Thread: Screw Cutting , Cutting oil or Soluble coolant

I'll give a good quality cutting oil a try this week when I'm back in the work shop on thursday. might be a combination of taking heavier cuts with Soluable coolant and taking the last few cuts with cutting oil.

Ask Brian Hjelm for advice, If anyone knows, he will.

From the look of the tool alignment to the job, you are plunge cutting. In this case on small threads like those, two cuts are all you should need.

I have not used coolant for years, I don't like cleaning up the mess or replacing stinky coolant. It is years since I regularly used HSS toolbits, for that matter.

I think I last ground up a parting tool in a cranked holder to screwcut a fine thread up to a shoulder about 5 years ago. Otherwise everything I do nowadays is with TC inserts. I use an oil can with kerosene for turning aluminium, and EP diff oil for stainless steel. A good coolant is water, liquid laundry detergent, and diff oil. Use your nut to adjust the proportions. Cheaper than buying commercial cutting fluids.

If you are really desparate you can use good old Spit. It available 24/7 and does a good job. I did all the valve heads on a ship in Newcastle as it saved the dockyard workers time in having to go back to the workshop to machine the valve heads.

I just merely wanted to know if there is vast difference in results of the finish between the two ,I have access to cutting oil at tafe and was going to give it try in place of the soluable coolants,they do supply the oil so I'm not out of pocket with the cutting oil and it seems to be reasonable quality, ,I did get very good results from cutting v-threads with HSS tool running at 25 rpm with coolant dripping on the tool,the swarf shaving was quite nice and shiny and curling up beautifully , took me a few cuts instead of just 2 x cuts , but the end results i was hapy with . we didn't seem to have the right carbide inserts for the thread that i wanted to cut hence why I started and finished the whole job with HSS and that's why I asked about the cutting oil.

D-O i am no expert but only use a castrol sol oil and am happy with it enough to not experiment!
Out of interest, why plunging the threads and not running a 29* compound?

Steve

Originally Posted by roverrescue

D-O i am no expert but only use a castrol sol oil and am happy with it enough to not experiment!
Out of interest, why plunging the threads and not running a 29* compound?

Steve

Hi Steve,

I used the plunging method in this instance as a trial ,However last week I tried the 29* deg method for cutting V-Threads as part of my course, actually prefer the compound slide method( 29 *deg ).
It permits takier heavier cuts and reduces the tendency to tear the thread, since practically all thread cutting is done with the leading edge of the tool while the trailing edge just shaves the side of the thread smooth
and produces a great finish.
AFAIK most machinist prefer the 29*deg method.I was also able to produce a good finish with the Plunge method using soluable coolant , just taking lighter cuts , it does take longer that's the only down side , no cleaning the threads with the file or srubbing after wards, that's how the threads looks in picture after the cutting is done. we have some good quality cutting oil available , so I will give it a try tonight and may be post some piccys here as a matter of interest.

the Tools store only carries 1 x type of insert to cut an M40 x 2 thread.Just for practice i gave the TC inserts a run on tuesday night.


It all happens so quick.