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Evan
05-14-2007, 07:39 AM
I am making some sleeves for the bearings on my ring roller as per Roger's suggestion in my ring roller thread. I snooped around my junk pile and found an old defunct automotive generator that has no further use so I dissected it and cut up the casing to make a couple of sleeves for the idler bearings. This has the dual purpose of protecting the bearings and making the rollers wider.

As generator housings are not welded at the seam I had to weld it up and this made turning more difficult, requiring a carbide tool to rough it down. I needed a good way to hold it for the inside cut especially and since I am working with an ID of about 4 inches a simple solution came to mind.

http://vts.bc.ca/pics2/boringbartp.jpg

I normally use a spacer anyway to bring the tool holder on center and with this thicker spacer only had to drop the tool holder down a bit. It does a fine job and I found it also allows a lot of flexibility in offering the tool to the work for other cuts.

Now the alloy question: If it weren't for the welds this old generator housing is made from some sort of steel that turns about as nice as it gets. Since it isn't turned in the first place it can't be for that reason so I assume it must be the magnetic properties. Does anyone know what alloy is used in generator housings?

ptjw7uk
05-15-2007, 05:26 AM
Evan,
I think it would be soft iron as that will not become a permanent magnet.
Peter

micrometer50
05-15-2007, 05:36 PM
It might be mallable iron, in which case the heat affected zone from the weld will be hard and brittle.

topct
05-15-2007, 05:51 PM
The same alloy as transformer plates?

Evan
05-15-2007, 10:10 PM
Transformer iron is usually a silicon alloy and is fairly brittle. I don't think it's that. This stuff turns like leaded steel with a superb finish.

Ian B
05-16-2007, 03:36 AM
No idea what alloy it is Evan, but when I was at school I remember parting off a ring from a car starter motor and using it as the outer ring on a gyroscope that I made - the rotor was steel, about 2.5" diameter, and an inch thick; worked really well...

Ian

oldtiffie
05-16-2007, 04:10 AM
Deleted/edited-out

JCHannum
05-16-2007, 05:47 AM
If it were a leaded alloy, it would not weld well. They tend to produce very porous welds.

oldtiffie
05-16-2007, 06:31 AM
Deleted/edited-out

Your Old Dog
05-16-2007, 06:42 AM
Sounds like you're building one macho ring roller :D The wheels on mine arent near that size and I can roll any diameter size circle I want if the material is long enough.

By the way, if you're putting pikes on your iron fence make sure they're low enough you can clear them on the run if BearDog allows something in the yard you don't want! :D

Evan
05-16-2007, 08:43 AM
Oldtiffie,

I think you misunderstand. I had to weld the seam in the case as the case was not welded at all. Many generator housings are just keyed together at the seam to hold the shape. And yes, I did stick weld it with mild steel rod. The welds weren't all that hard but compared to the machining properties of the housing they are. I only used the carbide tool to rough down the weld on the inside where I couldn't easily grind it. I use C1 solid carbide for that purpose as it can withstand interrupted cuts very well.

Jim, it certainly isn't leaded steel, it just turns like it. There is no trace of porosity in the welds and they can't be seen after turning except for disturbing the cut slightly.

YOD,

When I admitted to my wife that I might be making this thing a little.. um, stronger than is required she just laughed and got all sarcastic saying that I never did that before...

http://vts.bc.ca/pics2/rollidler1.jpg

This is one of the idlers and I am using bearings that I happen to have since Tryp gave them to me when I picked up the shaper. They are well used and I rebuilt the bearing in this roller but that's another story.

wierdscience
05-16-2007, 08:48 AM
I made an under cutter to mill a groove in starter cases so larger tie bolts and insulators could be used.Company I did the work for said the cases were 4130 aluminum killed silicon steel.It had nearly 5% silicon which is why one or two machined easy,but 5 or 600 cratered the carbide inserts unless they were Tin coated.I also noticed they took quite a while to rust.I had one dummy case that sat outside in the scrap pile and the cuts I made didn't sweat a pimple for a couple months.

Evan
05-16-2007, 09:00 AM
4130 you say? That's a nice strong heat treatable alloy. I'll have to try hardening a piece and see what happens. Hardened idler rollers would be nice to have. Less damage and lower friction too.

Your Old Dog
05-16-2007, 10:39 AM
Just an "aside" here....

When you get some spare time, maybe before lunch or during the Canadian High Tea/Donut break, you might want to consider knocking out one of these little beech bikes :D

http://www.makezine.com/blog/Custom_Beach_Bike.jpg

Evan
05-16-2007, 10:57 AM
I've been multitasking a lot in the last while. I'm working on several simultaneous projects as well as doing housework and preparing for the deck job. I've just about finished the picket twister and should be twisting metal later today.

The "tires" on that thing are just inner tubes, right?

wierdscience
05-16-2007, 11:19 PM
Picket twister? Not doing that ala manual I hope.

That's one thing I did plenty of years ago,I had a couple fixtures for the lathe I made from 1/2" drive impact sockets.One to fit up in the chuck with a drive dog welded on and another to clamp up in the toolpost.Back gear about 20 rpm and count the twists.After the first two or three I could get the feel of how much over travel I needed to overcome the spring back.Most I ever did was 45 pickets in one hour,fun,fun and a big pile of mill scale in the chip pan at finish.

Evan
05-17-2007, 12:50 AM
It's manual. I'm feeling strong lately. :D

I don't think my lathe has enough snoose to twist 3/8" square into a pretzel and it's not long enough anyway. I'm not going into production except for myself and maybe the occasional custom job for friends.

I have it finished and painted but still need to make a couple of dies to hold the stock. I'll do that in am and will post it tomorrow (if it works :D ).

oldtiffie
05-17-2007, 03:52 AM
Oldtiffie,

I think you misunderstand. I had to weld the seam in the case as the case was not welded at all. Many generator housings are just keyed together at the seam to hold the shape. And yes, I did stick weld it with mild steel rod. The welds weren't all that hard but compared to the machining properties of the housing they are. I only used the carbide tool to rough down the weld on the inside where I couldn't easily grind it. I use C1 solid carbide for that purpose as it can withstand interrupted cuts very well.



Many thanks. I just assumed that the casing was welded as for an automobile generator (ie DC) or starter motor - and not seamed like a tin can.

Thanks too for the info on the weld.

As regards minimising the post-weld hardening perhaps due to a post-weld "chill" effect, perhaps it could have been reduced by "soaking" it with pre-heat and then cooling it slowly (dry lime) or else TIG welding it (and optionallly slow cooling it).

The reason I mentioned TIG is that several welders and panel-beaters tell me that TIG welds are much easier to "work" in the post-weld state as the weld, by its nature, cools slowly and has an annealing or normalising effect and/as there is much less "chill" ("heat-sink") effect
and it cools slower anyway.

I am also told that a similar effect can be achieved with "stick" and MIG by using a "step" weld technique with lower currents and a multi-pass weld.

I guess that oxy-acet or oxy-LPG should work as well on that principle.