Slawek's angle grinder drive

[AussieJester]

I was just looking at the hv ESC sitting in your bag there, did add a couple of extra capacitors
on the "+" & "-" input wires? Helps with the voltage spikes that kill these speed controllers.

KiM

[etard]

Awesome build! Nice video! I wonder if you have been able to do any calculations on what kind of efficiency your drive is getting from motor to rear wheel? No blown controllers?

We'll just put this build down in the win box for sensorless controllers.

[slawek]

2000 Miles on this drive – I think is time for report.

1. Battery pack 7S10P – almost died. From 40AH from beginning only about 20Ah left with significant voltage sag under load. BatterySpace.com over rated current (10A continuous, and 20A peak 15sec) at least 2 – 3 times. I wrote feedback to them and now they wrapping this battery in green thermal shrink with lower ratings. I have $700 less in my pocket and I will never buy battery from them.
My average current at cruising speed 25-27 MPH was ~ 40Amps, and up to 85 during acceleration – this is what I was able read from CA. However CC ICE 100 shows up to 135A but never longer than 1 – 2sec.

2. Gear box – no significant wear. I change oil every 500 miles. Neodymium magnet really does job. On each oil replace all surface of magnet was coated with thin layer of metal powder. Once I even found small metal piece of metal of size of 1/16 inch. I could not locate where this came from, but if this thing could get on gear, that definitely could end the life for gearbox. Also I had tiny oil leak on main shaft but this is no big deal, I wipe once a week with paper towel.

3. Controller – CC Phoenix Ice 100 it does job very good when cruising speed is with full open throttle. With lower speed over heat in 1 – 2 min and then there is this annoying beeping until temp goes down.

4. Timing belt – I have to say Gates did great job designing this belt. Is strong like a hell. I put already 1600 miles since I change from chain. Is quiet, clean and transfer less vibration from gearbox. I notice about 1/32 wear out from rear sprocket (Al 6061-T6) and about the same front sprocket (Cast iron).

Now by natural evolution I am planning modify this drive to one stage reduction, and frame - it need suspension because rear rack with battery keep bending on path hole.
There is my beginning of this modification: http://www.endless-sphere.com/forums/viewtopic.php?f=28&t=36559

[Byte]

Wow, awesome, 2000 miles Nice!

[bigmoose]

Compliments! Very nice battery pack arrangement, and outstanding angle drive. As battery capacity has increased, I have been thinking that the efficiency loss using gears may not be as important as it once was. Your packaging arrangement with the angle drive and about 10:1 ratio is indeed, sweet!

[rojitor]

You made your first project like a pro, i wanna see what's next.

[GITech]

Dude! Slick!

[apyles]

Hi Slawek,

I like the Angle grinder gear box idea. What model of Dewalt grinder did you use for this?

Andy

[slawek]

Hi Slawek,

I like the Angle grinder gear box idea. What model of Dewalt grinder did you use for this?

Andy

Hi Mate
I used gear set from grinder Dewalt D28499X Type2
Crown gear and bevel gear
I purchase them from http://www.ereplacementparts.com/

Slawek

[bobc]

Oh dear.
I just acquired a broken 9" JCB grinder for its box.
And I've got 3 big outrunners on a single shaft to stuff into it -
Target is 0 - 60mph in 8 seconds.......

[slawek]

Oh dear.
I just acquired a broken 9" JCB grinder for its box.
And I've got 3 big outrunners on a single shaft to stuff into it -
Target is 0 - 60mph in 8 seconds.......

Hi bobc

I don't know what you have in mind, but if you want put them all on one bevel gear I can assure you, torque from motors will ground this little gear down.
Form my torque calculation, I already overloading this gearbox during acceleration by 2 times on small motor like Hacker A60-18L.

Unless you think about something like my concept V2 I had in mind for long time but I never did. I your case with three of them or more



Slawek

[bobc]

It only has to work for a few seconds ;^)
Fair enough - it is a LOT more peak power than the 1500W or so of the 9" grinder. I think you're right, it will be destroyed quickly if not immediately. I think I'll do it anyway, on the basis that the gearbox is actually pretty robust & will be EP oiled in place of the factory grease.
I like your idea of having a small pinion for each motor - not an option for my collection of scrap parts I'm afraid.....

[Lebowski]

Slawek

I really like this look, like a 2 cilinder motorcycle. Can you imagine how cool
this would look with 2 colossus motors filling the bike's triangle ?

[crossbreak]

+1 subscribed

The design is very neat. I guess it would be even possible to fasten the motor at the swing arm to get it closer to the rear axle and save frame space for lipos

The grinders have output speeds between 4500 and 6000rpm, or about 15.000 to 20.000 rpm at the input. At 2KW thats only about 1Nm. The motor you use shoudl do about 5Nm, if you use a 6374 outrunner like I want to.
What's the outer diameter of you larger bevel gear? I can get 75mm ones for less than 5€ online, thats why I ask. At my local supplier an equal gear set with induction hardened teeth costs 12times as much

[nicobie]

You do nice work! Lots of clever ideas here.

Watch out for the cops in NYC. I hear that they take your bike if caught riding it in the city.

[slawek]

The design is very neat. I guess it would be even possible to fasten the motor at the swing arm to get it closer to the rear axle and save frame space for lipos

The grinders have output speeds between 4500 and 6000rpm, or about 15.000 to 20.000 rpm at the input. At 2KW thats only about 1Nm. The motor you use shoudl do about 5Nm, if you use a 6374 outrunner like I want to.
What's the outer diameter of you larger bevel gear? I can get 75mm ones for less than 5€ online, thats why I ask. At my local supplier an equal gear set with induction hardened teeth costs 12times as much

Thanks crossbreak

Motor in swing arm is my next project I have made motor 80-85 mechanical modification and rewindening.
This time will be 110 teeth rear pulley with custom bake disc 8,625" and 22 teeth on motor shaft, but is hard to find time to finish.





Your are right about calculations, but each machinery are designed with safety margin about 7-10 (except aeronautics) and I am using this margin in my application.
5Nm Hmmm, after I put new battery A123 pouch (these are freaking amazing) I saw on my CA max 223A. Motor have 150kV - You do the math. Although is geared to 23mph max. acceleration is
really ....

Large bevel - I can't tell you right now because I don't remember, but I will measure on next oil change. From case size it might be 75mm. But dude for 5€ you should order hundred and make some money on gear boxes drive. I payed over $50 for big one and about $40 for small. I wonder what is a durability these for 5€, but I will tell you this from my experience, durability is key factor especially in RC type drive. Currently I have 2497 miles on mine.

by nicobie » Wed May 09, 2012 3:03 pm
You do nice work! Lots of clever ideas here.
Watch out for the cops in NYC. I hear that they take your bike if caught riding it in the city.

I just hope it will never happen to me. I ride slow, and try do not stand out.

[crossbreak]

Your 150KV drive does 10/150=0,0666..Nm/amp. At 223amps thats 15.5Nm. Your savety margine of 7-10 wont be taken in an chinese made angle grinder for a hundred bucks. I can only recommend to get better gears if you really want to use the 80-85. You get them here for example:
http://maedler.de/Product/1643/1619/273/292/296.aspx
I once saw that there is a similar company like maedler anywhere north of NY city.

As a rule of thumb, most outrunners are most efficient at about 40-60% of their rated torque and at about 60 to 80 percent of the calculated idle rpm. At 36Volts thats 4320rpm and 5Nm(2.1kW)
Your 15.5Nm are beyond any specs of this motor- don't try this too often. I would not run more than 100 or maybe 130 amps through this outrunner to get a better range .

I ordered 2 of these gearsets (12 to 44 teeth) here: http://ar-tec.tradoria-shop.de/p/597475445/zahnraedersatz-zu-winkelschleifer-ws-230. Looks more durable than the ones in my 10€ 230mm angle grinder. I will use a Aeolian 170KV 6474 outrunner wired in Star so it has 100KV. I'll try a #25 chain which I have laying around here for the final drive with 12 to 45teeth. Thats a total ratio of 13,75. For the first tests I will use a cheap sensorless 12Fet controller which is modded to 60amps by reducing resistance of the shunt.

I see you use the orginal gearbox of the grinder. I would like to build a new more compact one. Sadly, one should not turn the gear set the "wrong" direction cause it won't last long then either.

[slawek]

Hi crossbreak
I just have first bearings replace on small gear after 2550 miles, by the way I have check large bevel diameter - 81mm.

I see you use the orginal gearbox of the grinder. I would like to build a new more compact one. Sadly, one should not turn the gear set the "wrong" direction cause it won't last long then either.

I use only oryginal gear set, not all gear box. The only thing is that, the big bevel comes with front cover and bearings already. Everything else is made by me.
And on my next project will not have any gear box. I ma planing only one stage reduction by timing belt. 22 tooth on motor and 110 rear wheel.
I never wrote about this before but I have made very simple test in idle condition and turn out that gear box isn't very efficient.

This might be interesting for you and others.

Conditions of test - Idle run on 25V (my current voltage on bike)
Test 1
Hacker A60-18L. Power compsumption - 62W
Test 2
Hacker A60-18L + Gearbox. Power compsumption - 150W
Test 3
Hacker A60-18L + Gearbox + rear wheel trough timing belt. Power compsumption - 195W

Conclusion is only one: gearbox have worst efficiency in this setup.

[crossbreak]

Nice test - thx for that!

But:how tight did you postion the drive? You should be able to axially move the motor sprocket setting up the sprocket clearance. this has great influence on idle friction

thats why most angle grinders mostly come with large clearance - and run so loudly

to set up the clearance you will have to

in small sized angle-gearboxes this is done by a screw which positions the dc-motor shaft by pushing this shaft (friction axial bearing).
to set up the clearance you will have to turn the screw (while the motor's running) till it's the most noiseless - while coming from large clearance

We should compare it with a big gear drive, I should just measure this with my 80100 and a 1:5 ratio steel/plastic straight-teethed spur gear set (module 2) that I once used in my fail 4kw project (the teeth of the sprocket cassette on the rear wheel quickly got cavity) -which is still an option when thinking about such a drive. Helical spur gearsets would be very nice, sadly they cost so much... isn't there a supply of casted ones like the ones of the angle grinders ??

Maybe an electric lawn-mover?