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Electric resistance rivet heating


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#1 monstermetal

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Posted 22 November 2010 - 11:11 PM

In this video they use a machine that looks like a spot welder that has water cooled shoes and is used to heat rivets. I have done a bit of research and at least learned that this machine is not a spotwelder but specifically built for the task.

Has anyone ever used or seen one of these? Could a spot welder be modified to do this?

Locomotive riveting

I know there are other ways, I am really just interested in information on this method
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#2 bigfootnampa

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Posted 22 November 2010 - 11:56 PM

I think that most spot welders will be too light duty for that kind of use. A big old arc welder might do it though. Well on second thought maybe you will be setting somewhat smaller rivets, in which case a spot welder might be adapted to do the job.

#3 JosephPrivott

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Posted 23 November 2010 - 01:06 AM

seems like a smart way to heat those rivets up; maybe you could wind your own coil and make a hefty 'spot heater' with old arc welder tolerances?
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#4 Nakedanvil - Grant Sarver

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Posted 23 November 2010 - 01:31 AM

Given the speed of heating, I don't think it's more than 5 - 10 KW. That one looks suspiciously like a spot welder, doesn't it?
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#5 monstermetal

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Posted 23 November 2010 - 01:36 AM

I think there are spot riveters out there with enough ommph I think the issue would be not nuking the contacts with prolonged exposure to the rivet...

But I am kind of hoping to find someone with real experience or better yet with a machine....
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#6 rawtiron

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Posted 23 November 2010 - 02:31 AM

I think there are spot riveters out there with enough ommph I think the issue would be not nuking the contacts with prolonged exposure to the rivet...

But I am kind of hoping to find someone with real experience or better yet with a machine....



I watched one in action the other day along with an old pneumatic rivet press. The owner lives here in NZ and has used it to rebuild and rerivet steam boilers for traction engines and alike. He's 80 odd years old and had plenty of experience(and only a long plane flight away :) ). I'm happy to get you his details.
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#7 pkrankow

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Posted 23 November 2010 - 07:59 AM

Isn't there a video making horse shoes using a resistance heater? They were forging using a closed die press.

This computer is disagreeing with the video, so I'll try another computer later.

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#8 Timothy Miller

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Posted 23 November 2010 - 08:29 AM

I know we are not supposed to talk about other ways this could be done. but if they had a mini one burner gas forge they could stock that thing with rivets and keep it inside with them. you could do that job with two people. It honestly seems like very a slow way to do it.

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#9 MattBower

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Posted 23 November 2010 - 09:30 AM

I talked to an electrical engineer about direct resistance heating a while back, and it turns out that it doesn't work very well for asymmetrical cross-sections. Thin parts of the work heat faster -- much faster -- and could very well burn up before thicker sections got up to temp. But for round bars and the like, it's pretty cool stuff. (I believe he also said you'd need a big transformer for any serious work. This was several years ago, so my memory is a little hazy.)

Check this out:

http://www.thefabric...ut-spot-welding

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#10 clinton

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Posted 23 November 2010 - 10:57 AM

I know we are not supposed to talk about other ways this could be done. but if they had a mini one burner gas forge they could stock that thing with rivets and keep it inside with them. you could do that job with two people. It honestly seems like very a slow way to do it.



I was thinking the same thing- whats wrong with a good ol forge- or cut out the middle man give the guy inside a can to catch the rivets and toss them up there instead of on the floor
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#11 ThomasPowers

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Posted 23 November 2010 - 11:22 AM

Would induction heating be a better match for this job?
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#12 Mainely,Bob

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Posted 23 November 2010 - 11:35 AM

Would induction heating be a better match for this job?


Just what I was thinking Thom.The induction unit is small enough and mobile enough to move to the work and seems to be much quicker than the resistance type heater.
With an induction heater the rivets could be heated right there and quickly.I`m betting they could take the two guys who heat and pass the rivets and put them on bucking and heading and double their riveting output.
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#13 monstermetal

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Posted 23 November 2010 - 12:12 PM

Its not about finding a better way.... Its about finding out about this way.

I have an induction heater and I am sure that is the most efficient way to heat the rivets, However at this point its not about heating rivets, Its about researching this machine and this method..

Thats why I made the statement I was not interested in other methods.. Not that I am close minded on the subject, its just It really is just about this proses
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#14 monstermetal

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Posted 23 November 2010 - 12:14 PM

I watched one in action the other day along with an old pneumatic rivet press. The owner lives here in NZ and has used it to rebuild and rerivet steam boilers for traction engines and alike. He's 80 odd years old and had plenty of experience(and only a long plane flight away :) ). I'm happy to get you his details.
Jason



Sure Jason anything you could provide would be helpful as these machines seem to be pretty scarce around these parts..


Larry
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#15 rawtiron

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Posted 23 November 2010 - 12:45 PM

Sure Jason anything you could provide would be helpful as these machines seem to be pretty scarce around these parts..


Larry


I'll email you Larry.
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#16 clinton

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Posted 23 November 2010 - 12:45 PM

I am sure we will find a way to turn this into some other avenue of discussion
maybe Grant has a recipe that calls for a hot rivet
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#17 bajajoaquin

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Posted 23 November 2010 - 01:20 PM

I talked to an electrical engineer about direct resistance heating a while back, and it turns out that it doesn't work very well for asymmetrical cross-sections. Thin parts of the work heat faster -- much faster -- and could very well burn up before thicker sections got up to temp. But for round bars and the like, it's pretty cool stuff. (I believe he also said you'd need a big transformer for any serious work. This was several years ago, so my memory is a little hazy.)


It kind of looks like this is what's happening here. The shaft of the rivet is heating up faster than the broader head.

Larry, can I ask a personal question? Why are you interested in this particular way of heating? Simple curiosity, or is there something specific that this may be applied to?

#18 Ben Hartley

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Posted 23 November 2010 - 01:32 PM

I've often wished I could heat small rivets in-place, they just lose so much heat while I'm setting them and then split because I work them too cold. Resistance or induction heating would work pretty nicely I think. Seems like a bit of a waste to use such a machine to heat up rivets and then walk them over to the guy who sets them.

#19 Monster

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Posted 23 November 2010 - 04:11 PM

MM,

I am the guy with the yellow hat on in the video putting the rivets in. Next Monday I have to go away for work and will go by where we keep that old green cooker. I will grab the details off the side and some photos of the beast and post them up for you.

From memory, as it has been a while since use, it is a 3 phase machine, with water cooled replaceable copper heads. It took just under a minute to cook a 3/4" rivet from cold. The name of the man driving the cooker is Don French, a well respected boiler inspector from the New South Wales Railways. I have seen the cooker get the rivets so hot that the centre blows out under the force of the contactor arms, but that was only when the old man was distracted talking boiler stuff. There is a bit of prep in getting the rivets ready for the cooker; we found that the makers mark placed on top of the rivet head during manufacture had to be ground off otherwise there wasnt enough contact surface to get the 'trons to flow.

As to the process. We had both a coke forge and a gas forge available but this was the most economical way to do it. The limiting factor was the hold up gear inside the tender. The mass of webbing meant that you could only get 2 or 3 rivets in at a time prior to having to put a new leg on the dolly and rearrange the props to get the right snap length. It ended up being wasteful on gas and coke. The best we managed was 70 rivets an hour, with the age of some of the guys that was moving. We have used that cooker for many jobs, from gun and snap to hydraulic horseshoe and it is perfect. In the time it takes to move the gear to the next hole you have another rivet ready.

As it was a volunteer workforce the curator was keen to have everyone doing something so that they felt part of the process. Some of the iterations and workflows are more involved people wise than they needed to be, but I think that in the end the point is to include everyone that sacrificed the time to be a part of the longgg rebuild.

As to the locomotive, it is now running on the main line around New South Wales.

I will be in touch,
Monster.

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#20 monstermetal

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Posted 23 November 2010 - 09:43 PM

Outstanding! Thanks Monster, couldn't ask for a better situation. ;)
My great concern is not whether you have failed, but whether you are content with your failure.
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