Steel for machining

[John Paton 1Participant @johnpaton1]

Adam, where do you live?

Our local blacksmith had two lengths of hexagonal cast iron about 80mm across. I have one of them (which I wish to keep) but if you are local / happy to collect I can see if they still have the other one.

They were offcuts from a bespoke lamp column and are' blinkin heavy'!

I can nip out to the workshop and give you an 'across the flats' dimension if interested.

[Adam HarrisParticipant @adamharris13683]

John that is a very kind thought but I am going down the route of casting (with hollows in the pattern)

[John Paton 1Participant @johnpaton1]

The overam on my Centec is solid with a separate ''hanger' with dovetail fitting and a bronze bush to support the arbor. There is / was an aftermarket overarm made for the Centec with dovetail slide in the top also and this both raises the vertical head slightly and also allows setting up in horizontal mode without the need to remove the vertical head assembly. This arm is about 100mm wide by 50mm thick and has never shown any indication of flexing, which is why I thought the CI section might just suffice (I have measured it – 90mm across flats). I am sure the height will be good if the width is sufficient to get the vees to match your mill.

(I got my bit for free but that might be because I live locally and am on nodding acquaintance with the blacksmith – there again he may just have a problem throwing 'potentially useful stuff' away!)

[Adam HarrisParticipant @adamharris13683]

Thanks again John but the casting looks like it will be the simplest option and if a pattern with hollows is too complex/expensive then I will make a solid cast and simply bore out some excess weight from the underside.

[JasonBModerator @jasonb]

Keep us posted on the progress and machining Adam, best in a new thread I think.

It will be interesting to see if you can do a core with the lost foam process. More likely you will need to make a traditional solid pattern and a separate "core box" to cast the sand core in.

[sean logieParticipant @seanlogie69385]

Posted by John Paton 1 on 08/10/2018 15:41:58:

The overam on my Centec is solid with a separate ''hanger' with dovetail fitting and a bronze bush to support the arbor. There is / was an aftermarket overarm made for the Centec with dovetail slide in the top also and this both raises the vertical head slightly and also allows setting up in horizontal mode without the need to remove the vertical head assembly. This arm is about 100mm wide by 50mm thick and has never shown any indication of flexing, which is why I thought the CI section might just suffice (I have measured it – 90mm across flats). I am sure the height will be good if the width is sufficient to get the vees to match your mill.

(I got my bit for free but that might be because I live locally and am on nodding acquaintance with the blacksmith – there again he may just have a problem throwing 'potentially useful stuff' away!)

That's strange that you're Centec overarm is solid mine is a hollow casting .

Thanks

Sean

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