# Turning small & slender parts



## MuellerNick (Jan 24, 2013)

Hi!

NOT my idea, but an old trick (some might not know).
How do you turn small diameters without bending the part?

Start with a "big" stiff stock, and cut in a *single* pass. Might require some test cuts to get the right diameter.

Here is a video:
[ame="http://www.youtube.com/watch?v=MoadFewMlzA"]YouTube[/ame]

If you have questions, ask!

Nick


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## Jordan (Jan 24, 2013)

Thanks Nick.
How did you control the profile of the part?

I like your verniers - the metric/fractional inch type are a useful format. I can't find them on Mahr's website. Anyone know who sells them?

Jordan


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## lensman57 (Jan 24, 2013)

Hi Nick,

I have only been in this hobby for less than 2 years, that is exactly what I taught myself to do as soon as I learned that to turn a 1.5 mm shaft out of 2 mm stock is not going to work, that seems a long time ago. I rather use a 5 or 6 mm free cutting stock and turn in one pass, there is wastage but it works for me, the other trick is to use the sharpest HSS tool that I can grind, normally I don't bother with carbide for such small work. 
Thanks for sharing the video and I did enjoy your video on scraping, I may have to ask some questions about that later.

Regards,

A.G


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## MuellerNick (Jan 24, 2013)

> How did you control the profile of the part?



I know it's unfair, but that is my CNC-lathe (400 * 1300 mm, almost 2 tons).



> I like your verniers ...


I don't like these. The imperial "crap" doesn't serve me. The finish is Chinese (yes, Mahr makes calipers in China). I complained about the quality at the representative. I also do have a digital Mahr caliper that is just excellent. And a Mitutoyo "mechanical" with prismatic ways. One of the best calipers you could get (but very pricy).



> the other trick is to use the sharpest HSS tool that I can grind


Yes, lensman, you are absolutely right on that!
You don't get the right surface speed at these diameters anyhow. HSS is more forgiving in that respect. Also, you have to reduce cutting forces by all means. Carbide inserts for Al would work too, they do have sharp edges. Also, use a small (if any) tip radius. That reduces the forces along the X-axis.

Nick


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## MuellerNick (Jan 25, 2013)

A few more of those huge parts. 




The rod in the topmost is 30 mm long, diameter is 1.4 mm. But here, it already deflects. Stock was ø10 mm. Increase in diameter was 0.13 mm at the very right. I could correct that by commanding to turn a cone. But this part doesn't have to fit into something, just a hole that can be drilled to match.


Nick


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## trumpy81 (Jan 25, 2013)

That is some very nice work Nick. I'd have a hard time trying to replicate it on my Sherline CNC gear that's for sure!


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## Topos (Jan 28, 2013)

The simplest is at the same time the most elegant.

Thank you for your kindly showing.

One use is to machine a firing pin for outdated firearms.


Best.


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## Rivergypsy (Jan 28, 2013)

Nick, top job, I was going to post the same thing. Back from when I was doing 1/32  posts on a Colchester. Nice one


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