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Haydns printed Mag Rods improved

Posted by o_lampe 
Haydns printed Mag Rods improved
January 07, 2018 11:43AM
While I'm waiting for the Delrin Mag arms for my Compact Carrier project, I printed a set from PLA. Haydn said, he uses a 3/8" ball end mill to smooth out the printed mag holder, I found a different way.
I replaced the M3 screw of a hotend with one of the ball studs, heated it up to 160°C and voilá :super smooth surface.



Edited 1 time(s). Last edit at 01/07/2018 11:44AM by o_lampe.
Re: Haydns printed Mag Rods improved
January 07, 2018 12:42PM
Nice idea!


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Disclosure: I have a financial interest in sales of the Panel Due, Mini IR height sensor, and Duet WiFi/Duet Ethernet [www.duet3d.com].
Re: Haydns printed Mag Rods improved
January 07, 2018 09:58PM
You can form delrin (acetal) the same way. It does give off formaldehyde gas if you get it too hot, which is rather hazardous to your health.
Re: Haydns printed Mag Rods improved
January 08, 2018 03:17AM
There is one more thing, I want to try: The air gap between magnet and ball stud should be equal for all rods.

The Delrin rods I got from T3P3 have a very small gap. I want to get there with printed ones, too.
My idea is to modify the M5 screw I used for pushing ( see pic 1 ) in a way, that it makes electric contact with the ball stud when the desired gap is reached. Then I have to use the multimeter to check for continuety while melting down the plastic.
Re: Haydns printed Mag Rods improved
January 11, 2018 09:18AM
Thank you for this idea I was intending to make these rods for my cylinder printer (I have a set of Haydns rods on my kossel Xl). So I will try this idea.

So are you making them so the magnet is just in contact with the ball stud? I suppose the less the gap the greater the magnet force.

Edited 1 time(s). Last edit at 01/11/2018 09:20AM by DjDemonD.


Simon.

[www.precisionpiezo.co.uk] Accurate, repeatable, versatile z-probe plus piezo discs, endstop cables, pt100, 50w heaters. PT1000 cartridge sensors plug straight into duet boards and others.
Published:Inventions
Re: Haydns printed Mag Rods improved
January 11, 2018 12:08PM
The idea is to make the gap equal for all heat treated mag-holders. I don't think it's good to have contact between the ballstud and the magnet.
I modified the screw, I used to press the mag-holder onto the ball. Now it makes contact with the ball 0.1mm before the magnet would.
It's hard to see, but the screw protrudes the washer by 0.1mm


Re: Haydns printed Mag Rods improved
January 12, 2018 12:28PM
With a cutting punch or the proper diam, cut pieces of 0.1mm PTFE sheet you put in the hole. Will not melt, will give the right spacing. I make bearings that way, magnets plus Igus or PTFE. A T° adjustable heatgun used for reflow comes handy too.


"A comical prototype doesn't mean a dumb idea is possible" (Thunderf00t)
Re: Haydns printed Mag Rods improved
January 13, 2018 03:35AM
Nice idea, if you have these sort of things or tools at hand. I also thought of 5mm OD shims, but they are even harder to get. The 0.1mm gap isn't "official" yet. I'll get my Delrin magball kits next week, then I have a chance to check their gap for reference.
Re: Haydns printed Mag Rods improved
January 13, 2018 11:22AM
Quote
o_lampe
Nice idea, if you have these sort of things or tools at hand. I also thought of 5mm OD shims, but they are even harder to get. The 0.1mm gap isn't "official" yet. I'll get my Delrin magball kits next week, then I have a chance to check their gap for reference.

PTFE sheet can be found in laser printers. Old printers in junkyards, just be polite with the guys toting baseball bats smiling smiley

Edited 1 time(s). Last edit at 01/13/2018 11:24AM by MKSA.


"A comical prototype doesn't mean a dumb idea is possible" (Thunderf00t)
Re: Haydns printed Mag Rods improved
February 10, 2018 07:57AM
I finally measured the Delrin sleeves and ball studs air gap. It shows continuity between magnet and ball stud in many cases or at several angles, so the airgap is "0".
Good to know, if I ever make some PLA sleeves and use the melting-method again.
Re: Haydns printed Mag Rods improved
February 10, 2018 08:40AM
Will try it with petg I think. Need to make another set for use in chamber bit concerned the pla ones will soften.


Simon.

[www.precisionpiezo.co.uk] Accurate, repeatable, versatile z-probe plus piezo discs, endstop cables, pt100, 50w heaters. PT1000 cartridge sensors plug straight into duet boards and others.
Published:Inventions
Re: Haydns printed Mag Rods improved
February 11, 2018 01:34AM
PTFE tape is available from McMaster Carr as thin as .0035". I'm using the conformable version that is .0045" thick and haven't seen any wear in a year or so of use.
Re: Haydns printed Mag Rods improved
February 11, 2018 02:58AM
PETG will work too, much lower stiction rate than PLA.

@ etfrench
is it the tape used for plumbing? Didn't know it is PTFE. But now we know there is no airgap, we don't need spacers anymore.
Re: Haydns printed Mag Rods improved
February 11, 2018 12:37PM
No, it's not the same. This tape has adhesive on the back.
Re: Haydns printed Mag Rods improved
February 14, 2018 09:38PM
That's a really cool idea, guy! If I didn't have delrin rods, I'd definitely have tried this!
Re: Haydns printed Mag Rods improved
February 15, 2018 02:10AM
I'm impressed! This is very clever!

I'd say it's ideal to have a gap of about 0.05mm between the magnet and ball stud.
Re: Haydns printed Mag Rods improved
February 15, 2018 02:55AM
What's the downside of having the magnet touch the ball as long as there is no pressure involved?
Re: Haydns printed Mag Rods improved
February 15, 2018 03:48AM
Quote
Haydn
I'm impressed! This is very clever!

I'd say it's ideal to have a gap of about 0.05mm between the magnet and ball stud.

Thank's a lot Haydn!
Have you seen my Rod-assembly Jig? It works like a toggle clamp and is very quick to engage/disengage.


If you like it, you can add them to your website or thingiverse. I don't claim any IP. ( Just a little bonus on my next order winking smiley )

Edited 1 time(s). Last edit at 02/15/2018 03:48AM by o_lampe.
Attachments:
open | download - rod-block.stl (96.1 KB)
open | download - rod-arm.stl (31.4 KB)
open | download - rod-hinge.stl (37.6 KB)
Re: Haydns printed Mag Rods improved
February 15, 2018 04:34AM
Quote
etfrench
What's the downside of having the magnet touch the ball as long as there is no pressure involved?

I've heard the ball and magnet collide, when they make contact. In one case ( so far ) the plating of the ballstud chipped off. But it would be even worse, if a piece of magnet would chip off. Now I slowly make contact to avoid any chipping.
Attachments:
open | download - chipped_ballstud.jpg (111.3 KB)
Re: Haydns printed Mag Rods improved
February 15, 2018 08:36AM
Quote
Haydn
I'm impressed! This is very clever!

I'd say it's ideal to have a gap of about 0.05mm between the magnet and ball stud.

Who is the supplier for these balls ? Eventually, do you make them ? If yes how, what kind of steel, heat treatment, finish ?

Edited 1 time(s). Last edit at 02/15/2018 08:41AM by MKSA.


"A comical prototype doesn't mean a dumb idea is possible" (Thunderf00t)
Re: Haydns printed Mag Rods improved
February 19, 2018 05:41AM
One thing bothers me about the Delrin Mag rods. Once you've assembled them with 2k glue, you can't reuse them.

Would it be possible to print the rod-sleeves from ABS slightly oversize ( or tight fit ) and use acetone to glue them in?
Later, when you want to reuse them with other rods, put them in an acetone bath until you can remove the rods.
Re: Haydns printed Mag Rods improved
February 19, 2018 06:09PM
Does CA (superglue) stick to Delrin? I doubt it, but if yes things would be simple: you can debond CA with acetone.
Re: Haydns printed Mag Rods improved
February 20, 2018 03:23AM
CA sticks to all rough surfaces I think. It's worth a try.
I tested the ABS rod-sleeves in printed PLA Mag-holders. I let it cure overnight and now it's very solid. It seems to help when the carbon rods have a rough surface.
Will try to remove it today and then do the real Delrin test.
Re: Haydns printed Mag Rods improved
February 21, 2018 04:09AM
It seems, the PLA I made the mag-holders of, dissolve in Acetone, too. I created a big mess, trying to soak up the ABS and pull it apart. Turns out, the bond to the carbon rod is very, very good.
Good news is, the Delrin parts don't seem to dissolve at all, so there is light at the end of the tunnel.

I have to test some of my older PLA parts, if it's normal to dissolve in Acetone. That would allow after_print treatment like glueing parts together or smoothing the surface and such...
Re: Haydns printed Mag Rods improved
February 21, 2018 06:41AM
Yeah I've never thought pla was dissolved in acetone. Is it plain pla or some hybrid material?


Simon.

[www.precisionpiezo.co.uk] Accurate, repeatable, versatile z-probe plus piezo discs, endstop cables, pt100, 50w heaters. PT1000 cartridge sensors plug straight into duet boards and others.
Published:Inventions
Re: Haydns printed Mag Rods improved
February 21, 2018 09:12AM
My PLA gets soft in acetone... can't glue it that way unfortunately. If you're looking for a PLA solvent/glue, use dichloromethane. Maybe available at your pharmacy, or as acrylglass glue. Here in Japan it is sold for gluing acryl.
Re: Haydns printed Mag Rods improved
February 22, 2018 03:49AM
Quote
DjDemonD
Yeah I've never thought pla was dissolved in acetone. Is it plain pla or some hybrid material?

That's a good question. How much PLA is in PLA-filament? I remember the smell of the first spools PLA I used. Since 3DP became a mainstream hobby, the raised demand in PLA probably made them mix other stuff in as well? The smell is different now...

I once bought a banana-milk which contained 0.1% banana! Just enough to legally call it banana milk.... eye rolling smiley
Re: Haydns printed Mag Rods improved
February 27, 2018 12:41PM
Hi Olaf,

That is a clever and perhaps new jig design!
I've learned that the most important thing to do when I have an idea on how to improve the process is to put it into production and then measure the results.
If the parts come out better, then it is a success.
If not, then I try to learn something from it.

With the threaded steel rod jig I've published, one can easily produce sets which match within 0.10 to 0.05mm, which is pretty good.
Re: Haydns printed Mag Rods improved
February 27, 2018 12:47PM
Hi MKSA,

I contracted with a machine shop in China to have these ball studs custom made.
They work great in delta printers, because they're inherently zero-backlash.

I sell them for $1.50 each.

You can order them directly from me. Postage to Europe is around $14 for a few sets.

In Europe, you might be able to order them from: [www.think3dprint3d.com]
They've got a shipment coming in.

I also build precision arms to work with them. Contact me directly for prices, etc. BTW, Think3dPrint3d usually keeps my 360mm arms in stock, if that length would work well for your printer.
Re: Haydns printed Mag Rods improved
February 27, 2018 12:50PM
Yes, I wish that the Delrin rod ends were reusable, because occasionally I botch one.
I am able to take them apart and recycle the magnets.
The CF tubing can be cut shorter and also reused.
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