New 4-way tool post for the min-lathe.

[David Kirtley]

Building a new 4-way tool post for my mini-lathe. Material: Free steel block I snagged at work that was abandoned at the horizontal bandsaw. Alloy: Mystery Meat.

About the same size as the original but with the slot to fit 3/8 tool bits with very little shimming if any where the stock tool post maxes out at 5/16 bits. Maybe 1 or 2 pieces of coke can shim strip to bring on center. Top and bottom faced in the 4-jaw chuck on the lathe. Drilled in steps on the lathe. Milling done on my X2 mill. 1/4 endmill slot done all the way around the bottom then opened up with a 3/8 two flute mill once I had the clearance. It actually is deep enough for the tool bit but It is just sitting there so I can test with tailstock for height. First time to use my chamfering bit from the "Little Hogger" carbide insert endmill set.

Still need to drill and tap the clamping screws. It's late so I will probably finish sometime this weekend. The dimple was just defect in the block but it makes a nice index mark so it stays. I think I will go for 3 SHCS for each side. Maybe 1/4-20 unless I have some 5mm or 6mm long enough. Whatever is on the original so I don't have a bunch of different sizes to deal with. I might try to heat treat and give an oil quench finish but I would have to go buy some gas. Also not sure I have a burner that puts out enough heat to get a piece that big up to temperature.

I have no idea about the sizing of the pics. First time for me to post images here.

 

[David Kirtley]

Well, all finished. I got lucky and the carbide insert tool holders hit perfectly on center. I did some testing with different materials to see what kind of surface finish I would get. Aluminum was already good with the QCTP, so no big difference there. Then came the steel. 12L14 came out really nice. Best finish I have ever had with it. O1 drill rod was reasonable. About as good as I have been getting on 1018 before. I have some hardened 4140 that I tried (I get samples left over from materials testing class at work.) Well, I can honestly say that it cut and wasn't *that* bad. Previously when I tried turning it, you could see the whole tool post and compound flex and the finish looked like I had just spun it on an angle grinder by hand.

The set screws are 5mm. I was going to put 6mm in it but I realized I had picked out the wrong tap and drill and I just went with it. I like that they are less in the way than the original holder. They have about one full turn left when tightened down.

Overall impression is that I am really glad that I made it. It was a quick project spread out over 3 evenings. First evening squaring up the block. Last night milling it. Today was just drilling and tapping the set screws and playing with test cuts with different materials. The fact that I don't have to shim it will make it a lot more usable than the original that came with the lathe. It is much more rigid than the A2Z QCTP toolpost. I won't get rid of the QCTP but I will most likely only be using it for my smaller HSS tools. Now I need to grind a parting tool and a boring tool to use in it.

 

[genec]

How do you raise and lower the cutter for centering.

 

[David Kirtley]

This type doesn't raise and lower. If the height was off, I would have to put a shim under it to bring it up to center. I made this one to fit the insert tooling without shims so it doesn't matter.

 

[papermaker]

Nice job! I like home built tooling.