finally had the time and the inclination to do a bit of repair work to my poor little lathe. unfortunately the first job was taking it to the dentist!
this poor lathe was badly abused in a past life and really needs a full refurb but that will have to wait. for now its just a case of fixing little bits here and there in the attempt of making some improvements.
anyway onto the job at hand!
when i picked up the lathe it had only a couple of its change gears and one of them was missing a tooth, iv put up with it for a few years, as there is a tiny stub of tooth left to drive things, but i had a bit of time so thought id get it done.
initially plan was to remove the offending stub, to braze some steel pins in and file to fit, but for some i didnt want to have to heat the whole gear up so i went for a different approach
first the gear was mounted in the mill for the extraction. A 2mm end mill took out the base of the broken tooth and provided a slot for the new one to sit in. The root was drilled out with a 2mm bit.
I also opted to leave the stub of tooth in place, it would have been a lot simpler to remove the entire tooth but i thought it might give some extra strength. and give me a guide to follow for filing the shape.
next step was to find somthing tooth shaped to make a new one out of, i dont have any cast iron and didnt really want a hard steel tooth to potentially damage the others so a bit of 2mm thick brass was cut to shape and filed to give a reasonble fit.
everything was given a clean up and soak in degreaser while i went looking for my jb weld, unfortunatly the elves must had hidden that as it was nowhere to be found.
not wanting to give up i thought about plan A and brazing things but that would likly melt the brass tooth leaving me with a mess
so instead i thought id silver solder it in place.
a bit of flux was applied to the mating faces and the new tooth was tapped into position, then out came the propane torch
after quite a bit of heating, ( cold workshop and no hearth ) i finnaly got the gear up to temp and managed to get some solder to run. whether or not its actually penetrated im not sure but the new tooth seems to be firm.
a bit of work with a file and the new tooth looks about right, iv given it a quick run in the gear train and it seems to mesh without any tight spots or odd noises o ill call it a success for now.
Time will tell if it holds in place, chances are it will be fine until im halfway through cutting a thread on a nearly finished part.