Cracked cross slide

I found this crack in the cross slide of the museum's Smart & Brown Model A, a few years ago. The crack is still there, but reinforced by a milled steel bolted on addition.

That's a very nicely executed repair.

Really good repair, like it!

Edited By Phil Whitley on 29/12/2019 19:23:58

To spread the load on the dovetail groove in the cross slide, I decided to use four bolts with longer bases than standard. For strength, they are one piece. They were as much bother to make as the rest of the repair put together. Not only are they dovetail, but they are also curved to match the circular groove. A friend of the museum made a custom tapered end mill on his cutter grinder. The rotary table played an important part making them, but I forget exactly how I did them. The picture looks like one of the old ones. The thickness of the bolted on repair can sometimes obstruct the tailstock.

Edited By old mart on 29/12/2019 19:45:06

Edited By old mart on 29/12/2019 19:49:01

Still, you made a good repair, and the machine is, again, useable. You achieved your object of putting back into service!

Howard

The four new dovetail bolts were made using the modified four flute endmill (5/8" or 16mm screwed shank originally) ground to match the angle of the original bolts. The 5/16" threaded end of the bolts was produced first in a 1" diameter EN16T bar fixed to the rotary table at the same radius as the centre line of the dovetail slot in the cross slide. The difficult bit was positioning the cutting edge of the end mill the correct amount inside and outside of that radius. I think I measured the diameter of the mill at the exact point where the modified tapered end joined the original diameter. The bolts were finally cut from the bar and their ends radiused and they fitted the dovetail first time, which was fortunate as no reworking was possible, or test fitting. Having four bolts now means that the compound can be secure without tightening the nuts so much, thus reducing the forces on the weakened casting. Another job that would have been much easier with DRO scales on the X and Y  on the mil

Edited By old mart on 30/12/2019 18:51:26

Edited By old mart on 30/12/2019 18:55:51

Edited By old mart on 30/12/2019 18:57:34

Edited By old mart on 30/12/2019 18:58:33