S50 valve chest cover is chilled

This topic has 7 replies, 5 voices, and was last updated 10 November 2019 at 18:58 by JasonB.

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9 November 2019 at 21:46 #436621
Lainchy
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@lainchy
Hi all,

I've machined the valve chest on the S50 today, which went really well, but when machining the cover, I've totalled the HSS endmill. I've only just touched off the edges of the cover because its SO close the finished dimension, but the casting is rock hard.

Ended up with emery cloth round a flat file. I have to machine the back flat though.

Do I struggle on? What are my options please… this is my first kit. I've read about annealing the iron, but I only have a plumbers type blow torch.

Many thanks

Ian
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9 November 2019 at 21:46 #9926
Lainchy
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@lainchy
9 November 2019 at 22:29 #436628
Baz
Participant
@baz89810
Send the casting back, they should replace it.
9 November 2019 at 22:35 #436630
Lainchy
Participant
@lainchy
Cheers Baz. Will try that.
9 November 2019 at 22:51 #436632
Jeff Dayman
Participant
@jeffdayman43397
Good advice to try getting a replacement one from the supplier. Hope that works out well.

For future reference though, should you run across a chilled casting you can not get a replacement for – you can buy a small piece of Meehanite or other continuous cast iron bar for very little money and machine the part from solid. A pic below of a steam chest cover for my 1 1/2" scale steam roller. The cylinders and all covers and the steam chests were machined from solid bar as mentioned. It machines beautifully and in small pieces is not expensive. Just food for thought.

I used several passes with an electric engraver tool (solenoid reciprocating type) to get the rough cast effect in the centre pocket.
9 November 2019 at 23:31 #436636
mechman48
Participant
@mechman48
Another option would have been to get a small outdoor BBQ light it up & put the item in the middle & leave it sit 'till its completely cold then it should be 'annealed enough to machine ok, or if you have a log burner / coal fire throw it in that & leave overnight, same result.

George.
10 November 2019 at 18:47 #436742
Lainchy
Participant
@lainchy
Thanks chaps. I will bear all the above in mind for the future. Email has been sent to Stuart… see what they say tomorrow.

In the mean time, I've been able to carry on with the valve rod and gland nut. Just a bit disappointed when one part gives me trouble though. I started to clean up the front, but it needs 0.5mm at least from both sides.Looking at the side of the casting, the shiny iron is perhaps 1mm deep on the back face.
10 November 2019 at 18:58 #436747
JasonB
Moderator
@jasonb
As has been said heat will work but you need it red hot for a while and then a slow cool down.

Carbide would more than likely cope with machining to thickness and the sides, if you are lucky the stud holes will clear the hard areas so HSS drill OK.
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