by Nigel Cliffe , from a design by Peter Clark© 1996, Nigel Cliffe and the 2mm Scale Association.
This article document was first published in the 2mm Scale Association Magazine. It is the second of three articles describing a drilling machine and lathe which can be built at home with minimal tools. The machines were designed for 2mm scale work (comparable to N), though are suitable for making small components in HO/OO.
The original machines were designed around Minicraft tools, which are widely available in the UK. The designs could be easily modified for other manufacturers ranges, such as Dremel.
All the photographs except the drilling machine were taken by Peter Clark, though errors in scanning and converting to JPEGs and GIFs are Nigel Cliffe's.
We now reach the final part of the Fonly drill and lathe saga. If someone comes up with some additional ideas or gadgets, or writes up some of the other bits Peter has made, they could find their way onto these pages, but this is my final say. There are many accessories for the Fonly. I propose to describe only a few - those I have found particularly useful, and those whose design struck me as novel.
Depth Stops and Feed Control
The depth stops and feed control provide measured repeatability. In principle, either could be provided with screw adjustment, though I will only describe screw adjustment for the feed control. By running the turning tools against the stops a repeatable cut is obtained. The feed control enables cylinders to be turned, and, optionally, tapers or cones.
The depth stop is a piece of round bar - say 5mm diameter - which can be pushed through the headstock front bearing and locked in place with a clamping screw. The clamping screw is held in the block mounted behind the headstock front bearing support. The clamping screw can be either a machine screw with a hexagon socket head, or a screw fitted with a small plastic knob (old radio, RS Spares, Maplin Electronics).
A nut is crushed into the clamping screw block to provide a thread for the clamping screw. The nut is deeply recessed into the block so that the emerging screw thread locks the depth stop bar. The block is shaped to clear the minidrill body and fixed to the rear of the headstock front bearing support with small wood screws. The position of the hole through the front bearing support is shown on figure 13.
Figure 14. The drawing is minus washers to aid clarity (and my drawing skills).
A M6 screw is used for the feed control. M6 has a pitch of 1mm, thus one turn advances the feed control by 1mm. By marking divisions on the screw, finer feed control is achieved. For example, a disk with 10 divisions attached to the feed screw would give indication of 0.1mm movement.
There are four sub-assemblies for the feedscrew: the screw; the fixed nut; the slide; the slide guide and clamp.
The screw is a piece of studding, which has a knob glued to one end. The spring ensures that the screw runs without slop in the nut. The fixed nut assembly is attached to the rear of the lathe base with two wood screws.
The slide guide and clamp has a M4 counter-sunk screw and nut for the clamping mechanism, and is secured to the lathe base with wood screws. The slide consists of a piece of round bar (about 5mm) and a piece of rectangular bar (about 5mm by 3mm). The rectangular bar is fixed with a small screw to a flat filed on the round bar. The slide is assembled last, and checked for alignment with a test bar. Adjustment of the slide is fiddly - the slide must be removed, tweaked, replaced, rechecked.
An optional component is an adjustable slide for taper turning. This is identical in construction to the fixed slide - I'd recommend marking it so that the fixed slide doesn't get altered by mistake!
Other Components and accessories.
There are numerous other gadgets which can be added to the fonly lathe.
Figure 15 - saddle construction.
The saddle provides a means of carrying components, such as the fixed centre and fixed steady. The fixed steady is very useful for supporting tubes (such as boilers).
Fixed steady, attached to saddle.
The fly cutter is made from hex bar, and is useful for scalloping the base of domes and chimneys. This is best done to a blank of metal before working it to final shape. If necessary, a mandrel to carry the work can be fitted to the work. Fly cutting must be done carefully, with very light cuts - remember where your fingers are, and that this is a mini-drill not a Myford!
Figure 16 - bar stock holder.
Fly cutter and bar stock holder.
The bar stock holder is used to carry round bar for fly cutting. Note the socket screw, which engages in a crushed nut, and the small bar (a piece of 2mm rail) about which the work holder can pivot. This pivot point allow the centre height of the bar to be adjusted. After assembling the stock holder, with the holder about central on the pivot, drill the stock carrying hole on the lathe so that it is at centre height. The stock carrying hole is drilled to match standard stock metal - say 5mm.
And finally, without explanation, a couple of other items - a tailstock centre and a drilling jig for locomotive frames (rest the frames on the bar, slide along infront of drill in headstock to drill all axle holes in a straight line).
Frame Drilling Jig
So there we have it, a DIY lathe, with light milling capabilities. Oh, and the name - for those who mutter "I could do that iF ONLY I had a lathe".