QCTP

[Howard LewisParticipant @howardlewis46836]

Bear in mind that once you buy a particular QCTP, holders from other maunufacturers / suppliers may not fit your basic toolpost, so once you have a system, stay with it!

QCRPs were inventef for industry where time is money.

The advantage is that once set on centre eheight, the tool should stiil be there, the next time that you use it. Useful if you do a lot of tool changing, but less ential (or cost effective) if you use three tools or so, which you can do in a four. Having a rear toolpost,can increase the number of tools available;

So think carefully about these points before you spend money

(We probablly, all have items thast we bought, as “A good idea at the time”, that we never use!)

Howard

[JasonB]

On JasonB Said:

I would have thought a QCTP with a ratchet or index pin is as quick as a ratcheting 4-way and then when you need an additional tool it will be even faster? You also get length ways repeatability when changing a QCTP, shimmed or milled holders will only go back in at the same height not position.

Much like my thinking when I came up with this: http://www.charleslamont.me.uk/iqc_toolpost.htm

[JasonBModerator @jasonb]

I was thinking of the Colchester size Dickson type posts that take 3 holders and have an index pin, similar to yours but with two more holders. And lets face it you can often only get 3 tools into a 4-way particularly if one is a boring bar and just hope you don’t need tailstock support which may mean removing tools to get clearance. Same clearance issue applies to a QCTP in many cases though quick to change to an extended holder when needed.

I suppose those with rigidity problems could take Charles’s design a step further and make the other sides slotted to take the commonly used tools like a 4-way and then just have the one simple dovetail profile for changeable holders  so you could keep a range of tools ready to go in their own holders.

[VicParticipant @vic]

These tools cater for about 95% of the stuff I do. Two Tangential Tools, one bought, one home made. Two carbide insert tools in 12mm holders, both with 2mm gauge plate glued to the underside. A 16mm shank TNMG tool which I trimmed down by 2mm to fit my four way. And a parting tool onto which I bolted a piece of gauge plate to bring that up to centre height.

I also have a boring tool somewhere also set to centre height.

 

One of the whole points of Carbide inserts is that fitted to the correct toolholder, on a suitable lathe, you never need to bother about height setting.

Not my words but someone else: “The problem with a QCTP is that once a tool is fitted to a holder you’re loathe to remove it for another one”. As a result you quickly end up investing in lots of tool holders, many of which don’t get used very often”.

If of course you grind a lot of custom HSS tools then I can see the justification, particularly if you’re a professional and every second counts.

[DiogenesParticipant @diogenes]

..a professional and every second counts?  -no, but perhaps have better things to do than f*nny about with shimstock and araldite during the <two decades that remain..

[Author]

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