Machining advice

[Joe Lavery]

Hi all,
A bit of advice if you will, for what I find to be a complex problem, but not I suspect to many of you
I'm building a 737 throttle for a flight simulator and I've bought some blanks for the handles which are shaped as shown (see images).



My problem is they do not come drilled or machined, but to give you an idea one end is drilled and counter bored to take a switch. that I can do albeit awkwardly. The main problem is the opposite end, which needs to have a pocket shaped roughly like a pie slice removed, in order to mount the lower part of the handle. I do have a small CNC machine that I'm sure would be capable of doing the cutout but I'm at a lose as how to hold it without marking the rim. The images below show the cutout and the opposite end of the handle.



If anyone has any ideas to help, in terms of holding the handles and a method of machining the cutout. As I've mentioned I have a small CNC machine, a pillar drill and a table router.
Any advice would be most welcome.

Regards
Joe.

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[awerby]

It's not clear (to me at least) exactly which piece you need to hold onto, but in general, you want to disassemble the thing as much as possible before trying to machine it. Take advantage of any holes that are already in it to use for mounting screws, and secure those into a base block you can hold down to your mill bed or hold in a vise. If there are any especially weird shapes still in the way, you can use a fixturing plastic like Jett Sett to cast a rectangular block around them you can then hold onto: https://www.riogrande.com/Content/Je...mpound-VID-psd

[Jim Dawson]

If it was a cylinder it would be easy. But the spool shape is more complex, I had to think about it for awhile. I might build some tall MDF soft jaws for my mill vice, pocket a hole the length and the major diameter of the part. Use a couple of 2mm or so shims to space the jaws when pocketing to get some squish space. That would at least grab it around both ends. Maybe some electrical tape around the part in the center just to bring it up to the same size as the ends for added hold. Then when you mill the ''pie slice'' out of the end, it will still be captured about 75% on the end you are working on. Mill right through the MDF. I have held a number of parts using that method.

[Joe Lavery]

Thank you both for some very good advice,

Building some sort of soft jaw seems to be the way to go, so I'll have a think on that and see what I can come up with.

I'm sorry Andrew if I didn't explain very well which part I was talking about, in the world of flight simulation you tend to think that everyone else knows the parts of an aeroplane. And of course the reverse is true when I enter the world of a different specialty, like CNC or electronics, (where I'm mostly in the dark).
So to clarify this is the part I'm talking about in its raw form. It's the larger knobs are the main concern, although I'll need to tackle the others at some point.



Thanks again,
Joe.