Rounding off brass rod

[Devin]

I admit, I just do not understand how this is not working, so hopefully someone can enlighten me.

I have a solid brass stock, chucked it in the Dremel, ran it at high speed, put various files and sanding sticks to it. Since it's spinning at high speed it should be perfectly symmetrical, I thought. But, as you can see in the photo below (primed so it shows up better), I'm ending up with different degrees of roundness at different points around the radius. Even if the rod is flexing in the Dremel chuck, shouldn't it still be the same all of the way around?

This is one of the many reasons I am not a machinist, because I don't understand how this is possible. Can anyone enlighten me and give me some ideas how to fix this?

Thanks.

[Mike Reading]

Yes the problem is very likely slackness of the bearing and/or spindle holding the chuck and/or that the chuck itself is not perfectly symetrical. Sadly there is no substitute for a lath when really accurate work is required.

If the rounded end of the rod does not have to be that prcise, have you tried mounting the rod in a pin vice/the like, and then simply rotate it in your fingers and apply the file. You can see how it's going and easily make corrections, finishing off at the end with emery/the like to get a smooth finish.

Hope might help
Regards
Michael Reading

[poulw]

I don't think a Dremel tool is stable enough for that purpose. After all it is a hand tool.
As I have no access to a turning lathe, I use fine files and my drill press when I have to round the end of a rod (being acrylic, brass etc.) and polish with fine sand paper.

Here are two examples:

The ship's bell made out of a 3mm brass rod



A paravane using two copper pipes (1.5mm and 2mm) and a core of 1mm brass wire inside each other

[carr]

..

[Devin]

Thanks for the feedback, everyone. I do have a benchtop drill press that I can use. I'll give that a go.

[Devin]

The drill press came to the rescue. Thanks for the help, everyone!