It seems the , " Creaking like an old man " , was not just me :lmao:
When we got back home today ( Been out shopping with my lass ) & I managed to start playing on the lathe this afternoon , the boring bar moved in the clamp on the tool post . Being normal I got the spanner and nipped the head nut tight only to find that as soon as the cut was restarted the boring bar came loose & moved again .
Thinking that the head nut or the post bolt had started to strip thread again I replaced both with more new unused zinc plated mild steel studding & a new nut .
T'was only when I started to tighten the head nut again that I felt & heard things graunch & jump a bit under the spanner.
Puzzled , I undid it a bit and observed from eye level with the tool post , found that as things started to tighten up the small stand off /height compensating precision hardened bolt on the tool post clamping plate ( An old Myford post clamp ) has " fretted " in the threaded cast iron plate's hole and was starting to slip through half a thread or so every time I've been tighten it up for the last few days .
No wonder I was getting a cone shaped "parallel " bores hole out by 3 thou. towards the face plate . I just didn't recognise what was causing it , for I'd run thorough the test bar checks several times and found everything hunky-dory . I thought it might have been the friction heat in the block of aluminium as it was some what slightly hotter than comfortable for my poor little pinkies .
The solution was to drill out the damaged thread and re tap with an 8 mm coarse metric one , but even this was not satisfactory as the meat of the plate was only about 1/4 " thick at the vital point .
The common bolt ( choice of several ) I put in was a tiny bit sloppy & would soon be following the same course as the other bolt in the cast iron clamping plate .
Not having any better bolts to hand I slipped a flat washer over the free end of the thread and added two plain hexagonal nuts , then gave them a gentle lock nutting tweak with a 10 mm spanner . Now the whole clamp is rock solidly supported on the brace side , the whole tool post and tool is clamped up very well indeed.
First indications of my success are that I have reverted to getting parallel walled cylindrical bored holes again.
It looks like I'll have to go and buy some case hardening powder to harden up a few frequently worked mild steel nuts & bolts on the lathe as well as some precision high tensile machine nuts , screws , bolts for I'm sick of these cheap and nasty British standard American Chinese mild steel ones giving up the ghost & bringing the house down .
It also looks extremely likely that because of having to have had to drill out the fretted threads to effect a quick repair that I'll have to add , " Make a new tool post clamping bracket out of steel rather than cast iron " , to the list of must do's ... SOON .
This is the cheapest option because I have several different thickness of cutting tools . Otherwise it will mean I'll have to get a rather expensive QCTP & centre mounting bolt set up to cover all cutter /tool sizes and I can't justify that to , " The love of my life " , just yet , ........... or can I ? :thinking: :lmao:
