Hand-held collet holder
This gadget is shown in the 1912 Wolf, Jahn & Co. catalogue and advertised for the larger larger lathes to go into the three-jaw chuck and hold 8 mm collets for small work. According to Dingler's Polytechnische Journal (1896, Vol. 300, p. 180, http://dingler.culture.hu-berlin.de/article/pj300/ar300043) this gadget was developed by a mechanic Richard Nerrlich in Berlin the tool company Grundmann & Kuhn in Berlin obtained a trade-mark for it. It is equally useful as a hand-held collet holder. I got it with a box of other pieces for WW-lathes. The tightening nut was missing and I have made a new one.
| From a 1912 Wolf, Jahn & Co. catalogue
and the original
to show the replacement nut
Quick-change tool post
Quick-change tool post tend to be expensive, but useful items. The main body of the Leinen-made one cost EUR 90 net equivalent in 1996 according to my catalogue. The inserts would have set you back another EUR 60 each. So I decided to make my own; inspired by the Leinen design. I actually made two dove-tailed slots, but this is really unnecessary, as I found that I am turning it anyway to provide clearance etc.
If the repeatability of height-setting is all what you need, then there are simpler designs; for instance a round stud clamped into the T-slot and simple slotted holders sliding on it and being tightened down with a compression screw.
Drawing for shop-made
click on image
Large boring head
Good boring heads tend to be equally expensive. Also, I wanted one that is not too heavy for use on the small mills and that has not too much off-centre mass when extended. It is made of aluminium and fits onto an 8 mm arbor with a M8 thread. It is bored for 8 mm shank boring bars etc.
A simple micro-adjustable boring bar was
fashioned from a piece of 8 mm rod. One end was chamfered 3 mm
wide at 45°. Through this chamfer a 2.5 mm through hole was
drilled at the same angle. The hole was tapped M3 for about a
third of the length from above. The other side of the hole then
was enlarged to 3 mm for the cutting tool ground from a short
length of HSS tool-bit. The tool-bit can be pushed out with a
set-screw to increase the cutting diameter in a controlled
fashion. The boring bar is drilled and tapped from the opposite
site of the first hole to take a set-screw for locking the
||Ready to mount
Upright collet holder
The Wolf,Jahn & Co. Model A milling machine has an integrated rotary table for indexing and it is convenient to hold workpieces upright in a collet or even a chuck. for this pruposes I made a non-indexing collet-holder that can be mounted in the centre of the rotary table. It can take ordinary split collets, wheel chucks, ring-chucks, or even the three-jaw scroll-chuck. The cone on top mimics the spindlenose on the lathe for this purpose. The collets are drawn in by a nut, which can be tightened by a bar.
(not to scale)
of the original (still needs painting)
various types of collets. Also shown is the
finished collet holder mounted on the Wolf, Jahn
& Co. miller. Right a six-jaw chuck is held in
blocks (picture from www.lathes.co.uk)
||Raising blocks and raised toolpost
||Working on a large pulley
|Miniature tilting and swivelling vice|
(body, LED ring, lid)
||... and working
|Hobbing a concave