Building a mill - Spindle Ideas?

[greywynd]

I'm thinking about trying to build a bench top style mill for light duty use (aluminum and plastic is my thought), but I'm wondering most about how I would build (or what might be available?) the spindle assembly. Ideally I'd like to be able to use it for drilling as well as milling, so would like a quill that will go up and down.

Any thoughts or ideas of where to start?

Mark

[applescotty]

Perhaps Harprit Sandhu's Spindles book:
http://www.powells.com/cgi-bin/bibli...4-1854861492-0

I haven't read it, but I've heard it referenced before, and have been meaning to purchase it. Looks like it might only cover fixed spindles, though.

Scott

[TGTool]

Perhaps Harprit Sandhu's Spindles book:
http://www.powells.com/cgi-bin/bibli...4-1854861492-0

I haven't read it, but I've heard it referenced before, and have been meaning to purchase it. Looks like it might only cover fixed spindles, though.

Scott

That is a very good book on spindle issues for many applications. It's true, it doesn't cover a quill design. However, he does show several designs with both ball and tapered roller bearings and shows how to adapt or design your own around the important criteria so you'd be more than half way there with that book.

[greywynd]

A couple suggestions from friends I've had today are a router motor, or a die grinder. I think the die grinder would be too fast of an rpm for what I want, and maybe the same with a router motor. Is there any way to control the speed of a motor like this that won't break the bank? I'm thinking that soemthing like this might get me started, and then I can upgrade it later.

Mark

[Evan]

If you are looking for a high speed spindle then consider a spin saw. They are designed to take high side loads and usually have variable speed. I have one I am going to mount as an auxiliary spindle on my mill. It even has a perfect mounting point at the lower spindle bearing where it is designed to be mounted in a circle cutting jig. They usually have a 1/4" collet chuck. The up-down part is something you will need to figure out.

[greywynd]

I wasn't really looking for high speed, they were just options that came to mind during discussions. This is going to be a hand feed machine, so slower rpm would be a benefit, and allow more options in general. I have a lead on a start for the machine, just have to get it home and set up, and if we can find our MIA camera, post some pics. As far as up/down, I'm just hoping to avoid having to crank a leadscrew up and down to drill a hole.

Mark

[BobWarfield]

greywynd, the spindle seems the hardest part of a project like this, particularly if you feel a need for a quill. The quill is very convenient, but it is a source of slop and complexity that will be hard to overcome if you are fabricating a spindle. Personally, I would be looking to skip it.

You haven't really given us much detail to go on regarding the relative size of the machine you're building nor much about how you intend to use it. For example, you have alluded to very high speed spindles such as routers and Dremels, which would primarily be suited to aluminum and other lightweight materials.

My suggestion would be to look for a suitable spindle or most of the parts thereof on eBay. You'll find everything from a raw spindle (i.e. no bearings or housing) to complete Bridgeport heads.

A second alternative is LittleMachineShop, which will sell you a spindle. I've read several accounts of people having success with it:

http://www.littlemachineshop.com/pro...ProductID=1663

Sandu's book is a fine introduction to spindles, and would be a cheap way for you to read about what might be involved in making your own spindle. I will add to that my own notes on a belt driven spindle design:

http://www.thewarfields.com/cnccookb...BeltDrive.html

Best of luck to you!

BW

[Evan]

Here is one way to make a high torque variable speed spindle. Goes up and down too.

[lazlo]

Sandu's book is a fine introduction to spindles, and would be a cheap way for you to read about what might be involved in making your own spindle.

I have Sandu's book -- it's excellent. It gives you step-by-step directions to build several different spindle designs.

The "classic" spindle design, used on countless machine tools for the last hundred years, is a duplex pair of angular contact bearings at the nose, and a deep row radial ball bearing at the back to stabilize the shaft.

The Quorn (tool and cutter grinder) has a sophisticated spindle -- a pair of opposing magneto bearings (poor-man's angular contact bearings), and there a chapter in Professor Chaddock's book which walks you through the machining, including the critical step of finish-boring the spindle in it's own bearings (to minimize runout).

I posted a 3-part article from Model Engineer on a modernized version of the Quorn spindle to the Quorn Owners group. Broadley's design preloads the bearing stack with Belville washers to compensate for thermal expansion. It's a great article, and a good place to start if you're looking to build your own:

http://groups.yahoo.com/group/quorn_..._Spindle_1.pdf

[Peter Sanders]

I wasn't really looking for high speed, they were just options that came to mind during discussions. This is going to be a hand feed machine, so slower rpm would be a benefit
Mark

Not necessarily

Don't forget that many plastics DO require high speed when routing, ie "milling".

[greywynd]

Not necessarily

Don't forget that many plastics DO require high speed when routing, ie "milling".

I don't see me doing a lot of plastic, just on occasion. Primarily it will be aluminum and some brass. If I can get it so that I can do steel (mild, not tool steel or ss) that would be great.

I recall seeing it discussed before, but can't recall where, about using a drill press spindle for milling. I know the chuck and taper aren't up to the task, but what if the spindle end were modified to something stronger that could do a light duty job of it? Again just kicking around some ideas, hopefully I have some more information on the rest of the machine in a few days.

Mark

[chesapeake]

Have a look here...

http://mmu.ic.polyu.edu.hk/mu_proj/2003/M6/index.htm

[Swarf&Sparks]

Perhaps one of these little critters?
http://www.sherline.com/8900pg.htm
Works fine for PCB drill/mill, engraving, etc.
I've used mine hand-held on occasion, cutting eggshell.

edited to say that the "engraving points" supplied are crap.
You'll need carbide burrs/mills/drills 1/8" shank.
try
http://drillcity.stores.yahoo.net/
dealt with em several times, fine people (usual disclaimer)

The supplied oiler needs some fiddling too.

[lazlo]

Have a look here...
http://mmu.ic.polyu.edu.hk/mu_proj/2003/M6/index.htm

Dang, that web page is unreadable in FireFox...

That's a great (undergraduate?) project -- he's designing a 3-axis vertical mill from scratch.
He's got a nice spindle design too -- opposing angular contact bearings like the Quorn spindle.

Well done!

[cynic]

I've been considering something similar, but what I need to do is covert a 1.865 o.d. quill in a drill press to take R-8 collets. It looks like the business end of the quill could be increased in size (added to/made large) enough to accommodate a tapered roller because a new larger drive spindle will be needed to fit inside the quill allowing enough room for a draw bar through the spindle. I think using needle bearings instead of rollers would work to get the larger spindle inside the quill.

The drill press is a massive old radial arm Zewo that I want to extend out over a 24" Rotab once I have converted to R-8.