Jan's Hot End MK-II

Hi everyone,

I am fairly new to this, but have been reading a lot on this forum and ended up making my own printer based on the Wolfstrap.
I have also made all my hot ends from scratch and they work quite well.
Just made a new small version without a fan and it is working very well on my machine.
Just thought I like to share my design with you. It is the way I make the brass nozzle/barrell attach to the PTFE that is the secret here I think.
I don't use threads as that is a lost course. Instead I make grooves in the rod which is pressed into the PTFE. Very tight fit and then to really secure it I press a copper pipe onto the PTFE.
I am very happy with this design and if anyone tries it please let me know how you go.
To see more details I have made up a blog/site for you to look at. ( My Blog )
What I have tried to do is to make a hot end without any expensive and specialized tools, such as a lathe.
This way most of you should be able to make it. It is only around 50mm long.
If you do make it please let me know how it performs.

All the best

Jan
MyBlog

Thanks for sharing the info! I have been having trouble with my hot end and would like to eventually build my own so this will help.
Did you use silver solder for the heat sink?

No, I just use stock standard materials.
So far working great.
Normal solder that you can get anywhere.
Regards
Jan

I can't find your hot end on your blog. Can you post a direct link?

[3dprinting4u.wordpress.com]

Interesting design. How did you machine the brass rod?

lincomatic Wrote:
-------------------------------------------------------
> Interesting design. How did you machine the brass
> rod?


Hi,
The process of making each part is explained under my first hot end design.
Every single menu has got info. Top menu as well as all sub menu's. Click on each and it should open up.
This is where there are more details on how I made the brass:
Hot-End : My way of Making the parts
Drill press and a file.
Kind regards
Jan

Drilling the nozzle hole has always been the hardest part for me. An alternative to doing it your way is to make the nozzle with a brass acorn nut. That way, you can drill the nozzle hole from the back side (where the acorn nut already has a cone-shaped indentation) and it is almost guaranteed to be centered.

THE TRICK IS: you do that first, then you mount the acorn nut on a threaded rod or a bolt, and grip the bolt in a drill press to file the outer cone. The reason for doing that is the threading is concentric with the cone part that you used to drill the nozzle hole, but the outside hexagonal part is NOT concentric with the conical indentation.

Then you hollow out a brass bolt (also has an indentation for easy centering) for the heater barrel. I'll get pictures of my setup when I can but the gist is you clamp the heater barrel with a piece of sheet metal to your extruder, squishing the PTFE barrel between the nozzle and extruder. I've had great leak-proof success with this when printing with ABS. haven't tried with (admittedly more leak-prone) PLA.

Hi destroyer2012,
Yes there are many ways of doing this. And you are correct in that it is easier to drill an acorn nut which I mention on my blog but, I tried the acorn nut trick and find it too fiddly with anything that has a thread on it. I find the PTFE tape (on the threads) is a pain to use and was looking for a solution that has as few joints as possible. One joint only after the filament enters the hot end design.
I also like to have the heater barrel as close to the nozzle end as possible (without desturbing printed layers). With the acorn nut I find it sits up too high but, I am fairly new to this, and my experience is not there so I am not going to elaborate too much on how to do this and that.. Maybe a combination of the different ways of doing things will lead to the perfect part? Who knows.
I do feel though that the showstopper for many is the hot end. It needs to be as simple as possible, as soon as things leaks it is a pain to pull apart and clean when it as an assembly.
If you are going to make it yourself:
It needs to be cheap to make, no expensive tools such as a lathe.
It needs to be made of readily available parts.
It needs to work.

To be honest, the cheapest option is most likely to buy one already made.(The cost of drills and bits here and there will add up, especially if you don't have anything at all.)
But if you make a machine from scratch, not standard, like the one I made, that option may not be any good.
Then of course you have got the element of pride.....oh yeah...I made this one myself.... And that is priceless.

I also don't like to be dependant on a vital part such as the hot end, having to order it overseas. You can always have a spare, but you know what I mean.

Ok, I have been going on too too long now.....(I am watching my machine print at the moment, just love it..I think I need to get a life)
Looking forward to see other designs and ideas.

Kind regards
Jan

Jan,

I understand about the pride of making your own hot end. I can not get the glass transition zone "just right" I have a few working hot end of my design, but I can't make more, reliably, and repeatedly.

If my hunch is correct, you sound like you qualify to make one of these:

[www.thingiverse.com]



Regards

Hi destroyer2012,
I am curious to know how you seal the joint between the acorn nut and the bolt?
Do you manage to get a solid tight lasting seal?
When I tried some time back, with PTFE tape on the threds it still leaked after a while.Don't think the tape liked the heat.

Regards
Jan

huh, interesting way to join the ptfe and threaded tube.
I might have a go at that.

Tbh I didn't try too hard to get the seal tight I just twisted the acorn nut HARD into the barrel (like, I held the barrel with pliers and torqued the nut a lot to try to get the brass to seal itself). I also used a nicrome and jb weld heating element and slathered the jb weld all over the joint between the acorn nut and barrel. works well for abs, haven't tried with anything else.

se5a Wrote:
-------------------------------------------------------
> huh, interesting way to join the ptfe and threaded
> tube.
> I might have a go at that.


Hi,

Please note, there are NO threads. Threads and PTFE does not work. (Not for me anyway)
They are grooves. Very important difference. When you press the copper pipe over the expanded PTFE the PTFE "sinks" into these groves and forms a seal like with O-rings. And it is very strong! Will not come out easily.
To make it even stronger you could put like a flange on the copper pipe end, facing the nozzle.
Good luck, Hope it works great for you.

Kind regards
Jan

destroyer2012 Wrote:
-------------------------------------------------------
> Tbh I didn't try too hard to get the seal tight I
> just twisted the acorn nut HARD into the barrel
> (like, I held the barrel with pliers and torqued
> the nut a lot to try to get the brass to seal
> itself). I also used a nicrome and jb weld heating
> element and slathered the jb weld all over the
> joint between the acorn nut and barrel. works well
> for abs, haven't tried with anything else.

I was hoping the acorn nut could have been easily replaced. That way you could do a quick and easy nozzle size change.
Might give it try again one day, but just thinking about the PTFE tape....nehh..maybe later. Have to do some more research.

Thanks for the info.

Kind regards
Jan

IceMan Wrote:
-------------------------------------------------------
> se5a Wrote:
> --------------------------------------------------
> -----
> > huh, interesting way to join the ptfe and
> threaded
> > tube.
> > I might have a go at that.
>
>
> Hi,
>
> Please note, there are NO threads. Threads and
> PTFE does not work. (Not for me anyway)
> They are grooves. Very important difference. When
> you press the copper pipe over the expanded PTFE
> the PTFE "sinks" into these groves and forms a
> seal like with O-rings. And it is very strong!
> Will not come out easily.
> To make it even stronger you could put like a
> flange on the copper pipe end, facing the nozzle.
>
> Good luck, Hope it works great for you.
>
> Kind regards
> Jan

I can see that, it's still groves in threaded tube. even if there's no thread where you're joining it to the PTFE.
semantics.

I really like your method though I think I'm going to try making an ultimaker nozzle with your groove seal technique

if you want to test for strength, try extruding cold for a bit.
then try printing onto of layers that have had too much fill. (so the hotend gets dragged through the layer below, which will cause it to flex side to side)
if it can survive the above then I think you've won the prize for the best technique

destroyer2012 Wrote:
-------------------------------------------------------
> I really like your method though I think I'm going
> to try making an ultimaker nozzle with your groove
> seal technique


Yes, go for it. There is always room for improvements. If you combine the good from several ideas you may come up with the "perfect" hotend.
I am still printing almost day and night with mine, and it has not missed a beat yet. I will be performing some testing when it comes to "speed extruding" later on. Right now I am printing a bracket to use as a mounting for this hotend. That way I can test how the temperature effects the ABS, which will simulate a plastic extruder/carriage. As you know my extruder is a simple block of wood at present.
Good luck, and let us all know how you go.

Kind regards
Jan

Edited 1 time(s). Last edit at 04/03/2012 04:46AM by IceMan.

se5a Wrote:
-------------------------------------------------------
> if you want to test for strength, try extruding
> cold for a bit.
> then try printing onto of layers that have had too
> much fill. (so the hotend gets dragged through the
> layer below, which will cause it to flex side to
> side)
> if it can survive the above then I think you've
> won the prize for the best technique


Thanks for your suggestions/advice.
I am not after any prize , but as soon as I have printed some needed parts I may give that a try.
Maybe during the long easter weekend.
When it comes to dragging the hot end through plastic I am not too keen on trying that just yet, as my printer has got slides (drawer slides) and they may get damaged before the nozzle. I have collided with my bed though and the nozzle did not budge. The whole z-carriage lifted...I think my right hand broke the sound barrier on it's way to the reset switch on the Arduino board.
Maybe if I try to actually pull it apart with pliers while it is hot?
I'll do some of that testing later on. For now it is printing, and I love it.


All the best,

Regards
Jan
MySite

Edited 1 time(s). Last edit at 04/03/2012 07:32AM by IceMan.

Rather than simple grooves it might be better to file barbs like these: [www.componentforce.com]

---

[www.hydraraptor.blogspot.com]

nophead Wrote:
-------------------------------------------------------
> Rather than simple grooves it might be better to
> file barbs like these:
> [www.componentforce.com]
> nnectors

Hi nophead,

Yes, that may even work better, especially at the assembly process.
It may be a bit tricky to file though if you want to keep the brass small, but very good idea, might give it a try.
By the way, thanks for your fantastic contributions on the forums. Thanks to you and all others who has contributed with their expert advice I have my own printer and I am printing. It made the journey from start to print a lot more easy.

Kind regards
Jan
MySite

Jan, did you measure the cooling tube temperature by any chance?
Interesting concept, for the first time i have the feeling i could do a hotend myself. I'm tempted to do it, i now have an arcol hotend v3 wired with steel wire to my x carriage, losing a lot of z-height in the process.

Any recommendations on what to get as a base material for the heater block?

Evert

evilb Wrote:
-------------------------------------------------------
> Jan, did you measure the cooling tube temperature
> by any chance?
> Interesting concept, for the first time i have the
> feeling i could do a hotend myself. I'm tempted to
> do it, i now have an arcol hotend v3 wired with
> steel wire to my x carriage, losing a lot of
> z-height in the process.
>
> Any recommendations on what to get as a base
> material for the heater block?
>
> Evert


Hi,
I have not measured it accurately. My aim was to avoid the filament go soft as it travels down the PTFE and that is not happening on my setup.
I am still printing without any issues what so ever. Long 7hrs continuous prints. All up I think 50hrs in the last week (a lot of overnight unattended prints). I have made a bracket that I will attach to my wooden extruder. This bracket will be to hold the nozzle. This way I should be able to tell if it affects the abs bracket. I don't see why it should as the filament is not affected at all. But as I have mentioned before, if it does then maybe a 40mm fan will be necessary. I hope not (and don't think so), as I am aiming for simplicity with the hot end.
Remember this concept works brilliant on my setup, but there are always room for improvements.
Maybe a hint better cooling (2mm longer pipes etc) may make a lower top temp if it becomes a problem.

I am printing parts as we speak, but on the weekend I may do some more testing with my plastic bracket etc.

It is very cheap to make, and it takes me probably between 1 and 2 hrs to make one up. (never timed myself as I get lost when I start on this.....)

The heater block I have is 20 x 25 x 10mm aluminium block. Threaded hole and tightened with a nut.
2 x 6.8 ohm resistors in parallell gives me 3.4 ohm total. In 3min approx I have 230 degrees. Used this block since December last year, never failed me. No insulation around it either by the way. (so lot of improvements to look at there, another time)

I will let you know how I go with my testing and abs bracket.

Kind regards
Jan

STOP THE PRESS!

Compulsary modification needed to my hotend.
The seal is still going strong and I am printing.
The middle copper pipe needs to go approx 2mm below the PTFE. Cut some slots and bend in to make a flange/finger grip.
Just making one now to test.
Will post photos asap

ATTENTION ALL!

Just made another unit and tested,
On my printer I have no issues.
I increase the extruding speed it seems to work ok up to aprox 30mm/min. This is very fast for my machine, but most likely slow for any other.
I am researching at the moment how fast the extruders go on "normal" machines.
If anyone can post the speeds , I would greatly appreciate it.
(This is the speed in pronterface)

Sorry for any inconvenience.

Regards
Jan

Edited 1 time(s). Last edit at 04/04/2012 04:34AM by IceMan.

Hi again,

Have done some mods to the design and have successfully extruded at 80 to 100mm/min in pronterface whithout any problems with the hot end.
My poor wooden extruder is struggling, so I need to get my next printer done, so I can play on same playing fields as the rest of you. Get some proper extruder etc...
I even tried at 150mm/min and it worked but I had to help feeding my extruder with my hand. Gee there is a lot of pressure going down that hotend.

Anyway after all that I still think this design is ok.
I will update my mods soon. Basically it is a flange below the PTFE, and some minor adjustments. The ptfe was starting to eject from the pipe at high speeds.

Again I do apologise for any inconveniance.

Kind Regards
Jan

In my experience the PTFE must be totally enclosed at both ends. Otherwise it just gets longer and thinner and lets go eventually.

---

[www.hydraraptor.blogspot.com]

well my first attempt at making a hotend was a partial success, though it failed at the pfte-barrel join.
used the same method Iceman uses here, but it extruded itself.

I was using an 8mm rod (though would have been more 7.something after I'd filed the thread off it and put groves in it) going into a 20mm PTFE
I used a 5mm hole and hammered the two parts into each other, then used a hose clamp.
I'm wondering if because the 20mm ptfe is a little bigger the hoseclamp is not pushing it into the grooved barrel enough.
maybe I should have heated it up then tightened it again.

another mistake I made, is I think the thermistor is a little close to the element.
the thing extruded ok, but when I started printing, I may have been too close to the bed, pressure built up inside the barrel, it then extruded itself.

I did also try the threaded way + hoseclamp, but found it was way too easy to screw up either by screwing the tap too far in, and ruining the thread, or screwing the barrel in too far and ruining the hotend. (heh pun not intended)

I'm thinking I'll try Icemans way again, but put barrel into the ptfe, screw the crown nut on, then wrap the nicrome/apply the fireplace cement - should be way easier than attempting to put the barrel into the ptfe AFTER I've got a delicate fireplace cemented element on it.

also wondering if maybe a 3mm screw through the ptfe and into one of the groves in the barrel would be a good idea.

Hi se5a,
I am not surprised it did not work. 20mm ptfe is way too big, 10mm is what I use. With 20mm there is way too much PTFE between the brass nozzle and the outside of the PTFE. It goes soft and there will be no grip.
I am still using my hot end, not failed once on me, but remember I dont print at the speeds "normal" printers do. Threaded rods makes it slow.
If you are going to use my method I strongly recommend using the materials I specify. The PTFE is pressed really hard between the copper pipe and the nozzle. Very little room for it to go soft.

Regards
Jan
MySite