Off Center Turning on Lathe

[brino]

I made one from aluminum last weekend.
It was based on something I had seen online the week before..... maybe the same source your wife saw.....

I get some pictures tonight......

Brian

 

[jbobb1]

I made something similar for my wife also out of aluminum I had on hand. It really wasn't as hard as you'd think.

 

[markba633csi]

Waste of good brass if you ask me

People will do anything to get on youtube

 

[brino]

okay below are pictures of mine.

I usually do NOT go in for things that are just ornamental, but this one piqued my interest.
I think it's due to the mathematical possibilities.

I started with a piece of 1-inch diameter aluminum.
That means the circumference is ~3.14 inches.
That divides nearly evenly by 5/8" (0.625) to give about five steps around.
I laid out a piece of masking tap on the bench and marked off six pencil lines 5/8" apart.
I wrapped the tape around the bar and the end-most marks were basically coincident.
I set it up in the 3-jaw with a pencil line in the middle of jaw #1 and a scrap of 1/4" thick aluminum under jaw number two.
I stepped one parting blade away from the free end and made a plunge cut until I could hear the cut was continuous, that is, just under the interrupted cut cause by the off-centre turning.
for each subsequent cut I simple rotated the top of the workpiece towards me, with the next pencil line in the centre of jaw #1, and the spacer again under jaw #2 and stepped the parting tool over by one width.
while on the lathe I gave it a quick sand and polish.

One beauty of this process is that you can have a minimal amount sticking out of the chuck.
For each step or two you can pull it out further, just mind the pencil mark and the spacer.
You just need to index the cutting tool from the last edge to move to the new one.
I used a dial indicator off the carriage.

I wish I had the CAD knowledge to make a parametric model, so I could play with:

• the stock OD,
• the offset (spacer under jaw),
• the number of steps around,
• the diameter of each land,
• the width of each land

It is mathematically beautiful.
Think about the parameters required to leave a hollow down the middle of all those steps.
You could drill the end and insert a centre rod of a contrasting finish.

Brian







View attachment thing3.mp4

 

[Parlo]

I tried two methods, milling and turning.
I did not like the idea of constantly moving the part in the lathe chuck so I devised my own method.
I liked the idea of running unattended so I milled one instead.

Eccentric turning a candlestick -

Eccentric milling a candlestick -

 

[brino]

I tried two methods, milling and turning.
I did not like the idea of constantly moving the part in the lathe chuck so I devised my own method.
I liked the idea of running unattended so I milled one instead.

Those look great!
I really like the thin disks you did, and your photos and video is way better than mine.

Brian

 

[Chewy]

Parlo, really nice job. I will try this whe I get some time. As far as being a waste of brass, everything is a waste of metal unless you are being paid for it. Why else would some one like Jo Pi spend a month making a brass navel canon that can't be fired.

 

[Parlo]

Parlo, really nice job. I will try this whe I get some time. As far as being a waste of brass, everything is a waste of metal unless you are being paid for it. Why else would some one like Jo Pi spend a month making a brass navel canon that can't be fired.

Mine was from some spare Aluminium.

 

[Joe Pie]

Parlo, really nice job. I will try this whe I get some time. As far as being a waste of brass, everything is a waste of metal unless you are being paid for it. Why else would some one like Jo Pi spend a month making a brass navel canon that can't be fired.

Greetings Chewy. I hope you get a chance to read this. making that brass naval cannon was a bucket list item for me and required some tricky machining to complete. Rotary table specific for the trunion straps and chain eyelets. As for your comment about it not firing, you are correct, but the barrel was intentionally left deep enough for it to be bored deeper and with an added fuse hole....BANG. But, YouTube has many policies covering home made firearms, so I decided to keep it a static model for the series to stay within the platform guidelines. Who knows what happen once the cameras stopped rolling ?

 

[RaisedByWolves]

Greetings Chewy. I hope you get a chance to read this. making that brass naval cannon was a bucket list item for me and required some tricky machining to complete. Rotary table specific for the trunion straps and chain eyelets. As for your comment about it not firing, you are correct, but the barrel was intentionally left deep enough for it to be bored deeper and with an added fuse hole....BANG. But, YouTube has many policies covering home made firearms, so I decided to keep it a static model for the series to stay within the platform guidelines. Who knows what happen once the cameras stopped rolling ?

With your channel being what it is I can see your concerns.

However there are people making nitro glycerin and blowing stuff up with it.

I doubt however if those types would be out much if they lost their channel though.