Shafts, Rotten Wood, Rusty Iron

 Note:  All pictures are high resolution.  Click on a photo to enlarge it.

One of the sub-assemblies of a carriage that represents nearly all the tasks involved in restoration is the shafts.  There is evaluation, disassembly, surface preparation, painting, and to a certain extent, upholstery.  Shafts are a good warm-up painting project because it is much easier to paint narrow surfaces than it is to paint broad panels, as on a carriage body.

Because I hope to drive this vehicle before I start full-scale restoration, I decided to tackle the shafts while the wheels are out for professional restoration.

The shafts that came with the buggy are toast.  This picture is of a very skillful repair; a broken shaft has been spliced with a neat metal plate.  

These are tubular metal repair sockets.  Both shafts have been broken at some time.

The singletree yoke is broken...

And the shaft eyes are excessively worn.

I can probably salvage the iron braces, including the shaft eyes, but I have another old set of shafts which have been rotting away outdoors for decades.  The ironwork is much more ornate, and less worn.  I'll give it a try.

I have ordered new wood from an Amish supplier*, and I do not know if any of the old ironwork will match the new wood.  New irons are not very ornamental, but if push comes to shove, I'll have to buy new.

*Witmer Coach Shop, 1070 E. Main St., New Holland, PA, 17757 ph.717-656-3411

DISMANTLING THE OLD SHAFTS

The extra pair of old shafts has been dismantled.  Because the nuts and bolts are rusted together and the wood is rotted, the old bolts simply want to spin in the wood.  There are a number of ways I can approach the problem:

• Take as many photos and notes of everything as you can, so that you will have instructions on how to put everything back together!  This is actually the primary reason for my blog; to photo-document and comment on every detail of the process, so I can go back and remember what I did.
• First decide if the fasteners HAVE to be saved.  Sometimes nuts and bolts specifically fit ONLY ONE HOLE in the carriage wood.  These must be saved if at all possible and their position on the assembly mapped.
• The nuts and bolts on these shafts are expendable; it is even desirable to replace them because the old ones are weakened.  Enough rust will eat away at the threads, causing a loose fit in the future.
• HEAT applied to the nuts was sufficient to unscrew them from the bolts.  A soldering iron or fine tipped torch applied to the nut can be used to loosen it.
• If you must tap the end of the bolt to loosen it from the wood, run the nut back onto the threads far enough to act as a surface for the hammer to strike, thereby avoiding damage to the threads.

 There is no salvaging the old wood in this case.  So we'll concentrate on cleaning up the iron work.  As you can see, it is exceedingly rusty.

METAL CLEANING

Despite the fact that these shafts sat out in the weather for decades, an examination of the metal suggests that all parts are sound and re-usable.  But they are filthy and covered with rust.  Again, there are different ways of handling the cleaning of the parts.

Probably the first method that comes to mind is sand blasting.  We don't have a sand blaster, and have determined that buying a small one is not cost effective.  In addition, I'm very wary of sending out parts to a commercial shop, partly for fear of losing pieces, and partly because my experience of relying on others has not always been rewarding.

Furthermore, sand blasted parts rust quickly and you must deal with them right away.  If you have a large pile of sand blasted parts, many will start to rust again before you can get to them.

You can also lose track of what goes where if you send a whole bunch of ironwork out for blasting all at once!

I could wire brush the parts on the bench grinder.  This is pretty practical for smaller parts such as these, but can be difficult to get into tight spaces and has limitations when we get into larger pieces.

Fortunately, there is an extremely inexpensive, easy and effective alternative to sand blasting, called electrolytic derusting.

I was first introduced to this method on my last restoration project and ended up derusting about four hundred pounds of hand forged ironwork with it.

I found details of the process here:  http://www.stovebolt.com/techtips/rust/electrolytic_derusting.htm

Basically, the process involves immersing the metal parts in a solution of one tablespoon caustic soda (such as 20-Mule-Team Super Washing Soda) to one gallon of water, attaching a battery charger to the metal parts and to a "sacrifice" piece of iron or steel called an electrode, and letting "electrolysis" perform the chemistry of turning rust back into iron.

Take the time to read the above excellent article before doing this yourself.  What I am about to write is only an account of what I did; it's not a how-to explanation of how to do it..   I will use this process to clean all detachable pieces of metalwork on the carriage, including the axles and extremely long side springs as restoration proceeds.

Electrolytic derusting does not remove paint or dirt like sand blasting does.  It's best to strip old paint and clean off dirt first.  Polish a small area on the old metal with a wire wheel or sandpaper to provide good contact.  Then if you are going to entirely immerse the parts in the solution (as for small parts; longer parts such as axles will probably stick out of the solution), you must attach a wire (electric fence wire here) to the parts that will stick up out of the solution.  Here, I've wired several parts together, but I think it might have been better to attach an individual wire to each piece and then join  the wires together to attach to the battery lead.

Here the rusty parts have been placed in a 12 gallon PLASTIC tub.  Emphasize plastic.  Don't use metal.  The wire is hanging over the side of the tub.

The parts have been immersed in the soda solution.  A piece of "sacrifice" steel can be seen sticking out of the water in the upper left corner.  Do NOT let the sacrifice electrode touch the parts to be cleaned.  The tub is placed outside.  The process emits a bit of hydrogen, but is otherwise harmless.  A common battery charger is seen to the left of the tub.

The POSITIVE lead (red) of the battery charger has been attached to the sacrifice electrode, which will be eaten away during the process.

The NEGATIVE lead (black) of the battery charger is attached to the wires which are connected to the parts being cleaned.

IF YOU REVERSE THE POLARITY, THE PROCESS WILL DESTROY YOUR PARTS.

Plug in the battery charger and walk away.  You cannot over-clean the parts with this process.  I left the parts in solution for about 24 hours.

The parts being cleaned will start to fizz.

The solution becomes very disgusting!

While the parts come out looking nice and black.  One part didn't clean up very well, so it went back in solution overnight.

The parts are still rather dirty to handle and will require further cleaning.  They will also begin to rust again immediately.

1/24/15 IMPORTANT UPDATE!

When you take your parts out of the solution, wipe them down with a dry rag, then IMMEDIATELY wash them off with acetone.  Acetone drives the moisture off the surface of the parts and seems to greatly delay flash rusting!

This is the sacrifice electrode.  It has been considerably eaten away.

The parts need to be dried immediately, with heat if necessary.  This piece has been further cleaned with a wire wheel on a grinder.  Remarkable condition after decades outdoors!

As part develops a light layer of rust, I coat it with a liquid "rust converter" to prevent further oxidation until I am ready to do something with it.  I use SEM Rust-Mort, an automotive product.

Since I don't know if the new wood and the old iron will fit together until the new wood arrives, I'll set these parts aside for now.

Hmm, is there something wrong with my planning and work flow here?  It's possible I could have saved myself a lot of bother by waiting to de-rust these parts until the wood arrived! My writing muse, however, said it would be fun to do something NOW so there would be blog-fodder.

LATER, SAME DAY...

New wood has arrived.

Maybe with...

A little wood trimming....

...and a little metal heating and re-shaping...

Yeah, I think we'll be okay!