Set Screws for QCTP holders

GL

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Never started a thread before, this should be interesting....

As I have read along over the last few years, many have commented that the set screws in QCTP tool holders are often less than optimum (too loose or too soft most often cited as issues) and should be replaced with "good ones". I have kind of kept that in the back of my mind as I leaf through hardware catalogs and such - yes, entertainment comes in many forms for the "afflicted". Without too much fuss, in general, set screws come in several flavors: dog point (or half dog point), cup point, and flat point. Socket heads and square heads are available for tightening things down. Most tool holders seem to favor the dog point style and most have allen head/hex socket drive. Which brings us to the question - if you are replacing set screws for a tool holder, which type of point and which type of drive do you prefer?

The extra threads at the end would seem to be an advantage for the flat nose, especially for tools that fill up the whole slot in the holder. In some cases you would lose almost half of the thread engagement, although you still probably have 1.5 diameters and should be good by normally accepted practice. It just looks funny. Square drive would seem to be an advantage for durability and dimensional variation over the hex socket style (which many seem to comment about). If there are space considerations, the driver or drive system (socket or wrench or ?) for a square head would be larger than an allen key, but not wildly so. Making a metric square head driver is more difficult than buying a hex key, but challenges are what we live for.
 
I think the biggest issue with the imported set screws is they are lacking hardness and when you crank them down you deform the threads and the points. I've replaced them with cup pointed set screws and they hold plenty well for me. No signs of tool slippage when I check them but then I am not taking Abom size cuts.

I wish I had saved some of the set screws from the tool holders I got with the lathe. The dog points were more like mushroom points after 1 tightening. And the number that stripped out the allen slot was just too high. No such trouble with the USA made replacements. And getting them at the local fastener store by the box was super cheap.
 
All the set screws that came with my tool holders including the USA ones were cup point. The set screws that came with my China holders were either very loose, broached off center, or the wrong size. Like I have some that are metric thread but have an imperial size hex. I replace them right away so no idea how soft they are. Just the loose fit of the hex makes me not want to use them.

I replace all mine with flat point instead of cup point, just my personal preference. I don't like cup points trying to dig into my tools, especically on my carbide shank boring bars. I have never had one slip. Also for tools that are 2 sizes smaller than what the tool holder can take max I use longer set screws so there is more thread engagement.

I prefer to just stick with a hex socket instead of something else like a hex head. I prefer my screws to have minimal stickout from the holder. Less chance of stringy chips or whatever to snag on them. But mainly so there's no need for another wrench to keep by the lathe, I keep a hex t-handle set by the lathe anyway as most everything on my lathe is hex socket.

I buy the set screws in bulk from Mcmaster.
 
My original set screws were replaced in the first week with quality hex socket set screws. The tips were ground to flat to prevent damage to the tool shanks. You get plenty of holding pressure from using an ordinary T wrench and moderate torque even when using only 2 screws to hold a small boring bar. There is plenty of thread available and a good fitting screw will last indefinitely. Needless to say that with quality socket screws you need to use a quality wrench.
 
I prefer square head, flat point screws. The flat points don't tend to damage tool shanks and the square head allows use of one of the common lathe tool, 8-point box wrenches. I purchased my screws from McMaster-Carr.

Ted
 
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