Parting on the Lathe

[dallen]

(12-11-2013, 08:48 AM)PixMan Wrote:

(12-10-2013, 10:41 AM)dallen Wrote: I have one of the standard aloris parting blade holders and I can never stop the blade from slipping.

DA

I've heard of that happening with the import ones. I do not care for either the cam type nor the single wedge type, for two reasons. First, I believe the single point of contact puts a stress riser on the blade, making it a likely failure point. Secondly, the small point of contact offers minimal clamp pressure as compared to the long line of contact in the style holder I choose to use. When tools aren't held rigid, they move. When cuttings tools move opposite of the intended, they fail.

The blocks I have are known as 7-71 and 7-71C, and both Aloris and Dorian sell them. You may notice one has a shiny new clamp block. My dad had made that because the original one was broken in half when I bought it off eBay for cheap. I can only assume the original owner tried to tighten all four screws while holding only a half long blade.

I stopped using the HSS blades and holder, pitched it in a drawer on the tool box, and went to a GTN insert blade that I had, with some overly wide inserts in a holder that I originally made to work on my 9" lathe, which I modified so I could clamp it in one of the BXA tool holders by silver soldering a steel bar to the side of it.

So far it works, wish I had some narrower inserts for it, but then who knows maybe Santa will drop some out of his bag as he and his team of raindeer fly past at mach 4.

DA