I wanted to build a test rig for my cloverleaf cable drive. A simple weightlifting platform. I only had nine 2020 extrusion, 300mm long to play with. Not enough to build a cube and a bed frame. So I started to minimize extrusion count and came up with this: [attachment 107024 frame_front.jpg] The single linear rail will lift the 'U'-shaped bed frame. The bed frame will be stabilized by 'parallel bar' cables. I believe, the extra friction will keep the bed from dropping or at least will slow it down. [attachment 107025 parallel_bar-1.jpg] I have to print some brackets before I can test it. But if it's halfway successive, I want to build a CoreXY printer with two more cloverleaf drives. [attachment 107026 2018-08-2510.03.05.jpg] https://reprap.org/forum/read.php?177,833766,833766#msg-833766 Wed, 14 Oct 2026 10:27:57 -0400 Phorum 5.2.23 https://reprap.org/forum/read.php?177,833766,834429#msg-834429 https://reprap.org/forum/read.php?177,833766,834429#msg-834429 [attachment 107132 encoder_wheel.jpg]
Slip wouldn't be a problem with a closed loop stepper driver. ( here we go again 8-) )
Something like the mechaduinos?
Surely the resolution wouldn't be good enough. Maybe, if I fit it on the idler pulley? That would also work for the XY-gantry.]]> o_lampe Extruded Aluminum Frames Sun, 23 Sep 2018 02:14:12 -0400 https://reprap.org/forum/read.php?177,833766,834136#msg-834136 https://reprap.org/forum/read.php?177,833766,834136#msg-834136 I also need a better bottom idler, it limits the max. tension now.]]> o_lampe Extruded Aluminum Frames Thu, 20 Sep 2018 00:50:27 -0400 https://reprap.org/forum/read.php?177,833766,834084#msg-834084 https://reprap.org/forum/read.php?177,833766,834084#msg-834084
At the risk of making it over complicated, you could add a second set of idlers at the corners and replicate the setup for double the cable wrap. That could possibly be less conducive to cable binding than wrapping the cable twice?]]> gmedlicott Extruded Aluminum Frames Wed, 19 Sep 2018 14:36:22 -0400 https://reprap.org/forum/read.php?177,833766,834031#msg-834031 https://reprap.org/forum/read.php?177,833766,834031#msg-834031 I thought of wrapping the cable twice around the stepper shaft before wrapping around the next idler pulley. Have to add washers to increase offset.
Also have to write a code, that moves xx# steps up and down instead of the timed approach in Ramps_test.]]> o_lampe Extruded Aluminum Frames Wed, 19 Sep 2018 00:55:20 -0400 https://reprap.org/forum/read.php?177,833766,833967#msg-833967 https://reprap.org/forum/read.php?177,833766,833967#msg-833967 video of the Cloverleaf drive.
It's running a long test now to test for slipping or wear of the rubber tube.

Here's a closeup of the stepper.]]> o_lampe Extruded Aluminum Frames Tue, 18 Sep 2018 11:49:51 -0400 https://reprap.org/forum/read.php?177,833766,833937#msg-833937 https://reprap.org/forum/read.php?177,833766,833937#msg-833937 The pulleys are offset by M3 washers. The cable hasn't given me any headache yet, it's a 0.5mm Aramid fishing line.

I have a mocked up bed frame running with 1.3mm PP-cable for the parallel bars. That cable it too stretchy and I'll replace it with aramid.
But the parallel bar is a full success already. :) There's a significant difference with cables attached or just lifted by the linear rail.
Maybe I have to add diagonal struts on top of the 'T-bar'. It doesn't deflect now, but the PP cable isn't very tight.

[attachment 107043 temporary_bed_frame.jpg]]]> o_lampe Extruded Aluminum Frames Tue, 18 Sep 2018 01:12:12 -0400 https://reprap.org/forum/read.php?177,833766,833910#msg-833910 https://reprap.org/forum/read.php?177,833766,833910#msg-833910 gmedlicott Extruded Aluminum Frames Mon, 17 Sep 2018 15:47:34 -0400 https://reprap.org/forum/read.php?177,833766,833895#msg-833895 https://reprap.org/forum/read.php?177,833766,833895#msg-833895 obelisk79 Extruded Aluminum Frames Mon, 17 Sep 2018 13:44:49 -0400 https://reprap.org/forum/read.php?177,833766,833766#msg-833766 https://reprap.org/forum/read.php?177,833766,833766#msg-833766 I only had nine 2020 extrusion, 300mm long to play with. Not enough to build a cube and a bed frame. So I started to minimize extrusion count and came up with this:
[attachment 107024 frame_front.jpg]

The single linear rail will lift the 'U'-shaped bed frame. The bed frame will be stabilized by 'parallel bar' cables. I believe, the extra friction will keep the bed from dropping or at least will slow it down.
[attachment 107025 parallel_bar-1.jpg]

I have to print some brackets before I can test it. But if it's halfway successive, I want to build a CoreXY printer with two more cloverleaf drives.
[attachment 107026 2018-08-2510.03.05.jpg]]]> o_lampe Extruded Aluminum Frames Sun, 16 Sep 2018 06:12:30 -0400