Annealing

Yes this has been tried before, and no it does not work well.  You need rim insulation.  Before you start machining, make sure you don't already have insulation - many outside third locomotives are indeed insulated.

Annealing cast iron is not that simple.  You need to bring the heat up, stabilize it, then let it cool over a very long time.  If your drivers were machined, they are probably already annealed.

There are several reasons for rim insulation - wobble and side rod isolation are two.  If these are not insulated, bite the bullet and send them to Joe.

I think all the old Max Grey and USH engines were insulated.   but I have seen many with outside 3rd pickups.

another way to do this which I have read about, is to drill a small hole in the rim.   then insert a jewelers saw through the hole and cut halfway around the rim.   fill that half with epoxy for insulation.   After it sets up, cut around the other half and fill it with epoxy.   doing half at a time means the rim is never floppy loose to get out of alighment.

It is a good read, but I would send them to Joe!

The annealing process is performed by heating the material (generally until glowing) for a while and then slowly letting it cool to room temperature in still air. The temperature range for process annealing ranges from 500 °F - 1400 °F, depending on the alloy in question. 

Pretty involved as a starting point for machining.

Gilly is correct; the only thing I would add is that I like to put the casting in sand to let it cool.  I keep a bucket of sand by the forge with another small container of sand beside it.  Once the casting has reached the eutectoid temperature long enough to permeate the thickest part of the casting (that won't be long on an O scale driver) I pull it out of the forge, drop it in the sand bucket and pour the sand out of the small container over it so it is covered.  This gives it a nice insulating blanket of sand, and it will cool down at an even slower rate than still air.

By the way, a forge isn't always necessary; you may be able to get a small casting like that hot enough in a barbeque grill... propane or charcoal.  The grill will heat the casting more evenly than a propane torch.

Just my two cents, though... your casting, your choices.  Let us know what you do and how it turns out.

Thanks fellows.  Help me out--How do I contact Joe.?

When a piece of steel or iron reaches it annealing temperature it is no longer attracted by a magnet so you can test your casting by placing a magnet against it.  I have never attempted to anneal a cast iron driver and have found most of them, especially those that were machined once do not need to be annealed.  I have found some 3 rail axles on steam models to be hardened and I anneal them with a propane torch at their ends to allow me to reduce their length as part of a 3 rail to 2 rail conversion.  I have a coal forge in my shop and could easily bring a driver casting up to red heat to anneal it.  I just have never had to do it.

How do you enlarge a driver casting on the lathe?

Joe Foehrkolb

Interesting thread.  Is in necessary to temper/put the hardness back in the piece after you are done??  If so how is that done?

There are significant differences:

Cast Iron

Cast Steel

Steel

Many different varieties/types of steel.

 Thanks to All for posting

Mike CT

No - not in O Scale.  I have a live steamer in O Scale where the builder chose to harden the ends of the valve rods, but even that is not necessary.  Typically the hardening process has to do with what color you heat to and how rapidly you cool down.

i harden my female rivet dies.  First I form them, making sure I have the exact shape and spacing, using drill rod.  Then I heat to a straw yellow color, and immediately fling them into cold water.  They last forever.  If I didn't do that, I would get maybe a tender side worth of rivets and have to re- contour the thing.  I use a carbide tipped male die.

The Joe of whom we speak is rrjjf above, and I believe his website is Clifton Forge.  His rates are more than reasonable, and he is the only person on the planet who does this stuff professionally.

Thank you,

Mike CT

Hi,

My conversion business is Baldwin Forge & Machine in Glen Arm, MD

Joe Foehrkolb

Oops!  Wonder what I was thinking?  Joe does very good work, no matter what I call his website.

bob2, thankyou for Joe's introduction.

Joe, I bought a Taig lathe and set it up on plywood so I can move it off my workbench (space is a premium). I have never turned any thing on it.  A friend, who have a small lathe, has helped me insulate trucks by removing the axles, boring out the center with a larger diameter, filling it with epoxy, then drilling in the center for the the axle size.

I thought i would drill out the center with a 1/2" bit.  I'd fill the center with a pcb plastic or even epoxy.  Then center drill the driver and insert the axle.   I have a 2-8-2 chassis complete with valve gear.  I maybe naive and bob2 has suggested reason side rod isolation and wobble.  I also question if the insulators would be striped and not turn the driver.

John - once again, axle insulation on steam models is a lousy idea, and your small lathe won't really cut cast iron anyway.

If the mechanism is a throwaway, try it.  I guarantee it will wind up in the recycling.

Isolating the side rods is possible - remember that if you isolate them at the crankpins, whatever you put in there will wear out in a hurry.  Also, imagine how you are going to hold the drivers in place while the epoxy sets - check out Joe's fixtures on his website; you really do need collets and fixtures to do this kind of work.

John,

I agree with Bob, you are probably going to destroy the driver castings.  Machining the drivers with insulated steel rims is the way this job should be done.  Machining drivers can be done on a small lathe but it is very tedious.  I use a 9" Southbend lathe for finishing and re-machining drivers.  I also use my 10" Southbend Heavy 10 for cutting out the rough tire blanks from steel tubing.  I invested in these tools over many years and they have served me well.  If you have never machined anything on your Taig lathe (or any other metal lathe) starting out machining cast iron drivers may not be a good idea.  Forty years ago, I threw lots of metal into the scrap pile because I did not know what I was doing.  I am not a professional machinist but I have learned to do the machine work required to work on O scale locomotive models.

Joe

Here is my 9" South Bend. It is, in a word, cute.  It is probably the smallest practical lathe ever made.  Its table is totally inadequate - Harbor Freight, loosey goosey.

I use an 11" Sheldon for driver work, mounted on a 2" thick wood table with well braced 4x4 legs.  Even that will hesitate when really leaning in to a piece of steel.  A 13" lathe is a thing of beauty, but sort of out of place in a home shop.  You can cut drivers in one cut on such a lathe.

I failed to note that you were going to re-drill the epoxy.  Better to use some engineering grade plastic, and machine bushings to press in the drilled drivers.  When cleaningnup the axle bore, you need to do it with a fixture on the lathe, and not just in a 3-jaw chuck.  Also use a very stubby drill with proper rake, or better yet, a reamer.  Still, not a good idea in the first place - you have no idea how many places those rods will short out.