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Guest seev_39

Gears - magic material !!

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Guest seev_39

Hi all,Finally I got it. After many experiments I found the magic material for building your onw gears (you can also use it for other shapes). It is called "Propoxy 20" made by Hercules Chemical Co. Inc (www.herchem.com).The company makes the steel hard, non conductive putty for plambers, but I found it is easy to use for making all other shapes. After hardning (20 minutes) you can drill it, file it or saw it.From the producer site;"Pro poxy 20 is a fast acting, co-extruded single stick, epoxy putty. Made of a pre-measured, steel reinforced dark gray/black epoxy resin with a contrasting strip of hardener embedded in the center. The two part epoxy compound mixes quickly and easily to form a permanent steel-hard bond in 20 minutes. Adheres to almost any surface with strength often greater than the materials it has joined. After curing, it can be drilled, filed, sanded, painted, and machined. Can be applied to damp or wet surfaces and even makes underwater repairs. Pro poxy 20 is non-conductive and may be used for electrical insulating repairs and can be used on applications where it is subject to temperatures up to 300

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Guest GeorgeDorkofikis

Oh Please DO!!!!Great news Seev! Thanks for sharing with us.George DorkofikisAthens, Greece

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Guest seev_39

Hi George and all.It is very easyFirst buy the putty material. Here in Israel you can find it in hardware stores under plambing material. One tube cost about $4. I believe that in the States it will be not more than $2 per tube.How to make the gear?1. Cut out a disk from any soft steel. I use computer case material.2. Make a center hole, a bit larger than the final axis. I use normal threaded bolts for the axis. The hole can be off-center, it does not mater because you will center the bushing later on as I will explain.3. Devide the disk into any number of teeth you wish and cut them out with a cliper (I think that's the name for steel scissors)4. Make an O-ring from same computer steel. Measurements; diameter a little smaller than the gear groove. hight, about 8 mm.5. Make a little putty as explained on the tube's instructions (you cut out about 15 mm of the material and knead it with wet fingers until it becomes a paste). Then adhere the o-ring to the disk.6. Wait 20 minutes and make more paste. This time fill the gap between the o-ring and the outer line of the gears.7. Wait half an hour to one hour and file the excess material, so only the gear teeth are left. Final work next day when the material is 100% hard.8. Make the bushing by drilling a bigger hole into a bolt nut. For instance take a 7 mm nut and drill a 9 mm hole in it. The hole size shoult fit the axis you use.9. Adhere the nut to the gear disk with a little putty. But this time be carefull to center it before the putty get hard. I do the centering with a caliber by going around the gear and moving the nut from side to side until I am satisfied. I assure you that the outcome will be an excellent centered gear (maybe not for Boeing Company, but O.K. for our hobby).I also made small gears for driving pots from the same putty. I took a water bottle cover and lined it from the inside with a piece of a rubber belt used for car alternators. These belts have small teeth. Then I filled it with the putty and after the material became hard I drilled very carefully a 6 mm hole in the middle of the gear. The counter gear (Throttle) is 3.5 times larger in the number of teeth and is made from the rubber belt. The basic idea came from Thoumas on this forum some time ago.Have funSeev

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