Norco Empire 8150 build (page 20 pic heavy)

[Timma2500]

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[etard]

Man, I cant imagine hacking up a perfectly good frame. People must think we are crazy here on ES!

I personally wouldn't have a problem unscrewing 8 screws to get at a battery once in a while. Every ride, now that is a different story.

Two thoughts:

1. It would be very trick to have a custom tool kit attached somewhere in the frame. It would be even more trick to have a small electric drill/driver that you could plug into your bike and use. Perhaps we will leave that to one of the motorcycle guys, huh?

2. Have you considered lights front and back? Those new LED lights are incredible and draw very little power.

And dammit, put those front skewers on right !!!

[Timma2500]

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[liveforphysics]

The mechanical properties of 6061 depend greatly on the temper, or heat treatment, of the material.

6061-O
Annealed 6061 (6061-O temper) has maximum tensile strength no more than 18,000 psi (125 MPa), and maximum yield strength no more than 8,000 psi (55 MPa). The material has elongation (stretch before ultimate failure) of 25-30 %.

6061-T4
T4 temper 6061 has an ultimate tensile strength of at least 30,000 psi (207 MPa) and yield strength of at least 16,000 psi (110 MPa). It has elongation of 16%.

6061-T6
T6 temper 6061 has an ultimate tensile strength of at least 42,000 psi (290 MPa) and yield strength of at least 35,000 psi (241 MPa). In thicknesses of 0.250 inch (6.35 mm) or less, it has elongation of 8% or more; in thicker sections, it has elongation of 10%. T651 temper has similar mechanical properties.



Welding
6061 is highly weldable, for example using tungsten inert gas welding (TIG) or metal inert gas welding (MIG). Typically, after welding, the properties near the weld are those of 6061-0, a loss of strength of around 80%. The material can be re-heat-treated to restore -T4 or -T6 temper for the whole piece.

[liveforphysics]

This is the reason why I didn't make a single weld, hole drilled, or hot spot on my full suspension frame when I fitted a pair of big motors onto it. Frames can be built and heat-treated to be strong, and they are done being modified.

For a quicky DIY test, take a couple 1"x 1/4" scrap strips of 6061 T6, and make a proper 100% fill butt weld on them. Makes no difference how pretty the weld is, or if the process used is TIG or a quick and dirty spool gun. Pinch one end in the vise, throw a cheater bar or big pliars onto the other end and start bending that joint. You will quickly notice the material away from the weld shows no signs of flexing, while the material right beside the weld shows surface stress fractures almost immediately upon stress. About 3 mild back and forth cycles and it will snap at an area about 1mm away from the weld point, while the rest of the 6061 never even flexed.

[Malcolm]

I'm also wary of welding Al alloys, but even if you assume that the material only has the same strength as zero temper 6061 the additions are so thick-walled and oversized that they should easily compensate for the loss of temper. For peace of mind I'd still check the frame regularly for cracking though, particularly at the ends of welds and at the open corners of the box section. The lid on the box section will help to reduce flex if it is a tight fit and securely screwed in place.

I look forward to seeing how this build works out!

[liveforphysics]

The lid on the box section will help to reduce flex if it is a tight fit and securely screwed in place.
!

A more rigid member joined to a more flexible member = critical stress riser point. What is at this stress riser point location? An XXXX alloy of frame material and temper, joined onto T-0 grade 6061 with 6061 filler rod alloy, and mystery level of new alloy and heat treating in that critical stress riser point. If the rest of that bike frame is tempered and rigid, and the area a few mm from that welded point is not, and it's got something rigid on each end of it, it seems like something begging to start cracks.

But! These things often have massive engineering safety factors on them, so if the frame was 20 times stronger than it needed to be, an now it's only 1/5th-1/10th the strength it was before, then it should still be ok for typical E-bike duty.

[Malcolm]

Yes, I agree about the stress concentration, particularly at the top of the box where it meets the neck of the frame. Like I said, I would recommend checking the frame regularly for cracks (and wearing a helmet ). Despite finite element analysis and fracture mechanics there's still an element of black art in frame building. Many people are put off welding to aluminium frames by dire warnings of failure when, as you say, there are often generous safety margins built in. I wouldn't encourage anyone to go hacking alloy frames without doing some careful research first, but there seems to be very little practical experience around, so it's good to see someone like Timma pushing the envelope.

[Timma2500]

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[keyne]

Timma2500 or anyone else who knows, how do you connect to the input side of the gear box?
Has anyone else used banebots gearboxes? They look great, but can the handle the torque?

[Timma2500]

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[Timma2500]

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[deecanio]

SUPER SWEET PAUL.

How long do you think before you get to test ride?
am i right in thinking you'll have a second chainring linked to your rear cluster? so when pedaling you'll only have the drag of the eno (and motor chain)? that should be much easier to pedal than mine is what parts are you waiting on, or is it a wallet refilling period ;p
very very nice.

D

[Timma2500]

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[recumpence]

Timma,

If you want to increase rigidity of your carbon sprocket plates, you can rough up the sides that touch and glue them together. I have used thick CA and various two part epoxies for this purpose.

Just a tip.

Oh, also, electrolysis (spelling?) occurs between CF and aluminum. You will notice discoloration of the clear top surface of your CF plates over time. If you spray clear paint over the surfaces (or use gaskets) of the CF, this will not happen.

I have gone through THOUSANDS of square feet of CF panels (CNC cutting and what-not) over the last 5 or 6 years. I have screwed up enough CF to fill a dumpster learning a few things. After all that, I have one or two pearls of (dare I say it?) wisdom to pass on...........

Matt

[Grinhill]

Looking great.

Those two chains look mighty close together, and when they spin at high speed they may actually move a little more.

I think y-pedal had some issues with chains running very close to each other. May be worth spacing an extra millimetre or two if you can.

[deecanio]

Hi Paul,

looking awesome, love the carbon adapter, chains do look fairly close so give that a check, they will wear and gain a bit more slop too so do keep an eye on it.
i want to go 3220 direct drive, the gola is to lose weight and complexity so 2 x 3210's isn't my bag, but we'll see
looking forward to seeing this baby go

D

[keyne]

Hi Timma2500,

Your build is looking awesome!

I've got a couple of questions for you about your gearbox, (I've recently received a banebots gearbox and am starting a build similar to yours, but it won't look nearly as good) how did you organize the input shaft? I know it needs a 8mm keyed shaft, but is there space in the mouting block for a bearing or how did you do that?
Also what bottom bracket are you using? I guess a standard one doesn't have enough space for the freewheel cranks. (Atleast mine doesn't)

Cheers,
Keith.

[HAL9000v2.0]

This is realy,realy awsome bike. One of my favorits. Great!!!

[Timma2500]

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[deecanio]

very sweet

have you put on some pedals and tried a pedal ony ride yet paul?
your suggestion of a 3220 delta wye setup is where i want to try first, hopefully Garys board will be done soon, also i'm waiting for the eno mod the guys are smashing through on the other thread, very exciting times!!!
how lo9ng before we see this bad boy in action now?

D

[Timma2500]

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[Miles]

Wouldn't mind taking out 3 pawls to take it back to being like a normal eno... is this possible does anyone know?

Sure, you can take out every other pawl and spring. The ratchet teeth are the same as for the 3 pawl freewheels, I think.

[deecanio]

Yeah the delta/wye is a good way to fly, does the motor need halls/ be sensored to do this?
I'm an electronics numnut but am slowly picking it up lol...

Paul

hi Paul,

im not sure if you must have halls/sensors but i believe to have delta/wye you need 6 wires coming from the motor?
being a fellow numnuts on most stuff i not exactly sure but i think thats right? would make sense as three would fire in delta and three in wye mode though im not sure how delta/wye works i would guess they are set at different angles or some such?

D

[Timma2500]

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