#robotics Logs

Apr 22 2015

00:03 Hyratel need a 3/16" (4.75mm)
11:28 malinus This might be a stupid question, but how do you guys usually connect gears/wheels to dc motor shafts? They are usually round and smooth. Do you use glue, or just a tight fit?
11:29 deshipu personally I used glue, but it's hard to center
11:29 deshipu tight fit is good for small robots
11:29 Tom_itx woodruff key, grub screw, flat on the shaft, hex shaft with a hex gear hole etc
11:29 deshipu you can also always shear a flat surface on that shaft
11:29 deshipu with a grinder
11:29 Tom_itx weld it on?
11:29 Tom_itx :D
11:29 deshipu Tom_itx: even harder to center
11:30 deshipu Tom_itx: unless you use friction welding
11:30 malinus hehe, thanks for all the suggestion. I think I got the idea.
11:30 Tom_itx splines work good
11:31 malinus Tom_itx: could you dremel out usuable splines?
11:32 Tom_itx i doubt it would work that well
11:36 malinus Another question then. Let's say I have a 2mm shaft, and want to fit it into a wheel, which has a 4mm axel hole.
11:37 malinus Would 3d printing a "sleeve" be a good option?
11:38 Tom_itx no
11:38 Tom_itx you want metal
11:38 malinus well, the wheel-fit is plastic
11:39 malinus while the shaft is metal
11:39 malinus so it's gonna be metal->plastic no matter what, no?
11:39 Tom_itx a larger diameter metal would give more stable surface area than a small shaft in a hunk of plastic
11:53 malinus how do would I find a piece of metal that is exactly 4mm, and can fit a 2mm shaft?
11:56 Anniepoo mcMaster Carr
11:56 Anniepoo metalbythefoot
12:18 Tom_itx talk to your local machine shop
12:18 Tom_itx i would make one on my lathe
12:22 malinus It sounds like over-engineering. For my application at least. Obviously you can't know, because I haven't said what it's for. So thank you for your advices.
12:24 Tom_itx not over engineered, just a simple collar
12:24 Tom_itx i've done it a few times
12:24 Tom_itx http://tom-itx.no-ip.biz:81/~webpage/cnc/new_pulleys/spindle_enc8.jpg
12:24 Tom_itx one such example
12:25 Tom_itx the small pulley has a collar i made
12:25 malinus oh I see. That looks like tool-quality, I'm aiming for toy-quality :)
12:26 malinus Tom_itx: that's your CNC?
12:29 Tom_itx yes
12:29 Tom_itx then print a collar
12:45 malinus Let's say you have something that is 50mm*50mm, and you want to 3d print a nice tight square for it to be pushed in. Should the 3d print be exactly that size? A single mm bigger? A single mm smaller? A few mm bigger?
12:50 veverak depends on the printer usually
12:50 veverak and depends on how tight it should be
12:50 verak usually oes for
12:56 malinus veverak: thanks I just need some ballpark-value to have something to test with :)
12:56 veverak :)
17:09 Hyratel rue_house, yooo
17:09 Hyratel rue*