A few months ago I described how I made a boring table to fit my lathe in order to machine a pair of crosshead guides for the Mclaren Road Loco I have under construction. To recap, the guides are in cast iron with a bore of 1.937 inches, having an overall length of 8.75 inches. To say I have not been looking forward to machining these would be an understatement. Having run out of excuses I concluded I had better get on with it. bviously the first thing to do would be to fit the boring table, the first time to actually machine something. This presented no problems other than a painful finger having trapped it between the table and the saddle assembly – a not particularly auspicious start! The next problem was to find a method of squaring the guide with the bed of the lathe – this was overcome by bolting an angle plate to the table and clocking it square. By the use of packing beneath the casting I was able to achieve centre height.

Clamping down was carried out with a dog in the usual way. Those members present at the “bits and pieces” evening when I brought my table along will recall I proposed to use a centre in a boring head in the lathe headstock to facilitate a controlled advance of cut to the between-centres boring bar. I set this up and must say it worked very well indeed. The bore was machined with no problems using a fairly slow speed and relatively fine feed. So far so good! How to do the outside diameter of the bolting flange?
Obviously the boring head would have to be used. Of course I did not have a cutter/cutter holder which would get anywhere close! However, five minutes with a fly press soon bent a holder to a shape which would reach – problem solved. The bolting face must of necessity be at exactly 90 degrees to the bore – this was done by mounting a fly cutter bar in the boring head and traversing using the cross-slide power feed.
The trunk guides need to have the bolting face counter-bored by 1/8 inch deep to allow the guides to clear the cylinder end covers.This was not a problem in that it could be done using the boring head but what was really needed was a boring and facing head to achieve a good finish, alas, I do not possess one so a compromise had to be sought.I am fortunate that my lathe is fitted with a slipping clutch on the feed shaft. This enabled me to clamp a stop to the lathe bed and run the saddle right up to it until the clutch slipped. This worked quite well but the finished face is not one I would like to put on display, fortunately it will never be seen.

Try as I might I could find no way of machining and facing the other end of the guide in situ. This is not a critical area so I carried out this operation by gripping the bolting face in the three-jaw chuck and putting the back centre against a previously machined tapered plug in the bore. In order to make the boring operation easier, the castings are supplied as a cylinder without the side openingsTherefore the next job was to set them up on the milling machine and mill the openings for each side. I went through with a 5/8 slot drill initially and finished with a ¾ inch end mill to the 1.625inch wide opening called for.The second trunk guide was machined using the same method without problem. This being done, all that remained was to drill the holes for the studs, mill a flat on each of the bolting faces and job done. What a boring job (no pun intended) making studs is! At our exhibition I bought 3 lengths of 2BA studding (I am far too lazy to make them with a plain bit in the middle which nobody will ever see). What an under-estimation – I will now buy six more lengths in the hope this will give me sufficient studs! I am quite pleased with the result – the assembly looks quite impressive with everything bolted together. The question I am now asking myself? Why on earth did I not make a boring table much sooner? After all I had the slab of cast iron in stock for years and a boring table is such a useful accessory – I suppose laziness ruled yet again, but that’s me all over.