Looks like I will be needing 5X23" 3" sections, and an overall length of 53" per tread loop.
How many idlers should I order (can’t post pics yet, but after this question I will)?
My shopping list so far:
5X23" 3" track
4X pairs 6 link sprocket pairs (each side, front and back =4 pairs right?)
4X pairs 6 link sprocket pairs (2X idlers each side = 4 pairs right?)
2X 3" passive Idler hubs (one for each idler, they come in pairs right?)
2X 6mm Hubs (to mount on the Gearhead motors, then to the drive sprockets right?)
2X 1:30 Gearhead motors 6mm shaft (one for each side, mounted at the back)
Sound right?
I see now the previous thread about 2.5" spacers and the kit not yet offered. I will commence to sourcing them from the provided links (or make my own from Alum.
was looking at the stall numbers, and teh GHM-13 has the lowest RPM and highest stall torque in that group.
The batteries are in the “tub” of the original tank chassis along with the Sabertooth 2X10 R/C, recierver, BEC, and some other small USB boards.
The tank chassis runs fine by itself, but the transmission out of the box is totally at risk of stripping, and the treads/springs/hubs are made of compressed styrene IIRC.
I am considering using 1/8" aluminum for the spacer plates, finding 2.5" threaded aluminum standoffs, and then mounting it to the chassis with matched U channel held together with 8-32 bolts.
Nice drawings. If I were going to use the GHM-13 I would opt for a 4 motor design. There’s no good way to know what the resulting chassis will be capable of, but I think that’s a reasonable arrangement. The two motor design may not carry the chassis. It’s not necessarily the weight, but the surface area of the tracks combined with the weight.
I would try .09 aluminum plate for the track assemblies. .125 plate may be a little overkill.
It shouldn’t matter if the motors are both in the rear or one in the front and one in the rear. They will sync up just fine. I was going to mention the planetary motor. The speed will drop though.
With a 2.75" diameter sprocket and 14 rpm yields a blistering 2" per second of estimated vehicle travel. Going with the PGHM-02 yields a more realistic 9.3" per second. A 300 rpm motor gets you 43" per second motion. These were calculated using our website. lynxmotion.com/images/html/wheelspd.htm
I would still opt for two motors per side. Figuring this is a lot more complicated than you might think. It involves things like the traction of the tracks, environment surface friction, chassis geometry, vehicle weight, motor torque. All effect how reasonably the thing operates. I would rather error on the side of caution and not have to worry if one motor per side is enough.
I guess I better return to my 3D and mock up a planetary motor to see if I can fit two pairs back to back in the chassis tub.
Thanks a ton, will analyze and the prep to order the first set.
This puts my shopping list, per side, at:
2X Hub-13 (4 total hubs then?)
2X PGHM-02 (one side, two motors)
3X TRK-02 (53" +/- can use the extra on second loop)
5X SPRK-05 (in pairs 2X for drives on motors, 3X for idlers)
1X HUB-02 (pairs, one each for motors?)
Sorry I just don’t see the potential for problems here. It would be quite painful to try to quantify what percentage of difference in the RPM’s from two motors would be required to actually see compression. Now if one of the motors developed a problem that slowed it down, then you may have trouble. It would need to be corrected regardless of if it were a tracked vehicle or a 4WD wheeled vehicle.
I see, just didn’t want to leave anything on the table while readying to order.
Thanks so much, I can’t wait to get my side plates laid out.
Can you recommend the drilling offsets from the edges for the idlers and sprockets?
BTW, I found aluminum and nylon in 1" and 1/2" lengths so will experiment with assembling 2.5" spacers with 8-32 threaded rod as the core, then aluminum threaded spacers and wrapping nylon spacers around it as a bushing.
The offset is about 1/8" but it’s not critical. You shouldn’t have to be too concerned with the polyethylene tracks touching the acrylic side pannels (I think that’s what you were going to use) as dissimilar plastics making contact wears quite well.
so if the Sprocket diameter with tread is 2 3/4" I should drill 2 5/8" away from the edge for the sprocket to hold the tread away from the finished edge of the plates?
I’m not sure if we’re on the same page here. I make the side panels the same outline as the flat of the sprockets. You will need to adjust your idlers to support the vehicle directly onto the tracks. The sprockets should not support the weight of the vehicle. Beyond that I don’t know what else to tell ya. It took me 6 or 7 revisions to make the tritrak chassis.
I plan to build something very similar to this for Robomagellan. We built the first version of it using a very large toy tank, but I"m concerned that the tracks and chassis won’t last long.
Robomagellan is an outdoor, rough terrain course and I’m thinking I should do something different than just nylon bushings. the toy tank has a small amount of suspension built into it using bogey wheel assemblies. Is it possible to make bogey wheels? Maybe using standard wheels like the molded urethane wheels in a paired, pivotable configuration?
