Myford induction hardened beds

My early Super 7 power cross feed model has an induction hardened bed however there is no riveted plate signifying this present on the front face of the bed (I have the original receipt for my machine stating the hardened bed was specified at purchase)

Am I correct in thinking that prior to the plate being fitted the Super 7’s were painted white between the two bed faces to signify the induction hardened bed, instead of the usual cream paint for the standard bed?

Don't know about the paint but Myford still sell the "Induction Hardened Bedways" plate on eBay if you wanted to fit one.

An easy upgrade then.

As an ex Myford (Beeston - 60s/70s) employee, l can confirm Induction Hardened Beds we’re painted a different colour to the standard bed. But sorry I cannot remember what colour that was.

May I suggest you talk to the ‘new’ Myford about this for confirmation.

Regards. Alan.

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MichaelG.

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Edit: interestingly, this is listed as suitable for the ML10

https://www.ebay.co.uk/itm/373512849086

Edited By Michael Gilligan on 21/04/2022 08:32:45

You could test the bed with a sharp screwdriver

When I bought my Speed 10 brand new from the original Myford many a long year ago I asked for the bed to be induction hardened. I was then told that this was not an option for the Speed 10 so I wonder if it was ever an option on the ML10 or Speed 10.

My big bore S7 was ordered with an IHB but the bed is the same colour as the rest of the lathe, and I'm fairly certain as the non-IHB version. It does have the plate, I don't think I'll be testing the bed though.

Usually CI beds etc are not hard-hard like hardened steel anyway. Just harder than untreated cast iron. So a scratch test could be a bit inconclusive.

My Warco lathe is meant to have an induction hardened bed, it has the nice shiny label but I'm not convinced it has been 'hardened', as you say a scratch test is inconclusive.

Tony

Anyone know how hard a cast-iron lathe bed can be made? I found some figures suggesting induction hardening could lift the hardness of ductile cast-iron from about 15HRC up to about 50. So not in the same league as HSS (about 65HRC) or Tungsten Carbide about 90HRC. Grey cast-iron is less suitable.

Seems to fit; although they don't like it much you can machine HSS with Tungsten Carbide and chilled cast-iron with HSS.

For best results items are induction hardened more than once. My guess is a hobby lathe only gets one pass because each quench risks cracking the casting and writing it off.

My lathe bed claims to be induction hardened and it's distinctly harder than my mill table which doesn't. Better than not bothering but don't expect miracles,

Dave

This local firm has some notes which may be of interest : **LINK**

http://www.inductionheattreatment.co.uk

MichaelG.

Hi again. Further to my previous post on IHBs.

The castings for the IHBs were cast from a more 'exotic' grade of iron than the standard beds, that was more suitable for induction hardening. Production runs for the ML10 were much smaller than the 7 series machines so probably not high enough to offer the option of Induction Hardening on the ML10 beds.

At the time the 7 series lathes were designed, these were serious Industrial Standard machines. These were later followed by the MiniKop, 245 and 280 series lathes.

I may have inadvertently misled one of the previous posters - The machines whether they had hardened or none-hardened beds, were always painted the standard Myford grey (unless a special order), it was the trough between the bedway shears that was colour coded to identify whether it was an IHB or not.

I suspect that I had left for 'pastures new' when the IHB name plate was introduced, so I cannot comment if colour coding of the beds continued after that.

Alan

Aha! So the trough down the middle of my bed was painted white, which checks out! Though now it's dirty grey...

Mine is a green IHB with the plate saying so and the middle of the bed is an off white.

That might explain why some of the Chinese lathes claiming to have induction hardened beds don't seem very hard in that area. (Quite soft in fact). If they don't use the higher, more expensive, grade of cast iron, it is not going to end up as hard as the better stuff.

Ah, I should have said "off white" - though dirty grey is a better description of mine! 20 years of cutting oil...

Thanks for replies,

Mine is a early Power Cross Feed with induction hardened bed lathe in original Myford grey before the changeover to green, however the trough is painted Myford green, which I had assumed had been repainted so I was going to repaint it the correct white, however on closer inspection the green looks to be original, there is no trace of either white or cream underneath it, so I will leave it as is!

Am I right in saying the hardening only extends into the bed a few thou deep?

Hi.

This is an opinion based on my observations of the induction hardening process while at Myford (Beeston). I am unable to back it up with any data.

The IH head moves along the bed and heats the top 15% of the bed shear depth immediately under the IH head. Once heated to the required temperature it is immediately quenched, thus hardening the material.

I would expect the upper surface of the shear to take on the full hardness from the process, and the material to be progressively softer as you go deeper into the material. There could (?) also be a tempering effect on the surface layers of the shears from the heat held deeper in the metal. The bed would then lose a little metal by the final bed grinding process.

So I would anticipate that that the FULL hardness depth to be only a few thou deep.

Alan