Model Engine Maker
Help! => Specific Engine Help => Topic started by: vcutajar on December 24, 2013, 06:26:11 PM
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Hi everyone.
I have started work on the MEM Corliss crosshead but had to stop because I wasn't sure which sequence of operations is the best.
(http://www.nam-engineering.com/cm/albums/userpics/10009/CORLISS%200195.JPG)
I am going to make it from a piece of 60mm BMS. There will be a 3mm flange at the end with a diameter of 51mm. The OD of the body of the crosshead will be 29mm and I need to make a hole through the body of 22mm.
So, to all of you expert machinists, should I rough out the OD to 29mm first and then make the 22mm hole, or is it better to do the hole first and then the OD of the body?? :noidea:
What do you think?
Merry Xmas to all.
Vince
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If you need to do it in two set ups....do the bore first...then mount on an arbor and do the OD and the flange.
If you can, do the whole thing ( ID and OD) in 1 set up if possible.
Dave
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I intend to do it in one setup (not removing it from the chuck). So bore first and then do the OD.
Vince
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Rough it first...including the bore....stuff moves around, stresses are released...so drill the ID, and rough the OD, put a parting tool in to get the flange face, then finish the OD, then bore the ID. Then finish the parting operation. If you have to, you can then mount in a 4 or 6 jaw or on an arbor to finish face the flange...but if your careful, you won't need to.
Dave
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Hi Vince,
I'm with Dave on this one - Rough out all round first - then finish bore first then mount on an arbor as my preferred choice.
However,
As you want to do it all in one hanging I would rough the bore to within a mm of finish then the OD down to plus a mm or so - no more than 2mm. Then do your finishing - the bore first followed by the ODs That way there's a minimum amount of stress on finishing - Finishing the bore then turning the OD down from 60 to 29mm may induce enough stress to distort the bore slightly especially in mild steel - always an unknown quantity when machining big lumps off though to be fair not so frequent when turning. It's a big lump of steel though - always a risk there.
Hope you don't mind the input after such a while
Regards - Ramon
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Thanks guys.
Vince