Go Back   DIY Go Kart Forum > Building Plans And Advice > Electric Projects

Notices

Reply
 
Thread Tools Display Modes
  #21  
Old 12-16-2019, 01:03 AM
bnolan bnolan is offline
Junior Member
 
Join Date: Nov 2019
Posts: 16
Thanks: 1
Thanked 1 Time in 1 Post
Default

Ok, new problem. I've got 25H chain, and it fits the 91T rear sprocket perfectly, but the 9T sprocket I have for the motor skips.

This video shows it:

https://imgur.com/a/rkE36Cz

What causes this? Is it a bad sprocket? Or is my tension / alignment bad?

You can see the problem clearly here:

Reply With Quote
  #22  
Old 12-16-2019, 04:37 AM
itsid's Avatar
itsid itsid is offline
Moderator
 
Join Date: Jul 2013
Location: Ruhrpott [Germany]
Posts: 10,523
Thanks: 1,432
Thanked 4,425 Times in 3,328 Posts
Default

Well, because the motor sprocket isn't a #25 chain but 8mm instead
(#25 is 6.35mm pitch)

you will have to order a new motor sprocket ..
the unfortunate information here is,
you will not find a #25 sprocket with nine teeth for that motor..
AFAIR 11 teeth is the minimum to wrap around the shaft

so that'll throw off your calculated gear ratio again.
dropping from 10.1:1 to 8.27:1

'sid

PS hang on 8mm should bind on the second roller, not the third...
third means slightly smaller pitch... 219 sprocket perhaps?? (7.77mm pitch)
maybe an oddling 215 (7mm pitch)
Anyways.. wrong sprocket
__________________
Jokes about german sausage are the wurst.
Reply With Quote
  #23  
Old 12-16-2019, 02:48 PM
bnolan bnolan is offline
Junior Member
 
Join Date: Nov 2019
Posts: 16
Thanks: 1
Thanked 1 Time in 1 Post
Default

It's meant to be a 25H sprocket (I ordered it from aliexpress as 25h 9t but lol). I've sourced some 11:54T sprocket and t8f chain locally so I can at least get everything hanging together while I wait for a replacement 11T 25H sprocket (from a different supplier) to come in from CHIIIIINA.
Reply With Quote
  #24  
Old 12-17-2019, 04:54 AM
itsid's Avatar
itsid itsid is offline
Moderator
 
Join Date: Jul 2013
Location: Ruhrpott [Germany]
Posts: 10,523
Thanks: 1,432
Thanked 4,425 Times in 3,328 Posts
Default

easy to test..
if the circumference of the sprocket is less than 2.6" or bigger than 2.65" it's not a #25 sprocket.

well in fact the easiest test is to wrap known #25 chain around it and see if it fits,
it doesn't, sooooo yeah

'sid
__________________
Jokes about german sausage are the wurst.
Reply With Quote
The Following User Says Thank You to itsid For This Useful Post:
JagLite (01-15-2020)
  #25  
Old 12-17-2019, 06:10 PM
bnolan bnolan is offline
Junior Member
 
Join Date: Nov 2019
Posts: 16
Thanks: 1
Thanked 1 Time in 1 Post
Default

Ok - I found something interesting. If you put the sprockets very close together so that only 3 or 4 teeth are contacting at once - then it runs quite well without skipping. I'm going to try shorten the chain and see if it works.

Reply With Quote
  #26  
Old 12-17-2019, 07:22 PM
itsid's Avatar
itsid itsid is offline
Moderator
 
Join Date: Jul 2013
Location: Ruhrpott [Germany]
Posts: 10,523
Thanks: 1,432
Thanked 4,425 Times in 3,328 Posts
Default

DON'T!

that is a terrible idea.. it's still the wrong sprocket,
and it'll eat the chain in no time (ruining not only the chain but the big sprocket as well )

plus, having only two teeth engaged puts a lot of additional stress on the sprocket teeth
speeding up such premature wear even further
[a teeth can only count as engaged if the roller is in full contact with the base]

short: it's not interesting, it's stupid I'm afraid

'sid
__________________
Jokes about german sausage are the wurst.
Reply With Quote
The Following User Says Thank You to itsid For This Useful Post:
JagLite (01-15-2020)
  #27  
Old 12-18-2019, 03:36 AM
bnolan bnolan is offline
Junior Member
 
Join Date: Nov 2019
Posts: 16
Thanks: 1
Thanked 1 Time in 1 Post
Default

Ok! Hah. I fixed it

I pulled the sprocket off and it fit the chain perfectly. So I noticed a large spring washer on the motor spindle. It was larger than the valleys in the sprocket so wasn't letting the chain sit properly. I removed the spring washer and now the chain sits on the sprocket perfectly! Phew!

But, had already ordered $60 worth of T8F chain and sprockets. :'(

Anyway - the ESCs arrived (they're bigger than the motors!), hoping to drill and mount the big sprockets tomorrow, then mount the motors and hopefully get it running!

I'm tempted to test fit the motor and just drill holes into the plywood to mount the motor with the right amount of tension on the chain for testing. Will use some remaining aluminum profile and cut some slots for a proper adjustable motor mount later on.

Here's what it looks like atm:

Reply With Quote
The Following User Says Thank You to bnolan For This Useful Post:
JagLite (01-15-2020)
  #28  
Old 12-18-2019, 04:49 AM
bnolan bnolan is offline
Junior Member
 
Join Date: Nov 2019
Posts: 16
Thanks: 1
Thanked 1 Time in 1 Post
Default

Ok, got the ESC spinning the motor. Tomorrows job is to get an arduino to generate voltage ramps of 0-4v and try feeding that to the throttle wire.

edit: Tested the throttle signal line at 1.5v (nice slow speed) and 3v (scary fast with nothing connected). Hahaha. Better make sure I get my arduino code right
Reply With Quote
  #29  
Old 01-14-2020, 08:39 PM
bnolan bnolan is offline
Junior Member
 
Join Date: Nov 2019
Posts: 16
Thanks: 1
Thanked 1 Time in 1 Post
Default

Ran into problems with the chain coming off, and don't have the tools to mill a proper motor mount with slots to adjust tension. Biggest problem is ran out of time for this festival season, will have to revisit this later in the year and hopefully finish the project for summer next year!
Reply With Quote
  #30  
Old 01-15-2020, 12:19 AM
landuse's Avatar
landuse landuse is offline
Moderator
 
Join Date: Nov 2010
Location: Pietermaritzburg, South Africa
Posts: 17,497
Thanks: 2,219
Thanked 3,507 Times in 2,863 Posts
Default

Quote:
Originally Posted by bnolan View Post
Ran into problems with the chain coming off, and don't have the tools to mill a proper motor mount with slots to adjust tension. Biggest problem is ran out of time for this festival season, will have to revisit this later in the year and hopefully finish the project for summer next year!
To get slots, just drill a few holes and then use a file to break through them to create a slot. It looks slightly messy, but it gets the job done just fine
Reply With Quote
  #31  
Old 01-15-2020, 10:32 AM
Functional Artist's Avatar
Functional Artist Functional Artist is offline
Senior Member
 
Join Date: Jul 2016
Location: Toledo, Ohio
Posts: 2,067
Thanks: 805
Thanked 794 Times in 628 Posts
Default

Quote:
Originally Posted by bnolan View Post
Ran into problems with the chain coming off, and don't have the tools to mill a proper motor mount with slots to adjust tension. Biggest problem is ran out of time for this festival season, will have to revisit this later in the year and hopefully finish the project for summer next year!
Maybe try a spring loaded chain tensioner
https://www.ebay.com/itm/Motorcycle-...0bb467378e196a

...or a slide style tensioner
https://www.ebay.com/itm/10mm-Chain-...dcd01f40fa75b5
__________________
RESISTANCE IS FUTILE
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -6. The time now is 03:33 PM.