with 4 pre-load washers between them? And for the housing/motor interface a standard roller bearing? Where would be a good place to buy the AC bearings with matching pre-load washers (either UK or eBay).... any spec available so I know what to ask for?
- I'm guessing the AC bearing assembly needs to sit proud of the housing before the cover plate clamps it all in place - how much of the bearing should be proud?
- I am looking at 24V power supplies and wondering if I need to have one large power supply to run both the NEMA17 steppers and the spindle of if I should really split this into 2 suppies with about 5A @ 24V for the steppers and 20A @ 24V for the spindle?

Thanks for any tips :-)

[blackburn mark]

belleville washers
708a bearings, these are a bitch to find at the moment so a search for magneto bearings would be my second choice

I'm sure mine has about 1kg of tension (on standard skate bearings) still runs ok but doesn't get used much compared to the larger ones... if your going to hammer it to death angular contacts makes sense and would need even less tension/pre-load than the skate bearings to perform the same task

I run all my spindles at 12v (350w power supply... its never tripped)
the 100A ESC gets pretty hot but the motors are fine at that
if your cutting wood and need the extra speed you will have to stick your neck out and let us know how you get on

I'm guessing the AC bearing assembly needs to sit proud of the housing before the cover plate clamps it all in place

mine was about 1mm proud... maybe a touch less

bearings with 4 pre-load washers between them?

i think there is 8 or 10 in mine, so with only 4 you want to be approx 0.5mm proud or less, it depends on your washers

you could get really technical and do the maths but you would need to know your typical cutting force triple it, pray to the moon god and add some fairy dust :)

having at least some tension stops the bearings skidding and self destructing but if your cutting force or resonance overcomes the tension you will get a shit finish

[Point25]

Thanks for getting back to me Mark, much apprecited.

The Magneto Bearing looks ideal and avoids the need to install belleville washers by the looks of it? If going down this route would I use one magneto bearing between the chuck and housing and one standard bearing between the housing and motor?

I am hoping to cut wood but perhaps starting with an old computer ATX power supply will let me feel my way into the power question - sounds like this might be waht you are using.

[Jonathan]

You require two magneto/angular contact bearings and they need to be pre-loaded, hence Belleville washers are mandatory, unless you can find a matched pair of bearings but that wont be cheap. There are sellers with 8mm angular contact bearings on Aliexpress.com - Online Shopping for Electronics, Fashion, Home & Garden, Toys & Sports, Automobiles from China.

[Point25]

Thanks Jonathan - looks like finding the Belleville washers is going to be the hardest part, wonder why they are so rare.

I have spoken with www.simplybearings.co.uk but they need to know more tech info to allow them to advise - any idea what I should be asking for.... or perhaps there is another (afforable :-) bearing in their range which would get round the Belleville washer requirement?

[Point25]

Hi, I now have what I think I need - 2 Magneto Bearings and some Belleville washers :-).... now just wondering how to arrange the bearings and washers in relation to oneanother?

Do I put the 2 bearings back to back - ie with their 'open' faces both towards the inside and the washers separating them?


Thanks.

[blackburn mark]

iv never looked at the implications I think back to back is the standard but id fit them in which ever way was easiest to implement
I had to make a couple of washers with a grove in the face for the outer Belleville springs to sit in to keep them central and clear of the shaft

I "think" I pulled tension on the inner races via the spindle.... errr, no hang in, I used epoxy to lock one of the races.... bollocks! I cant remember now? when you have all the parts in your hands you'll make sense of it

tight fit on the pointy end bearing (housing and the shaft) and allow the other bearing to float to some extent so the Belleville washers can overcome any movement (if that makes sense)

EDIT: i assumed "back to back" meant open ends out?

[Point25]

Thanks Mark,

I think I have this assembled right but thought I would post some pictures to confirm and help others who have the same question.

I didn't quite get what you were saying about fixing the washers - I guess the aim is to center them to stop them rubbing on the spindle - seems like that might be quite difficult?

Cheers.