Technique for turning 3mm diameter valve spindle

[Matthew EllisParticipant @matthewellis85598]

[Matthew EllisParticipant @matthewellis85598]

Can anyone point me to a good tutorial for turning a smallish valve spindle please (for an SM32 size loco)?

The rough dimensions are total length 40mm of which 25mm needs turning down to 3mm from 5mm, and I am unsure how to keep the piece supported to keep the 3mm part running true.

I have a Warco WM180 lathe if that matters.

Thanks.

[JasonBModerator @jasonb]

Small BS-0 ctr drilled hole in the end and use your tailstock ctr to support the work, can be made over length and the bit with the hole in turned off if you don't want the hole to remain. Do all my IC engine valves this way which is the same sort of process.

 

Edited By JasonB on 15/05/2019 07:44:08

[HopperParticipant @hopper]

Use a good sharp toolbit and it should be ok. No need for special support at 3mm diam by 25mm long. I would use a good sharp HSS knife tool to minimize cutting forces, take one cut to slightly oversize then one finishing cut of just a few thou.

[Paul LousickParticipant @paullousick59116]

Just turned on my computer after spending the afternoon making valve spindles.

These are for 6mm globe valves and made from 316 stainless. The round bar was held in a collet chuck (more accurate than my 3-jaw) with only a small amount protruding from the chuck to prevent any bending. Each section turned to size and the spindle extended a bit further in the chuck to do the next section.  The small end then threaded M3 and the larger M5.  The spindle then cut from the bar stock.  I then changed collets and held the spindle by the M5 thread to finish turning the head end.

Paul.

 

 

Edited By Paul Lousick on 15/05/2019 07:26:25

[Matthew EllisParticipant @matthewellis85598]

Thanks to everyone who replied (very quickly!)

Now I jiust need to decide which method to try first..

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