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Posted by dave sanderson on June 20, 2008, 3:54 am
Please log in for more thread options On Jun 19, 8:27=A0am, jontom_...@hotmail.com wrote:
> wrote:
>
> > Evening all,
> > before I commit to making several little bits form Ti I thought Id ask
> > the more knowledgeable about machining it.
> > The parts I have in mind are:
> > 1, a Bar about 3mm dia, 10mm long tapped M2 in each end and cross
> > drilled 1mm in the center
> > 2, flat plate with 3 M1.4 tapped holes in it
>
> > I have no idea what grade of Ti to make them from, thats on my list of
> > things to find out.
> > They are parts for a micro helicopter, currently made from alloy or
> > steel.
>
> > Dave
>
> Dave Hi, not as difficult to machine as many like to make out but it
> does benefit from a couple of particular techniques. In general,
> depending on particular alloy, you should use a cutting speed of at
> least 150 sfpm with a reasonable depth of cut and fairly high feed
> rate. We would have used something like 200 sfpm with a depth of cut
> no less than 0.010" and a feed rate of 0.006" per rev for finishing.
> While we used C2 grade carbide HSS is perfectly OK but must be kept
> very sharp, if you hessitate and the tool squeaks the tool will be
> blunt and the Ti might well work harden and be difficult to finish,
> With small diameter bar this speed might be difficult to achieve but
> you get the general gist. Tool sharpness is the most critical factor.
> Plenty of coolant and here your intended use is important, if you are
> going to use it in a fatique critical area then the type of coolant is
> critical. Soluable oil (at 15-1) works OK but for critical aerospace
> components avoid chlorinated oils. Dry machining is possible but it is
> quite possible to start a Ti fire and you wouldn't want that, believe
> me. Don't stop feeding when the tool is in contact with the work
> unless you want to re-sharpen. The material is quite flexible and will
> push away from the tool unless good support is provided.
>
> Have a look here as it has been mentioned before and there are a
> couple of good links that cover the various grades and machining
> hints:
>
> http://groups.google.co.uk/group/uk.rec.models.engineering/browse_thr...
>
> best regards
>
> Keith
Thanks Keith, good pointers. Guess Ill obtain some small bits and see
how I go. :)
Dave
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> before I commit to making several little bits form Ti I thought Id ask
> the more knowledgeable about machining it.
> The parts I have in mind are:
> 1, a Bar about 3mm dia, 10mm long tapped M2 in each end and cross
> drilled 1mm in the center
> 2, flat plate with 3 M1.4 tapped holes in it
>
> I have no idea what grade of Ti to make them from, thats on my list of
> things to find out.
> They are parts for a micro helicopter, currently made from alloy or
> steel.
>
> Dave