Tool post drill ?

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Tool post drill ?

This topic has 8 replies, 5 voices, and was last updated 25 April 2016 at 09:56 by Gordon W.

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24 April 2016 at 10:15 #235948
Brian Stone 2
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@brianstone2
This harks back to 2011. Michael Cox (MEW 178 p.21) described converting a flexible shaft for tool post mounting and reasonable precision. He wrote that he replaced the 12mm dia. integral shaft for the chuck with a proper bearing, smaller shaft and precise drill chuck.

Till re-reading the article, I thought I owned the only surviving example of the ancient flexible shaft he used! (At least 30 years).

Question: how is the 12mm shaft removed without wrecking the flexible inner flexible element, which does not seem willing to slide out?

In hope … Brian.
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24 April 2016 at 10:15 #38349
Brian Stone 2
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@brianstone2
24 April 2016 at 12:53 #235990
Gordon W
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@gordonw
On my old shaft ,30 yrs. plus, there is a knurled locking nut, take this off and the inner cable pulls out. The actual shaft is fixed to cable, but can be turned by by pushing thru' the mandrel and supporting the flex cable. Slow speeds only, or else a lot of fun. I just made a simple block with brass top-hat bushes and a new shaft, driven from origenal old chuck.
24 April 2016 at 13:48 #236007
Michael Cox 1
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@michaelcox1
Hi Brian,

The flexible shaft are still on sale at Toolstation (item number 28938, price £14.79)! The shaft is not 12 mm diameter but 6.7 mm diameter. It has a small cross hole in it. You can see this hole in Photo 4 of the article. If you insert a small bar and tap it anticlockwise with a hammer then the shaft should release and it can be unscrewed. Of course this is probably easier on a new unit than one that has been lying around for sometime. The shaft is only 6.7 mm diameter (see Fig 3 of the article). Once the shaft has been removed then the chuck end diecasting can be drilled out 12 mm for the phosphor bronze bush.

I hope this helps

Mike
24 April 2016 at 13:51 #236011
steamdave
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@steamdave
Posted by Gordon W on 24/04/2016 12:53:03:

On my old shaft ,30 yrs. plus, there is a knurled locking nut, take this off and the inner cable pulls out. The actual shaft is fixed to cable, but can be turned by by pushing thru' the mandrel and supporting the flex cable. Slow speeds only, or else a lot of fun. I just made a simple block with brass top-hat bushes and a new shaft, driven from origenal old chuck.

A simple way to support the flexible drive to prevent a tangled mess is to push a length of tube into the spindle bore with the flex inside it. The tube can be prevented from wiggling its way out by wrapping rags or other stuff around the tube to fill the gap 'twixt tube and bore.

Dave
The Emerald Isle
24 April 2016 at 14:33 #236017
Gordon W
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@gordonw
That's what I did Dave. Plastic overflow tube with insulating tape on outside, a bit more technical. For longer bits I've got a small hole in the end wall of shed.
24 April 2016 at 20:19 #236054
capnahab
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@capnahab
No affiliation. Not sure of size but you can get these at most jewellers supplies and mine has seen years of use.

https://www.cousinsuk.com/category/foredom-pendant-drill-motors
25 April 2016 at 07:48 #236097
Brian Stone 2
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@brianstone2
Apparently we have three variants of this device. Gordon's has a knurled nut, Mike's has a 6.7mm shaft with a larger collar, but mine has a shaft 11mm or 12mm in the apology for a bearing, relieved outside to between 10mm and 11mm, up to a thread to fit its chuck (chromed, smaller than Mike's in the article) 7/16" over the threads by, not 20 or 28, but 24TPI. So not UNF or UNFX. This shaft is not at all willing to unscrew from any internal connection. (Driving end shaft is exactly 1/4", 6.35mm).

Not needing a flexible (sorry!) commercial device like capnahab suggests, I'll probably make a block as Gordon did, to fit a quick-change tool holder, with new shaft driven via the flex shaft chuck. Thanks gents!

Cheers, Brian.
25 April 2016 at 09:56 #236109
Gordon W
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@gordonw
Hi Brian, if you go ahead with making a new block and bearings just turn a Jacobs taper on the shaft end to suit a chuck. Easier and more accurate than a screwed fitting.
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