Advice on conversion to 1.75mm

I am in the planning stages of converting my printer to work with 1.75mm filament instead of 3mm. I looked into just refitting my J-head with a new PTFE liner, but found that wasn't feasible. So now I'm looking into replacing the entire hotend. So that opens up the options quite a bit.

First, I need to decide on the hotend itself. I kind of like the J-heads. They've been very reliable for me and their cost is very reasonable. I'm reading a lot about the E3D, though. Early on I seem to recall people having issues with it, but it seems they might have addressed most of them. Does anybody have any recommendations in this regard?

The second item I need to decide on is Bowden or direct drive. I tried a bowden setup with the 3mm filament, and it was a complete failure - I would stop the extruder, and plastic would continue to come out under force for 5 or more seconds. And then when I would start the extruder, it would take too long before the plastic would start extruding again. There was no way to offset that with retraction. It left a bad taste in my mouth. I've read since that people have had more success with a bowden setup with 1.75mm filament. I like the idea of Bowden because it would lighten up my X carriage considerably. I just dont want to start down that road only to abandon it. The Bowden decision will also affect the hotend decision because some hot-ends - like the E3D - come setup for bowden drive. So my question is this: Is bowden inherently better with 1.75mm? Are there stories of failure with respect to bowden and 1.75mm?

Thanks

I was thinking to convert my i3 to use Bowden,but I did not do it because the Y-axis still anyway has it's weight and speed limit. Why then 1.75mm? I thought that 3mm is better with flexible filaments?

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I don't know about the availability of flexible filaments, but look at filament vendors such as justpla and even monoprice. There appears to be a much wider variety of colors available in 1.75.

It's possible someone could convince me I'm wrong in this, but it seems to me as if 1.75 is the direction things seem to be moving.

It's leaning toward 1.75 but you can still get good prints from 3.0. I think the color choice is a vendor specfic issue. I just changed the machines in the farm to E3D. I'd used the v4 and v5 and had issues with low temp plastics. The V6 is much better in that regard though I still had to work through issues. The primary issue is the heater block getting loose after the first few kg of material. After a kg or so I remove the hotend from the mount, heat it up and retighten.

I like the real JHead. I also just started using Genie with the Smartrap kits and those are nice as well. I went from a JHead to the E3D because I wanted to have the flexibility to use high temp material on any machine. I'd been using an original i3 single plate (more than 2 years old...) with a Prusa v1 nozzle for high temp material.

The temp profiles may change, most all of mine did. The part that took the most time was reslicing all the files for the new setup. I have MM2s and i3s and have to slice them differently. The main advantage I see with the 1.75 material is a more granular control of the temps. With the larger material I could change 5* and barely see a difference. Now that's a big change. On some of the profiles I've had to reduce the temps by 5* or so. Mechanically adding the fan was easy. On Rambo I did an auto fan code in Marlin and on RAMPS I just plugged it in with the main rail. You could use the 12 volt aux on the RAMPS but I use mine for the stepper driver fans. The mechanical issue I had with the MM2s is that the Maxstruder lower guide isn't snug enough for an E3D. It needs to be shimmed, which is less than elegant, or it needs to have a thicker lower guide. Ohmeye has a thicker guide as well as another chap from the MTW IRC channel and they work well.

Going from JHead to JHead will require less tweaking. (I used a 1.75 JHead for the initial testing before the change). Going from JHead to E3D will require more tweaking and some hardware implementation for the fan. A fan on the heat sink with the shround E3D provides is a must. On the first test on one of the i3 Reworks I used the stock Rework fan shroud. The nozzle jammed about 5 mins into it. I put the E3D shroud on and though one of them has jammed twice, it works on the other machines. I wouldn't change both the hot end and the extruder at the same time, though. Learning a Bowden is tweaky and if you aren't familiar with the hot end and try to change that's a recipe for disaster. The 3 mm isn't a good Bowden choice and it can be difficult enough to master with 1.75 at first particularly the retraction. I'd wait on the Bowden until you get to a point you are comfortable with the 1.75 and know how it works.

vegasloki - Thanks for all of the information. You were pretty thorough with your advice.

I realize you can get good results with 3mm; I do so now. I just think 1.75 is a better choice right now.

I've been leaning towards the J head (and I would ONLY use a J head form hotends.com). It's hard to tell from the pictures I see, but it seems as if the e3d uses more vertical space than the J head; I don't want to lose any height in my print envelope.

I appreciate the advice regarding waiting on the bowden - It's probably a good ides to only change one thing at a time.

Since I've posted I'm swapping out the E3D on the production MM2s. Two more have jammed since then.

Unless you are buy them in resale batches Brian usually has them on his site. If he's out he'll post a batch on Fri morning PA time. The only thing I don't like about them is the polyimide tape attachement. I kept threatening to drill and tap small holes for mounting (which is one area the E3D excels over others). JGR's Aluhead works well too.And the Genie.

There is a difference in usable height. I'm not too concerned as these particular machine print printer parts so Z envelope isn't an issue for me. It's about 10 mm less Z with the E3D v6 compared to the JHead MK V-BV.

Edited 1 time(s). Last edit at 01/19/2015 03:47AM by vegasloki.

as a bowdenhot end i can recoment the repparpro one it's cheap also