MT 6 1/2 One Piece Dead Center

[erikmannie]

I worked on one more of these today which is made out of hot rolled 1045 steel.

I have the angle set correctly (using the compound). I just need to bring down the diameter more, & make sure that I get the best finish that I can get.

A friend of mine is coming over tomorrow who has worked with taper attachments for a long time. I have still never tried my taper attachment, but he is going to get me started.

 

[erikmannie]

It should go without saying that I used a live center for my work. I moved the tailstock away to take measurements before I took this photo.

I did this all in one chucking. I used carbide inserts to rough it down, & HSS when I got closer to the final dimensions.

I will do the base (a cylinder of reduced diameter) & the tip (a temporary 60° tip) after I fine tune the taper.

I will have to part it at the end.

Everyone can see that I am having issues with the finish. I can get a great finish with my A6 carbide inserts if I take an (oil cooled) .075”-.100” cut (off of the radius) at 380 RPM using the power feed at .004” per rev.

Using the compound for the taper, I never could get a good finish. I used HSS because I had to be as quiet as possible after 7 PM (reduced RPMs) because my neighbor is a complaining crybaby. I will be able to go back to the carbide tomorrow morning to bring the taper down to final dimensions (another .050” off the radius).

Does anybody have any recommended starting settings for using the carbide insert to take .050” off of the radius?

 

[erikmannie]

After this one, I’m going to make 2 more. I will be using the taper attachment. I am sure that I will be able to get a better finish with the power feed.

 

[erikmannie]

I have done all that I can do with this one until I put it in the spindle nose and cut the 60° tip.

I have my compound set now to the correct MT 6 1/2 angle, and I have still not tried my taper attachment. I don’t want to lose that setting until I am sure that I can get the taper attachment going.

The dead center on the left is the one that I just made. The sleeve on the right is from the factory.

 

[macardoso]

Great finish for hot rolled IMO. Using something like stainless or 4140 prehard will yield a much better finish but be a lot harder to machine down. All a question of how much you will use this.

Since this isn't hardened, you'll wear the tip over time. I'd give yourself as much length on the tip as you can tolerate so you can skim it many times to recondition the point (as needed).

 

[erikmannie]

I made my third one of these today.

Everything was wonderful in the first 2 photos, but then tried to chuck the front in order to face off the nubby left after the parting operation.

There wasn’t enough of a shoulder to grip the work so, long story short, I had to finish this stubby dead center with (1) a flap disk on the bottom, (2) wire wheel, (3) 80 grit and then 220 grit sandpaper, & finally green Scotch Bright.

At least I got rid of the chuck marks.

 

[erikmannie]

Here it is finished. I am kicking myself to have finished it with my welding tools. Such a poor, scratched finish.

This is 1045 steel. I wore out four A6 carbide inserts making it. It took me 7 hours from raw stock to this:

 

[7milesup]

Looks good. I don't understand the comment about the welding tools though.

 

[davidpbest]

Too bad your chuck doesn't have 2-piece jaws - you could have made soft jaws to hold the tapered part when you turned it around. Looks like you got what you need out of it though. Nice job.

 

[erikmannie]

Looks good. I don't understand the comment about the welding tools though.

I was considering a flap disk, wire wheel & sandpaper “welding tools”.

I HATED that scratched finish so I chucked it up at the bottom and fixed the finish with files & 80 grit emery cloth. Well, time to clean ALL the grit off the lathe.