If your Doodle Bug hops, and pops going down the track making clicking sounds, your gears are split and need to be replaced.
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REPLACEMENT TECHNIQUES:
1.) Loctite 271 threadlocker P/N:27121 can be used for adhering a 3D Printed gear to axle.
SPLIT GEAR FIELD SERVICE KIT:
: 1 EACH. LOCTITE 271 THREADLOCKER (HIGH STRENGTH) ................P/N:27121
: 1 EACH. NMRA HO STANDARDS GAUGE (WITH RP-25 CONTOUR) ...MARK IVb
: 1 EACH. ELECTRO-WASH CLEANER DEGREASER (PLASTIC SAFE) ......P/N:ES1210
: 1 EACH. No. 50 DRILL BIT.
: 1 EACH. No. 47 DRILL BIT.
: 2 EACH. BALSA WOOD.
: 1 EACH. MINIATURE GEAR AND WHEEL PULLER.
https://www.micromark.com/Miniature-Gear-Puller (https://www.micromark.com/Miniature-Gear-Puller)
: 1 EACH. HO SCALE BACHMANN DOODLE BUG AXLE REPAIR KIT.
https://www.shapeways.com/product/ZXTD5WA4F/ho-scale-bachmann-doodle-bug-axle-repair-kit?optionId=248454086&li=marketplace (https://www.shapeways.com/product/ZXTD5WA4F/ho-scale-bachmann-doodle-bug-axle-repair-kit?optionId=248454086&li=marketplace)
REPLACEMENT OF GEAR ON DRIVE WHEEL ASSEMBLIES:
: PLACE MODEL BOTTOM SIDE UP, IN A FOAM CRADLE.
: REMOVE SIDEFRAMES.
: USING A 1.44 MM LONG SHAFT FLAT TIP SCREWDRIVER OR EQUIVELANT, INSERT SCEWDRIVER
IN BETWEEN THE COWCATCHER AND WHEEL POPING OFF THE GEARBOX COVER CLIP FROM THE
GEAR BOX TAB, SAME BOTH SIDES, REMOVE GEARBOX COVER.
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: REMOVE DRIVE WHEELS FROM GEAR BOX, CLEAN GEAR DRIVE WHEEL ASSEMBLIES WITH THE
ELECTRO-WASH CLEANER.
: USING THE MINIATURE GEAR AND WHEEL PULLER, REMOVE THE WHEEL WITH THE BLACK INSULATOR
BUSHING AND SLIDE OFF THE SPLIT GEAR.
NOTE: THE HO SCALE BACHMANN DOODLE BUG AXLE REPAIR KIT COMES WITH FOUR 3D
PRINTED GEARS. WE USED TWO KITS FOR TWO MODELS, WE WERE ABLE TO INSTALL FOUR,
TWO PER MODEL, DESTROYED THREE LEARNING HOW TO INSTALL THEM.
(1) DO NOT PRESS FIT, THE GEAR WILL SPLIT. (3D PRINTED IN MATTE TRANSLUCENT PLASTIC)
(2) DO NOT USE TEMPERATURES OVER 200 DEGREES FAHRENHEIT.
(3) HAND DRILL IN STEPS (No. 50, 49, 48, 47). CAN SPLIT IF PUSHED TO HARD,PIECES CAN CHIP OFF ON
THE EXIT SIDE.
: USING A HAND DRILL ENLARGE THE GEAR AXEL HOLE IN STEPS STARTING WITH A
No. 50,49, 48 ENDING WITH A No. 47.
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: CLEAN GEAR AND GEAR DRIVE WHEEL ASSEMBLIES WITH THE ELECTRO-WASH CLEANER.
: APPLY A COAT OF LOCTITE 271 IN THE CLEAN GEAR HUB AXLE RECEPTACLE.
: APPLY A COAT OF LOCTITE 271 TO THE CLEAN WHEEL AXEL.
: INSERT THE WHEEL AXLE INTO THE GEAR HUB RECEPTACLE. REMOVE EXCESS LOCTITE.
NOTE: THE GEAR WILL SLIDE ON EASY FOR A STRESS-FREE FIT.
ON A BACHMANN GEAR WE WOULD PUT THE ASSEMBLIES IN A 200 DEGREES FAHRENHEIT OVEN FOR 1 MINUTE. SO,
WE TRIED THIS WITH THE 3D PRINTED GEAR AND IT WORKED. HOWEVER, WE MISALIGNED ONE 3D GEAR. WITH THE
BACHMANN GEARS YOU CAN HEAT UP TO 500 DEGREES FAHRENHEIT WHICH IS THE RELEASE TEMPERATURE FOR THE
LOCTITE 271, BACHMANN GEARS CAN BE REMOVE AND REUSED. THE 3D PRINTED GEARS WILL DISINTEGRATE AT
THIS TEMPERATURE MAKING THEM A SINGAL USE.
: REINSTALL THE WHEEL TO THE AXLE.
: USING THE NMRA HO STANDARDS GAUGE, MARK IVb CHECK THAT THE WHEEL WIDTH IS CORRECT.
: USING THE BALSA WOOD MAKE A CENTERING JIG FOR THE 3D PRINTED GEAR ON THE AXEL.
: ALLOW THE REPAIRED GEAR DRIVE WHEEL ASSEMBLIES TO CURE OVER NIGHT (24 HRS).
: PLACE THE WHEEL AXLE ASSEMBLIES IN THE GEAR BOX, BE CARFUL WITH THE WHEEL CONTACT ARMS
THEY DAMAGE EASLY. REINSTALL THE GEARBOX COVER AND SIDEFRAMES.
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: TEST RUN.
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Quick update, Shapeways just filed for bankruptcy. Their website will still let you order the gears, however, after a month you will realize that you have to dispute the charges on your credit card. Anyone have another source for the gears?
NWSL has metal gears for the Doodlebug.
Rob