e's ExMT

[ekd]

Thanks! I took the clue straight to Tower (they sometimes give valuable specs), and although I couldn't find these in the Duratrax section.... I found every part these will need to last indefinitely. At very reasonable prices.

If these are not obsolete Duratrax... they are close enough to prevent worry about part sources. They are precisely made, and light... It's a go.

One more off the details list... "thumbsup"

 

[ekd]

From what I've gathered, the XRs are run at around 40:1 FDR.... as are the Mads. My uneducated guess, that 45t will be a decent starting point, seems to me to be close.

I still haven't found anyone to confirm or reject whether my Losi ESCs will take 3s (LiFe 3.2v). Looks like I'll be risking one to find out... I bought a ton of M/M parts, so the kids will have their own rigs, and I don't have to make T's childproof.

If someone can tell me if wattage is what kills ESCs, or if just slightly excessive V will do it, I'd sure appreciate knowing. Couldn't get an answer on that "out there".

Are there 2.2s out there that can put >45* steering to use?

 

[ekd]

It looks like in order to set up an FPV system with the headtracker gyro, it will be smartest (given my limited electronics skills) to buy a FlySky TH9X, and just plug the tracker in. I haven't entirely given up on comping someday, and this system would allow me to simplify operating a decent set up.

 

[ekd]

The latest batch of Mad tubes weren't any straighter, but had no voids... so, this style doesn't look too bad. This still has >3mm walls, so it's rigid. Weighs 19g less than unshaven set (1/2 as much).

 

[ekd]

7g less than stock Mad.

 

[ekd]

2 full length tubes.

 

[ekd]

26mm axle C/L to upper link. 10* increments. Symmetrical side to side, only 1 part #.

 

[ekd]

Down to 24g, so far.

 

[ekd]

Just under 20g.

 

[ekd]

After doing research on the bewildering array of compounds and patterns of race grade MTB tires, I'm becoming convinced that a decent basher tire can be made from them. Some of the good brands publish durometer ratings (wish R/C did that), and the shear numbers of users makes a good tire somewhat reasonable in price.

I had to try my first cut and shut... :mrgreen:"thumbsup"

UPS just brought me 2 of these, ebayed at $20 a pair. I wanted something to learn on without regret... and that's what happened. I got a decent seam, and am encouraged enough to start looking for sidewall rubber. Turns out this stuff is fun, and I only glued a bit of myself to the thing.

 

[Abavuso]

From what I've gathered, the XRs are run at around 40:1 FDR.... as are the Mads. My uneducated guess, that 45t will be a decent starting point, seems to me to be close.

I still haven't found anyone to confirm or reject whether my Losi ESCs will take 3s (LiFe 3.2v). Looks like I'll be risking one to find out... I bought a ton of M/M parts, so the kids will have their own rigs, and I don't have to make T's childproof.

If someone can tell me if wattage is what kills ESCs, or if just slightly excessive V will do it, I'd sure appreciate knowing. Couldn't get an answer on that "out there".

Are there 2.2s out there that can put >45* steering to use?

I'm running 55t with a 10t pinion. But you've got to run it on 4s lipo to get the power to the wheels you need for a super. Bashing 3s is ok.

Sent from my PC36100 using Tapatalk 2

 

[ekd]

I'm talking about motors for the Hawk, I'm trying to get everything lined up for when the links show.

Is there a 2.2 that can use >45* of steering?

 

[ekd]

At least at minimal amp draw, the Losi ESCs will indeed take 9.6V.

This was the lightest brushed load I could come up with. I still don't know if they can take real amperage at this V, but my question is at least half answered. :mrgreen: I have a bunch of these escs...

Also, NRCX just back ordered a bunch of MT metal gears. The timing was perfect.. I just stocked way up on drivetrain parts, and intended to do a run of lightened gears. :roll: So...

I pulled the trigger on something I have been wanting to do for a while. I'm now buying all the stuff I need to build a cast ( tiny) heat treating oven, and have 4140 and 8620 gear bar stock in transit. I bought stock for the final set of MT's (48 and 12T), and the MIW project.

I'll be offering the 12T with integrated shaft, and the 48 with integrated outputs. Client's choice of hardness/temper.

This also means I can go for treated axle shafts, so we'll be working with lighter stuff soon. "thumbsup"

 

[Abavuso]

I'm talking about motors for the Hawk, I'm trying to get everything lined up for when the links show.

Is there a 2.2 that can use >45* of steering?

Same motors, 12t pinion and 3s lipo is what I use.

 

[ekd]

"thumbsup"

 

[supercooper]

I still haven't found anyone to confirm or reject whether my Losi ESCs will take 3s (LiFe 3.2v). Looks like I'll be risking one to find out... I bought a ton of M/M parts, so the kids will have their own rigs, and I don't have to make T's childproof.

If someone can tell me if wattage is what kills ESCs, or if just slightly excessive V will do it, I'd sure appreciate knowing. Couldn't get an answer on that "out there".

According to Losi's site here (assuming this is your ESC), your ESC is only rated for 7.2V. Usually, manufacturers design in a 25% to 50% safety margin for both voltage and current (the two things that kill electronics). At 3x3.7V (the max charge voltage for LiFe cells)=11.1V you would be way over that limit for voltage, so I would expect to see a puff of smoke :shock:, but if you want to experiment and risk frying one, please report on the results ;-). For your edification, over voltage will kill electornics instantly (sometimes quietly, sometimes with fireworks) and there is about a + 10% variation in commercial production lots (hence, the reason for safety margin being designed in) which means some units will take more abuse than others. Over current kills electronics by overheating and literally melting the semiconductor junctions, and takes a little more time (seconds to minutes, depending on the thermal conduction design of the chip and the external heat sink/fan). The higher the voltage drop across the chip at a given current (or the higher the current draw at a given voltage), the higher the power (wattage) that must be dissapated by the chip/heatsink/fan combination. The power dissapated in Watts = Volts x Amps. I'm a card carrying IEEE Electronics Engineer, so this is no BS 8). Your best bet to be safe is to contact Losi and ask for the real engineering specs on the ESC. 'Hope this helps.

 

[ekd]

Oh, it helps. Thanks.

Explains why John-e killed only 1 of his stock MTs at 4s. It's their LD50.

I'm running mostly LFP, so these see 9.6V at 3s. We'll know soon if the safety margin gives me enough room.

 

[John-e Bravada]

I only smoked the one ESC at the time:twisted: I put my MT back to "stock" with one ESC for the kid to bash with and the other ESC that saw 14.8v gave up in a matter of minutes. I have a feeling it started to melt but hadn't completly given up on 4s. As soon as I tried to run it 3s with 2 motors it burn what was left of the semiconductors. Oh well now it's a waiting game till they are back in stock.

 

[ekd]

It could be a long wait... nrcx has pulled the listing. They were on backorder a long time.

I haven't seen cheap brushed ESCs for a while, do you have an alternative in mind for this?

 

[crawlerbeast]

try this, 300A Brushed HV ESC Twin Motor 1:8/10 RC Auto Rock Crawler Buggy Car | eBay