Yesterday brought some good news on the Boxford project. Looking through eBay and craigslist ads for electric motors, I was finding mostly incompatible motors at near-new prices, so wasn't overly impressed with the chances for any near-term resolution on my power issue. There was this one ad that had just been posted overnight, though. I initially blew that one off because the entire ad consisted of "Electric motor, good shape." That description covers a lot of ground, ya know? It could be anything from a slot car motor the size of your thumbnail up through that 300hp motor I once saw being rewound where my wife works. Having no luck anywhere else, I sent the guy a text. It took most of the day to extract all the info from him but by mid afternoon was satisfied that his motor was almost exactly what I was looking for. Best of all, he only wanted $40 for it. I'm scheduled to pick it up this morning and it should be a bolt in, plug and play swap for the original. I stated earlier that the original motor was a 1/2hp, but was confusing the Boxford with a tool post grinder I'm also currently working on. The Boxford motor is 3/4hp and the one I'm picking up today is 1hp. That appears to be the only variation in spec between the two.
As to the damaged clapper box, I mentioned the possibility of inserting the damaged area to carry along until I can make an entirely new one. On the chance that some of you may have never dealt with inserting procedure, I thought it may be helpful to briefly discuss what this involves. I've worked in plastic injection molding off and on for many years and inserting damaged areas in tooling is so common a procedure that we come to take it for granted. The internal forces produced during a molding cycle are tremendous, so it only makes sense to me that the clapper box could be repaired, at least temporarily, using these same techniques.
I was taught that capturing an insert on at least three axes would usually produce an acceptable repair. Using this advice, I've envisioned what I think is a suitable insert to withstand the forces acting upon the clapper box during operation. Sorry about the cheesy MS Paint sketch, but it's what I've got to work with...
View attachment 230078
You should be able to see how the insert will be captured on the
X, Y, and
Z axes above. The
X-axis will be controlled primarily by the flat head screws seen near the bottom of the insert. To reinforce this, I may turn out a temporary taper pin with a threaded section on the small end. A locking nut snugged against the undamaged side would transfer support from the good "ear" over to the inserted side, which would in turn give us three points of support for the insert. The
Y-axis is pretty straightforward, as there will be original material blocking the insert in at two points along this axis. The
Z-axis will be captured at three points, both a "foot" running along the underside of the clapper box, the undercut seen running along the
Y-axis toward the rear, and the flat head screws will also be resisting shear forces along the
Z-axis.
This insert will be fitted pretty tight and since it isn't backed up (on the right side,
X-axis) by standing steel as it would be in an injection mold, I'll be coating all the mating surfaces with some type of epoxy, such as DevCon Liquid Steel, during assembly. I can't imagine this not holding together long enough to get the new clapper box blanked out. Actually, I can't imagine ever generating enough force with the little Boxford to blow this repair. I may be dead wrong, but I don't think so. I'll try to get video of the first cuts in case it does.