adding high speed spindle

[jerome]

Hi,

I have a Denford triac which works great, but I would like to mill brass using a 0.6 mm cutter.

I plan to add a high speed spindle to do this, perhaps just one that bolts on and off.

I have looked at spindle kits on ebay but I am slightly lost on how many watts my motor would have to be.

Has anyone got any ideas or suggestions ?

[magicniner]

Have you considered building a "Spindle Speeder"?
I built a 1" OD belt driven spindle cartridge based on a 10mm shank ER11 Collet chuck, a bit of ally bar and 3 bearings rated for 30000rpm, it mounts on one side of the head and a large pulley on the main spindle gives me around 7:1 speed increase allowing use of very small end mills and engraving cutters at up to 28800rpm. Spindle & pulley cost was around £25 plus a little of my time.
Regards,
Nick

[jerome]

Thanks Nick,

Have you got a picture of your design ?

Regards,
Jeremy

[magicniner]

I'll chuck it together and take a photo tomorrow, my implementation includes a sprung linear slide which allows the use of an engraving spindle with a depth setting nose, this allows engraving to a fixed depth on complex 3D surfaces for which you don't have a 3D model.

[magicniner]

Here's my set up fitted with the ER11 Milling Spindle which I built, it's genuinely an afternoon job and by applying the principles in Harprit Sandhu's book on spindles I came up with a design using a pair of bearings at the nose which are bonded to both the spindle and sleeve and a top bearing which is bonded to the spindle only and is a sliding fit in the sleeve.
The pulley on the mill spindle gives 4.7x which gives a theoretical 32900RPM top speed with my mill's 7000RPM top spindle speed, the belt is round polyurethane, bought by length and welded with a disposable gas cigarette lighter ;-)

23456

You don't need a slide but I used the Deltron slide modified to micrometer adjustable spring loading to allow the use of a spare micrometer depth controlled spindle which came with my Gravograph IM3 shown fitted here -

23457

The engraving spindle has an adjustable "nose" which is micrometer adjustable to allow a precise amount of the cutter to protrude, by applying spring pressure on the slide the engraving spindle nose will follow uneven and curved work surfaces maintaining a fixed depth of cut, the nose fitted incorporates a spherical follower which is very good for maintaining depth of cut over significant changes of surface angle, up to around 30 degrees -
Springing also allows "Diamond Drag Engraving" without the spindle running,

23458

This is the milling spindle -

23459

It's had 40+ hours of run time with no sign of any issues.

Post any questions you have and I'll do my best to give a useful answer,
Regards,
Nick