By continuing to use this site, you agree to our use of cookies. Find out more
Forum sponsored by:
Forum sponsored by Allendale Until July 27th

Heat hardening?

All Topics | Latest Posts

Search for:  in Thread Title in  
Steve Crow20/03/2019 17:58:31
108 forum posts
22 photos

In "Watchmaking", George Daniels describes how he hardens a tourbillon bridge by placing it in a box turned from a copper disc before heating.

My question is, why copper?

Is there any reason I can't use brass or mild steel for that matter?

Cheers

Steve

jaCK Hobson20/03/2019 18:13:33
163 forum posts
20 photos

Copper has the best thermal conductivity so better for even heat. I think you could get acceptable results with other materials. Dimensional stability during quench could help.

Steffen Pahlow https://www.youtube.com/watch?v=nT2oVtc5wh4 seems to use sandwich of steel parts held together with binding wire.

https://watchmaking.weebly.com/tourbillon-bridge.html just wraps in binding wire - I would be surprised if the dimensional stability of the wire contributed to reducing warping. Daniels uses binding wire approach for other things - helps retain heat for really small items like pivots and holds borax to reduce scale.

 

Edited By jaCK Hobson on 20/03/2019 18:19:55

John Reese20/03/2019 20:26:32
742 forum posts

Check out Clicksping's You Tube videos. He wraps his parts in fine iron wire and coats it with a paste of boric acid and denatured alcohol before hardening. That prevents scale formation during hardening. Cliclspring uses a pan of brass chips when tempering small pieces. That assures even temperature around the parts. Steffen Palhow's method using a copper plate is ideal for flat parts. If tempered using an open flame there would likely be some temperature differences in the part resulting non-uniform color. The tempering to a specific color could also be done in a controlled temperature oven provided the parts were left in long enough to reach uniform temperature throughout.

Michael Gilligan20/03/2019 20:56:27
avatar
13234 forum posts
578 photos

Thanks to 'Google Books' there is no need for me to dig-out my copy of 'Watchmaking'

The description is on p312, but the additional text on p318 is important: Daniels [ever the perfectionist] describes a process which is pretty-much certain to work ... any deviation from this carries risk ['though, of course, you may get away with it].

 

MichaelG.

.

https://books.google.co.uk/books?id=ZWq8c0xvGxsC&pg=PA318&lpg=PA318&dq=george+daniels+watchmaking+tourbillon+bridge+copper+box&source=bl&ots=P1v5cRgFW2&sig=ACfU3U2YIMYQNbiculM5H8g2d9199CEupg&hl=en&sa=X&ved=2ahUKEwjjvOT7ypHhAhVNOBoKHRvaDqoQ6AEwC3oECAkQAQ#v=onepage&q=george%20daniels%20watchmaking%20tourbillon%20bridge%20copper%20box&f=false

Edited By Michael Gilligan on 20/03/2019 20:56:50

John Reese21/03/2019 00:38:22
742 forum posts

The modern equivalent to enclosing the work in a copper box for hardening is the use of stainless steel foil to wrap the part.

Steve Crow21/03/2019 17:12:26
108 forum posts
22 photos

Thank you all. I've used the iron wire binding method before.

The reason I ask is that a brass one would double up as a blueing tray for brass chips.

Can I just add that I'm not making a tourbillon bridge!

Maurice21/03/2019 18:30:12
435 forum posts
50 photos

I once read a book by a retired blacksmith, who said that watchmakers, casehardened items by putting the parts in an old shoe, packed with salt and horses hoof clippings! I have no idea if it should or did work, but I bet it smelled wonderful !!

Maurice

John Haine21/03/2019 18:36:25
2541 forum posts
132 photos

Great descriptions of case hardening in Lautard's Machinists Bedside Readers, parts put in small clay flowerpots with bonemeal and other stuff. Smelt like a charnel house he says! This to produce nicely patterned parts for gun making.

John Reese21/03/2019 21:06:33
742 forum posts
Posted by Maurice on 21/03/2019 18:30:12:

I once read a book by a retired blacksmith, who said that watchmakers, casehardened items by putting the parts in an old shoe, packed with salt and horses hoof clippings! I have no idea if it should or did work, but I bet it smelled wonderful !!

Maurice

One of the old case hardening methods was to place the part in an airtight box surrounded by bone charcoal or charred leather, followed by prolonged heating, quenching, and tempering.

Michael Gilligan21/03/2019 23:15:55
avatar
13234 forum posts
578 photos
Posted by Steve Crow on 21/03/2019 17:12:26:

Can I just add that I'm not making a tourbillon bridge!

.

You certainly can, Steve ... It might ease my inferiority complex.

MichaelG.

jaCK Hobson22/03/2019 08:54:52
163 forum posts
20 photos
Posted by Steve Crow on 21/03/2019 17:12:26:

a brass one would double up as a blueing tray for brass chips.

I'm confident you could use a copper one for blueing.

Steve Crow25/03/2019 07:55:39
108 forum posts
22 photos
Posted by jaCK Hobson on 22/03/2019 08:54:52:
Posted by Steve Crow on 21/03/2019 17:12:26:

a brass one would double up as a blueing tray for brass chips.

I'm confident you could use a copper one for blueing.

The reason I want to use brass is it needs to be 1 1/2" OD and I have some scrap of that size.

IanT25/03/2019 09:35:05
1266 forum posts
128 photos
Posted by John Reese on 21/03/2019 00:38:22:

The modern equivalent to enclosing the work in a copper box for hardening is the use of stainless steel foil to wrap the part.

A slight drift off topic I'm afraid. I once wrapped a part in kitchen foil before annealing it in the incinerator overnight (thinking it would be easier to clean up after). Of course the aluminium foil melted and made things even worse...

IanT

Ian S C25/03/2019 11:02:05
avatar
7382 forum posts
230 photos

If you heat brass to hardening temp for steel, it will melt, copper takes a bit more temperature. I often use brass for brazed steel joints.

Ian S C

Steve Crow25/03/2019 17:27:40
108 forum posts
22 photos
Posted by Ian S C on 25/03/2019 11:02:05:

If you heat brass to hardening temp for steel, it will melt, copper takes a bit more temperature. I often use brass for brazed steel joints.

Ian S C

Thank you Ian. Back to the drawing board.

All Topics | Latest Posts

Please login to post a reply.

Magazine Locator

Want the latest issue of Model Engineer or Model Engineers' Workshop? Use our magazine locator links to find your nearest stockist!

Find Model Engineer & Model Engineers' Workshop

Support Our Partners
Eccentric Engineering
TRANSWAVE Converters
Ausee.com.au
ChesterUK
Warco
Eccentric July 5 2018
Sarik
Allendale Electronics
emcomachinetools
Subscription Offer

Latest "For Sale" Ads
Latest "Wanted" Ads
Get In Touch!

Do you want to contact the Model Engineer and Model Engineers' Workshop team?

You can contact us by phone, mail or email about the magazines including becoming a contributor, submitting reader's letters or making queries about articles. You can also get in touch about this website, advertising or other general issues.

Click THIS LINK for full contact details.

For subscription issues please see THIS LINK.

Digital Back Issues

Social Media online

'Like' us on Facebook
Follow us on Facebook

Follow us on Twitter
 Twitter Logo

Pin us on Pinterest