Mk. 4.5, the better E-Tard

[Farfle]

Heya all, After flogging the crap out of mk.4 for a season, the already three year old battery took a dump over the winter. I have some new cells, but they dont fit into Mk.4's skinny frame.

So, I am building a new frame and re-using the swingarm, forks, motor, wheels and concentric pivot system from mk.4.

It damn near made me cry cutting that frame up, but the next one will be so much better, its all worth it.

 

[Farfle]

Here is the tentative design for 4.5, I havent done the simulation on the linkages yet, so they will probably end up a different shape, but this is the rough idea for now. Inside the square panels in the center of the frame there will be a CNC cut sheetmetal trellis.

 

[bzhwindtalker]

Beautyfull stuf man!
can't wait to see what you build this time!

 

[Farfle]

Here are some shots of the real modeled linkages, and the CNC plasma cut center structure which I am now referring to as the cobweb.

 

[DanGT86]

It's sad to see the other frame cut up but guess it's all in the name of progress. I am really looking forward to watching this build. I love the idea of the swing-arm pivot being the motor since it really simplifies the chain tension situation. Your packaging of the rear suspension looks like a great solution. It also seems like it would reduce the un-sprung weight of the swing-arm since it doesn't have to lift half of the shock weight vertically. I'm no suspension expert but it seems like every little bit would help. Does the software that you use for simulation take into account the loads and stresses on the parts or is it simply the geometry of the travel that its simulating?

Very cool! Thanks for posting it!

 

[Farfle]

It's sad to see the other frame cut up but guess it's all in the name of progress. I am really looking forward to watching this build. I love the idea of the swing-arm pivot being the motor since it really simplifies the chain tension situation. Your packaging of the rear suspension looks like a great solution. It also seems like it would reduce the un-sprung weight of the swing-arm since it doesn't have to lift half of the shock weight vertically. I'm no suspension expert but it seems like every little bit would help. Does the software that you use for simulation take into account the loads and stresses on the parts or is it simply the geometry of the travel that its simulating?

Very cool! Thanks for posting it!

It has the option to do the physical sim aswell, but I am going seat-of-pants on this one. The biggest advantage of the linkages is that it lets me adjust the effective rates and progressivness of the suspension with only a linkage change.

 

[Farfle]

Just got the chromoly ordered. 28 feet of 1.25 Dia .049 wall tubing.

 

[spinningmagnets]

Thats a very clever configuration for the rear suspension shock, I'm looking forward to how this turns out...

 

[Farfle]

I love machining 4340. Its stupid strong, and machines into a beautiful finish . The shavings are very strong, and wicked sharp though.

 

[Farfle]

Thats a very clever configuration for the rear suspension shock, I'm looking forward to how this turns out...

I would like to say it was my idea, but Its an adaptation of whats on the brittan V1000

 

[Thud]

for referance.
Anxious to see how it turns out team farfle.

 

[John in CR]

What are those giant slots? I'll give you a useful hint though it's probably too late...all centrifugal fans intake at the center and exhaust at the perimeter, and if you can combine that with good flow from one side to the other for fresh air flow through the air gap as well as through the stator, then air cooling can make ideas like dumping water into the motor that's sure to cause traction problems unnecessary. To me the potential for better cooling in such a manner combined with the greater torque of perimeter magnets designs for a given weight, make outrunners the clear motor of choice giving you a distinct advantage over the field.

 

[Farfle]

What are those giant slots? I'll give you a useful hint though it's probably too late...all centrifugal fans intake at the center and exhaust at the perimeter, and if you can combine that with good flow from one side to the other for fresh air flow through the air gap as well as through the stator, then air cooling can make ideas like dumping water into the motor that's sure to cause traction problems unnecessary. To me the potential for better cooling in such a manner combined with the greater torque of perimeter magnets designs for a given weight, make outrunners the clear motor of choice giving you a distinct advantage over the field.

Giant slots?

 

[Farfle]

Woot! Shiny bits!

 

[Thud]

Giant slots=lathe face plate maybe?

Loving the handy work J.

 

[John in CR]

Oh, I thought those were the motor's side covers with the cutting tool in the picture making cogs to match the sprocket. I don't have cool tools so I guess I'm way out in left field pulling my pud while Farfle is cutting some shiny cool clamps.

 

[Farfle]

Aaha lol. Yeah, those are slots in the rotary table.

Heres the finished product:

 

[Farfle]

Woot, got about a third of the frame done today. More tomorrow!

 

[Farfle]

Finally got most of a day to work on the frame. And got a visit from a friend of mine and helped him finish his lightsaber handle that will probably become a high powered laser or flashlight. That was a bit of a machining exercise.

 

[Farfle]

More progress made, might be a rolling frame tomorrow night.

 

[Farfle]

More progress! Still have to finish up the last bit of welding on the trusses and then throw the forks, seat and wiring on!

 

[jansevr]

beautiful work. looking forward to seeing the finished product and how it compares to your last bike

 

[Farfle]

beautiful work. looking forward to seeing the finished product and how it compares to your last bike

Thanks, I am hoping that the chatter goes away, this frames mass is so much more centralized, and the progressive rear shock is going to be ages ahead of the slightly antiprogressive suspension on Mk.4. Speaking of which, shock linkage magic happening today!

 

[Farfle]

Linkages are tacked in place and the range of motion looks good!

 

[vax]

Wow, this frame looks heavy and over engineered...