MTH 2-Rail Scale Wheels?

I am converting a set of PA1s right now.  Unlike most other 2 rail manufacturers where one wheel is insulated on each axle, the MTH 3-2 wheels I am using have an axle that is split in half (side to side) so it is important to keep the insulated bushing on the correct side of the truck.  The bushings will fit nicely in a 3/8 inch hole but it will be necessary to mill or Dremel out a small pocket at the edge of the hole in two places for the bushing flanges to seat.  Be careful on the depth of the pockets so that the bushings sit flush with the truck block.   I use wheel wipers to make sure each wheel gets pickup from the track.

 

Most MTH Premier locos newer than 2005(?) are already set up to convert without drilling or other gymnastics.

Jim,

 

I see what you're talking about, there's a small black "spacer" approx center of the 4 wheel shafts.

 

Do they come apart there or do I have to pull off a wheel?

 

I don't have a mill, just a mini-lathe and a drill press, not sure if I have a bit that could do it using the drill press.

The drop-in wheels were designed around the Premier 3/2 truck blocks. It might be more cost/time-effective to send the truck blocks out to Joe at Baldwin Forge and have them 2-railed. My thought is that it would be better to use single-insulated on the locomotive so you only need to put wipers in on one side and it preserves the frame as electrical common. After the conversion, judicious installation of a DPDT switch would allow you to operate the locomotive as a 2-rail/3-rail hybrid by re-installing the pickup rollers.

Matt,

 

I'll have to think this over carefully.

 

The old truck blocks came from a RK F3, but they're the same blocks as those on the RK RS3 and NW2, neither of which are the "drop-in" type blocks.

 

The F3 is in a junk box, parts used as needed.  I may try to mod the old blocks just to see if I can do it.  I was thinking I needed to pull 1 wheel off each set of the 2-rail wheels, but I'll take another look to see if the axle does come apart at that black "spacer".

I know. I have a couple of diesels I was thinking about having converted with the plan of making hybrids out of them. I think Northwest Short line has the replacement wheels, but you need the right puller and need to be mindful of which truck is going where so you have the insulated rails on the engineer's side of the locomotive front and rear.

Matt, here's what I found on their site:

 

MTH/Lionel/Weaver/Atlas/KLine 3-rail to 2-rail wheels/axles KIT
These component kits enable conversion of 3 rail “trapped-axle” design (early
diesels from China for various importers/brands—with 3/16” axle) and newer
“removable bottom cover” units to be converted to 2-rail and choice of wheels,
including P:48. Can be VERY difficult to remove original wheelsets; electrical
pickup requirements must be addressed by the installer. PULLER V (#75-4)
was designed to remove these difficult to access ‘no clearance’ wheels, arbor
press (such as the SENSIPRESS+) or bigger required to reassemble with
new wheels.
Specify wheel dia/tread in addition to kit #
4-axle units $44.95 6-axle units $54.95
42"/172 2646/10-6 2647/10-6
40"/172 2646/20-6 2647/20-6
36"/172 2646/30-6 2647/30-6
33"/172 2646/40-6 2647/40-6
42"/145 2646/11-6 2647/11-6
40"/145 2646/21-6 2647/21-6
36"/145 2646/31-6 n/a
33"/145 2646/41-6 n/a
40"/115 2646/24-6 n/a
36"/115 2646/34-6 n/a
33"/115 2646/44-6 n/a

 

Not a bad price!

Bob,

There is an excellent article in O Scale Trains by John Sethian where he 2 rails the truck blocks you have with the wheels that MTH sells for the 3/2 trucks. I plan on converting one myself but I currently lack the necessary tools to do the job. I am saving up for them. If interested I will look up the issue number for you later on tonight. I think John's method of conversion is better than the NWSL conversion set but that's just my opinion.

Thanks Phil, I recall his article, looking now.

Well, the easiest way on the older truck blocks might be the NWSL kit.  I have not done an MTH, but I have done maybe five K-Line Train Masters.  I did a sixth before they came out with the kit, by rim-insulating the MTH sintered iron wheels.

 

Having a good wheel puller is the first, and most essential step.  I found that MTH wheels are pressed on with a great deal of force, so I use an arbor press (we are always changing axle gears - the MTH stuff is all factory 2-rail on older truck blocks).

 

As a side note, the early MTH axle bearings are identical to the Piper Cub control surface bushings. Yes, we even wear those out after about 15 years of all day every day running.

Interesting topic.  I have a circa 2001 BNSF dash-9 ps2 that I would like to convert to 2-rail some day. 

Even with the guidance from the nwsl site, this does not sound like a simple operation

Bob it is issue #53 Nov/Dec 2010. (Just in case you had some trouble finding it)

Thanks Phil, it took me about an hour but I found it.  I thought I had downloaded it but it's one I actually have in my bookcase!

Martin,

 

Drilling the blocks for the bushings is probably the most touchy thing, but I think I can do it.

 

Good thing is I have the "spare" F3 blocks to play with so if I mess up no harm to the RS3 or NW2, yet

I would not recommend the use of any "back of wheel" wipers. I have had passenger cars from Weaver and also the 20TH Century Limited set of Scott Mann. After some time, the squeaking will "make you crazy". As info, 3RD Rail passenger equipment no longer uses wipers and one wheel is insulated, which is a far superior method for two rail operation. I tried conductive grease and other lubricants on the wipers on my Weaver cars, but the wipers wore grooves in the back side of the wheels. I won't buy any equipment with wipers, either lit cars or engines.

All of the early 2- rail MTH has wipers.  We merely soldered pieces of phosphor bronze on when the contact point wore out.  For heavy duty, I replace them with spring-loaded plungers.  2- wheel pickup has never worked well here.

 

We have over 2 decades of daily 8- hour use on a few of the MTH Diesels - so far, no grooves in the backs of wheels.  I don't think they pay much attention to lubrication.

 

being sorta deaf, I cannot comment on squeaking.

Speaking of plungers, I found 5 of these in my parts drawer the other day:

 

 

 

I'm pretty sure they came out of an old printer.  Old electronics is a good place to find all sorts of parts we might use in our model RRing.

I can't remember if it was John Sethian or Dan Dawdy, but one of them posted an article on installing wheel wiping plungers on "China Drive" truck blocks that was pretty impressive. The plungers themselves were brass nail heads.

 

As for the wheels, if I were changing out a locomotive, I'd opt for .172 treads. Admittedly this is "old school" but they clear modern track work just fine but are more tolerant than the newer .145 wheel sets.

Matt,

 

I didn't want to go too skinny on the wheels, is .172 close to the width of 3-rail wheels?

 

I'm going to re-read John Sethian's article and make sure I have all the drill bits I need, I checked the MTH wheelsets and all are out of gauge.  I took one wheel off and it came off easily with the Portline puller.  Haven't measured the MTH wheels to see how wide they are.

There's bushings already in the block, do I remove them completely or just drill out to the depth I need?  with the bushings supplied in the kit I don't see where the old bushings are necessary.

 

Duh, read the article Bob   It's all in there if I'd only comprehend it.

So from reading John's article, I only bore out the 2 bearings, on the non-gear side of the block with a 3/8" end mill, deep enough to insert the plastic bushings.

 

I need the following:

 

#17, #10, #1 drills

3/8" end mill

.006" Phosphor Bronze sheet for wipers.

 

I should have at least a couple of the drills, but I need to buy the end mill and Phosphor Bronze sheet (where?).

 

Micromark has the Phosphor Bronze sheets and end mills, do I need a 2-fluted end mil or a 4-fluted end mill?

Hi Bob,

Make it easy on yourself, go to the well.. eBay.  I see 0.006" Phosphor Bronze sheet and 3/8" end mills are both available in exchange for your Paypal dollars .  I purchase most of my mills, drills, and assorted cutting tools off eBay.  Plenty of options to pick from.  

 

For the end mill, I would go with just a 4 Flute High Speed Steel (HSS) 3/8" end mill and not get a Carbide or TiAN coated version unless you want to use it for other applications down the road that may require such attributes.  

 

Scott K.

Austin, TX

This thread was recently brought to my attention! 

 

Bob D:,

 

You can probably get away without an end mil, if you have a flat bottom drill.  You just need to make sure the hole is at the right depth and has a flat bottom. 

 

So from reading John's article, I only bore out the 2 bearings, on the non-gear side of the block with a 3/8" end mill, deep enough to insert the plastic bushings. 

  

Bob D:  Not quite, you want to make sure the same side (rail) has the insulated bushing.  In some cases MTH reverses the trucks, so the gears are on one side on one truck, and the opposite on the other.  So just watch out for that. Here are some more photos that may help you

  

 

 

Regarding wipers:

 I would not recommend the use of any "back of wheel" wipers. I have had passenger cars from Weaver and also the 20TH Century Limited set of Scott Mann. After some time, the squeaking will "make you crazy". 

 

Hudson5432:

 

What you say is true of you use thin width wipers.   What you need to do is make sure the wipers are massive enough so their natural frequency is below your hearing.   As Bob2 points out, that gets easier as you get older:

 

being sorta deaf, I cannot comment on squeaking.

 Here is an example of what I used to do.  I have had no problem after several years:

  

 I can't remember if it was John Sethian or Dan Dawdy, but one of them posted an article on installing wheel wiping plungers on "China Drive" truck blocks that was pretty impressive. The plungers themselves were brass nail heads.

 

Matt

 

That would be me (although Dan may be doing that as well).   I do this routinely now in all my conversions and electrical pickups:  On this one, it was a 2 rail model to begin with, but the pickups were flaky

 On this one I simply used the roller post:

 

Speaking of plungers, I found 5 of these in my parts drawer the other day:

 

 

 

I'm pretty sure they came out of an old printer. 

 

Bob D

 

Be very careful of that design!  The current goes through the spring wire, which causes all sorts of problems.  The wire gets hot, because the current has to go through a long path through a resistive wire. The spring loses its temper and the plastic melts, and the whole thing falls apart.  And you are hosed.  Atlas O used to do that.  I don't know if they have since changed it or not. Note with my design the spring provides the contact pressure, but the current passes through a relatively large diameter brass escutcheon pin

 

 

 

 

 

Thanks John!

 

I was re-reading your article and noticed something.  You said to insert a #1 drill to start the initial cut.  The size in the article was given as .280" but I believe a #1 drill is .228", typo maybe?

 

I have a Harbor Freight Mini Lathe and often go to The Little Machine Shop for tools, etc.  They have a set of drills and an End Mill set that should provide everything I need, just need to get the Phosphor Bronze from Micromark.

 

I'll keep an eye on which side is suppose to get the bushings, don't want to make too big a scrap pile this early!

 

Thanks for your help guys

You said to insert a #1 drill to start the initial cut.  The size in the article was given as .280" but I believe a #1 drill is .228", typo maybe?

It would appear to be a typo!  But then it doesn't matter what the initial cut is, as long as its less than the  final diameter.  That way you get a nice clean hole

I really like the external spring idea.  Next time I do this I shall copy that.  My plungers all have internal springs, and while there is plenty of contact between plunger and block, the springs have been known to do what John says.

 

Maybe even a plastic block, and solder the wire on the other end of the nail?  That would stop spring collapse cold.  Thanks for the idea !

Plungers, wipers, no matter what shape...."not gonna do it!" I have a hearing loss and I can hear them! The problem is not the frequency, it is the groove that they wear into the back of the wheels. (Perhaps we should question the quality and hardness of the wheels and axles here?)

I have never seen the slightest wear on the backside of any of my wheels. I have seen the rounded heads of my pins become slightly flattened.  This is to be expected as Phosphor bronze or brass is softer than steel, iron, and sintered iron.  If your wheels are made of brass, copper or aluminum, then they will indeed show wear

 

Sound is caused by something vibrating, whether it is a pin riding in a groove (as in a record player), a nail head on a wheel, or chalk on a board.  The trick is to figure out what is vibrating, and change its frequency by either increasing it weight, of making the spring stiffer

 

Hudson5432, all that being said, I agree a through the bearing electrical pick up is superior, because it has less rolling resistance, and a larger current contact area.  The problem, of course is it needs to be engineered in from the start.  The MTH split axles offer that opportunity, if one can make a sound electrical connection to the bearing.

My intuitive feel is that sliders and brushes offer better, more reliable electrical contact than rollers, bearings, and axle stubs.  I certainly get smoother operation with sliders.  The best seem to be track sliders, which I don't use very often.  Second- best for me are sliders that press against the wheel tread, as opposed to the back side.

 

We operate 8 hours a day six days a week, and so far no grooves after a quarter-century on the MTH stuff.  We do wear the sliders out.

I got my drill bits in today, still waiting on the end mill and Phosphor Bronze sheets.

 

I ordered my drills from Grainger YESTERDAY and got them around 530PM, they must have come from their warehouse in Norfolk but I can't see it printed on the package.  Now that is fast service!