Hey! This thing is still a Work in Progress. Files, instructions, and other stuff might change!

Tank Track, Idler Sprocket and Hub

by fastmike75, published

Tank Track, Idler Sprocket and Hub by fastmike75 Sep 23, 2014


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More Tank stuff to go with Tank Track 2in and related parts to build a RC or Robotic Tank.
This is the idler sprocket that goes on the free spinning end of the track from drive sprocket. Uses 1/4"x3/8"x1/8" sealed ball bearings and 1/4" shaft with lock collar/spacer or 1/4" shoulder bolt. Use #4 sheet metal screws to attach hub to sprocket.
This is what started it all. An idea for a track tensioner to make a RC tank like the Howe and Howe Rip Saw Tank, that would allow the track to stay in place with long travel suspension and not flop around or loose tension when you hit bumps. If you watch the rip saw tank it just takes the bumps like they are not even there. This tank is a stable go anywhere platform for anything mobile.
Made the tensioner arm and shaft out of a long 1/4" bolt and some 1/2" flat steel with an arm welded to a lock collar and spring to keep tension on the track. Lock collar allows you to adjust track tension on bolt shaft. The spring has to be a stiff one, because when the tank backs up, the spring has to overcome the all of the weight of the tank trying to move in reverse. But you also have to give the track a little flex room to digest small pebbles that get in the track and sprockets in dirt.
Tensioner shaft goes through 1/8" aluminum frame with some bushings (1/4"IDx3/8"ODx1/2" long with flange) I found at True Value. 3D printed support for bolt in middle of tank with 1/4" bearings.
This was my second design. I placed the shaft further forward on the frame, and angled the arms back like other swing arms so the spring and tensioner would soften the first hit of anything the track has to go over at speed.
Would love to see any other ideas for ways to do a track tensioner! Have fun!
Added a hub cap for the idler sprocket. Use #2 screws, drill (2) holes in sprocket to hold hub cap.


The hub will need raft and support.
Sprocket will print without raft or support.

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Mike, you said a lot of filler. It boils down to money. You've complained about money. The military or government simply won't pay it. Why? One word sequester. Google it when the government implemented it months back. Google how people in Iraq and Afghanistan where buying off the shelf kids toys (Air Hogs) and other things like 1 & 1/2 metal to weld upon their vehicles at a slope to prevent bullets from penetrating. You're asking for someone who earns less than a school teacher to pay you? For something that would help people like me know what's around the next corner? That sounds mighty selfish of you shipmate. We have a Makerbot from a person who bought one with his pay and had it shipped here. Then we have had people design stuff for us which we use in the field. We don't have to ask Sears for thousands of dollars in tools. We can just order 20 dollars worth of plastic and print it ourselves it works better than Sears's cheap crap. Why should those who are defending the front line to keep people like you safe have to pay for tools they require that their government won't provide them to do the job? My recommendation to you is this, NextEngine 3D Scanner the Pentagon uses it, NASA uses it, the CIA and every fortune 500 company uses it. You can scan objects and make them out of plastic or metal in any new 3D printer. If you can see it you can scan it. I hear what you're saying and understand it. Yet in a military view point that excuse isn't acceptable or as we say Sat. Instead of sending out a person to go get blown up we make inexpensive robots like yours. A motherboard does not cost much. It cost around 25 cents per mother board. The soldering Iron 10 bucks. The lead to solder the diodes into place and upload the programming all it takes is time. And it's time we have plenty of over here. Why? Why, leave a IED in a road which we won't encounter but a child will. Just because we don't encounter it doesn't mean a child will. We use these cheap RC cars, or cheap RC tanks to see what's over the ridge if it gets blown to bits by a sniper we already know where he's at. One less casualty sent back in a body bag or back wounded. If the guy from Sweden can figure out how to make a Open RC car and all the materials to make it cost around 15 bucks. I'm sure you can figure it out.

Mike your comment where you posted, "is not to build a tank piece by piece and screw it together, this stuff is for people to use to build your own tank. If I had a step by step, with tutorials and videos, I would be selling it, not giving it away." Then why do you have your stuff online. What you're saying and what you're doing doesn't add up. I gave you constructive criticism as I looked at it as a way to help the United States Navy in recon missions by using your nifty little toy with a camera to give us a better view what's over the next ridge. My advise was to put every part in a file, label it, put a PDF how to put it together. I do not accept your thesis nor your conclusion that if you had this all in instruction, and parts you'd be selling it. Here is someone who put together a RC Car and is giving it away world wide for free and provides instructions, http://www.thingiverse.com/thing:42198 . This person is listed in 3D Printing Magazines as the person to look toward as the innovative person of 3D printing. Where people charge for their designs he provides it to the masses for free. I utterly reject your notion and thesis outright professionally and respectfully. There are parts on this website where I've 3D printed and put into the Navy's tool box because they're free. If you're unwilling to step to the plate I'll use other peoples models which are easier to put together that come with instructions and are free. Enjoy shipmate.

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