francist
Super User
I had to come up with a tap today to clean out a couple small holes. They’re on an old Singer Model 27 (circa 1909) that I’m giving a once-over to in the shop. It used to belong to my older sister but she never used it other than as a display piece so all the old oil is really dried up and turned to varnish.
The two holes in question are on the bed and right close to where all the action happens so easily get filled with accumulations of fabric lint. And once any old oil hardens up in there too it’s impossible to get a screw in anymore. What turned this into more of an adventure than I had thought was that the holes are threaded for #7-40 which isn’t exactly the most common. Hence the “making” part.
Long story short, I threaded some 1/4” W1 drill rod to 40 tpi and the same major diameter as a thumbscrew off my own machine. For the gullets I just ran the corner of a regular end mill on one side of centre to give some room for debris to collect. I also milled a turning square on the opposite end so I could grab it in a T-handle as finger grip alone wasn’t sufficient. That dried oil is hard, I tell ya.
And the acid test — yup, works great. Turns in nice and smooth but still does the job of getting all the gunk out. I hold no illusions that this would cut metal, there’s no relief behind the cutting edges and I didn’t harden it at all, but for cleaning out the existing threads of an oddball size it was just the ticket. And it’s in my box of tricks for the next machine to come my way. (which I’m thinking will be a very real possibility)
Thanks for looking.
-frank
The two holes in question are on the bed and right close to where all the action happens so easily get filled with accumulations of fabric lint. And once any old oil hardens up in there too it’s impossible to get a screw in anymore. What turned this into more of an adventure than I had thought was that the holes are threaded for #7-40 which isn’t exactly the most common. Hence the “making” part.
Long story short, I threaded some 1/4” W1 drill rod to 40 tpi and the same major diameter as a thumbscrew off my own machine. For the gullets I just ran the corner of a regular end mill on one side of centre to give some room for debris to collect. I also milled a turning square on the opposite end so I could grab it in a T-handle as finger grip alone wasn’t sufficient. That dried oil is hard, I tell ya.
And the acid test — yup, works great. Turns in nice and smooth but still does the job of getting all the gunk out. I hold no illusions that this would cut metal, there’s no relief behind the cutting edges and I didn’t harden it at all, but for cleaning out the existing threads of an oddball size it was just the ticket. And it’s in my box of tricks for the next machine to come my way. (which I’m thinking will be a very real possibility)
Thanks for looking.
-frank
