Material choice for a custom delta effector platform

[Edward Simpson]

Hi all,

For the past couple of months I've been working on a custom mini-delta printer that I call the Micro Kossel.

Micro Kossel with experimental effector

I've posted the design files on my blog, along with some more photos. Lately, I've been designing a custom effector for the Micro and I've hit a bit of a snag with the current effector, I'm happy with the basic design but when I tried a simple 15 minute calibration cube print, the effector warped at a narrow point. In the design, I've got the heater block partially recessed into the base of the effector with some Kapton tape for insulation, but enough heat apparently got through to warp the underlying PLA.

Experimental effector after 15 minutes of printing at 230C

What I'm wondering is would ABS or Polycarbonate (PC) handle the heat leakage better for the next iteration of this design?

Edward Simpson

Cobalt Griffonary

[Nick Wimpney]

Well, either of those will handle way more heat than PLA.  A bit of airflow might help too, though.   I've been running my rostock with a PLA effector no problem.

--
You received this message because you are subscribed to the Google Groups "3D604" group.
To unsubscribe from this group and stop receiving emails from it, send an email to 3d604+un...@googlegroups.com.
To post to this group, send email to 3d...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/3d604/5c318b9a-c584-4735-9b3a-84a693c5da6f%40googlegroups.com.
For more options, visit https://groups.google.com/d/optout.

[Nick Wimpney]

Oh, looking at your blog, that is likely your problem.  Kapton will handle a lot of heat, but it isn't a good thermal insulator.  You will want to make sure there's plenty of airflow to prevent any hot spots.

[Edward Simpson]

So your suggestion is to raise the bottom of the effector to create an air gap, or find a better insulator than Kapton?

Edward

[Nick Wimpney]

Yep, cooling is probably the way to go, even insulators will reach a high steady state temperature eventually if they don't have adequate cooling.  An insulator with some airflow outside it will be the most effective of all,  On my printer I have the hotend sticking down.under the effector, and some fans blowing across both it, and the print.

To view this discussion on the web visit https://groups.google.com/d/msgid/3d604/a6415863-e27c-493a-9720-91774a071f0a%40googlegroups.com.

[Graeme Bennett]

I agree with NickW: on Kossels I've built, adding an "Always On" fan (e.g., connected to the D9 connectors if you are using a RAMPS-type board) pointed (slightly) up at the effector really helped. I used a fan a little smaller than this one, but the angle is about the same: http://galexander.org/kossel/kossel043t.jpeg.  You may also wish to add another fan under software control that blows air at the print, as shown in this wiring diagram: http://www.minuk.net/wp-content/uploads/2014/05/wiring-1024x717.png (Note that not all RAMPS boards have that 2-pin fan connector....) 

[Edward Simpson]

Hi Graeme,

Just to clarify things a bit:

1) This is my second delta, I'm mainly experimenting with a custom effector platform (the plastic bit) designed for this particular machine.

2) I've currently got the fan that cools the hot-end heat sink wired directly to the power input lines at the main terminal blocks.

Mainly what I'm looking for is some design feedback/what do people think might work better? I'm already working on a fourth version that puts the heater block below the effector completely.

Thanks,

Edward

[Nick Wimpney]

I think the main thing is to just have some cool air blowing across any PLA that's anywhere near where it's hot.

I've thought about insulating the heater block for a little better efficiency and warm-up time, but if you want to do that, you'll want to make sure not to interfere too much with the cooling of the barrel.  In the case of an all metal hotend, it would cause jams, and in the case of a PEEK barrel like on the J head, you might melt it with not too much overshoot.

If you do want to insulate it, I would suggest finding some woven fibreglass.  The type they use for protecting wires from heat in appliances could work okay if wrapped around the block in a couple layers.  I've also used fibreglass cloth intended for epoxy composite construction, and it is quite effective as insulation, but you need to be sure there's no exposed edges to fray.

All in all, I'm not sure it's worth bothering when you could just use a slightly more powerful heater, and better airflow to keep your PLA solid.

on mine, I'm using 2 40mm fans primarily to cool the print, but the airflow also helps keep heat from building up on the PLA effector.  Mine's dead simple, though.  It's just  a flat plate with a slot to mount the J head.  when I make another one, I'll put bosses in to hold the fans, where my current ones were just glued on.  The fact that my J head is sticking down entirely below the effector helps keep the heat away from the PLA too, so I expect your next itteration will help.

All that said, if you make it work well with PLA, and then switch to a higher temperature plastic, you will have a good safety margin.

--

You received this message because you are subscribed to the Google Groups "3D604" group.
To unsubscribe from this group and stop receiving emails from it, send an email to 3d604+un...@googlegroups.com.
To post to this group, send email to 3d...@googlegroups.com.

To view this discussion on the web visit https://groups.google.com/d/msgid/3d604/1cf22965-b114-4dc3-b875-7cf8612a2b73%40googlegroups.com.

[Nick Wimpney]

https://www.youtube.com/watch?v=JeX2sV_F_68

There is mine, BTW.

It's also quite a small machine, but with round rods.