Hardening a replacement part

Jersey John · Nov 26, 2017

Hi folk

I recently acquired a Walter Dividing Head HU100E and sadly the direct indexing plunger / lever didn't work.

Walter HU100E - Broken part

On strip down a very small part was found to have snapped in two. I'm not sure Walter in Germany can supply a replacement part so I've made a replacement in 302 Stainless. The original Walter component was a ground and hardened item ...

Question is: Can I harden the 302 Stainless by heating and quenching in oil :confused:

... not done anything like this before.

All comments welcomed.

John :typing:

Red James · Nov 26, 2017

No, you picked the wrong material to make your part from. You need something like 1045, 1144, or a tool steel.

On the other hand, does the part really need to be hardened?

Jersey John · Nov 26, 2017

Well as for the material ...

I didn't have any other hard material as I only work soft free cutting steel EN1/EN8 and Stainless 302 so that could well be my first mistake!

As for "Needing" it to be hardened ...perhaps not as it's not a stressed part but tried to follow Walter's item.

Thanks for your comments

John :typing:

michiganbuck · Nov 26, 2017

QT OP:[so I've made a replacement in 302 Stainless. The original Walter component was a ground and hardened item ]...

likely that part will last a coon's age (a very long time) so should be fine IMHO...

Jersey John · Nov 26, 2017

michiganbuck said:
QT OP:[so I've made a replacement in 302 Stainless. The original Walter component was a ground and hardened item ]...

likely that part will last a coon's age (a very long time) so should be fine IMHO...

Thanks MB ... Well I guess as I'll be using the DH no more than 2 or 3 times a month so IMHO it "should" last

John

Peter. · Nov 26, 2017

Make it with a shallow taper so that if it or the holes) wears it'll still index centrally just deeper in the hole.

Jersey John · Nov 26, 2017

Thanks for your input Peter ... appreciated!

John :typing:

Clive603 · Nov 26, 2017

High tensile bolts are a quick'n dirty way to find a small piece of reasonably hard steel. Core hardness range for metric 8.8 bolts is quoted as Rockwell C23 to to C34 and a 10.9 (if you can find such) runs around C32 to C39. It's not a particularly well controlled parameter as it comes along for the ride with the important tensile and shear strength stuff.

Judging by where that one broke the original hardening was poorly controlled making it brittle at the large section change.

Annealed 302 barely makes it onto the Rockwell C range, its about 1 to 5, usually quoted as around B 80 so significantly softer.

Clive

Jersey John · Nov 26, 2017

Hi Clive

Thanks very much for the information and advice

... I did the "quick n dirty" with a 10mm SS bolt, right idea - wrong material!

I'll get my hands on a suitable HT bolt tomorrow and reproduce the part

John

billzweig · Nov 26, 2017

For maximum accuracy the plunger should be hardened. The whole accuracy of the head depends on the close fit of this part. As well a part like this made from soft material can easily deform making plunging it difficult. I would recommend making it out of A2 or D2 (or similar) steel, harden and grind to final size.If you do not have grinding capability, one can turn the part with carbide tool after tempering to about RC50. An alternative can be case hardened mild steel.

JST · Nov 26, 2017

It's not a complicated part. Make it to size from oil or water hardening steel. Get it thoroughly red hot with a torch, can be propane if you shield the part a bit, then drop it into the appropriate stuff, water or oil as appropriate.

Pull it out when it quits boiling. Polish an area on the part, and re-heat carefully until the polished area gets to straw-light brown color. stop heating (you can cool it in the quench again, that won't hurt it any.. The part is now hard, but not brittle.

It will probably be on-size, but if it is a little over and will not quite fit, just stone it to size.

Richard King · Nov 26, 2017

Or cut a small piece of the bar-stock and test it before doing your machined part **. I always heat it up to a cherry read and not orange or white. Also if you can pick it up with a needle nose pliers and stir it in oil instead of dropping it. I find dropping it in water you get fine cracks in the material. Rich

**I have no clue what part your referring to, just an observation on hardening
Rich

Jersey John · Nov 26, 2017

JST said:
It's not a complicated part. Make it to size from oil or water hardening steel. Get it thoroughly red hot with a torch, can be propane if you shield the part a bit, then drop it into the appropriate stuff, water or oil as appropriate.

Pull it out when it quits boiling. Polish an area on the part, and re-heat carefully until the polished area gets to straw-light brown color. stop heating (you can cool it in the quench again, that won't hurt it any.. The part is now hard, but not brittle.

It will probably be on-size, but if it is a little over and will not quite fit, just stone it to size.

Thanks for your input JST ... detailed and clear for me

... Once I get some suitable material I'll follow your method.

Thanks again

John :cheers:

Jersey John · Nov 26, 2017

Richard King said:
Or cut a small piece of the bar-stock and test it before doing your machined part **. I always heat it up to a cherry read and not orange or white. Also if you can pick it up with a needle nose pliers and stir it in oil instead of dropping it. I find dropping it in water you get fine cracks in the material. Rich

**I have no clue what part your referring to, just an observation on hardening Rich

Thanks for your responce Rich ... the part concerned is shown in the top left corner of the picture in my opening thread

John

JST · Nov 26, 2017

Oil hardening is indeed a less violent sort of quench. It may be better due to the change of section on that part.

dgfoster · Nov 27, 2017

If you want to know what alloy you are dealing with and hence confidently heat treat it, just buy some common as can be O1tool steel. It is cheap and widely available. Machine your part. Wrap tie wire around the part in a tight loop or two so you can hold onto it. Heat it a nice bright red color and then immediately quench it in ANY oil available by rapidly moving it up and down in the oil for ten seconds while it quenches and then just let it rest in the oil to further cool. Don’t just drop it in. Clean it off and then gently heat it to a medium yellow color and again quench it in oil. I will “guarantee” the part will not crack and will be at least in the mid 50’ Rc. Plenty hard and very durable. I have made hundreds of small parts like this using this method and millions have been made this way for many decades.

The method I am suggesting could be refined a bit, but for a one-off it will reliably work just fine.

Denis

Jersey John · Nov 27, 2017

JST said:
Oil hardening is indeed a less violent sort of quench. It may be better due to the change of section on that part.

Thanks for the further advice JST, again greatly appreciated

John

Jersey John · Nov 27, 2017

dgfoster said:
If you want to know what alloy you are dealing with and hence confidently heat treat it, just buy some common as can be O1tool steel. It is cheap and widely available. Machine your part. Wrap tie wire around the part in a tight loop or two so you can hold onto it. Heat it a nice bright red color and then immediately quench it in ANY oil available by rapidly moving it up and down in the oil for ten seconds while it quenches and then just let it rest in the oil to further cool. Don’t just drop it in. Clean it off and then gently heat it to a medium yellow color and again quench it in oil. I will “guarantee” the part will not crack and will be at least in the mid 50’ Rc. Plenty hard and very durable. I have made hundreds of small parts like this using this method and millions have been made this way for many decades.

The method I am suggesting could be refined a bit, but for a one-off it will reliably work just fine.

Denis

Hi Dennis

Thanks for the detailed response - most welcomed

Most messages are singing from the same "hymn sheet" which gives confidence since I've not needed to do this before.

Thanks again

John :cheers:

dgfoster · Nov 27, 2017

Jersey John said:
Hi Dennis

Thanks for the detailed response - most welcomed

Most messages are singing from the same "hymn sheet" which gives confidence since I've not needed to do this before.

Thanks again

John

Yes, the only reason I "sang" is to be sure you heard the entire hymn start to finish as some had done various parts of the song and a few had suggested different songs altogether.

Denis

Jersey John · Nov 27, 2017

dgfoster said:
Yes, the only reason I "sang" is to be sure you heard the entire hymn start to finish as some had done various parts of the song and a few had suggested different songs altogether. Denis

Humour too - Brilliant

- Thanks again!

John :cheers:

Hardening a replacement part

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