by the way it is very easy to make and install. the preparation of the teflon will hopefully be made clear.
Reprap delta magnets and spectra line springs plus#
it's night here but tomorrow I will add videos and still images plus more detailed explanations. JCS: I apologize ! I wrote your name as JCB instead of JCS,but you easily realized it is you.įrankvdh and jcs: I realize the still image is not clear and my explanations need more details. I was not aware of it until today, but credit for the idea goes to him.Įdited 1 time(s). Note:JCB posted a year ago few words about doing something similar. The results: perfect repeatability! under the same tests, the position variance were within one hundredth of a mm. (I am now waiting for 0.1 mm thick teflon sheets for further testing). there was some reduction in the holding force but not significant. the feeling of the joints was now very smooth. each piece was pressed in place by forcing the ball into the socket (in a vice, with a piece of wood) so the teflon piece achieved the exact shape of the cavity. Then I took the critical step: I added teflon pieces (cut from 0.25 mm sheets), between the balls and the sockets, to act as friction reducers. this gave me an initial indication that the joints are at fault. and indeed the variance was very small - within 1 hundredth.
my expectation was that the repeatability will be good. why? in such moves there is no change at all in the joints - no movement of the ball relative to the socket. I then performed another test: repeatability in moving only in Z - up and down - direction. I checked the assembly, the diagonals, the balls mounting, the rigidness of the effector as held by the diagonals, and everything was fine.Īt that point I was convinced, still without proof, that the stick-slip action in the magnetic joints interfere with the last micro movements. I was alarmed to see variance in positions in the range of anything from 5 hundredths of mm up to 0.4 -0.5 mm. I had macros move the effector in three dimensions and finally return the effector to the same position, with the last move always in line with the dial indicator. I set up a test for positioning repeatabily using a dial indicator securely mounted on the frame. I searched for information about wear and could not find a single word on it. somehow, because of the "stick-slip" effect, it will affect accuracy I am using chinese magnetic joints, 13 mm balls and same diameter sockets, which are stated as having 50 N holding force.įrom the beginning I had a vague suspicion that the high friction in the joints can cause: I am now testing my self designed and recently built delta printer.
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