Here are a few of my favorite insert tool bits for the lathe:
The first two on the left are shop made using 3/8" 1018 steel. Nothing special except that I like to put an insert on each end of the tool blank. With that config I can turn to a shoulder either left or right depending on the tool and then just remove and replace the tool holder on the 90 degree side of the tool post (parallel with bed) and the same tool (opposite end) will face the end of the part that is being turned.
The pair in the middle are purchased tool holders for small triangular inserts but I machined the blank end to handle an insert also. This converts it to my kind of tool that cuts from both sides of the QCTP.
The pair on the right is another set of shop made tools. They are also 1018 3/8 steel with small square inserts for facing and chamfering on the back end.
The tool at the top was too large for my lathe but it works fine now. The last two pictures show this tool in better detail. It is commercial in manufacture but I milled it down to 1/2" thick so it would fit my tool post. Probably too large for my little lathe but great for roughing. I will grind the inserts with little to no nose radius and just re-grind it when it breaks. Great for removing scale on hot rolled steel.
I like your modifications by machining the blank end of the tool holder to handle another insert and all the additional position options this provides. Great idea about regrinding old inserts and re-purposing these for removing scale on hot rolled steel.
By the way, I had to replace all my imported QCTP tool holder set screws with USA made dog point set screws. The original ones that came with the tool holders didn't last long and set screw cup points tend to mar the tool holders. Dog point set screws hold well and don't mar the tool holder surfaces.
Thanks Paul, I checked all of the QCTP holders that I have to verify that they were in fact dog point. They are all dog points, however it seems that the quality is a bit lax. The dog is not flat! I guess that is why they are leaving marks on my tools. I will keep an eye out for a box lot special and pick up at least 50 of them.
Google for "dog point set screw images" (but without the quotation marks) and you will see what these look like. The ends of the set screw are flat and without a thread so when tightened down on the tooling, the set screw leaves practically no marks on the tooling. I use the word "images" in most of my google searches because I find it easier to first see what I am looking for than click and read, only to find it is not what I am looking for.
Last edited by Paul Jones; 09-09-2016 at 04:57 PM.
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