Bachmann 2-6-6-2 1st run needs tuning

[peteski]

It's turning out to be harder than I expected (and yes, you all warned me...).  Even regauging the tender wheels isn't simple - they're .015" too narrow, but if I simply widen the gauge then the axle tips bind in the metal contact strips.  Similarly, if I widen the trailing truck gauge by 0.15" it will bind in the truck frame.  About the only axle that looks easy is the pilot truck.

George, if these wheelsets use construction similar to Kato, you could widen the gauge (use washers to make sure they stay properly gauged), and push the half-axles inwards to stop the binding.  Like I described in https://www.therailwire.net/forum/index.php?topic=33107.msg596466#msg596466

[mmagliaro]

Peteski's method might work on Bachmann tender wheelsets, but I think there will be problem.

To wit:
You probably just pulled the wheelsets outward from the center plastic tube a little.  And as you found out, that makes the axle points bind in the sideframe holes.

Peteski's alternative (and Pete, if I misinterpret your tutorial, hit me here...)
You push the wheels outward on their respective half-axles, but leave the half axles inserted into the plastic axle tube by their original amount.  So the axle points are no further apart than they originally were, but the *wheels* are further apart, the gauge is now correct, and the axle points won't bind in the truck frame.

But having messed around with a lot of Bachmann tenders (nearly all of which have this problem with gauge, by the way), I think you will run into a problem where the faces of the wheels themselves rub on the insides of the truck frames.  If that happens, you can just take a flat diamond file to the insides of those truck frames and file away enough plastic so that the wheels don't rub anymore.  I strongly suggest diamond because the truck frames are Delrin and and ordinary file will take a long time to file that down (and will load up easily and need frequency cleaning).
In fact, a fairly harsh-grit sandpaper glued to a stick would work well too.  I've use something like 150 or even 100 grit to sand away Delrin.  It's not going to show, so we really don't care about the sanding marks.

 

[peteski]

Peteski's alternative (and Pete, if I misinterpret your tutorial, hit me here...)
You push the wheels outward on their respective half-axles, but leave the half axles inserted into the plastic axle tube by their original amount.  So the axle points are no further apart than they originally were, but the *wheels* are further apart, the gauge is now correct, and the axle points won't bind in the truck frame.

You understood it perfectly.
I did not know that there wasn't much clearance between the truck's inner part of the sideframe and the wheel face.  Bachmann wheels have fairly wide tread. How about replacing them with other similar wheelsets with narrower tread?  Maybe Kato?  They offer them in 33, 36, and whatever is used in the FEF3 tender (is it 36" or 40"?)

[nickelplate759]

Yep, I've considered all of those ideas. I'm going to see if the wheels can be moved on the half-axles in the tender - I think there's enough clearance in the truck frame.  In the trailing truck there is not enough clearance, so widening the inside of the frame is a good idea.   

Changing wheelsets is another possibility.  That reminds me - Pete, you never posted your how-to on regauging the Aerotrain wheels...

[edit] the Kato Mikado/caboose wheelset drop right in and work perfectly so I'm not going to bother trying to fix the Bachmann tender wheelsets. Plus, I don't have to strip the white striping off the wheels!   Oddly enough, I have some Bachmann tenders sold individually that do NOT have the narrow gauge problem.

[second edit] Try as I might, I cannot move the Bachmann 2-6-6-2 tender wheels on their half-axles.  I wonder if they turned them out of a single piece of metal - although that would be wasteful.

More hopefully, Bachmann must have made a significant tooling change shortly after making the 1st run 2-6-6-2.  I have quite a few Bachmann add-on tenders, and their wheelsets are different (blackened for starters), as is the underframe.  Gauge on these is inconsistent (some are perfect, most are a shade narrow), but can be adjusted to be correct. They do NOT fit in the tender trucks on the 2-6-6-2!

So - I really only need a few sets of Kato axles to make this all go.

[Chris333]

I would take the Bachmann 2-6-6-2 and spike it as hard as possible directly into a concrete floor. Pick up what is left and repeat until you got as much satisfaction as possible. I worked on mine for months and then just tossed it.

When I crack on Bachmann I have a pile of non-working locos to back it up.

[nickelplate759]

I would take the Bachmann 2-6-6-2 and spike it as hard as possible directly into a concrete floor. Pick up what is left and repeat until you got as much satisfaction as possible. I worked on mine for months and then just tossed it.

When I crack on Bachmann I have a pile of non-working locos to back it up.

I'm tempted.   But more likely I'll just park it by the roundhouse if I can't make it work.  Today the decoder seems to have lost its mind ... It worked fine yesterday.   ...sigh....

[peteski]

I'm tempted.   But more likely I'll just park it by the roundhouse if I can't make it work.  Today the decoder seems to have lost its mind ... It worked fine yesterday.   ...sigh....

You *WILL* replace that crappy decoder, right? 

You are right - I still need to post the Aerotrain writeup. So many things to do - so little time.
I should have checked before opening my proverbial mouth here. I just looked at one of the Bachmann tender trucks and I see that the wheel and half-axle are single brass turning. Just like the wheels in the Aerotrain.

What I basically did is to figure out by how much to shorten the conical axle end, then chuck each wheel assy. in a lathe and cut the conical end down by that amount.  I suppose that will be difficult to do without a lathe.  A Kato wheel retrofit will likely be easier (and those are nicer wheels).

[nickelplate759]

Yes I'll replace the decoder.  It's a digitrax Dz126 I installed last week.  Alas I found the short in the light board after I hooked up the decoder -  I suspect that damaged it.    The decoder responds to inquiries but only drives the motor for a fraction of a second before going comatose for a while.

[nickelplate759]

Well, I got the 2010 Ntrak Steam supplement with Max's article in it. Lots of good information on getting the mechanism to work well (and nothing that scares me off) but it doesn't address regauging the drivers (they are quite narrow).  I'm nervous that doing so will screw up the valve gear, but I can't run it as it is, so -- any pointers on how to do this with the least risk?

Alas, Bachmann doesn't have any driver parts for this engine (or the C&O H5) available, or I'd try just replacing them.

[mmagliaro]

I looked through all my photos from that project and I don't have anything on regauging the drivers on that particular engine.  But I am pretty sure I had to spread the drivers because nearly everything Bachmann makes is too narrow.

Here's how I usually do it. 
Pull the rods, pull the drivers out, put them in a wheel puller (the NWSL "The Puller") and spread them.  This is much more precise and kind to the drivers than prying on them.

I don't think you'll have a quartering complication on this engine because only one axle is geared in each engine truck.  So you just have to drop all the drivers back in and put the rods on.  You won't be able to put the rods on unless you line up the crank holes by eye, and since there are no other geared drivers, that's all you need to do.  The rods will automatically make the drivers be in quarter.

But I am sympathetic to the fact that pulling all the pins, rods, and valve gear gives people the willies.   

If you really want to do this without pulling out all the drivers, there's the tried and true... and in my opinion risky... method.  Slip a thin screwdriver or Xacto blade in behind the wheel, get it in close by the axle and pry THERE (so you are exerting pressure near the axle, NOT out near the rim of the wheel).  That will pop the wheel outward a little.  Then check with the gauge and see if you have it right.  It's not easy to get both sides pulled out evenly with this method, but if the amount of correction is small, you can probably get away with just prying a little on one side and hoping it's good enough.

The risk is that you pry the wheel so it's not square to the axle and you introduce wobble, or you pry too much and the wheel gets loose on the axle.   Sometimes if you have the right sort of claw wheel puller, you can get one on the driver without taking it out of the frame.  But I have never had much luck getting those to be able to fit in place on an N Scale engine.

I think Peteski has one of those claw pullers and has done some wheels that way.  He might chime in here with a photo.

[peteski]

I looked through all my photos from that project and I don't have anything on regauging the drivers on that particular engine.  But I am pretty sure I had to spread the drivers because nearly everything Bachmann makes is too narrow.

Here's how I usually do it. 
Pull the rods, pull the drivers out, put them in a wheel puller (the NWSL "The Puller") and spread them.  This is much more precise and kind to the drivers than prying on them.

I don't think you'll have a quartering complication on this engine because only one axle is geared in each engine truck.  So you just have to drop all the drivers back in and put the rods on.  You won't be able to put the rods on unless you line up the crank holes by eye, and since there are no other geared drivers, that's all you need to do.  The rods will automatically make the drivers be in quarter.

If you really want to do this without pulling out all the drivers, there's the tried and true... and in my opinion risky... method.  Slip a thin screwdriver or Xacto blade in behind the wheel, get it in close by the axle and pry THERE (so you are exerting pressure near the axle, NOT out near the rim of the wheel).  That will pop the wheel outward a little.  Then check with the gauge and see if you have it right.  It's not easy to get both sides pulled out evenly with this method, but if the amount of correction is small, you can probably get away with just prying a little on one side and hoping it's good enough.

I think Peteski has one of those claw pullers and has done some wheels that way.  He might chime in here with a photo.

You mean one of these?  If those drivers have plastic center (spokes) then I would not recommend using it as it might distort (or pull out) the plastic center.

[nickelplate759]

...
But I am sympathetic to the fact that pulling all the pins, rods, and valve gear gives people the willies.   

...

Actually, it's putting them back that gives me the willies (or howling fantods).    But prying the drivers out with a knife or screwdriver scares me even more.

[mmagliaro]

Actually, it's putting them back that gives me the willies (or howling fantods).    But prying the drivers out with a knife or screwdriver scares me even more.

Take some photos of each side of the engine BEFORE you pull out the crankpins and remove the rods.  You don't really have to take the whole valve gear "apart".  If you are careful, you can pull out just the crankpins for one driver (one on each side), then take off the cover plate, lift out that driver, fix the gauge with a wheel puller, put the driver back in, reinsert the crankpins and rods, and then move to the next driver.  It's slower that way, but then you won't have all the rods and possibly other valve gear parts completely off the engine at any one time.  That might make it less scary.

A very important point here is that this engine has only one geared driver per engine truck.  That makes it impossible to screw up the quartering, which eliminates the scariest part of doing a job like this.

But definitely take close photos of the sides and rods before you do it.  It's common to forget which way a rod was oriented, or at what rotation the main eccentric crank was, and then rods can jam if you put them back on wrong.

[mmagliaro]

You mean one of these?  If those drivers have plastic center (spokes) then I would not recommend using it as it might distort (or pull out) the plastic center.

Yeah... that's the thing I was thinking of.  You are right about the plastic wheel center.

Really, the "puller" is the best way to go. It puts a sturdy flat "V plate" surface behind the wheel and just nudges the axle in or out.  I won't do mine any other way.

[craigolio1]

Where can I get one of those pullers?

Craig