32 replies to this topic

[Pablo]

1. Use 60/40 solder. Radio Shack part # 64-018.
2. Use acid flux, then clean up/neutralize with Isopropyl Alcohol. QTips and Pipe Cleaners.
3. For soldering in a motor, use the highest iron temp you have.

[Guy Spaulding]

Another question regarding soldering in motors: What is the best type of solder to use? I have a difficult time getting anything to stick to a Cheetah 21 chassis, and I'm really not comfortable with using acid flux without being able to neutralize it on the can and chassis. I have a Haikko FX-888 soldering station. What is the best temp for soldering in a motor? (My blistered fingers will thank all who contribute!)

Sorry, Paul. There's no getting around the use of acid flux. None at all. And there's no need to blister fingers.

Solder flows and adheres to clean hot metal. The hotter the better. BUT you dont want to get other things hot, like motor magnets or fingers.

Use regular electrical solder, 60/40 like you get at Radio Shack
Use a good size iron, like 50Watts, and turn up the heat to max

Make sure your surfaces are prepped. Bare surfaces should be clean. New surfaces are fine. Old solder remaining is no problem. Cleaning agents and/or wire brush may be needed for contaminated or rusty surfaces.

Place your chassis, flat on your soldering block, at an angle so the rear wheels are away from you and dangle over a corner of the block. Then position your motor for your desired gear mesh (how to do this is another lesson)

We're gonna TACK Solder the corner of the motor nearest to you to the chassis, just enough to hold the motor in place
Use a #0 or #1 SABLE paint brush, a Q tip, a pin-point oiler, or whatever your weapon to apply a moderate amount of flux to the desired joint area.
Wipe both sides of your solder iron on a damp sponge (some dont like this), then apply a little solder to BOTH sides of the iron and stick the iron in the corner just long enough to watch the solder flow to the chassis and motor.

Now put another spot of solder closer to the endbell, being careful not do disturb your gear mesh.

Now, the next step is only for Cheetah 7, Cheetah 21 and TFlex.

Remove the rear axle/gear/wheels from the chassis

Add piece of tubing, maybe 3/32" diameter, 3/8" long behind the motor, and repeat the soldering technique.

Finally, add more solder to the front of the motor to make things more bullet proof

Remember! When you're soldering, get in and get out as soon as you can. If you're iron is hot enough and you have enough solder and flux, you dont need much more than a second on each solder joint. If one solder joint takes longer than you think it should have, place a hunk of aluminum on the motor and walk away for 5 minutes. The aluminum will keep the motor from running away (jk)

Last step. Flush your area with alcohol, naptha (lighter fluid) and/or motor spray. Use a tooth brush helps too.

Note: Never clean the soldering iron tip after use. The leftover solder and flux protects the tip from corrosion and contaminates. Always wipe the iron just prior to use.

Well, all of this was hard to put into words without pictures. Hope it helps



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[Tattoo_Paul]

Guy, thank you! You've identified my problem (well, one of many, anyway ) - not enough heat in the soldering iron. I'll have to turn it up more and give it a try.

[Phil Hackett]

I take it the old "glow in the dark" Ungars aren't around anymore! (Old Timers will know what I'm speaking of.....) Those were the ultimate motor soldering irons. 30 second changes with one iron.... two irons.... humph... you kids now days!

[Guy Spaulding]

Phil. You remember my green pit box with the old version slick7 power supply built into the inside of the lid. I tapped off the medium tap of the variac, giving me 130 volts from a 120 volt outlet. Makes my newer Weller glow

[anarot]

I just use a solder sucker or the swing/bang method

[Tim Neja]

Well, I like using this motor brace. Wish it was USRA legal

I LIKE this one---with the spur gear protection too!! :Smart!!

[GearBear]

On a new chassis, I use acid flux to tin the chassis. Once I've tinned the chassis I flush it clean with water. From then on I only use paste flux to mount the motor. If you are having trouble getting the solder to flow to get the motor out, brush it with flux first. That will get through the oxidation and the solder will slow easily.

Guy, I like your motor brace! I use one similar to the center section of that... IE Just the U shaped section for the motor. And it is still legal for USRA as it is less than an inch in length.

Oh, and I NEVER mount a Falcon or Hawk 7 in more than two places if I can help it. I want to keep the heat to a minimum. In fact, if I have to pull the motor out, I will put a new one in rather than remount the old one.