Bending HSS

And try a bit of torque instead of speed, live a little.

Edited By ady on 18/09/2010 21:48:22

Peter

Rather than trying to bend HSS another alternative is to look at using a tool holder that fits into the toolpost to carry the HSS tool bit. The holder can be mild steel and shape limited only by your own imagination. The holder gives you the bends and offsets that you prefer and then you just need a short straight length of HSS clamped in the end to do the cutting. The tool holder can also give you some of the rake angles to simplfy the grinding of the HSS. It has the advantage of allowing you to use smaller sections of HSS but still keep good overall rigidity because the tool holder can be as chunky as you can accommodate. Chester list some holders in right and left hand cranked form as well as straight and I think I've seem similar in the Chronos cat. as well. The older patterns from makers such as J&S and Eclipse come up regularly on EBay as another source.

Keith

Edited By Keith Long on 18/09/2010 22:31:58

Peter

For HSS bits its prolly best to use an Armstrong type holder in a four way or single slot block tool post.  If you are using one of the smaller lathes, say under 5" centre height, the odds are you will have to make the post as the standard issue probably won't be high enough to take the holder shank.  Fabricated construction is fine.

Use the bent to the right holder for normal turning.  This lets you get close into the chuck without endangering the saddle. Set the business end 90 degrees to the bed and put the angles on the tool bit.  Don't mess with pivoting the post.  Although the American lantern type tool post is allegedly suitable for Armstrong holders its propensity to move in approximately 65 directions simultaneously if you are careless with the clamp bolt coupled to sadly inadequate rigidity will soon convince you that it's an invention of Beezelbub to improve the profit ratio on workshop swear boxes.  If you must try one pull the boat and flip the washer over to give a flat mounting surface, as advised on page 27 Newnes Complete Lathework Vol 1.

When using carbide on the smaller lathe its worth considering the angles and shapes given in the older books, like the Newnes set, written before negative rake and inserts became de-facto standards.  Modern inserts of all types are designed for high speed cutting with most of the energy dissipated in the chip and pretty much don't behave unless the chip is short, curled and blue.

Clive 

Edited By John Stevenson on 20/09/2010 00:14:49