How far to be off tool centre before a turned finish becomes poor?

Ross, I dont have a QCTP and I shim the tool height with feeler gauges, if you have a set you dont use for other purposes remove the gauges from the holder and use them. With the various thickness of gauge you can get the tool height spot on to where you need it. The length and width of the gauges are also a good fit in the tool post, I bought a cheapo set from a stall in a market.

Edited By Ron Laden on 15/12/2018 10:27:56

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... and also of looking at the microscopic detail of the wood, not just a single tree or a group of trees

The English langage is wonderful

MichaelG.

My height gauge is a 6" engineers square, I sat it on the saddle, and scribed a line across the blade at centre height. There are actually two lines about 3 mm apart, the other is for the Vertex rotary table,

Good source of shims is the I laminations from an old transformer, drink cans off cuts of hot rolled steel. On my lathe some tools may need up to 1/2" packing.

A boring bar should be from 0, to a few thou high.

Ian S C

I do aim for this but does it really matter as long as the tool is appropriately presented to the bore?

GHT advocated running the tool upside down at the back of the bore.

Across the pond some of us use pallet strapping as shims, some is .020, some is .023, and the biggest is .030.

Not only might the tool deflect slightly downwards the work may try and climb over the tool. There seems to be some aversion to setting the tool slightly too high. Depending upon the offset and work diameter it may not matter in the slightest. If a tool is set 10 thou too high and the work is 1" diameter then the tool will be 0.0001" closer than if it was set dead on height. I can't see a tenth of thou having any affect at all on the cutting process.

I suspect that finish problems are mostly caused by the material, cheap tooling or incorrect grinding, and wrong speeds and feeds. Tool height is probably some way down the list.

Andrew

Useful stuff that pallet strapping it's made from some kind of springy steel. I use slightly bent as a parallel retainer on the mill.

Phil.