Cato
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I live in Birmingham, the council issue everyone here with a Babel Fish otherwise nothing would get done.
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Cato
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I crossed the border from Coventry to Brum, I don't think they've rumbled me yet.I have to have one in each ear as I moved from the black country to brum
not done it yet
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You want the largest cutter to just fit below centre height when the tool holder is sitting on the compound. If the tool holder has to hang over the side of the compound, to achieve centre height you will just finish up with far more overhang than necessary. Overhang is the enemy of getting a good finish.
If you ever wish to cut with the lathe in reverse (not recommended with a screwed-on chuck!) the cutting height will be different, of course. With a screwed chuck, parting off is nearly always easier with a fixed rear tool post (upside down cutter with the lathe running in forward direction).
Just look at the dimensions given and buy the largest one that can be used. The cutter is always at its most rigid position when over the centre of the cross slide. QCTPs are convenient, but not the ideal for tool holding if the machine is less than perfect. Angling the tools up or down, to make them point at centre height, is a no-no.
If you have a four-way toolpost, and are just beginning, I would suggest you use that before moving to a QCTP.
I bought a plunger type toolpost and am quite happy with it. Much easier to make extra tool holders for that type.
If you ever wish to cut with the lathe in reverse (not recommended with a screwed-on chuck!) the cutting height will be different, of course. With a screwed chuck, parting off is nearly always easier with a fixed rear tool post (upside down cutter with the lathe running in forward direction).
Just look at the dimensions given and buy the largest one that can be used. The cutter is always at its most rigid position when over the centre of the cross slide. QCTPs are convenient, but not the ideal for tool holding if the machine is less than perfect. Angling the tools up or down, to make them point at centre height, is a no-no.
If you have a four-way toolpost, and are just beginning, I would suggest you use that before moving to a QCTP.
I bought a plunger type toolpost and am quite happy with it. Much easier to make extra tool holders for that type.
Wedg1e
They call me Mr. Bodge-angles
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One thing to watch for with the Dickson QCTP is that as the holders get bigger, if you want to use a smaller shank tool, once it's properly seated in the holder the clamping screws might only be grabbing the outer third/ quarter/ edge of the shank.
The Dickson holder on my VSL will take 16mm shanks, but 20mm sometimes and 25mm always need the bottom face milling off to get them within range (and the 25s sometimes look ridiculous
).
The Dickson holder on my VSL will take 16mm shanks, but 20mm sometimes and 25mm always need the bottom face milling off to get them within range (and the 25s sometimes look ridiculous
).
Cato
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Thanks for the explanations and information gents, much appreciated. 
It's all making much more sense now. I was OK with the tooling side of things, and understood the relationship between sizes and positions. I think I was overcomplicating the relationship between the tools, tool holders and post. It's frequently helpful for a few people to explain the same thing in slightly different ways for clarity. That way when you look at the thing in question the mists clear.
It's all making much more sense now. I was OK with the tooling side of things, and understood the relationship between sizes and positions. I think I was overcomplicating the relationship between the tools, tool holders and post. It's frequently helpful for a few people to explain the same thing in slightly different ways for clarity. That way when you look at the thing in question the mists clear.
