Bubba's Build 5

[dontsendbubbamail]

Now it is time to do a build with some gears. The gears are for me and not the motor. My single speed ebike works great, but I miss having gears that allow me to match cadence to speed. My other builds used wood as all or part of the structure but not this time. Everything is going to be aluminum with a smidge of steel. I will be staying with the rear rack mounting method which has worked well for me. Previous builds used the Turnigy 80-100 motor and this time it will be a Turnigy 63-74. It is about ½ the power, but still overkill for my electric assist needs.

I was thinking about going with sliding the motor to tighten the 1st stage chain, but after doing a test in wood, I just didn’t like it. Getting the hall effect mounting to move with the motor was too much of a pain, so I am going to continue with sliding the jack shaft to tighten the chain. A little wood may sneak in as part of the hall effect mounting system.

Bubba

 

[spinningmagnets]

I like the choices you're making. I also very much appreciate all the pics you post.

If a friend of yours wanted a detachable friction drive, you wouldn't have to change much, the box could pivot and the jackshaft could have a friction-sleeve slid on...are your shafts 1/2" diameter? if yes, what is a good supplier?

 

[dontsendbubbamail]

I like the choices you're making. I also very much appreciate all the pics you post.

If a friend of yours wanted a detachable friction drive, you wouldn't have to change much, the box could pivot and the jackshaft could have a friction-sleeve slid on...are your shafts 1/2" diameter? if yes, what is a good supplier?

The jack shaft is 1/2". I use drill rod from wt tool. They have a store here in Charlotte, NC. I will be using 10 mm drill rod to make a longer shaft for the motor.

Bubba

 

[recumpence]

Your machining is looking really good, my friend.

I like the fact that you are staying with a relatively known setup and evolving it. That is very wise engineering.

Keep the pics coming.

Matt

 

[AussieJester]

I like the choices you're making. I also very much appreciate all the pics you post.

+1 *subscribed as always Bubba...best ofluck...

KiM

p.s instead of wood 'sneaking in' for the halls use delerin or polyethylene maybe?

 

[dontsendbubbamail]

Jack shaft bearing supports. Cut out of 3/8" aluminum. 1/2" flange bearings.

Bubba

 

[AussieJester]

Nice Bubba.... you have 'trained beavers' also don't you Bubba

KiM

 

[dontsendbubbamail]

Put a 1/2" thick piece of aluminum on a home brew cnc mill and 4 hours later you get this. Pockets are 3/8" deep. It doesn't cut fast, but it get the job done.

Bubba

 

[recumpence]

Looks great, Bubba!

I totally understand your situation. Hobby mills take freakin FOREVER to cut metal. But, hey, if the quantity is not high, that is fine.

I love the design. VERY nice!

Matt

 

[AussieJester]

THATS IT! im dragging my DIY mill out while my bikes out of action and doing some more work on it...thanks for
the inspiration Bubba!...

KiM

 

[dontsendbubbamail]

Thanks for all the complements. Another 4 hours and the other has been milled. This side will mount to a brace going to the seat post. The motor mount has a 10X30X9 extra bearing to help support the motor shaft. A longer 10 mm motor shaft will be fabricated from drill rod so that the 12 tooth #25 gear will have enough bite and to mount a fan off the rear of the motor should it be needed.

Does any one have any good suggestion for getting a broke tap out? I am a bit pissed because I broke a 4-40 tap off on the side where I am going to mount the hall effects. Luckily it is a hole that I would only need if I go with 120 deg spacing of the hall effects. My current plan is to use the 17.14 deg spacing.

Bubba

 

[AussieJester]

Does any one have any good suggestion for getting a broke tap out?

ooooh i freakin HATE when that happens and with drill bits too, busted two drills off yesterday 10mm jobs to not lil uns ...
unless theres a lil bit hanging out the top no idea how you will get it out Bubba

KiM

 

[boostjuice]

Google digs up a fair bit. GL

1. Ignore it and work around it
2. Junk the part and make another
3. Drive it out with a punch and tap a larger size (or plug the hole and tap the plug)
4. Insert pins in the flute passages to grip and turn the broken stub
5. Drill, grind, or generally worry away at the fragment with something harder than it is until it breaks apart
6. Drill into the tap with something harder than it is, then insert an "Easy-out" or a hex-key to get a grip on it for unscrewing
7. Disolve the broken bit with some acid that will attack the tap faster than the surrounding metal
8. Burn it out by "Spark Erosion"


http://www.brokentap.com/easy-outs.html

 

[rodgah]

I have used easy outs quite a few times, but for this (a extremely hardened piece of steel) I would say....1 you wouldnt be able to sucessfully drill a hole in it and 2 it would probably take more than 4 hours of stuffing around (and a hundred or so on an extreme drill bit and easy-out set). I know it sucks but it might be just easier to machine another part. Im not familiar with imperial sizes of taps but snapping one off in aluminium....were you rushing it? Not having a go at you, as I have done this before too and I know the pain, but in my cases I am always rushing it. Hope you get it sorted bubba, I look forward to seeing this thing going.

Rodger

 

[amberwolf]

If you could get to both ends of the tap, you could supply electrode "ground" to the tip end, and the remaining piece of the tap (or something equally hard) pressed against the broken end with electrode "power" on it, then turn on the welder just long enough to weld the two together so you can back the tap out.

It may damage the hole, but it shouldn't weld to it since it's aluminum. Then cool the whole assembly in the fridge or something so it's easier to back it out.

I did this once with a big bolt in an aluminum box I was trying to build, about 1/2" thick AL plate salvaged from something had a bolt thru it to hold it to the original object, and the head sheared off as I was trying to loosen it. I didn't want to drill it out, and I had no way to drill just a small hole and tap something into it to extract it, so I welded another bolt to it. It did spatter-damage the AL face near the hole, but it also did work to get the thing out.

I tried it once since then in a similar situation but with a broken drill-bit, and that did not work, but I couldn't reach the other end of the bit, so current flow was thru the whole AL block, and I probalby welded the bit to the block.

 

[dontsendbubbamail]

Thanks for all the good advice. I was hoping that was a slick trick for getting the tap out that I was missing. It will just have to stay in the piece and I will work around it. I just need to go a little slower with the tapping next time. It does not take much to snap off those little bitty 4-40 taps.

Bubba

 

[AussieJester]

I just need to go a little slower with the tapping next time. It does not take much to snap off those little bitty 4-40 taps.

Bubba

Yup and use heaps of lube Bubba, back the tap out
regularly to clear the hole/tap...

KiM

 

[dontsendbubbamail]

Progress!! No wood yet. The hall effect mount (lower right) was milled out of pvc and uses 17.14 spacing. On the left is the 1/4" plate that bolts to the two main 1/2" support plates together and will bolt to the 1" square tube that is yet to fabricated. The notches about mid point on the plate will accept some 10-32 hooks that will be for pulling the jack shaft back for adjusting the tension of the primary gear reduction.

I went with 6-32 instead of 4-40 for the hall effect mount. Less chance of snapping a tap.

Bubba

 

[AussieJester]

HAHA when i first looked at pic before reading your post i spotted the hall sensor bracket and
thought woot, he used Delerin...PVC is good though ... Lookin good Bubba...

KiM

 

[dontsendbubbamail]

HAHA when i first looked at pic before reading your post i spotted the hall sensor bracket and
thought woot, he used Delerin...PVC is good though ... Lookin good Bubba...

KiM

I have some delerin, but it is a bit of an overkill to be using it for holding up hall effects.

Took the sand paper to the parts to give them that brushed look. I am not liking that 72 tooth #25 gear too much. Wish I had a lath to cut the hub down. I guess that I will have to make do with drilling it full of holes. The good new is that I don't have to make another motor shaft. Both gears line up with the 12 tooth coming flush with the end of the motor shaft.

Bubba

 

[recumpence]

Artwork, plain and simple..............



Matt

 

[Jeremy Harris]

Really nice work.

The only thing I'd watch is the proximity of the inside face of the hole in the alloy plate to the motor can. I found that there was a fair bit of magnetic leakage through the can, (which is what is driving your Hall sensors) and this will create eddy currents in the alloy. When I fitted a smaller outrunner in an alloy box, with one inside face close to the motor can, the box got pretty hot just from eddy current heating. Boring the hole out so that it's a fair way (maybe 1/4" or so) from the motor can might help reduce this loss.

Jeremy

 

[dontsendbubbamail]

Really nice work.

The only thing I'd watch is the proximity of the inside face of the hole in the alloy plate to the motor can. I found that there was a fair bit of magnetic leakage through the can, (which is what is driving your Hall sensors) and this will create eddy currents in the alloy. When I fitted a smaller outrunner in an alloy box, with one inside face close to the motor can, the box got pretty hot just from eddy current heating. Boring the hole out so that it's a fair way (maybe 1/4" or so) from the motor can might help reduce this loss.

Jeremy

Jeremy,

Thanks for the heads up. I didn't think about that one. Currently there is a 1/8" gap. I think I will spin the motor up and see what happens before I go further.

Bubba

 

[AussieJester]

Pleeeeae get cap screws & nyloc nuts on the threaded rod ends (at least) to replace all those galvanized cheapo looking nutz-n-bolts though Bubba it deserves the best :wink: ...excellent job!

KiM

 

[dontsendbubbamail]

Pleeeeae get cap screws & nyloc nuts on the threaded rod ends (at least) to replace all those galvanized cheapo looking nutz-n-bolts though Bubba it deserves the best :wink: ...excellent job!

KiM

AJ,

If I ever get a design that I think I am not going to change then I will add the proper bling.
8)

Bubba