How hard is an induction hardened bed supposed to be

Hi,

I've just bought a Warco 290V, which so far is looking good. I have noticed a couple of nicks on the ways (undoubtedly caused by my own carelessness)

The lathe has an induction hardened bed, but I can't see it is noticeably harder than my unhardened sieg c2a (e.g. I can scratch it with a piece of unhardened mild steel). Does anyone know whether this is as it should be ?

Regards,

Dan

Hardened beds are not that hard, its more just to stop the surfaces picking up than making them as hard as a cutting tool.

My colchester student bed cant be touched with a vigorous filing so i'm assuming its induction hardened

As they were available either as is or hardened why would one choose one over the other?

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Price, I presume.

Probably a significant increment when new.

MichaelG.

My 280V is the same, I think the bed is slightly harder than the cross slide but not as hard as an industrial machines bed.

Steve

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You need a new file.....................

Or better still a good sharp Stubs file if you have one. One of those will scratch mine but it wouldn't be much fun trying to remove a significant amount of material this way. It would go through ordinary cast iron pretty quickly.

I'm fairly sure my Boxford is induction hardened as it has seen some use and the surfaces are still nice and smooth where as the unhardened ones tend to get a sort grainy scratched surface to them - at least the unhardened ones I have had do. There is some wear on the cross slide which indicates a fair amount of use so I always wonder why they don't harden them as well.

John

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Ive just uploaded a quick youtube video of me attacking the bed of my student with a new file ( british made etc) and as a sample a piece of silver steel

Theres a massive difference in hardness

The file does just glide over the bed cuts easily in the ss

https://youtu.be/d9P5AfjZl7w

Very hard to find figures, I did find an article that quotes cylinder liners as being hardened to HRC 47-49, which is about as hard as an Axe - which is soft enough to file, but still hard enough to take an edge (in steel).

Neil

Yes, that looks pretty hard to me!

That is certainly a lot harder than mine - If I did that would shortly have a pile of filings on the floor instead of the lathe.

I might give warco a call to see how hard they are expecting it to be, would hate to have the one which somehow skipped the hardening section ...

Can you flame harden cast iron? I have seen beds where there was a colouration along the bed associated with hardening. Just like tempering colours. I have not yet come on one that is so hard I could not use a file on.

Clive

Just one more thing re my bed

It does not have any serial number on it...certainly where it should be at the tailstock end between the vee and the way

Does that mean its been reground? how much would be taken off in a regrind?

Its also worth bearing in mind that induction hardening is similar to case hardening so depending on time and current will only penitrate so far into the surface. So you could still have a hard surface but softer iron below so any knocks will dent the metal just like unhardened. Much like case hardening the surface can be made about 5 times more resistant to wear by induction hardening which is what you are after on a lathe bed not being able to hold a cutting edge

J

Beds have been flame hardened. From what little I can find on the subject flame hardening is usually deeper than induction hardening which can be controlled. Flame has more risk of distortion. There used to be a video knocking about showing a bed being hardened. No luck finding it. Bed goes red followed by a wash with water. It was pretty crude really, might have been flame or induction. I can't remember.

The ML7 I had was harder than my ME10 but still had significant wear. It was easily possible to measure it across the width of the ways, not so easy on the thickness. The wear on the saddle and gib strips was very significant. I found I couldn't easy lap the bed to even out the wear.

Boxford appear to have started offering it when they introduced the under drive lathes. Theory has it that they used up the rear drive parts by making ME10's. I vaguely recollect an advert for ME10's with hardened beds at no additional cost - sort of why buy Myford type of thing. They were rather well equipped as well, not that I ever use the powered cross feed. People have also bought VSL's with hardened beds and most other types.

It's interesting that this is a student as I have used the square head models and there was no mention of a hardened bed. I'm sure it would have been mentioned if they were.

John

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Usually and for some time now if a significant amount is ground of the bed it's made up with stick on packing under the ways of the other parts. They usually arrange to remove about 0,030 which would prevent parts lining up correctly if they didn't restore the various heights. I'm not sure how accurate the 0.030" is or if more is sometimes removed. The saddle will have had strips added to the V's that rest on the bed if this has been done. Some reconditioners will also add wear strips. One even offered to convert my ML7 to a prismatic bed. That was a company in Worcester but I don't think they are around any more.

John

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Dan, I think you have started something here, hundreds of model engineers attacking their lathe beds with large files, think before you act, what if it's not hardened? thousands of pounds worth of treasured machinery reduced to scrap at a stroke or two.

Consider the non-stick saucepan!

Dave

The Raglan Little John had a neat solution - hardened and ground replaceable steel strips fitted to the bed.

Neil

The strips were very hard Neil and could still wear on the edges. I persuaded some one to clock them up on a grinder and remove the wear. They did a perfect job I didn't even need to redowel them to the bed - a bit of a relief because at the time I couldn't touch them with a drill. It just skidded and wouldn't mark them at all.

Going one the swarf hidden in corners, brass and conduit steel it had just been used by pipe fitters in some factory or the other.

At work we purchased a new large Colechester lathe, which is made in China. The superbly ground bedways on that are extremely hard.

I remember a couple of years ago speaking to a chap at the Harrogate Show. He had bought a version of the Warco 280/290 lathe from a different supplier. He liked the lathe but was very dissapointment with how easily the supposedly hardened bedways were becoming scratched and scored. I assume he wasn't using it for sanding and grinding.

While some of the low cost lathes may go through the motions of hardening, it can sometimes just result in a bed that is a bit harder than one that hasn't, if at all, rather than a glass hard surface.

It also depends on the grade of iron used. I remember some years ago that Myfords adverts for the long bed Super 7 lathe stated that it was not available with a hardened bed. Thinking this was because of some highly technical reason with the Induction Hardening process itself, I asked John Moore of Myfords about it during one of their open days. He replied that it was simply because he had 60 raw long bed castings in stock that were cast from an iron that could not be hardened.

Regarding the removable Raglan bed guideways mentioned by Neil, I removed them from a Raglan 5 I once had and took them to Myfords for regrinding. They were rock hard, and a superb job they did of regrinding them, and the underside of the saddle.

The Warco 1330 lathe that I bought new about 10 years ago has a somewhat hardened bed. But after just several hours use I noticed a scuffing pattern appearing on the front vee way.

Removing the saddle to look underneath at the mating bearing surface revealed the most appalling scaped surface I had ever seen. Checking with Engineers Blue revealed just three pin points of contact with the bed surface, which easily broke through the oil film. A shame as the bed itself had an excellent finely ground finish. After several hours spent correcting things the bed remains otherwise unmarked to this day.