Tracked vehicle construction?

LeChatNoir · Post by **LeChatNoir** » Wed Mar 29, 2006 10:01 am

[bad infulence] And it sounds to me like, with such costly parts, you could justify buying a lathe and milling machine... [/bad influence]

dragonfly Jafe · Post by **dragonfly Jafe** » Wed Mar 29, 2006 1:05 pm

yes, but then I'd have to build a shop, which would mean eliminating a neighbor or two first premptively. But alas, I have no executive powers...

Tiahaar · Post by **Tiahaar** » Wed Mar 29, 2006 10:23 pm

Yeah, attachment chain!!! Dude you are rocking now. I am still hunting for my chain but two weeks ago retrieved the chassis that will become my EXERTRAK from Van Nuys and started work! Gotta keep from falling too far behind. First was to take the thing apart then start adding the cyborg stuff in...first was a big sprocket where the power will feed out to the transaxle, which is currently awaiting new shift keys so I can put it back together.

Tiahaar · Post by **Tiahaar** » Sat Apr 01, 2006 9:54 pm

http://cgi.ebay.com/Lot-of-95-of-Attach ... dZViewItem
YEAH Found my attachment chain! And yes that's a pallet its sitting on there, 1200 pounds shipping from Florida to California will be a bitch but its just what I need...BF111 4 3/4" pitch with K attachments for making a super tank track

Heheh April Fools...that stuff would be a bit toooo big for my project!!

dragonfly Jafe · Post by **dragonfly Jafe** » Sun Apr 02, 2006 1:29 pm

just got back from the Kinetic Sculpture Racing seminar on building bicycle powered madness. Also got to play with Bob's dual-wheel thingy (very impressive!)

I highly recommend this seminar to anyone bicycle-ey inclined in their engineering. It is only offered once a year, but hopefully soon the material will be put on the web.

I am now convinced a bicycle powered tank is feasible. The differential steering will work, possibly better than I had hoped. It will not go fast, my original goal of a top speed of 5mph is probably not going to happen (unless I can get a few guys with yellow jerseys for my crew!).

I will have to see what sprockets are available and start playing with my gearing and everything now...one general rule is that you want a low gear of "5" for mud and sand (typical mountain bikes are maybe 12-100), which means a second gear stage is essential (maybe even a 3rd).

The second stage must be much stronger than bicycle stuff (KSR racers break bike chains all the time)

I have a video of the differential steering, I'll try to post it on the web somewhere for anyone that is interested.

dragonfly Jafe · Post by **dragonfly Jafe** » Mon Apr 03, 2006 9:29 am

the bikes I am using have the following sprockets (all in number of teeth of the sprockets);

front: 48 - 38 - 28

rear: 28 - 24 - 20 - 17 - 14

assuming 60 rpm pedalling (with 100 rpm for emergency power mode) and an 8" drive sprocket dia, the lowest gear would provide 8 gear inches and the highest would provide 27.

(28/28 * 8 inches = 8 inches , 48/14 * 8 inches = 27 inches)

speed would be 1.4 mph in low gear (assuming 60rpm) and 4.9 mph in high gear. But I don't think 8 is a low enough gear for a tracked vehicle.

So I will add a second stage, I want maybe two gear ratios so I can fiddle and see which works best. One for greatest torque (but lowest speed) and the other for greatest speed (with reasonable torque). Fortunately there are many gears above if it is possible to go faster (or a guy named neil joins the team).

so maybe an 3/8 and a 5/8 second stage gear ratio (say 12 teeth / 32 teeth and 15 teeth / 24 teeth). That gets me a low end of 3 gear inches or 5 gear inches and a high end of 10 gear inches or 16 gear inches.

Speed-wise that yields (again assuming 60 rpm) .5mph - 1.5mph with the lower gear setting or 1mph-2.5mph with the high gear setting. Of course, if I don't need that much torque, I can eliminate the second stage, but I have a feeling I will need it!

Turning will be by differential steering using a second drive system that is hand cranked. As you are steering differentially, and in fact since 1 track is getting positive and the other negative, the speed is effectively doubled. This plus the width of the vehicle combine to make it not so hard to get an effective turning speed. I am hoping to be able to spin 180 degrees in place within 15-20 seconds, or a 90 degree turn in 10 seconds or so. With a top estimated speed of 2.5 mph (around 4 feet a second) that means a 40' turn radius at top speed (BRC city streets are 30' wide).

I will probably also add disc brakes (for emergency stops) to allow skid steering also. I assume friction will bring it to rest fairly quickly even at it's top rated speed. But someday it may be on a hill going down....

dragonfly Jafe · Post by **dragonfly Jafe** » Fri Apr 07, 2006 3:18 pm

here is the finished mock-up of all the axles and gears needed. There are two chains that will need gaurds (one for sure!), the rest appear to be out of the way. Also, everything can be worked on, etc, if needed.

I couldn't figure out an easy way to attach the sprocket to the hubs, so I just welded it. Hope I don't have to replace it!

dragonfly Jafe · Post by **dragonfly Jafe** » Sat Apr 08, 2006 5:24 pm

only a few hours without rain today, but I put them to good use! I added the left seat (adjustable +/- 6" or so) and some hand rails (one is actually part of the chain gaurd that will be helping to prevent the drivers from getting their fingers cut off or mangled). The seat is made of shade cloth zip-tied to 1/2" EMT. This is how some of the KSR racers do it, provides some ventalation underneath. I have decided to leather wrap the handles for a little added class (and to prevent from gripping sun heated metal). I will probably do the same for the seat bars. The handles also serve as grip points when pedaling and not steering. It is getting heavier, but I can still lift it so far....

In tank mode, the tank commander will be standing on a battery box (holding the 12v battery for lighting and sound effects) located just behind the seats. The top of the seats will probably have some kind of padded "whip-lash" bars to add support higher and prevent the commander's legs from hitting the drivers (also give a brace point for the commander). The Turret will be basically centered over the bar at the back of the seats, maybe a bit back. I am using the wheel of a 26" tire left over from when I scavenged the hub to use as the turret opening (this also will be padded). The turret itself will rotate manually on golf ball bearings contained in a track.

Elliot · Post by **Elliot** » Mon Apr 17, 2006 9:08 pm

.
Wow, that's coming right along, Jafe! Glad you enjoyed the KSR seminar. Remember everybody, the Grand Championship Kinetic Sculpture Race (all human-powered and amphibious) takes place Memorial Weekend in Humboldt County, CA. www.kineticsculpturerace.org.

(I think my 'puter works now -- it has had a major tune-up. But scanner still out.)

phil · Post by **phil** » Wed Apr 19, 2006 11:38 am

http://www.tankchair.com/default.htm

Elliot · Post by **Elliot** » Wed Apr 19, 2006 1:11 pm

.
RE: Tankchair.

I was going to post a couple of real battle tanks, but now I have to
just stand here and salute for a while.

phil · Post by **phil** » Wed Apr 19, 2006 1:16 pm

Elliot wrote:.
RE: Tankchair.

I was going to post a couple of real battle tanks, but now I have to
just stand here and salute for a while.

If your salute lasts for more than four hours, seek immediate medical help. :->

dragonfly Jafe · Post by **dragonfly Jafe** » Wed Apr 19, 2006 4:32 pm

latest progress photos...not that that othet thing hasn't been given me wood!

Elliot · Post by **Elliot** » Wed Apr 19, 2006 5:37 pm

.
Patton M60

Elliot · Post by **Elliot** » Wed Apr 19, 2006 5:39 pm

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Patton M47 rear

Elliot · Post by **Elliot** » Wed Apr 19, 2006 5:42 pm

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Patton M47 front

Just in case it is of interest! Snapped at the Patton Museum in Southern California.

Tiahaar · Post by **Tiahaar** » Thu Apr 20, 2006 12:12 am

Wow. I'd forgotten how heavy-duty the track systems are on battle tanks, having only seen them in museums as a kid. Makes even the cat dozers seem fairly simple and uncomplicated. Soooo, I will post a photo of my own set of puny bogie wheels for one side anyway, I had them lined up on the lawn checking spacing...they are only 8"...but are getting new electric motor quality kart bearings (with seals!) to better withstand the wind-driven playa.

I'm getting concerned about the amount of friction in my design...16 bogie wheels, 4 main sprockets, main shaft, two jack shafts, 10 shaft bearings, etc. etc...plus a right-angle gearbox and transaxle. EEp.

The transaxle is now back together & works!! The two little toothpick-looking things at the bottom of the photo are the new shift keys that went in. The pinecone of gears next to it is what accounts for all the internal friction as they all turn at different speeds right against one another with lots of grease drag...only the gear with the shift key engaged to it drives the output shaft. Very clever design!

Dang dragonfly Jafe you've got a chassis practically built already! Awesome!

dragonfly Jafe · Post by **dragonfly Jafe** » Fri Apr 21, 2006 2:39 pm

View of turret structure (handles are for manually turning the turret). The upper part is basically view ports (will not be covered). The rest will be covered by very thin aluminum sheeting riveted to washers welded to the frame. There will be a propane tank on the back, balanced by a flame gun on the front (at least if I get my flame permit - if not there will be plastic mock-ups). I hear there may even be a MG that can be mounted to the front (say to a plate welded there...)

The flame cannon controls (gas valve, ignitor, and dump lever) will be mounted at the front of the turret with the 1-1/2" pipe extending out from the center at a fixed upward angle.

(also note the tarp covered Tongue in the back ground, awaiting it's fate)

robotland · Post by **robotland** » Sat Apr 22, 2006 8:16 am

DANG, Jafe!
When you get down to fine details and know what kind of weapon mounts you'll have, I'll make it a point to adapt the Greenkilts Q-Division's latest toy to fit.
I REALLY like the turret. Damn nice work, my friend!

dragonfly Jafe · Post by **dragonfly Jafe** » Sat Apr 22, 2006 2:46 pm

I think maybe another MG has already been pledged for the Tank Commander's cupola when she goes into battle..the real hardpoints for Q-type weaponry will be down lower, on the foward sloped hull, and also on the side sponsons that will be covering the access portals. Plenty of space for MG's, flamethrowers, rocket pods (a pair of those for the rear would be kool), etc. The tank I am basing it on, the M5 Stuart light tank, historically had a slew of weapons (up to 3 hull MG's and a turret MG plus the main gun). Basically, I am trying to add deterants to people wanting to try to climb on the thing...(maybe I'll wrap it in barb wire). Lightweight but menacing looking spikey bits have been suggested, but I am afraid they would become MOOP.

I spent most of today buying parts and really thinking about the flame cannon. I think I have the controls and gas hose routing figured, the only part I am not sure of is the ignitor (probably use a spark of some kind - I have a piezo-style that works remotely, but I don't think that would be robust enough or last more than a few shots!). The cannon will be fixed such that it is always 7-8' above the ground (pointed at maybe a 30 degree up angle). I plan on having a few 12v lights on the turret aiming outward that define a 25' radius arc (or whatever is needed) to aid the Tank Cammander in knowing when it is safe to fire. I wish they mad a laser level with a variable radius function...

I estimate the blast will be about 100 cubic inches of propane at 90 psi (or maybe less as the pressure will be regulated). Anyone know how to calculate a fireball size from that? I am hoping for 3-4 feet at least....

Elliot · Post by **Elliot** » Sat Apr 22, 2006 7:51 pm

.
I was just in Idaho, so I thought of Jafe and on the way back I "mentally invented" a cannon that would use shotgun-primers to blow a puff of talkum powder out the barrel. I guess that proves that I have not been to BM yet! Propane-fireballs over my head. I'll wear my hair extra short!

Q: I probably know this, but my mind is blank: Jafe, what are you using for tubing on that chassis? Electrical conduit? Welder -- wire feed?

StevenGoodman · Post by **StevenGoodman** » Sat Apr 22, 2006 9:19 pm

[quote="dragonfly Jafe"]
I spent most of today buying parts and really thinking about the flame cannon. I think I have the controls and gas hose routing figured, the only part I am not sure of is the ignitor (probably use a spark of some kind - I have a piezo-style that works remotely, but I don't think that would be robust enough or last more than a few shots!).[/quote]

Last year Dance Dance Immolation decided to go with Pilot Lights, instead of ignitors. We had built ignitors out of ignition coils, but there was some problem. (The problem may have been with the coils interfering with all the electronics and safety systems.)

I can ask Sunday evening, we are having a meeting.

dragonfly Jafe · Post by **dragonfly Jafe** » Sun Apr 23, 2006 4:28 am

I am using 1" EMT (electrical metal tubing) for the main chassis, 3/4" EMT for the stuff I am not sure off, and 1/2" EMT for everything else. MIG welder on a low setting (multiple passes where it goes to heavier stuff) - (and holding my breath in a futile attempt to avoid the vaporized tin,etc).

This is mild steel. I am a little concerned about the flex, but so far the weight is right on (I lifted the entire chassis w/ turret today, I would estimate maybe 150 lbs). I plan on lots of triangular bracing.

I would prefer chrome moly or aircraft aluminum, maybe that will be mk.II

I am ordering my last sprockets tomorrow. Can't wait to see if 1-2 slaves can make it go....

If not, it's 9 hp of pure gasoline where it will do the best...

Elliot · Post by **Elliot** » Sun Apr 23, 2006 7:24 am

.
Right. Please try real hard not to breathe the fumes from the galvanizing. Some people sand it away before they weld. Other than that, EMT ("conduit") is great stuff.

I'll honk and wave if I drive thru Idaho again -- I'm on my way out the door.

dragonfly Jafe · Post by **dragonfly Jafe** » Tue Apr 25, 2006 2:46 pm

Elliot wrote:.
Right. Please try real hard not to breathe the fumes from the galvanizing. Some people sand it away before they weld. Other than that, EMT ("conduit") is great stuff.

I'll honk and wave if I drive thru Idaho again -- I'm on my way out the door.

Yeah, the fumes are a bitch. I considered a breathing rig, but so far think by holding my breath and moving away after each weld before breathing in I am minimizing my exposure (I guess time will tell). Sanding it definetaly helps (especially in getting a good pool started), but I have been kind of cheating lately by just allowing the arc to burn it off and then form the pool. Seems to be working so far...I had a heck of a time when I had to remove two pieces yesterday that I put in the wrong spot...

Lassen Forge · Post by **Lassen Forge** » Tue Apr 25, 2006 3:02 pm

The old welders trick of drinking milk will help kill the queasy feeling from breathing galvy fumes...

Of course, it prolly doesn't do much for the heavy metal poisoning... but you survive the immediate aftereffects. Something in there counteracts whatever the burning zinc does to your bod... Don't know what or how or why...

but I know firsthand it works.

bb

capjbadger · Post by **capjbadger** » Tue Apr 25, 2006 4:37 pm

dragonfly Jafe wrote: (and holding my breath in a futile attempt to avoid the vaporized tin,etc)

Actualy its the vaporized zinc you want to avoid that's coming of the galv. Nasty nasty stuff.

'Typical “metal fume fever” begins about 4 hours after exposure, and full recovery occurs within 48 hours. The symptoms include fever, chills, thirst, headache and nausea. All of these symptoms, pain and suffering, as well as lost work (and play) time, can be avoided entirely by simply not inhaling the zinc oxide fumes. This can easily be done using any of the methods described later.'

dragonfly Jafe · Post by **dragonfly Jafe** » Tue Apr 25, 2006 4:57 pm

thanks for the encouragement that I probably am not poisoning myself. It has been in the back of my mind, but the first whif or two of that shit was all I needed to know it was some bad stuff. I have yet to experience anything (besides a hand burn last week) negative, so I'm guessing I'm OK. All that fritted lead I once uncovered in a college art drawer or the vial of Carbon-14 I spilled on my foot probably did far more damage...

Just to make it clear tho' - welding EMT is hazardous, as the zinc used to make it rust proof (galvanized) vaporizes during the welding process (this coating also makes getting good welds harder). Breathing vaporized zinc (like most any heavy metal) is not good. I knew all this before I started, am doing everyting outside, and take extra steps to avoid breathing the crap. Anyone else welding EMT should do be aware of what they are doing...

Dork · Post by **Dork** » Tue Apr 25, 2006 5:00 pm

I got that metal fume fever once.. felt like I had the flu for a day and couldn't go to work. Not fun. I won't even grind galvanized metal anymore without good ventilation and a respirator.

dragonfly Jafe · Post by **dragonfly Jafe** » Tue Apr 25, 2006 5:03 pm

LeChatNoir wrote:[bad infulence] And it sounds to me like, with such costly parts, you could justify buying a lathe and milling machine... [/bad influence]

I may be buying a small milling machine, found a combo drill/mill press for $300 that would fit into the corner of my existing shed and do the limited stuff I need to do. It's a hobby rig, and probably crap, but good enough for the end of the world tank korps...I just have to convince myself that all those slots would be worth it...

Tracked vehicle construction?

oooo me like!