Thanks lads

I've been reading up a little on quenching and tempering as I need to make a couple of tommy bars, but then confused myself So I want something tough, not brittle but not something that'll bend! I see you quenched at 800C then tempered at 240. From what I read on wikipedia (could easily be wrong!) you tempered at the sort of top end of a stress relief type temp , any higher goes into the TME range - or is that just for carbon steels? I don't have the ability to heat to 800C so can't really harden, but if I tempered mild steel without quenching would it make the material tougher or just anneal it? Or could I just try to get the things cherry red, quench then stick in the wifes oven at 220 or whatever to temper?!
Hi Nick , I
hardened the part at 800c and tempered at 240c , 240c is at the low end of the tempering scale , the part is very tough but not brittle . I would not believe all you read on wikipedia .
Not only dose the part need to be heated to the correct temp for hardening and tempering but it needs to be held at temp ,its no good just heating the part up to temp then quenching. Rule of thumb 1 HOUR PER INCH OF THICKNESS.
Forget mild steel ,hot rolled or BMS its has a low carbon content , and wont harden , it can be case hardened . So you would need to get hold of some steel with a higher carbon content .
The house hold oven can be used to temper parts , have used it many times myself

My next question is, why do you need a super duper flycutter if the cheapo one gives you a finish like that on the parts of the new one?! Is it just because you want to put the collet thingys to good use or have you got a monster project in mind for it?!
I wanted a no brainer quick project as my shop is still in a bit of a mess from all the upheaval of moving machines , also wanted to make use of an old arbour and at the end of it all have a larger fly cutter for the new mill , no plans for using the fly cutter yet ,but there has been many a time i could have done with a larger one , so its another job knocked off the list .
Well its finished , being a lazy git I went for chamfers


did the cutter bar relief .




Min about 5" dia cut

Max about 9" dia cut

Cheers Rob