Spindle Idea

[PEU]

I've been discusing this idea with a fellow CNCZoner (JRoque):

What if I take this collet & chuck set:


This is a ER-type R8 Shank collet chuck

and machine the shank to do this:






Opinions & Comments are welcome


Pablo

[JFettig]

Peu, have you taken a look at the different holders they have with ER tapers? they are usually called 'extentions'. They usually have 3/4" shanks and you may be able to use something like that which might end up being a better setup.

Jon

[PEU]

JRoque suggested this too, I said that I choosed this set because saw its picture first but yes an extender uses the same concept and maybe its better because there is no need to machine the hardened body.

Also maybe you can find bearings with the same ID as the diameter of the extender.


Pablo

[MikeAber]

I've been discusing this idea with a fellow CNCZoner (JRoque):

What if I take this collet & chuck set:
This is a ER-type R8 Shank collet chuck
and machine the shank to do this:

Opinions & Comments are welcome Pablo

Peu, What a great set of drawings! They are outstanding! How did you do that?

Mike

[gcz]

can you get a housing of identical material as the shank too?
and maybe seal bottom and an oil zert at top to let you keep it half full or so?
locking bearings in- how?

[MikeAber]

Peu, have you taken a look at the different holders they have with ER tapers? they are usually called 'extentions'. They usually have 3/4" shanks and you may be able to use something like that which might end up being a better setup.

Jon

Jon, what an excellent idea! Very practical, these are available in almost any size between ER11 and ER32 with shank diameters from .5" to 1.5" and spring collets are available in metric and inch sizes. Bearings would be no problem at all.

mike

[MikeAber]

the point about chips not dust is indisputably good.
one thing that the numbers show clearly is this:
if you're using tiny cutters, to get any real tooth travel - to get chip load - you NEED high speeds...but i'm not up for making a table atm to illustrate the point...
however, plz check out the cutters you CAN get - http://www.pmtnow.com/
at a certain scale, legitimate chip size is indistinguishable from talc.
there IS a niche for high speed
i have a 120 ct ruby i'm dying to carve up with tiny diamond bits completely submerged. for such as this, forget 6000 rpm - i need more like 60,000!

gcz, you have opened my eyes to another dimension of CNC. I thought PCB work was small with .014 endmills spinning at 30,000 rpm and up. If you were using a diamond dust covered tool to work on that HUGE ruby you are precision grinding. (and making beautiful ruby dust. Save me some.)

mike

[MikeAber]

This is a Mini Mill Spindle Box Assembly R8, Little Machine Shop.com sells for $99.95 US. If you made a set of sheaves and installed them in place of the top bearing spacer as Jfettig did on his mini-mill you could have an R8 spindle on your gantry or bench mill. Ask JFettig for the details --- more pictures in his gallery.

I purchased one of these last week and plan to take a good look at it for use on my mini gantry mill. I really prefer R8 tooling as I have lots of it. This is not good for any speed over 5-6,000 rpm. The runout on the one I received is .0001" -- EXCELLENT!

mike

[PEU]

can you get a housing of identical material as the shank too?
and maybe seal bottom and an oil zert at top to let you keep it half full or so?
locking bearings in- how?

The bearings are hold in place by the external case and retaining rings (green barely visible in the cut view)

If you find an extender and matching internal diameter bearings , the only part you need to machine is the cilindrical case (you can make it from a rectangular block too )

Now is time to find not expensive extenders

One thing I don't know is if this spindle needs lubrication and what is the better way to do it.

Pablo

[MikeAber]

I was doing some research on Jon's idea in the MSC catalog and a few bearing resellers online.
ER Streight Shank Collet Chucks (extenders) are made out of heat treated alloy steel and available everywhere; MSC, ENCO, etc. and cost $55 to $110 depending on size.
Sealed bearings contain grease, open bearings would require oil and seals.
Open bearings have higher rpm limits.
The smallest bearings have the highest rpm ratings.
I could not find any angular bearings in inch sizes. I am sure they exist, I just didn't find any.
I did not find any angular bearing listed for over 27,000 rpm. I am sure they exist, I just didn't find any (I'm not sure I want to $$$$$$).
ABEC7 bearings can run $400 or more for a matched pair. ebay --ebay --ebay

I like this concept best so far (for high speed).

Mike

[SPEEDRE]

This is exactly where I wanted to go. I mistakingly thought I'd need 30k rpm. . I have a Grizzly mini mill now and have access to R8 tooling. So, I take off the milling head, cut down the casting size, cobble up an adapter plate add pulleys and I'm in, right ?. The motor and speed controls are also salvagable to machine/route aluminum and stuff. When I want to mill wood I switch off to a router. I think I'm on to something.

[MikeAber]

This is exactly where I wanted to go. I mistakingly thought I'd need 30k rpm. . I have a Grizzly mini mill now and have access to R8 tooling. So, I take off the milling head, cut down the casting size, cobble up an adapter plate add pulleys and I'm in, right ?. The motor and speed controls are also salvagable to machine/route aluminum and stuff. When I want to mill wood I switch off to a router. I think I'm on to something.

Hi SPEEDRE,

This is your thread, look what you got us into!

Look in my photo gallery for more pictures.

This is a Dovetail Spindle mount. There is a 2.5" hole in the mount to hold the spindle. The mount has a dovetail base with adjustable gibb and lock to slide the spindle up or down to adjust for tool, drill chuck, or spindle height and a means of using several different spindles as no single spindle can do everything. This is my solution until I can find a better one.

I believe the weight of the motor and existing cast iron housing will be too much for my mini gantry mill. I will probably make a new housing for the spindle out of FORTAL, a 7000 series aluminum alloy that machines beautifully and is as strong as mild steel in most applications.

If your machine can handle the weight you might consider keeping the existing housing and change the motor to a higher speed and/or more powerful motor to give you two speed ranges and higher max rpm for wood and plastic work.

JFettig has much more experience on this subject, would you comment on this concept Jon?

Mike