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J-Head Mk 12 High Temperature Development

Posted by reifsnyderb 
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reifsnyderb
J-Head Mk 12 High Temperature Development
June 05, 2018 10:48AM
Hello,

Development of the new J-Head Mk 12 is going great! After one more round of positive testing, we expect to have it available at [www.hotends.com]


Here is a picture of the J-Head Mk 12 heat sink between an e3d and hexagon hot-end.


bA0dqwh.jpg

Latest video:

[youtu.be]

Edited 2 time(s). Last edit at 06/05/2018 03:33PM by reifsnyderb.
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jinx
Re: J-Head Mk 12 High Temperature Development
June 05, 2018 12:55PM
BUT,BUT that pic doesn't look like the heat block in the vid? ( appears more like the volcano in the vid )
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reifsnyderb
Re: J-Head Mk 12 High Temperature Development
June 05, 2018 01:14PM
The heater block is a vertical heater cartridge design. All new J-Heads will be using it. cool smiley

I'll post a picture of the heater block soon.

Best Regards,

Brian





Quote
jinx
BUT,BUT that pic doesn't look like the heat block in the vid? ( appears more like the volcano in the vid )
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MechaBits
Re: J-Head Mk 12 High Temperature Development
June 05, 2018 03:51PM
But But a Volcano heatblock is only $1, Looks more like a copy of a cheap chinese copy of your Jhead - 1
(I can only see a pic with one hotend)

Edited 2 time(s). Last edit at 06/05/2018 05:05PM by MechaBits.
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reifsnyderb
Re: J-Head Mk 12 High Temperature Development
June 05, 2018 04:00PM
I just looked up the price and e3d wants $20 for a Volcano heat block. I am not sure where you got your prices at.

The center part is the heat sink. The E3d shown is a real V5 and the Hexagon is real as well. No knock-off parts shown.

Brian



Quote
MechaBits
But a Volcano heatblock is only $1, Looks more like a copy of a cheap chinese copy of your Jhead - 1
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reifsnyderb
Re: J-Head Mk 12 High Temperature Development
June 05, 2018 04:23PM
Not the best pic, but here is the heater block.

leOcWh9.jpg
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jinx
Re: J-Head Mk 12 High Temperature Development
June 05, 2018 04:32PM
will the Mk12 have the grub screws holding the heat break into the heat sink ( think that a nice feature to bring in from the hexagon).

NO heat break! kind of hoping to see a chimera style break in the design

Edited 1 time(s). Last edit at 06/05/2018 04:45PM by jinx.
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jinx
Re: J-Head Mk 12 High Temperature Development
June 05, 2018 04:35PM
like that brass work,, but whats the stubby piece next to the threading
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reifsnyderb
Re: J-Head Mk 12 High Temperature Development
June 05, 2018 04:59PM
The aluminum piece above the brass is the heat sink for the J-Head Mk 12. cool smiley

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jinx
like that brass work,, but whats the stubby piece next to the threading
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reifsnyderb
Re: J-Head Mk 12 High Temperature Development
June 05, 2018 05:01PM
Hello,

The part with the heat break isn't present in these pictures. However, the heat break has a wall thickness of about 0.25mm. So there is very little heat conduction up to the heat sink.


Quote
jinx
will the Mk12 have the grub screws holding the heat break into the heat sink ( think that a nice feature to bring in from the hexagon).

NO heat break! kind of hoping to see a chimera style break in the design
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MechaBits
Re: J-Head Mk 12 High Temperature Development
June 05, 2018 05:06PM
Ok, Ok $4 [www.ebay.co.uk] must have gone up since i last looked.
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reifsnyderb
Re: J-Head Mk 12 High Temperature Development
June 05, 2018 05:18PM
Well, if you are interested in a cast chinese knock-off of dubious quality, yes, around $4 or so with free shipping.

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MechaBits
Ok, Ok $4 [www.ebay.co.uk] must have gone up since i last looked.
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MechaBits
Re: J-Head Mk 12 High Temperature Development
June 05, 2018 06:52PM
Was only joking(before seeing any pic with someone mentioning the volcano), didnt want to start the whole debate over again,
good luck with it, 0.25 on the heatbreak sounds like some feat on machining.
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Trakyan
Re: J-Head Mk 12 High Temperature Development
June 06, 2018 03:45AM
0.25 mm walls and a set screw to hold it in place? You'd need to be a surgeon to assemble this thing without crushing it. Also, that's a tiny heatsink, how effective is it and what fan will you use to cool it?
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reifsnyderb
Re: J-Head Mk 12 High Temperature Development
June 06, 2018 05:47PM
There is no set screw to hold the heat break in place. The entire part that contains the heat break is one machined piece and is held in place within the brass heat block. The tiny heatsink is highly effective due to the heat break design. Practically any fan can be used for cooling.

Best Regards,

Brian



Quote
Trakyan
0.25 mm walls and a set screw to hold it in place? You'd need to be a surgeon to assemble this thing without crushing it. Also, that's a tiny heatsink, how effective is it and what fan will you use to cool it?
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Trakyan
Re: J-Head Mk 12 High Temperature Development
June 06, 2018 08:41PM
I'm having trouble picturing how the heater block, heatbreak and heatsink go together.
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reifsnyderb
Re: J-Head Mk 12 High Temperature Development
June 06, 2018 09:23PM
I'll be posing a picture of the second revision of the prototype soon. Then you'll see. smoking smiley


Quote
Trakyan
I'm having trouble picturing how the heater block, heatbreak and heatsink go together.
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reifsnyderb
Re: J-Head Mk 12 High Temperature Development
June 20, 2018 01:59PM
Static testing continues with the new J-Head. There was only one failure. It failed to jam with PLA. smiling bouncing smiley Full print tests to commence in the near future....
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dc42
Re: J-Head Mk 12 High Temperature Development
June 20, 2018 03:09PM
Quote
reifsnyderb
Static testing continues with the new J-Head. There was only one failure. It failed to jam with PLA. smiling bouncing smiley

How much retraction did you use, and what length Bowden tube (if any) does your test setup have?

Edited 1 time(s). Last edit at 06/20/2018 03:09PM by dc42.


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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reifsnyderb
Re: J-Head Mk 12 High Temperature Development
June 20, 2018 03:22PM
The heat break section is 2mm. I tried 2mm retraction and 4mm retraction. No problems. The bowden tube is about a meter long.

Other tests:

Left to sit with PLA in for 30 minutes at 195 degrees without any retraction. No problem.

Left to cool down with PLA in it, no retraction prior to cooldown, heat it back up to 295 degrees and extrude. No problem.

Retract 2mm, at 295 degrees, and wait for 30 minutes. No problems

Retract 4mm, at 295 degrees, and wait for 30 minutes. No problems.

The static test rig is now torn down and I hope to be doing actual print tests this weekend.






Quote
dc42
Quote
reifsnyderb
Static testing continues with the new J-Head. There was only one failure. It failed to jam with PLA. smiling bouncing smiley

How much retraction did you use, and what length Bowden tube (if any) does your test setup have?
Reply Quote
dc42
Re: J-Head Mk 12 High Temperature Development
June 20, 2018 04:52PM
Quote
reifsnyderb
The heat break section is 2mm. I tried 2mm retraction and 4mm retraction. No problems. The bowden tube is about a meter long.

With a 1m Bowden tube, my guess is that none of that 4mm retraction at the extruder will actually reach the hot end. My experience is that you need retraction of almost 1% of the length of the Bowden tube just to take up the filament slack in the tube, before retraction actually happens at the extruder. A little less with high-quality PTFE tube such as Capricorn. So with a 1m Bowden tube I would expect you to need around 10mm to 11mm retraction to ensure that enough retraction occurs at the hot end to avoid leaving blobs at the start of travel moves.


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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reifsnyderb
Re: J-Head Mk 12 High Temperature Development
June 20, 2018 05:16PM
The retractions made a big difference in oozing at the hot-end. Even so, I'll do more testing once it's on the printer.

The bowden tube is made out of 4mm OD/ 2mm ID PTFE tubing. It's the same tubing I use for PTFE liners on J-Head Mk 8's and J-Head 10's.

Quote
dc42
Quote
reifsnyderb
The heat break section is 2mm. I tried 2mm retraction and 4mm retraction. No problems. The bowden tube is about a meter long.

With a 1m Bowden tube, my guess is that none of that 4mm retraction at the extruder will actually reach the hot end. My experience is that you need retraction of almost 1% of the length of the Bowden tube just to take up the filament slack in the tube, before retraction actually happens at the extruder. A little less with high-quality PTFE tube such as Capricorn. So with a 1m Bowden tube I would expect you to need around 10mm to 11mm retraction to ensure that enough retraction occurs at the hot end to avoid leaving blobs at the start of travel moves.
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reifsnyderb
Re: J-Head Mk 12 High Temperature Development
June 28, 2018 04:38PM
Hello!

Actual print testing with the J-Head 12 is going very well! Even though it's a bowden extruder, 2mm retracts are working fine.

Both ABS and PLA are now printing very nicely.

Printing ABS at 60 mm/sec works fine at 235 degrees and with 2mm retracts. At 125 mm/sec, I increased the temperature to 245 degrees and 3mm retracts. Prints great!

I have just started some serious testing with PLA. Thus far, no problems. Printing at 190 degrees, at 60 mm/sec, and with 2mm retracts works great. I'll up the speed with future prints.

In the near future, testing will commence with much higher speeds.

Brian
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jinx
Re: J-Head Mk 12 High Temperature Development
June 29, 2018 03:59AM
reifsnyderb just wondering if there a picture of the Jhead Mk12 yet
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reifsnyderb
Re: J-Head Mk 12 High Temperature Development
June 29, 2018 06:33PM
Hello,

No pic for release yet. When it's released there will be lots of pics. smiling smiley

Quote
jinx
reifsnyderb just wondering if there a picture of the Jhead Mk12 yet

Edited 1 time(s). Last edit at 06/29/2018 06:33PM by reifsnyderb.
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