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Milling/drilling spindle

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Steve Crow01/10/2018 08:06:52
151 forum posts
32 photos

I want to make a small belt driven milling/drilling spindle to accept 8mm watchmakers collets. I envisage making the body from 3/4" mild steel square stock.

Has anyone out there made one of these or similar?

I would welcome any advice regarding bearings etc and preventing any play along the spindle axis.

Many thanks

Steve

JasonB01/10/2018 08:15:26
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Given that you probably want at least a couple of mm of spindle around the collet body at a minimum then a 12mm spindle, more if the head is to fit without excess overhang. into a 3/4" housing does not leave much room for bearings, would probably have to be plain bronze to keep them thin enough.

Steve Crow01/10/2018 08:30:27
151 forum posts
32 photos

I was planning to use a 12mm spindle. The 3/4" dimension is not set in stone - I could go up to 1 inch square stock.

I realise I won't have much space so I am thinking about oilite sleeves. What concerns me are the thrust bearings to prevent play.

Hopper01/10/2018 08:41:20
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3714 forum posts
73 photos

Have you considered the modern approach of buying a readymade milling spindle, with collets and motor with speed controller all in a package for under 50 quid? eg this one here **LINK**

I don't think I could buy the material to make one myself for that. Not even for double that probably. Crazy world we live in.

Steve Crow01/10/2018 09:25:13
151 forum posts
32 photos

I have considered the ready made approach but the spindle you mentioned is a little large for my Sherline lathe.

I'm also considering using 20mm round bar for the housing so it will fit in the clamp seen in this picture.

mill_01.jpg

Ady101/10/2018 10:07:18
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3463 forum posts
513 photos

There are also brushless spindles about nowadays

Even on cordless drills you notice the extra grunt with a brushless unit, especially under load, and a small milling unit needs to handle load to be successful

IanT01/10/2018 10:42:04
1325 forum posts
136 photos

If you only need a vertical capability Steve - I'd consider using a Taig ER16 head. Mine (from Peatol) cost about £80 a few years back but it is a very solid piece of kit and works well. It will not fit within my EW's swing for end-milling/drilling though but works fine when set vertically - same as you have mounted your Proxxon.

For smaller DIY designs - Harpit's "Spindle" book in he Home Workshop series is about the best reference I think.

And for Brushless options - Steve Jordan (on YouTube) has been talking about various approaches with stuff he's purchased from BangGood & eBay. Maybe some useful ideas there too...

Below - My Taig head mounted on the EW.... a very useful vertical milling capability for smaller items

Regards,

IanT

EW with Taig - 101113.jpg

Steve Crow01/10/2018 11:31:52
151 forum posts
32 photos

Thank you Ian, that looks to be a very useful setup. I would really like to use the spindle in positions other than vertical and to continue to use my watchmakers collets, hence my desire for a small compact spindle.

As for the book, I am intending to purchase it.

Regards

Steve

Trevor Drabble01/10/2018 13:37:44
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201 forum posts
5 photos

Steve , Bit of a long shot , but although he's now retired from the model engineering business , Mr Jackson of Arrand ( 01664 454566 ) MAY just have one of his excellent spindles available from his old stock . Trevor .

Steve Crow01/10/2018 13:51:22
151 forum posts
32 photos

Thank you Trevor. I've googled them and seen area pictures. Have you any idea of the dimensions of the square housing?

Cheers

Steve

John Reese01/10/2018 14:41:13
784 forum posts

If you are building the spindle from scratch consider a straight shank ER collet chuck. The ER collets are better suited to holding tools than lathe type collets.

Harry Wilkes01/10/2018 15:12:22
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719 forum posts
60 photos

Hi Steve

This guy plays around quite a lot with various collet spindles etc maybe worth a watch https://www.youtube.com/watch?v=BuAp1VvOVrA&t=0s

H

Tim Stevens01/10/2018 18:43:25
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1085 forum posts

May I suggest that the bearings could usefully be magneto bearings. That is a trade description so you don't have to buy one of Mr Bosch's masterpieces and strip it down. They are like small cup & cone bearings, and they work like small tapered roller bearings, so if you adjust the pre-load on assembly you can get a free running shaft with no end play and no side play. Here is a link to an example:

https://simplybearings.co.uk/shop/p42605/E7-Magneto-Bearing-7x22x7mm/product_info.html?backstep=1

Hope this is useful

Cheers, Tim

Steve Crow02/10/2018 08:13:47
151 forum posts
32 photos

Thanks Tim, I've had a look at these and they seem ideal but the outer diameter is too large for the compact housing I'm trying to achieve. I'm looking at possibly a needle roller cage between spindle and housing but am still puzzled by how to eliminate endplay.

I've ordered the Workshop Practice spindle book and hopefully this will shed some light on the problem.

Cheers

Steve

geoff walker 102/10/2018 08:44:18
323 forum posts
140 photos

Steve,

I have a potts milling spindle which I use a lot.

I had problems with spindle end play and solved it by removing one of the adjustment collars and replacing it with a slim thrust ball bearing (from simply bearings). The remaining collar is squeezed lightly on to the bearing ring and the end float is gone, completely. I locked the collar in place with small grub screws to retain the setting.

My potts has plain parallel bronze bearings.

Geoff

JasonB02/10/2018 08:45:49
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16279 forum posts
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Plenty of small lathes just use a pair of ballraces for the spindle and end play is dealt with by threading the end of the spindle so a nut/nuts can be used to take up the play.

Assuming a 12mm dia spindle with a larger "head" to accomodate the collet taper then you can get thin ballraces 12mm ID and 18mm OD which you should be able to get into say a 20mm casing, could even narrow it down in the middle if you want to get it into a toolpost. This would mean a small amount of overhang due to the bearing not being around the widest point of the collet.

If you wanted to have the whole of the spindle within the bearings then you would need say a 15ID x 24OD thin bearing at the tapered end but could still use the smaller 12mm ID at the far end. Body would need to be 26mm or 1" at a push but could still be thinned down for most of it's length to make it easier to clamp but I would think one flat face would be a good idea.

The "head" would bear against the inside of one bearing and your fine threaded nut against the one at the opposite end. Spindle protrudes beyond the nut so your drawtube can bear on the end of the spindle

Michael Gilligan02/10/2018 08:49:49
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14023 forum posts
609 photos
Posted by Steve Crow on 01/10/2018 08:06:52:

I want to make a small belt driven milling/drilling spindle to accept 8mm watchmakers collets.

[ ... ]

I would welcome any advice regarding bearings etc and preventing any play along the spindle axis.

.

Steve,

May I suggest that you have a look for a watchmaker's lathe headstock, and adapt that ?

To the best of my knowledge there is no better compact bearing arrangement than the 'opposed double cones' which were common in those lathes.

Here is a beautiful example of exactly what I think you need. **LINK**

https://m.youtube.com/watch?v=LWHFpkc9xCg

Much, much, easier than building something of similar performance from scratch !

MichaelG.

Steve Crow02/10/2018 08:59:37
151 forum posts
32 photos

Hi Michael, that Lorch set up is gorgeous. I would give my right arm for a KD50 with all the bits. I might struggle to use it without a right arm though!

I've got this headstock. Maybe I can adapt this.

headstock.jpg

Ian S C02/10/2018 10:13:12
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7447 forum posts
230 photos

One way I got rid of end play in a shaft(plain bearings), I fitted the ball from a bearing, I think it was 1/8" in the centre hole in the end of a 1/4" shaft, this bared against a hardened disc in the outer end of the bearing bush, this could work with a ball race.

Ian S C

JasonB02/10/2018 10:16:33
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16279 forum posts
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Just had a look at the spindles book an they are all more or less of the same design I described above, just a few variations on the nut arrangement.

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