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Peter's Model Railroading | Articles | Tools | Attaching Stuff
P-B-L Hotip Resistance Soldering


The model railroading company P-B-L sold a resistance soldering system called "Hotip" manufactured for them by Contact, Inc. Unfortunately, the government lockdowns in response to "covid" has caused Contact to go out of business, so this system is no longer available for sale (I ordered some extra parts to carry me for several years). I got mine very lightly used. I have not yet had an opportunity to use it, as I have been busy with other projects. However, its operation seems simple enough. You connect two leads to the two thumbscrews on the unit, power it up, and select the desired voltage (2 or 3 are probably the most common ones). When you have the leads connected and held in place on the work, press the foot switch to send the low voltage/high current electricity to the probe/tweezers to melt the solder and attach the metal parts. Then, let go of the foot pedal and hold the probe/tweezers in position until the solder solidifies. I have included photos of the various parts and add-ons, because P-B-L tends to not want to photograph their products.
(external link: P-B-L; select category 5)

This is the tweezer set-up that comes with the system. This is for getting really close to tiny or hard-to-get-to items that need to be soldered.
(external link: Soldering a Turnout)

These are a pair of replacement tweezer tips. They can be filed to a desired shape.

This is a more conventional solder iron probe. It connects to one of the thumbscrews on the unit. You touch this probe to the work that you want to solder.
(external link: Resistance Soldering How-to)

This is the other lead for the probe. It completes the circuit and it can be attached or clamped to any area of the work, so long as there is electrical contact between where this cable attaches and where the probe will make contact. Generally, the space between these two will be affected by the current, so if you are soldering a small detail in among other details, you want this space to be as small as possible, to avoid other parts from becoming undone. The tweezers might be a better solution for tiny detail parts.

This is a photo of the large grounding clamp that can be used with the above-mentioned secondary cable.

I also have a small grounding clamp.

This is the replacement probe tip. As you clean or clear the tip, it wears down, so eventually you'll need to replace it. The probe on mine already has a fairly worn tip, so I'll be needing to use this one pretty soon.

These are some special silver solder that P-B-L sells.
(external link: Intro to Resistance Soldering)

P-B-L also sells this flux liquid, which comes with an applicator.