[rmtucker]

Well it's been a long time since i posted here but i am starting another spindle project and i thought i would share my experiences.

I have been using a 8,000rpm - 28,000rpm Router like most people but had the following problems:-
1.Everytime new bearings were fitted i had to play with shims to prevent endfloat.
2.Bearing life was very short due to vibration and over revving them.
3.Lack of power at any speed below max rpm.
4.Runout on the ER16 adapter i am using was excessive.

After hunting around i eventually found a guy that can supply ER16 extensions that have a step at the bottom to retain the bearings.
This cost me all off £26.00 so it was worth a go.



Let me know what you think initially?

Regards
Mark

[rmtucker]

I have decided to try 3 deep groove ball bearings insted of the usual angular contact bearings.
The reasons for this are cost and Max Rpm,The spindle cartridge in total will only cost around £40 excl the machining of course.
Also other than the problems mentioned in the prev post the router bearings were never a spot of bother if changed regular.
I would imagine in this instance that the bearing life will be far greater (Higher quality and faster bearings,also the rigidity of the housing and less runout).
I have attatched the drawing for the spindle body.

[rmtucker]

This is the drawing for the front cover of the spindle which also holds the front lip seal.

[rmtucker]

I have also picked up the following items.

2 off - 25mm ID x 35mm OD x 7mm thick double lip seal.
1 off - Aluminium Pulley with guides 20 tooth x 5mm pitch
3 off - 6804zz Deep Groove Ball Bearings

I should start the machining in the next few days,i will post pics as i go along.

[ger21]

What type of motor do you plan on using?

[rmtucker]

The usual cheap Treadmill 2.5hp motor with 7,500 rpm.
This will be 1:3 on the pulleys so it could achieve 22,500rpm even though i want to max out at 18-20,000rpm.
I even contemplated going 1:6 using an idler and this way i can stop the motor going into orbit.
I have the motor and DC controller working through PWM on mach3 using the little opto circuit that was used on the Cnc zone some time ago by J Fettig i believe.

[samakthachai]

Normally, I have found most hobby-spindles could drill or engrave on wood,acrylic or non-metal.:tired:
It's possible or not if hobby spindle can engrave on metal. example steel,brass,aluminium and so on. How many minimum horse powers does it can? Who know that?


Cheers
Samak

[rmtucker]

This is the last of the drawings for the Spindle unit.

Regards
Mark

[rmtucker]

Here is a cross section of the assembled spindle unit.

[andy_ck87028]

The usual cheap Treadmill 2.5hp motor with 7,500 rpm.
This will be 1:3 on the pulleys so it could achieve 22,500rpm even though i want to max out at 18-20,000rpm.
I even contemplated going 1:6 using an idler and this way i can stop the motor going into orbit.
I have the motor and DC controller working through PWM on mach3 using the little opto circuit that was used on the Cnc zone some time ago by J Fettig i believe.

Not having an engineering background, I can only presume that this arrangement requires manual intervention for speed control. Is it possible to utilise a motor / controller arrangement that is electronically controllable without being highly priced?

I'm happy for this to be split off onto a separate thread.

Andy

[rmtucker]

Hi

The speed control is controlled through mach3 using pwm.
The interface is only 1 optocoupler (about £1) to the Beel dc speed controller.
It has been shown elsewhere on the cnczone in the past,i will see if i can find the thread.

Regards
Mark

[FPV_GTp]

Hi

If bearing life is a issue , have you guys considered a oil mist ( spray ) lubrication system on the High speed spindles

rather than rely on the grease packed inside these bearings you guys are using.

cheers

[Greolt]

I'm following this with interest Mark

[dpuch]

This is an idea I have been thinking about exploring for some time. A nicely ground shaft, and collet taper. All hardened... I'm glad someone is working on it.

AC bearings have the large benefit of being able to set the preload pressure between them. With everything spaced just right... they can run a long time and be very rigid. That requires knowing just how much preload is needed, and actually hitting that target though. With an inexpensive design like this, I imagine it wouldn't be that hard to make a few carefully documenting the changes between them to find the right setup. It would probably take 4-6 spindles... Just a guess.

All this is moot if he is getting the desired performance out of the deep grove bearings though, so someone else will probably have to do that research.

The shaft of the collet extensions are available in either inch or metric
hardinge-workholding
centaurtools
parlec
Most without the steps...

As far as horsepower to cut material... sfcalc as well as some other little utilities. Ok. this only has numbers for calculating metals but still very useful.

For spindle lube, I hear it matters a lot as you get into the higher speeds how good of grease you use, and how much/little you use. Do not over grease high speed spindles, and ideally use grease specific for that purpose. The air mist idea is a good one, but means little more hardware. For the air mist, I would also change to a labyrinth seal design instead of rubber seals. This has the benefit of a positive pressure to keep debris out, as well as helping to cool the bearings a little.

Dale

[OzDragonflyer]

Nice job Mark!

So is the pulley holding the shaft against the spacers and bearings?

[neilw20]

Ever thought of air bearings.
100,00 RPM is quite practical.
http://www.airbearingtechnology.com/

[RomanLini]

Ever thought of air bearings.
100,00 RPM is quite practical.
http://www.airbearingtechnology.com/

I checked their web site and their air bearing spindles look pretty nice.

It worries me a bit about slop, an air bearing requires some gap for the air layer, and surely that will cause "give" or slop under peak load conditions? I think it could get nasty with a cutting tool resonance or similar.

But that might not be an issue if the RPM is very high which probably indicates a small delicate cutting tool and very light peak loads.

[tong67]

hi, everybody my name is Mike i'm new at this. I been reading all the great post and information in this communities.Will i need help on designing a high speed spindle for a small router (18"x36"x6"z travel ). The RPM i'm shooting for is about 10,000-20,000rpm. I have built 2,but they get noisy at around 8000rpm. i was wondering what kind of bearing and make that you guys recommend? the bearing was using is 20mmx47mm angular contact bearing. Please help...help help..thanks in advance.

Mike

[jimmyaz]

Have anyone consider using 1 thrust bearing to handle the down force load?