Expected print speed for Diamond Hotend

Whilst the Diamond Hotend has lots of promise, the force required by the extruders is extreme such the fastest feed rate is around the 12mm/s.

What feed rate should I get?

How critical is the quality of PLA? Should I use ABS?

There are no jams as such, such the viscosity of the melted filament seems so high to limit feed so I either get slip or the filament buckles between the bowden and the traction gear wheel.

Any hints or steers would be appreciated.

Edited 1 time(s). Last edit at 05/24/2017 06:33PM by Mikexx.

I found filament temp was critical with the Diamond. A light breeze from the part cooler and the extruders started skipping.
I then insulated the cone with cotton wool pads and Kapton tape, but it is difficult to make it stay in place. I glued the cotton wool to the hotend with silicone, but the pad fell apart after some weeks.
A silicone hood might be the best option.

Quote
o_lampe
I found filament temp was critical with the Diamond. A light breeze from the part cooler and the extruders started skipping.
I then insulated the cone with cotton wool pads and Kapton tape, but it is difficult to make it stay in place. I glued the cotton wool to the hotend with silicone, but the pad fell apart after some weeks.
A silicone hood might be the best option.

I appreciate the suggestion. The printer is in a place where there should be little draft. Any breeze would be from me walking past the machine.

What sort of print rate do you achieve?

The temperature sensor is fitted into a tube to one side of the heater. Given the small size and good temperature control, I might be surprised to hear that the print head wouldn't be a uniform temperature although it is making me wonder given the aspect ratio of the tip. But other printheads have the same aspect/taper and can still print at 50 - 100 mm/s.

12mm/sec extrusion rate is pretty dammed good. If you are trying to push filament through that fast, no wonder the force is high.

Assuming 1.75mm diameter filament the area is about 2.4 mm^2 so at 12mm / sec that's around 28.9 mm^3 per sec. The best you could hope for on something like an E3D V6 is about 15 mm^3/sec and on a volcano it's about 40 mm^3/sec. So your getting almost twice what a standard E3D V6 can give but slightly more than half what volcano would give you.

My maths may be a little off but if you have a 0.4mm nozzle, the area is about 0.12mm^2. If you use a layer height of 0.3mm then the volume of the filament bead is about 0.036mm^3 so if can melt it at 28.9mm^3/sec then you could theoretically print at (28.9/0.036) = 802mm/sec.

So with "normal" feedrates of around 5 to 7 mm/sec you'll still be good for 100mm/s plus (depending on you nozzle size and layer height). I get best results with PLA at 190 deg C which I know is at the low end, but happily print all day long at 90mm/sec. Oh, and I open up my nozzles to 0.5mm. That might not sound a lot from 0.4mm diameter to 0.5mm but it equate to about 58% bigger area. So if my maximum print speed is 90 mm/sec, then a 0.4mm diameter nozzle should be good for 135 mm/sec @0.3mm layer height.

HTH
Ian

---

[somei3deas.wordpress.com]
[www.youtube.com]

Quote
deckingman
12mm/sec extrusion rate is pretty dammed good. If you are trying to push filament through that fast, no wonder the force is high.

Assuming 1.75mm diameter filament the area is about 2.4 mm^2 so at 12mm / sec that's around 28.9 mm^3 per sec. The best you could hope for on something like an E3D V6 is about 15 mm^3/sec and on a volcano it's about 40 mm^3/sec. So your getting almost twice what a standard E3D V6 can give but slightly more than half what volcano would give you.

My maths may be a little off but if you have a 0.4mm nozzle, the area is about 0.12mm^2. If you use a layer height of 0.3mm then the volume of the filament bead is about 0.036mm^3 so if can melt it at 28.9mm^3/sec then you could theoretically print at (28.9/0.036) = 802mm/sec.

So with "normal" feedrates of around 5 to 7 mm/sec you'll still be good for 100mm/s plus (depending on you nozzle size and layer height). I get best results with PLA at 190 deg C which I know is at the low end, but happily print all day long at 90mm/sec. Oh, and I open up my nozzles to 0.5mm. That might not sound a lot from 0.4mm diameter to 0.5mm but it equate to about 58% bigger area. So if my maximum print speed is 90 mm/sec, then a 0.4mm diameter nozzle should be good for 135 mm/sec @0.3mm layer height.

HTH
Ian

I am talking of a print speed of 12mm/sec and not extruder speed. Your calculations suggest my extruder speed of 1/20, ie 0.6mm/s which seems about right.

I find it worrying you suggest I should be getting at least 10 times this print speed.

Oh sorry, but you did say feed rate which implies filament feed rate not print speed. Also, that is so slow that I was assuming you meant extrusion speed.

In that case, you have something very seriously wrong. A partial blockage is the usual culprit. Do you get the same with all 3 inputs? I've only ever had this happen once, just after I assembled a new one. The fix for me was to heat the hot end, then holding a 0.4mm drill bit in a pin chuck, poke it up the nozzle towards each of the three heat sinks. If you are careful, you'll be able to locate and probe all three holes. You'll need to keep removing filament from the drill bit as it'll set. Of course, it doesn't need to be a drill bit - some other 0.4mm diamater wire would work too.

---

[somei3deas.wordpress.com]
[www.youtube.com]

Quote
deckingman
Oh sorry, but you did say feed rate which implies filament feed rate not print speed. Also, that is so slow that I was assuming you meant extrusion speed.

In that case, you have something very seriously wrong. A partial blockage is the usual culprit. Do you get the same with all 3 inputs? I've only ever had this happen once, just after I assembled a new one. The fix for me was to heat the hot end, then holding a 0.4mm drill bit in a pin chuck, poke it up the nozzle towards each of the three heat sinks. If you are careful, you'll be able to locate and probe all three holes. You'll need to keep removing filament from the drill bit as it'll set. Of course, it doesn't need to be a drill bit - some other 0.4mm diamater wire would work too.

Thanks, I'm fairly new with all this and I find some of the terminology not so obvious!

In the end I dismantled the whole thing, cleared the heatsinks and dipped the hotend itself into some dichloromethane which after an day of soaking has completely cleared all of the PLA. I can see light at the end of all 3 holes!

The hole looks smaller than 0.4mm and I have access to pin-drills which I intend to use to better gauge the actual hole sizes.

If I use a 0.4mm drill to probe all 3 holes and break through, won't this enlarge the exit hole due to the angle of the 3 holes to the vertical?

What sort of print speed do you get with yours, what sort of speed should I expect?

Many thanks again.

I only had a Diamond hotend on my Delta, because I thought it was a good combination. But the weight of the hotend and the achievable speed ( IIRC 40-50mm/s ) didn't work out well. The speed was limited by ringing/ghosting and extruders slipping at the same time.
On a rigid printer and with geared extruder motors, the achievable speed would be higher.

Edited 1 time(s). Last edit at 05/29/2017 01:59AM by o_lampe.

Quote
Mikexx

Quote
deckingman
Oh sorry, but you did say feed rate which implies filament feed rate not print speed. Also, that is so slow that I was assuming you meant extrusion speed.

In that case, you have something very seriously wrong. A partial blockage is the usual culprit. Do you get the same with all 3 inputs? I've only ever had this happen once, just after I assembled a new one. The fix for me was to heat the hot end, then holding a 0.4mm drill bit in a pin chuck, poke it up the nozzle towards each of the three heat sinks. If you are careful, you'll be able to locate and probe all three holes. You'll need to keep removing filament from the drill bit as it'll set. Of course, it doesn't need to be a drill bit - some other 0.4mm diamater wire would work too.

Thanks, I'm fairly new with all this and I find some of the terminology not so obvious!

In the end I dismantled the whole thing, cleared the heatsinks and dipped the hotend itself into some dichloromethane which after an day of soaking has completely cleared all of the PLA. I can see light at the end of all 3 holes!

The hole looks smaller than 0.4mm and I have access to pin-drills which I intend to use to better gauge the actual hole sizes.

If I use a 0.4mm drill to probe all 3 holes and break through, won't this enlarge the exit hole due to the angle of the 3 holes to the vertical?

What sort of print speed do you get with yours, what sort of speed should I expect?

Many thanks again.

Sorry, I was forgetting that I enlarge my nozzles to 0.5mm at the tip. If you are worried about enlarging the tip, use a 0.3mm bit or just <0.4mm wire. I also forgot to mention that you need to do this with nozzle heated. However, as you have disassembled and cleaned it, none of that may be necessary.

I've just put a post on my blog showing how I assemble the hot ends. My method is a little different from the RepRap.me method. You can read it here [somei3deas.wordpress.com]

Print speed for me is about 90mm/sec max for PLA @195 deg C. Anything faster and the extruders start to struggle because that's as fast as the filament will melt. There are a few videos on my YouTube channel, which you can view here [www.youtube.com]

HTH
Ian

---

[somei3deas.wordpress.com]
[www.youtube.com]