26 Reply by kr15_uk

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Re: Jr Hotend - All Metal or PTFE lined

@gravy - my only issue with this design is that it blows fairly hot air from the fan which vents hotend's heatsink.
And due to the hotend cooling design where it pulls new air mainly from the bottom it will pull already "preheated" air through once again.
Going into the loops... It'll get quite hot quickly and I'm not sure how effective part "cooling" solution it will be.

I guess some airflow is better than no airflow...
Only thing what worries me the most is the comment that it's been designed by their engineers....

I am very tempted to try and print one to measure and log temperature (see if it goes up over the time to confirm my theory, or disprove it).
A bit short on time, anyone curious to that?! All you need is temperature probe with logging capabilities.

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27 Reply by reluttr

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Re: Jr Hotend - All Metal or PTFE lined

kr15_uk wrote:

@gravy - my only issue with this design is that it blows fairly hot air from the fan which vents hotend's heatsink.
And due to the hotend cooling design where it pulls new air mainly from the bottom it will pull already "preheated" air through once again.
Going into the loops... It'll get quite hot quickly and I'm not sure how effective part "cooling" solution it will be.

I guess some airflow is better than no airflow...
Only thing what worries me the most is the comment that it's been designed by their engineers....

I am very tempted to try and print one to measure and log temperature (see if it goes up over the time to confirm my theory, or disprove it).
A bit short on time, anyone curious to that?! All you need is temperature probe with logging capabilities.

Id be interested in seeing how well it works... although given that's the side of the fan that draws in air, I am doubtful there is even enough air pressure for it to actually reach the print. XD

28 Reply by gravy

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Re: Jr Hotend - All Metal or PTFE lined

kr15_uk wrote:

@gravy - yep, heater block size wise is exactly the same.

But just to clarify few things so people don't misunderstand that scary 250c.

1. I'm using Cura as my slicer so I do set temperatures manually.
2. If I define 240c then it goes to 240c (+ a bit of a overshoot), if I define 190c then it only goes to 190c, 210c = 210c, and so on.
3. If you are using XYZWare and temperatures depends from NFC chip of choice, they will only go to that temperature.
4. When using 40w heater cartridge instead of the stock 25w one themperatures doesn't overshoot any more that with the stock heater cartridge if you are using common 190c-210c range. It tends to overshoot if you are going above 235c.

Also about the overshoot when printing on 240c. 250c sounds quite a lot but actually it's only 4%.
4% of 190c is 7.6c, you see that often on stock config Jr when printing 190c that sometimes it goes close to 200c.

All and all. If you've been using your stock Jr heater and someone would swap the heater over the night to the 40w one without you knowledge you wouldn't see any difference what so ever!
By swapping the heater there are only 2x benefits: 1st - it reaches initial temperature quicker, 2nd - you can go over 214c if you want or need and ONLY IF you set higher temperature manually.


Sorry if all that sounds patronising but I just don't want people to misunderstand why there is 250c on the Jr display.

@kr15_uk. You say you are using Cura with Da Vinci Jr? How would i go about doing that? Which printer do i use in setup. Is their some sort of workaround?

29 Reply by kr15_uk

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Re: Jr Hotend - All Metal or PTFE lined

@gravy - yep, Cura + Jr. If you search on the forum for my posts you'll see quite a lot of Cura and Jr related topics. I've posted some config files for Cura so you can add Jr easily. Also you'll need app by Anthem called ThreeDubber for Win or ThreeDub for Mac/Linux to convert gcode to 3w file so Jr can do the magic.
I've been using Cura for 6month or so with Jr, quite happy.

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30 Reply by gravy

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Re: Jr Hotend - All Metal or PTFE lined

kr15_uk wrote:

@gravy - yep, Cura + Jr. If you search on the forum for my posts you'll see quite a lot of Cura and Jr related topics. I've posted some config files for Cura so you can add Jr easily. Also you'll need app by Anthem called ThreeDubber for Win or ThreeDub for Mac/Linux to convert gcode to 3w file so Jr can do the magic.
I've been using Cura for 6month or so with Jr, quite happy.

@kr15_UK. Brilliant. Got it set up now. Gonna play with the print settings tomorrow. This is a vast improvement to Xyzware. Thanks for that.

31 Reply by reluttr (edited by reluttr 2016-08-13 00:40:58)

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Re: Jr Hotend - All Metal or PTFE lined

I decided to crack open my hot end today and see how it works in person and I stumbled upon something interesting.

The exit vent for the cooling fan actually blows down toward the build area... and its designed to basically redirect all airflow out that way.

I am thinking about trying to make a simple vent to redirect the airflow to directly on top of the print and installing a more substantial cooling fan.

BTW I did the z-brace mod and it greatly helped with the z ribbing I was having issues with. big_smile

http://www.thingiverse.com/thing:1558580

I changed up their formula for the bearings though... They used lock washers for w/e reason as spacers for the bearings. I tried that and I felt there was way to much play, maybe they had more success... but I decided to go with regular washers. I also recommend using a slightly longer bolt than suggested, I did so on accident because lowes was out of the right size, but I feel it worked out better that way.

Here is the pattern I used on mine.

Top of bolt, bearing, 5 washers, another bearing, nut, washer, plastic piece, another washer, then the final nut. All of which are m5 as he instructed.

then just follow XYZ's tutorial on how to level the x axis, and install the brace before you move the gantry up. Make sure it is snug against the rod and make sure the mounting bolts are snug so it does not move.

There is still a little sagging, but it is VERY minimized. Honestly its impossible to totally eliminate the sagging just by design of the printer. You could do a pulley mod like I did with the QUBD Two Up, but that is a major pain in the ass. XD

32 Reply by kr15_uk

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Re: Jr Hotend - All Metal or PTFE lined

So... I have an update on this "All Metal or PTFE lined" question...

Hence no one really knew the answer there were only 2x options left to do.
1. Grab a saw and half it to see what's inside.
2. Heat it up to 300c and see if I get famous PTFE smoke.

Problem with option 1 is if after halfing it you discover that it's All Metal hotend that's all you left with - knowledge.
But if you go with option 2 - you end up still having usable hotend if it turns out to be all metal one.
+ Sitting at the front of my old poor Jr with fire extinguisher in one hand is kind of a fun! wink

So... Option 2 it is.

1. Bought 10m Polycarbonate sample of rigid.ink
2. Adjusted temp settings in Marlin so it can go over 300c+ (haven't tried on stock firmware, not sure if stock has some limits inbuilt, it took 245c with ease but never tried highher than that)
3. Turned it up to 250c, all good, 260c, 270c, meh - 300c

10mins in - all good.
Btw 300c does the magic to clean off nozzle! wink

Oh, did I mentioned that after 285c or so it became very very slow ramping up temperature?!
Clearly 40w heater cartridge was struggling.
(I've replaced heater cartridge from stock 25W to eBay cheapie 40W one)
So to see how high I can go I tried to go over 300c a bit. 312c was the very top.
(I'm using stock Jr cooler fan as well.)

So, next was to try to print something and see if I get clean print or mix with burnt PTFE instead!
Clean. Printed off 3DBenchy in PC. Yay.

So by the looks of it all metal it is then!

BUT....
Jr hotend isn't built for 300c - that became quite obvious when I tried to remove PC and swap it with PLA...
Heatbrake heatsink is way too small to deal with 300c.
After removing PC cooled down hotend to 200c to swap with PLA. Clog in the heatsink bit...
Heated it up to 300c again, cleared that clog and tried to swap with PLA while at 280c (so PC is still soft enough) - yeah, PLA was melting slightly on the very top.
So just to make it much smoother change and clean it at the same time I did PC swap to Nylon and then Nylon to PLA.

Also my custom hotend mount didn't liked that heat a lot either. Mount is printed in PETG and you can see little surface rippling where it was close to the hotend and standoffs which holds hotend in place sag a bit down as well.

Anyway, I hope you'll find this useful.

BUT... I'm not responsible if you burn down your Jr hotend, house or even whole street.
Closely monitor temperatures.
Don't relay only on Jr thermistor.
Grab a temperature probe and generic room thermometer or so when do this for the 1st time.
300c isn't the friendliest temperature for the most of the materials.
Also every machine is built different.
Just because my hotend is all metal doesn't guarantee 100% that's yours wasn't made with PTFE inline for some reason.
Anyway, experiment but always be careful!!!

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33 Reply by thegasman2000

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Re: Jr Hotend - All Metal or PTFE lined

I have the parts for a heated bed in the post from china hmm I want to print different materials like ABS and others and wondered what the best mod for the hot end is?

I looked for a cheap 40w heater block and found this on fleebay http://www.ebay.co.uk/itm/12V-40W-3D-Pr … SQBYKlxKPg

If I fit that to the stock hotend would I get the 250 degrees I need?

I am slicing in cura with the temp set there but my printer seems to ignore that setting and print to the tags setting. I am on firmware 1.0 so reflash the tag whenever it gets low but 210 is the maximum on there. How do I get over that like you did to get 300?

PS your heated bed thread made me buy this printer so you are fully responsible smile