Edward Adams's 2½" Gauge 'Monstrous'
I can't believe that it's over two years ago that I last wrote anything here! I've been tied up with other projects though and also have been somewhat incapacitated over the last twelve months due to my leg problem. That is much improved now and things are slowly getting back to normal.
I decided to spend a few hours in the workshop and make a start on the new wheel rims for the trailing wheels to replace the Vee shaped ones. As mentioned on the previous page, I had been given a couple of steel blanks to make the new rims so it was just a matter of maching them to size and fitting them to the wheel centres.
The blanks were much thicker than I needed and it took quite a time to machine off the excess. I used the Denham lathe to rough machine the blanks to thickness and then rough bore them to take the wheel centres. It's nice using the Denham as it has the power feeds on both the saddle and the cross slide but I was a bit disappointed with the performance of the lathe as it proved impossible to take a decent cut without a lot of chatter. This had been apparent when I had machined some wheels for a 7.25" B1 and I suspected that the main spindle bearings on the lathe were not adjusted properly. Setting up a dial indicator on the chuck and using a length of wood as a lever against the bed to try and lift the chuck showed that there was indeed a lot of play in the two main bearings at the chuck end of the spindle. I took the top off the headstock and tightened up the adjusting nuts as much as I dare without making the spindle stiff to rotate. This did improve matters considerably but it's still not right and needs further investigation. I hope the bearings are not shot as it will be virtually impossible to find suitable replacements. Even if I could find some, the cost would probably be more than the lathe is worth!
Anyway, I got the blanks rough turned and then used the ML7 to finish them to size. I intended to shrink fit the new rims and so bored them smaller than the diameter of the centres. I used the rule of thumb of 0.001" per inch of diameter plus 0.001" smaller than the centres. The centres are near enough 3 inches in diameter so I made the bore of the rims 0.004" less than that.
To fit the rims, I cut three bolts to fit between the two wheel centres, fitted them with nuts and tightened them gently to hold them in place between the edges of the centres. This gave me three 'stops' for the new rims to drop onto and align the backs of the rims with the backs of the wheel centres.
The 'stops' to aligh the rims. One has already been fitted
The rims were simply heated up on the gas stove and then dropped onto the wheel centres. I heated them to a very dull red but I don't think they needed to be that hot as there was quite a gap between the wheel and the rim until they cooled down.
Both rims fitted
Hopefully I have got the fits right and it just now remains to machine the treads which I'll do between centres. Nothing should move as the wheels are pinned to the axles and the quartering will not be affected.