I believe most smoke units used a substance called “angel hair” I think some sort of fiberglass or similar. You can still get it today, right?
I believe what you mean is called ‘long-strand fiberglass’ (as opposed to chopped/mat). I do see listings on eBay but for enough quantity to make hundreds if not thousands of wicks.
Of course fiberglass wicks don’t scorch, and with the amount of heat even from a couple of shorted turns of Nichrome, it won’t soften or melt. I surmise the “NOS” wicks in these generators were cotton, perhaps like lighter wick material, which would have been easy to find cheap in the Ronson era, but not now.
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As far as the resistor rype heating element, I do know that very similar ones were used by Gilbert for the 21088 and 21089 Franklin style engines. The smoke unit was much smaller and the element was a resistor wrapped with a wick and then stuffed in the chamber. If Bob could get a suitable one, he could make his own element and the soldering would be much easier.
Yes in my research it was mentioned a older one and newer one. Mine was the older one
The wick material is available from the usual parts suppliers as are the repair kits for the HO units used in the Franklin engine. A lot of O gauge operators report good results using replacement Tiki Torch wicks.
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The HO style smoke units used in the HO 0-6-0 and 4-6-4, as well as the Franklin 4-4-0 and docksider 0-6-0s used this style of heater element. It has a firm fiberglass(?) core, around which the nichrome wire is wrapped. It appears to me that the way they were manufactured was by having the resistor-wound core cut to length, and then the end caps with wires crimped on.
You can easily get them in 27 ohm, but not the 38-40 ohm typically used by 5-wire S gauge engines.
The ‘angel hair’ (aka stranded) fiberglass wick is tricky to wind, but with practice it can be done. And a lifetime supply of Nichrome wire is easily obtained for not that much money (I have 40 awg stuff, but a little bigger would probably be fine).
-El
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FINAL POST
Decided to talk with Port Lines ( as someone had suggested) today before finally giving up. We spoke about 15 minutes and he knew exactly what I was talking about and is sending me the parts and instructions to repair it. He said as you mention it was found in small locomotives like HO. He also said is a lot easier to replace the wick.
Nice chatting with everyone, been a pleasure, learned a lot, especially the right solder to, use already put it to use.
Thanks and so long,
Bob
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As Jack Nicholson once said:
I’m Back
I’m posting this because it looks like a lot people are interested in this thread and I wanted to give them this information in case they run into this problem and don’t make the same mistakes I did.
I have to admit I frustrated Doug from Port Lines because he told me he knew what smoke unit I had how to fix my problem. However what he described to me didn’t sound like it would fix my unit and I yielded to the man who probably forgot more than I know about trains.
Got the fix and directions today. When I looked at the parts they made no sense to me. Then I looked at the instructions it was for a Franklin Docksider HO. so went to web and a search found a repair kit and in addition the repair kit I found also included a disk which is mentioned in the instructions but my unit does hot have a disk . Doug also told me I needed an insulator which my unit does not have and sent me the one that is used in my parts engine which has a two chamber smoke unit.
As you know by now I’m a "Check But Verify guy .
So I asked Chat Gpt How to build a Franklin Docksider HO. Got the same info as Doug sent me.
As Cool Hand Luke once said " What we have here is a failure to communicate.
Here is a summary of the details
After I received the FDHO info from CG. I told CG that is not what have, CG asked for a picture. I sent it the one I had posted previously in this thread.
CG identified it as an AF "U-Bar (1940s-1950s style smoke unit
After that everything sounded like the smoke unit I have and the repair of the smoke unit I have made sense.
CHAT GPT responses below:
To rebuild the smoke unit in a Franklin Docksider HO locomotive (made by American Flyer/Gilbert or Lionel in HO scale), you’ll need to:
Step-by-Step: Rebuilding the Smoke Unit
Important Note
There are two main types of HO smoke units used in old Franklin Docksider models:
- Seuthe-style units (common in later models)
- Gilbert “resistor-style” smoke units (early versions)
If you’re not sure which, open the engine and check. If it’s a metal cylinder with wires on both ends, it’s likely Seuthe.
Rebuild/Repair Instructions for Seuthe-Type Units
Tools & Supplies:
- Soldering iron
- Solder
- Small Phillips screwdriver
- Smoke fluid (Seuthe or Lionel)
- Replacement Seuthe unit (typically No. 5, 6, or 7)
- Multimeter (optional for testing)
- Heat-shrink tubing or electrical tape
1. Disassemble the Locomotive
- Carefully remove the shell (usually held by 1 or 2 screws on the bottom).
- Locate the smoke unit near the front stack.
2. Remove the Old Smoke Unit
- Desolder or cut the wires leading to the smoke unit.
- Gently pull out the smoke unit from the smoke chamber or funnel.
3. Install New Unit
- Drop in the new Seuthe unit. Make sure the top aligns with the smoke stack.
- Solder wires back: polarity usually doesn’t matter, but keep original wire routing if possible.
- Insulate any exposed connections with heat shrink or tape.
4. Test the Unit
- Apply power (DC or AC, depending on your setup). If the unit heats up and smokes, it’s working.
- Add 1–2 drops of smoke fluid (don’t overfill).
If It’s a Resistor-Based Unit (Early Gilbert Type)
This is harder to repair and parts are rare. Here’s what you can do:
A. Check the Resistance
- Use a multimeter across the heater coil.
- If resistance is infinite (open circuit), the coil is likely burned out.
B. Repair Options
- Wrap new nichrome wire (32–36 AWG) around mica insulator or ceramic base.
- Ensure it connects to original terminals.
- Repack with wick material (cotton or fiberglass) around the coil.
- Soak wick in smoke fluid and reassemble.
This is very tedious. You might be better off converting to a Seuthe unit, which fits most HO boilers.
Final Tips
- Don’t run dry—always add a few drops of fluid before powering the unit.
- Don’t overfill—excess fluid can damage the heater.
- Use a low-output smoke fluid (Seuthe, Mega-Steam HO-compatible) to avoid overheating.
If you tell me your exact model number or a photo of the smoke unit, I can give you more specific guidance or a part number for replacement.
Ask ChatGPT
You said:
ChatGPT said:
Thanks for the photo — what you’ve shown is a close-up of the underframe and valve gear area of your HO Franklin Docksider locomotive. This part doesn’t show the smoke unit directly, but it’s very helpful because the design and detail confirm you’re working with a Gilbert-style HO Docksider, not a Lionel-era model.
From what I see, this engine likely uses the early resistor-style smoke unit, not a Seuthe.
Next Steps: Locating & Accessing the Smoke Unit
The smoke unit on these early models is usually:
- Mounted vertically inside the boiler shell, just under the smokestack
- Connected to the motor’s power leads or directly through a resistor
- A small cylindrical element wrapped with nichrome wire or a cartridge-style heater
How to Rebuild (If You Confirm It’s the Resistor Type)
Once you open the shell and reach the smoke chamber:
1. Inspect the Smoke Unit
Look for:
- A metal tube or chamber with wires
- A coil or resistor with a wick (fiberglass or cotton-like)
- Signs of burning or corrosion
2. Test the Heater Coil
Use a multimeter:
- Set to Ohms (Ω)
- A good coil will read between 10–50 ohms
- “OL” or infinite = open circuit (coil is burnt out)
3. Rebuild Options
- If intact: Clean, rewick with new smoke wick or fiberglass
- If coil is damaged:
- Replace with ~34 AWG nichrome wire
- Wrap around mica or ceramic insulator
- Solder leads to the frame or terminals
- Reinsert wick and soak with smoke fluid
4. Alternative Fix: Replace with a Seuthe Unit
If repair is too tricky:
- Remove the old smoke unit
- Install a Seuthe #5 or #6 unit in its place
- Wire it to motor pickup or lighting circuit
- Align it with the smokestack
Pro Tip
If you want, send a photo of the inside of the boiler (where the smoke unit is visible), and I can give you a step-by-step rebuild with diagrams or help identify parts to source.
Would you like a diagram of the smoke unit rebuild options next?
You said:
I took this out of a 326 American Flyer engine.
ChatGPT said:
Thanks — now that you’ve confirmed this smoke unit is from a 326 American Flyer steam locomotive, I can be much more specific.
You are dealing with the American Flyer “U-Bar” Smoke Unit (1940s–1950s style)
And from the photo you sent, that is the heating element — a U-shaped metal bar with nichrome wire wrapped around it, held between two ceramic or mica insulators. This is not a Seuthe-style unit. It’s a single-chamber “puffer” unit used in S gauge locomotives like the 326 Hudson.
Rebuilding the U-Bar Smoke Unit (American Flyer 326)
Tools & Supplies Needed:
- Fine nichrome wire (usually 34–36 AWG)
- Smoke wick (fiberglass or asbestos-style replacement)
- Soldering iron
- Needle-nose pliers
- Heat-resistant glue (optional)
- Multimeter (for continuity testing)
Breakdown of the Unit:
- U-bar heating element (your photo shows this)
- Nichrome wire wrapped around the U-bar
- Wick material packed around the U-bar to hold smoke fluid
- Metal smoke chamber or housing
- Air piston/air chamber (for puffing action — works with the engine’s piston)
Step-by-Step Rebuild Guide:
1. Inspect the U-Bar
- If the nichrome wire is broken or oxidized, replace it.
- The bar itself should be clean and not cracked or warped.
2. Rewrap Nichrome Wire
- Use bare 34–36 gauge nichrome wire
- Wrap tightly and evenly around the center of the U-bar (about 8–12 turns)
- Leave small tails for connection at the top (one on each vertical leg)
- Do not solder directly to nichrome; instead, wrap tightly and clamp, or use crimp terminals.
3. Replace Wick Material
- Use fiberglass rope or wick made for model train smoke units
- Wrap it around the U-bar in a loose bundle
- Make sure it fills the smoke chamber without packing too tightly (it needs airflow)
4. Assemble Unit
- Place the U-bar + wick back into the chamber
- Make sure power terminals connect properly to the U-bar legs
- Ensure no part of the nichrome touches metal housing directly
5. Test with Multimeter
- Measure resistance across the terminals: should be 5–20 ohms
- Check for shorts between nichrome and smoke chamber (should be open)
6. Reinstall & Test
- Add 2–3 drops of smoke fluid
- Apply power — unit should heat in 15–30 seconds and begin puffing smoke
Optional: Replace Entire Unit
If the U-bar is broken or rusted beyond repair, consider:
- Buying a pre-wrapped U-bar from aftermarket parts dealers (hard to find)
- Or replacing with a modern Lionel puffer smoke unit (requires modification)
Want Help with a Diagram?
I can generate a visual diagram of the U-bar smoke unit with nichrome wrapping and wick placement — just let me know.
Or feel free to send a photo of the rest of the unit or housing, and I’ll guide you further.
You said:
Yes
ChatGPT said:
![Generated image]
![Generated image]
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You said:
Nichrome wire is wrapped around horizontal bar
ChatGPT said:
Thank you — that’s an important clarification.
You’re absolutely right: on the American Flyer 326 smoke unit, the nichrome wire is wrapped around the horizontal part of the U-bar (not the vertical legs, as some modern units do).
Here’s the correct understanding:
- The horizontal bar of the U-shaped metal element is where the nichrome wire is tightly wrapped.
- The two vertical legs of the U-bar serve as the electrical contacts and connect to the power terminals via the top plate.
- The wick material surrounds the entire U-bar, ensuring fluid stays in contact with the heated area.
- The metal chamber holds everything in place and collects the smoke fluid.
Updated Repair Tip:
When rewrapping:
- Focus your nichrome coil on the horizontal section of the U-bar, spacing the wraps evenly.
- Keep the wire tight and secure, but don’t let wraps touch each other — shorting can occur.
- Attach the ends of the nichrome to the vertical posts by mechanically wrapping them to the tabs, not soldering.
Would you like an updated diagram with the nichrome correctly shown on the horizontal bar?
You said:
Yes
ChatGPT said:
Share
You said:
What does mechanically wrapping them mean
ChatGPT said:
Mechanically wrapping nichrome wire means physically winding or twisting the wire tightly around a terminal or post to make an electrical and mechanical connection — without soldering.
Why This Matters:
- Nichrome wire doesn’t take solder well because it resists bonding and dissipates heat quickly.
- So instead of soldering, you:
- Strip the end of the nichrome wire (if it has insulation)
- Wrap it tightly around a screw, tab, or terminal post
- Then clamp it in place with:
- A screw
- A crimp
- A folded metal tab
- Or press-fit contact
Example on Your U-Bar:
On the 326 U-bar smoke unit:
- You wrap the ends of the nichrome around the vertical legs of the U-bar, near the top plate connection points.
- Then use the terminal plate pressure or a clip to hold it tight.
- The wire must touch bare metal, not be loose or insulated.
Goal:
Create a secure, low-resistance contact point that lets electricity flow into the nichrome — so it heats up the wire, warms the wick, and vaporizes the smoke fluid.
If you want, I can generate a diagram showing how to mechanically wrap and secure the wire to a terminal.
*CatGPT can make mistakes. Check important info.
The original ‘Franklin’ steamers never used Suethe type units. Unless someone modified one, you’re very unlikely to see that.
I would argue that Doug sent you the right kit, but did not provide instructions for how to install it in your application. The Franklin smoke unit kit uses the same style heater element, but is installed in a different housing. But the idea is the same, as far as the relationship between the fiberglass wick material and the heater element. The wick is supposed to bring smoke fluid up from the bottom of the unit, to the heater element- then it is vaporized into smoke.
The ‘disk’ for the franklin/HO unit is equivalent to the top cover of your smoke unit. The way the “U-Bar” heater element, as you call it, is installed, is different, in order to fit within the smaller unit.
You need to think about how the unit works, to understand what needs to be done- the wick needs to make contact with the heater element, and it needs to make contact with the bottom of the chamber- so fluid can reach the wick, and so that the fluid-soaked wick touches the hot element and makes smoke. I would pack the wick in, such that it is either wrapped around the U-Bar element where the nichrome wire is, or have it lightly packed into the bottom, pushing up against the underside of the ‘U-Bar’. Either way, the wick touches the ‘U-Bar’, so the fluid will reach it.
Does this make sense?
-El
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I second what El says.
A Seuthe smoke unit was never used in a Gilbert engine. The only Seuthe smoke units used in S gauge engines were installed in the Lionel AF Pacifics and Mikados made from 2004 through 2008. They did not work very well and many people took them out and replaced them with MTH fan driven smoke units. All of mine have been replaced.
Once again the 5 to 20 ohms shows up. No Gilbert smoke unit was made with less than a 35 ohm smoke unit. Your 326 original has about 38 to 40 ohms because it has 15 turns of Nichrome wire. Even new smoke units made for command control engines with a regulated output voltage less than track voltage use a higher resistance than the 5 ohms.
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EI
First I want to thank you for continuing to help me with my challenge and offering solutions.
Secondly what you say makes sense. I was thinking in the “chamber” and you are thinking out of the “chamber”.
Lets call this photo “everything” 
and if you would be so kind, if you received these parts and instructions what would be your solution be to solve this smoke unit challenge.
Thanks Bob
As you saw I ignored that whole thing about a seuthe. I got enough problems don’t need a new one. Also I’m looking for 35+ ohms
Thank you for your continued attention to my challenge and feel free if you like to suggest a solution with the parts I now have.
Thanks
Bob
Bob, I’m looking at the “pile of parts” laid out, and I see the following:
-Your original smoke unit chamber, cover, and ‘U-Bar’ heater element
-Supplies for a traditional 2-chamber style S-Gauge unit that requires manually winding a nichrome wire around a wick (this would be the long white wick, and the length of extremely fine wire).
-Heater element for the Franklin/HO style smoke unit (short white wick with wires extending out either side)
If this were my spread of supplies, I would see myself with two or three real options, which I’ll lay out:
Option #1:
Set aside all the kit parts, go out and buy some Tiki Torch wicks, and cut one open, remove the stranded fiberglass inside, and use this to create some batting at the bottom of the smoke chamber- I would make sure to wrap some of it just a bit around the ‘U-Bar’. Get everything reassembled and test.
Option #2:
Like before, go out and buy Tiki Torch wicks to source stranded fiberglass. This time though, I would un-solder and remove the original ‘U-Bar’, and install the ‘Franklin’ style heater element in its place.
I would use the stranded fiberglass to provide some batting at the bottom of the smoke chamber, and set everything up so that the batting is gently pressing up against the bottom of the new heater element. Get everything back together, and test.
Option #3:
Remove the “U-Bar” heater element. Then follow the instructions for winding nichrome wire around the braided fiberglass wick. Once the wick is wound and tests good on a multimeter, carefully feed the nichrome up through the holes in the cover where the U-Bar was installed, and secure the ends of the nichrome to the solder lugs there mechanically by wrapping it around them if you can (solder will not stick to nichrome). Get the ends of the wick seated nicely in the bottom of the chamber, reassemble, and test.
That’s my take on the situation and best courses of action. Do the explanations make sense?
-El
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Thanks again for working with me on your day of rest. As usual everything you say makes sense.
It also got me thinking and I decided to pulled back the “fiberglass” surrounding the heating element with the wire wrapped around it. Now I’m thinking the KISS principle, If I removed “fiberglass” which I have no idea why it’s there , it looks just like my current U unit, with the posts going through the caps at each end of the heater element which I believe keeps the wire in place as it currently does on mine and the vertical posts would reach the cover to connect to the power terminals
What would preclude me from just replacing my current U unit with this replacement U unit and then fill the chamber with the wick material like before which lasted 70 years while making sure I don’t block the air whole?
What do you think?
Thanks,
Bob
Bob, that might work- the main challenge is that the fluid will land at the bottom of the smoke chamber, so your options are-
-have the replacement heater element with its wick sit so they just about touch the bottom of the unit
or
-have the replacement heater element and wick so they are above the bottom of the chamber, and add some wicking material to help bring fluid from the bottom of the chamber up to the heating element
I reccomend the latter approach, because it will be less sensitive to the level of fluid being “too high” to work properly- whereas if the element is at the bottom, then you can potentially have too much fluid around the heater and get poor performance- if the element sits at the very bottom, it can get a little ‘drowned’ in fluid, if that makes sense.
But of course, if you bring the element higher up, the fluid at the bottom of the chamber cannot get to it- hence the use of some fiberglass ‘batting’ to help wick the fluid up from the bottom. The wick can only get so saturated with fluid, so it will not drown the heater in fluid.
-El
Very happy with your response
The current element sits halfway down in the chamber and the wick filled up the chamber loosely including over the top. The only part of the work that burnt was the piece that was over the top between the bars touching the element.
Do you have any idea why that fiberglass is wrapped around the element? And is it better to leave it maybe???
Thanks
Bob
How much fluid do you think that I should put in to start?
The fiberglass sleeve is around the element, to help keep fluid touching the element. I would recommend keeping it there.
For fiberglass wick to put in the chamber, I would say you want just enough that it lightly presses up against the smoke element when assembled, nothing more should be necessary. basically, you want the wick to carry the fluid up from the bottom of the chamber, to the element, via capillary action. So long as there is good contact, the fluid will flow. But if you jam pack too much in there, it can make it hard for the vaporized fluid to escape, and could lead to having more wick get burnt to the point it doesn’t want to work.
For fluid, I would say 15-20 drops to start, for a unit that is completely dry.
-El
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Great. Removed the old unit and the new one fit in like glove, but not a OJ glove😂.
Enough for one day. Tomorrow I will put in the wick, the fluid and test fire it up.
Have a great rest of the day or evening depending which time zone you’re in.
Thanks,
Bob
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L’unità fumogena funziona.
Grazie davvero di tutto!
Sinceramente,
Roberto
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