Having come back to metal machining after a break of some 50 years the past 6 months have been to say the least somewhat of roller-coaster of a learning curve, leaving more questions unanswered than answered so I would be grateful for comments from you younger guys.
I took delivery of a Chinese Mini-lathe and duly took stock of what I thought would be required in the way of tooling for simple turning exercises (to bring me back up to speed) and purchased from my local supplier a set of carbide tipped cutting tools which contained a selection of tooling ranging from basic L/H , R/H ,Parting off tool ,thread cutting profile tool ,Boring bars etc. , You get the picture I'm sure,
Now from the outset finish was an issue for no matter how I tried varying feeds and speeds (the ranges of which far exceeded the lathes of old) the material was removed but fine finish eluded me. At this point I also felt that the tool post supplied left a lot to be desired needing an infinite amount of shim stock to set the various tooling to the correct height. A visit to ArcEuro solved this problem and I purchased an old fashioned "rocker" tool-post which proved to be a panacea to many of the problems I was experiencing. At the same visit I purchased a HSS parting tool and holder which I felt might help. My first attempt at parting off in the normal way was disastrous the whole set up was so unstable that it was abandoned in short order. I then read of rear mounted tool posts the theory of which made a lot of sense with a result I attempted the parting operation with the parting tool mounted upside down in its normal position and the machine running in reverse - the result was remarkable a parting cut thro' a 30mm steel bar as if through butter. Spurred on by my success I idly without thinking made a skimming cut of about 10 thou. on an off cut of 25mm stock the result was amazing at last a finish running in reverse with a tool being apparently abused!!
Now I have read somewhere that HSS tooling will give a superior finish as opposed to carbide tipped tools, but is the geometry of the set up the reason for this apparent move from the traditional set I learned so long ago? is the parting tool acting as a form tool? The only abberation appears to be the fact that the tool being only of the order of 1mm wide does tend to flex and on reaching say a collar will if permitted take a secondary cut but this can be exploited by using the lead screw to machine back out.
and a fine finish to high tolerance achieved.
Unsurprisingly I have continued to use this method for practice and will attach a couple of photos if I can fathom out the process!!
in anticipation,
kindest regards to all
terry
I took delivery of a Chinese Mini-lathe and duly took stock of what I thought would be required in the way of tooling for simple turning exercises (to bring me back up to speed) and purchased from my local supplier a set of carbide tipped cutting tools which contained a selection of tooling ranging from basic L/H , R/H ,Parting off tool ,thread cutting profile tool ,Boring bars etc. , You get the picture I'm sure,
Now from the outset finish was an issue for no matter how I tried varying feeds and speeds (the ranges of which far exceeded the lathes of old) the material was removed but fine finish eluded me. At this point I also felt that the tool post supplied left a lot to be desired needing an infinite amount of shim stock to set the various tooling to the correct height. A visit to ArcEuro solved this problem and I purchased an old fashioned "rocker" tool-post which proved to be a panacea to many of the problems I was experiencing. At the same visit I purchased a HSS parting tool and holder which I felt might help. My first attempt at parting off in the normal way was disastrous the whole set up was so unstable that it was abandoned in short order. I then read of rear mounted tool posts the theory of which made a lot of sense with a result I attempted the parting operation with the parting tool mounted upside down in its normal position and the machine running in reverse - the result was remarkable a parting cut thro' a 30mm steel bar as if through butter. Spurred on by my success I idly without thinking made a skimming cut of about 10 thou. on an off cut of 25mm stock the result was amazing at last a finish running in reverse with a tool being apparently abused!!
Now I have read somewhere that HSS tooling will give a superior finish as opposed to carbide tipped tools, but is the geometry of the set up the reason for this apparent move from the traditional set I learned so long ago? is the parting tool acting as a form tool? The only abberation appears to be the fact that the tool being only of the order of 1mm wide does tend to flex and on reaching say a collar will if permitted take a secondary cut but this can be exploited by using the lead screw to machine back out.
and a fine finish to high tolerance achieved.
Unsurprisingly I have continued to use this method for practice and will attach a couple of photos if I can fathom out the process!!
in anticipation,
kindest regards to all
terry