What Am I Doing Wrong

Bushing sounds good ,because everything else with the backplate was perfect. I made a sacrificial register to test fit when I was turning the actual part and the fit was perfect

Sean
 
Went out to the lathe for 5min;).... I reckon I've had the compound setup totally wrong .I was reading the protractor wrong :(:mad::rolleyes:.I had it set to too much of an angle ,and yeh i forgot to take a photo ... That'll explain why it was catching the top of the thread after about 3 passes and there after . This all marries up to the setup images I've been looking at today .... Feel such a fool now and annoyed with myself ... All the time in getting the backplate right in ever other aspect ..

Sean
 
Learn by them ... is what i was always told ...

Anyways ,looking like i have a bushing/slug to make ....This'll be interesting :concerned:
 
Feed with the xslide.

This is the way I do it most of the time because it is easier, if the machine can take the heavier cut. That way the compound setting is not important. I'm relatively new to this hobby (about one year of hobby use) and was confused by the need to set the compound at 29.5* until reading some reference material. From my understanding, the basic difference between the 2 methods is that using the compound and advancing it at 29.5* only cuts on one side of the tool tip. Using the cross slide (plunge cutting) will cut on both sides of the cutting tool and requires more power and exerts more force on the equipment. With my first lathe (10 x 22) I had to take very light cuts when plunge cutting and the machine would struggle, sometimes stalling and jamming in the cut, even with cuts as shallow as 0.001". It was easier to use the compound but the setup was important. I did the same thing you did and set it off the wrong reference. Oh well its all a learning experience. With my new larger lathe, I can take much deeper cuts while plunge cutting and there is no issue with lack of power or rigidity.

Not sure what size lathe you have but you could try plunge cutting and see how that works for you. Good luck.
 
It's a fortis/Clausing derived 12" swing with a 1 1/2 hp motor . When i was turning down the back plate i experimented in seeing what the lathe would do ,and i stopped (chickened out) at 60 thou on a 7"od interrupted cut . It's a tough old girl and that was tough on it too, I wont be doing that again .

Sean
 
It's a tough old girl and that was tough on it too, I wont be doing that again .
Fortise64, please don't stop experimenting. That's how we learn. I think your "experiment" was skewed by the large dia. and interrupted cut. I'm also new to this, but would bet that without the interrupted cut, your lathe would have been perfectly happy. Happy Machining, JR49
 
Yes, making a mistake makes an impression and you remember...unless your me then you have to do it at least one more time.
So learn by them...unless your were referring to "THEM!", the 50s movie...big ants and all that.;)
 
Feeding in at 90 deg (as when using the cross slide) for a 7 tpi thread is going to take a heavy cut at full depth. Why not stay with feeding the compound at 29.5 deg. for such a coarse thread now that you have it wired?
 
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