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Magnetic arms

Posted by DjDemonD 
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DjDemonD
Magnetic arms
August 11, 2016 09:23AM
So I got a set of magnetic arms and carriages/effector. They are not all the same length. Has anyone else had this problem and how did you go about fixing it? I am thinking I'll need to pull the balls off one end of all 6 rods. Mount them in a jig cut them, which will only be around 1.5mm off maybe 4 of them and then reglue them.

Are they difficult to disassemble?

Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions
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o_lampe
Re: Magnetic arms
August 11, 2016 01:19PM
Send them back to the seller, don't accept such misalignment.
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meq123
Re: Magnetic arms
August 11, 2016 01:34PM
I saw a recent post on the ali-express ones being like this. The poster R&R'd the balls cutting the arms to the same length as you suggested.

Ahh found it. Here: [forums.reprap.org]

Edited 1 time(s). Last edit at 08/11/2016 01:37PM by meq123.
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etfrench
Re: Magnetic arms
August 11, 2016 01:52PM
Depending on how the ball sockets are attached, I'd cut the tubes in the middle, then use a sleeve to rejoin them.
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DjDemonD
Re: Magnetic arms
August 11, 2016 01:54PM
Good advice etfrench, meq123 that was me! Olampe I would but a) I want to get building, b) returning things to China takes much more time and money that it's worth.

Edited 1 time(s). Last edit at 08/11/2016 01:56PM by DjDemonD.

Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions
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etfrench
Re: Magnetic arms
August 11, 2016 02:24PM
You may not need to return them in order to get a refund or replacement. If the vendor isn't responsive, file a dispute with Aliexpress for a refund.
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DjDemonD
Re: Magnetic arms
August 11, 2016 02:28PM
I'm quite happy to go with the sleeve idea my rods are probably a tad short for the size printer I'm planning so if I can find a really good sleeve I might lengthen them all, and I was looking forward to making up the rods as part of this build. I can print a jig with ball recesses in it and cut and glue them using it. Any suggestions on sleeve material, carbon fibre?

Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions
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etfrench
Re: Magnetic arms
August 11, 2016 02:41PM
I'd use aluminum, but I have a lathe that I can use to bore the sleeves accurately.
You could use one of the tubes as a mold for a carbon fiber layup.
Internal sleeve/plug would also work as well as an external sleeve.
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dc42
Re: Magnetic arms
August 11, 2016 03:11PM
For the sleeve, I would use a piece of carbon fibre tube with the same ID as the OD of the rods. I have done this before.


Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
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VDX
Re: Magnetic arms
August 11, 2016 05:51PM
... some ten years ago (before carbon becomes common) I did something similar with pieces of paper, glass fabric and cast epoxy resin - cut rods in halfs, elongated and fixed them in place, glued a tube of paper around for stiffness, then the glass fabric and the epoxy winking smiley

Viktor
--------
Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]
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DjDemonD
Re: Magnetic arms
August 11, 2016 06:29PM
Well I've designed a jig printed in two pieces with a puzzle cut between them, with indents for the balls giving me a 320mm length from the end of the balls, this is just 5mm longer than the rods are now. I've ordered some 6mm ID carbon tube for sleeving the rods are 5.85mm diameter. I have some epoxy.
Thanks for the advice. Looking forward to it.

Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions
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chris33
Re: Magnetic arms
August 12, 2016 07:05PM
id make a jig fit the balls into i did and made sure the centers of the balls was correct then epoxy glued them in place, good way of doing that if the tube is -/+0.5mm at least the thread can make up the difference, while getting the hinge point measurement correctly.

Check my rubbish blog for my prusa i3

up and running
[3dimetech.blogspot.co.uk]
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DjDemonD
Re: Magnetic arms
August 24, 2016 04:10AM
All done, some photos on my build log I just started. One end of my carbon sleeve was undersized but I sanded down the rods to fit them in. All very much the same length now.

Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions
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