Milling spindel idea, feedback wanted

[Insanety]

Hello...
Long time reader, first time poster.

I`d like to get some feedback on an idea i came up with.

First some background:
I currently don`t have a mill yet, so while I wait for the "perfect" deal. So I play around in CAD with building one from scratch.
I ran across Harold Hall`s Milling Head on his site, and thought that is what I need in my basement. Until I get a proper milling machine.

The more I looked at the plans, I realized that I rather have a standalone machine along the lines Mr Hall`s basic idea.

and now for the spindle idea.
Take a look at the pictures, and hopefully they convey the basic idea.
Only the collet shank and the two ball bearing are draw in there proper size.
Rest is free handed in to get the idea across.

So let me know what you think...

Link to Harold Hall`s site:
http://www.homews.co.uk/page158.html

 

[bazmak]

2 ball bearings are inadequate you also need to take up thrust
Use combined roller and 1 way thrust or tapered roller brgs

 

[goldstar31]

For once I might disagree with Barry but as far as I can see it, the Hall design is simply a copy of a whole host of earlier designs.
Only hours ago, I suggested that one poster read up on Lawrence Sparey and in the Amateurs Lathe he gives a very clear picture of what can be done using a small lathe. In Professor Dennis Chaddock's articles in Model Engineer which culminated in his book on the Quorn, he also hadn't a mill and culled from the manufacturers Rank Hoffman Pollard the basics to make a spindle from their bearings.

There are plenty of other contributors of great experience - going back- if you will not be too offended to Holzapffel. Again, Holzapffel is available on the 'net. You'll have plenty of reading----and learning! A bit more research will reveal that these milling, grinding, drilling and what ever spindles are still in use today in the clock, watch and ornamental turning fraternities.

However, these fraternities are extremely competent and know what spindles can and can't do. Again, you must answer what your own needs are. If you had read one of my earlier 'drivels', I think that I said that I had acquired yet another milling spindle -ironically to add to my growing collection. Somewhat with tongue in cheek, I also have a mill.

Conclusion? Really mills are so cheap and available in model engineering sizes that spindles have been relegated to 'specialist requirements' rather than an alternative to something that was out of normal part and parcel of model engineering----THEN.

Regards

Norman

 

[Wizard69]

Unfortunately I'm on my iPad at the moment and I'm not getting a good picture of the overall design. Very low resolution. So while I will comment I could be way off base.

First thing here is knowing what you expect out of the spindle! Without knowing that it is a crap shoot to say if the design is "good enough".

Standard ball bearings can be installed to take """some""" preload and might be good enough for your intended usage. However this is less than ideal and depending upon the specs of the specific bearings selected may have short life span potential. For small light spindles you may want to consider angular contact bearings properly installed at the nose with a ball bearing floating at the other end of the spindle. Tapered roller bearings are another possibility.

The next thing, that isn't clear at all to me, is the mounting arrangement for the spindle. Frankly this is critical as you don't want vibration, flex or anything else happening with the spindle. The spindle needs to be well supported, so how it attaches to the vertical column is of considerable interests.

As for making your own spindles and milling machine I say go for it. It is a good learning process for anyone and more importantly keeps knowledge alive in the community. I know full well that cheap imports exist but it is completely possible to get a "better" machine at a decent cost especially if you have a lathe to DIY as much as possible. If you have to farm anything out things go down hill fast.

Small stand a lone milling machines can easily outperform lathe centered milling attachments with out actually being big machines. The Tiag can in some ways be a good prototype of how to go about it. A simple steel column and a base for the table works out nicely. The other approach that might work out well is the bridge mill approach, something like a moving table router.

 

[goldstar31]

Whilst I pretty well agree with the foregoing, the real answer lies for about £7 or 14$ Oz or perhaps 10$Yankee.

That is about the price of one of my books on what is laughingly called 'My computer'. It is one of those books called Spindles by Harprit Sandhu. I don't know the gentleman but there is no question that he knows his subject which he has distilled into 81 pages of brilliance.

Well, that's my opinion. Perhaps others might comment.

 

[Nick Hulme]

I bought and read Spindles by Harprit Sandhu and found it very informative, I used the information and principles provided to build an ER11 high speed engraving spindle with belt drive from my mill's main spindle.

- Nick

 

[rodw]

I think if I were to make a small mill, I'd buy one of those spindle kits with an electric motor and integral ER20 collet chuck. Here's one, Water cooled running at up to 24,000 rpm with a VFD for speed control.
http://www.ebay.com/itm/CNC-2-2KW-Spindle-Motor-Frequency-inverter-Mount-ER20-Collet-water-pump-/281755856894?hash=item4199f52ffe:g:QiEAAOSwgQ9Vr52U

 

[Nick Hulme]

If you wanted to use an external motor with belt drive to give better torque at low revs but still have higher speeds available a good option would be to use an ERxx Collet Chuck on a straight spindle for the centre shaft and base the spindle around that,

- Nick