yellowshark

@SandervG Lol you suggested that a year or two back, which I did but it never went anywhere! We have not done much lately. We are engineers and the engineering side is doing well and, for us, is much more interesting that modelling buildings. But always happy to contribute if you/someone in that area gets a sub forum going

A brave man indeed; we are rooting for you.

It is a setting within the Shell settings group, called Z Seam alignment

It could be nothing more than your Cura settings (which we need to see), which affect accuracy. You should be able to hit 20mm with +/- 0.05 tolerance or better with the right settings.

Another complementary solution is to put a chamfer into your corners so it is not a 90 degree bend - of course if you want a 90 degree corner that will not work very well

I think the answer at this stage is to find yourself a Solidworks or Inventor engineer who has experience in designing for injection moulding manufacturing. They can tell you whether your design can be easily made using injection moulding or whether there are some issues, which he can correct. He can also advise you on the easiest way to get your model into the CAD software along with correct dimensions etc. Now that is not easy, indeed possibly impossible. We have imported STEP files into Solidworks but you loose all the dimensions - well at least we did! But your model shows the assembly and whatever software you used to produce it can give you all the dimensions needed. Worst case is that the engineer can redesign it in his software from scratch with your dimensions and produce a no doubt modified file for the manufacturer. It is impossible to say how much time would be needed without a view of the model but to give you an idea we would charge £120 for the first 4 hours and then £175 a day thereafter. We are no use to you, wherever you live (bring back the old forum!) as whilst we design and prototype for injection moulding we are not experts in injection moulding design considerations. Also not to forget that no doubt some injection moulders will have this expertise anyway ad so you could go direct to them.

Hi, we do architecture too, although not as intensely as you clearly do. Firstly some observations. I think your layer height of .200 is a good compromise, that is what we use for architecture normally. For your current settings I think you are too hot. With .4 nozzle .200 layers and 20mm/s we would be below 200; of course filament and your printer will affect this but likely to be within 5 degrees. Going cooler will probably improve your quality that you experienced with the previous models. 0.8mm for top layers is too marginal for 15% infill. Take it to at least 1.2mm. If we use infill it is normally 40% or greater and we use 1.0mm minimum for top layers. 15% infill needs more unless it is a very small model. This building was printed with .200 layers at 30mm/s and temp of 200. Size is 257mm x 145mm x58mm with a total print time of around 35 hours if I remember correctly. Things to try. 1. Do you actually need infill? – you seem not to have open windows so people cannot see inside. If you have a flat roof then either print it separately or print as many top layers as you need to get a decent finish. We never print infill in our buildings. 2. White is the worst colour; if it is possible use a different colour which will give you a better finish and so perhaps let your print faster (yes I know white is popular in modern architecture!) 3. Are you using Cura 2.n or 3.n? They have an increasing number of tuning options. Go for a faster speed and try some of them to see if you can recapture the quality. 4. Set all your print speeds the same, except 1st layer and travel. And do not forget that with all other things being equal, speed is the enemy of quality .

Hi @Bossler, OK I get your point about setting the raft air gap to 0. I still do not see the point about printing PLA on a raft rather than on the bed; unless of course you need to do that because the bed is in such a poor state that one needs to put plastic down to create a “smooth” base for the model to print on?; if it were that bad I would buy a new bed, in reality a new plate. The important point to make is that it is not accurate to say that the z-gap is not set in Cura; sure it does not have to be set in Cura but it can be, I do and IMHO it is a better method. One can be more accurate; even a difference of 20 microns but certainly 40 microns will move you from optimum distance to sub optimum distance, try getting that accuracy with your finger and thumb. It does not affect your bed level; one is not turning 3 knobs imprecisely the same distance; if they are not the same, one spoils the bed level. Of course all this is after setting the bed level manually which sets the distance hopefully reasonably close to the optimum - except one can see it does not do that consistently when one sees pictures posted on the forum by people with adhesion problems. The alternative method to tuning with z-offset is to tune the distance on the fly, which a lot of people like and I have used. I.E. start a print, preferably with a skirt and adjust the distance with the screws so you can see visually the exact pressure you are inducing. With some practice it is pretty easy to get it done accurately and I am sure quickly for those who are good at it. As an ex IT guy I guess I just lean towards using code rather than manual process for rigour and repeatability .

Copying @SandervG will make sure it comes to the attention of the developers although someone is normally watching.

Hi I have never printed a raft before so I am limited in what I can say. I assume the light blue area is the raft, which seems to have stuck to the bed well, in which case I would not worry about the z-gap as that affects the adhesion of the first printed layer. @Bossler is correct it is one of the keys to getting good adhesion. No it is not the same as Raft air gap, although I am not sure what that is!, it is the distance between the bed and the nozzle at rest and modifying that can fine tune your first layer to get it sticking like a limpet. It is actually very easy to tune in cura by using a z-offset command. It is also pretty easy to tune manually although personally I always use the z-offset. I am not sure why one would want to use this Raft air gap thing. That infers to me that you leave a small gap between the raft and the first model layer? That can only screw up your adhesion I would have thought. The first thing I would do is set that to ZERO and see what happens; BUT to reiterate I know nothing about rafts, just trying to use some common sense and leaving a gap between two layes of plastic is not going to enhance adhesion.

I know what you mean; I limit myself to 50m lengths and always totally unwind, carefully making sure there is not a twist in it and then wind it up again using big loops before laying it on the floor.

I had a similar problem in my early days, I would not have known how to decode g-code back then, but yours is very random whereas as mine was consistent. I was printing architecture and every time I jumped across a window the resumed printing would produce an effect like yours; with the smaller models normally right across the front face (4 windows) until it settled down on the side walls (no windows). The areas below/above the windows were perfect. I resolved it in the end by slowing the print speed - whether or not I also played with retraction settings I do not recall.

I manually start my print bed heating; when 5 degrees from target I start my extruder heating; when target reached and stabilised I run my g-code, can you not do that on your printer?

Great you fixed it - I was going to say and I still will, for your benefit. I have been using Solidworks to model and create stl files for over 4 years now and have NEVER had a faulty stl file produced. As they say you get what you pay for.

OK I get it, good idea and a nice setup you have there. Probably because of that reason and that I cannot locate the filament underneath or behind (using your method) the printer I nearly always buy loose filament because it does not have as a tight a curvature as spooled filament and so takes the 90 degree turn into the Bowden tube without giving problems.

.... of course Cura 3 may have disposed of skirts out of fear of sexual harassment charges but it is good discipline for all the obvious reasons. I do admit I do not print one if I am using a brim but if the brim is big enough it serves the same purpose.

Not having a UM3 I am not sure what this prime blob is but I would think that printing a skirt would resolve the problem of it getting dragged in the build area.

Hi @ahoeben I should add an important point. My memory is vague but when 2 came out a multi extruder printer could not print one at a time; or it may be that no-one could print one at a time. There were a number of people in the same position and there was a dialogue here which included several Ultimaker people. We were told that it would happen in a future release. I like to think that also included dual extruder printers. I cannot be sure without going back and trying to find the thread but all I can say is that I suspect that I would have changed to S3D if that assurance had not been given for dual extruder printers - as I said it is possible that I am wrong. I put this here as I feel a bit uncomfortable having done this by only using Cura 2.4 menus but you have used the phrase "not supported", although I am not sure what that phrase is referring to - presumably not to something that one can do 100% with Cura? cc @SandervG

Thanks for that @ahoeben. I have not personally created a json file. I just used the Cura menu structure and data items to add my custom printer to Cura. I am not sure how to interpret your first sentence. I just used the special modes/print sequence setting in Cura the same as everyone else has to to print in multi model mode - i.e. to ensure that whichever of the two modes available is set to the one you want. All I am trying to say is that I have done nothing techie or secret to achieve this. I have just come along as a dumb user and selected the options that Cura provides

Fair enough on 15.06 & 15.10, I only used up to 15.04.06. I have just loaded 2.4 and set it up to print one at a time with a multi extruder on a custom printer and everything is fine. The layer no. in the display is 73 and the first 3 copies are "printed" whilst the 4th is part way through. Each model is 20 layers so 80 layers in total. Pic here err no it is not I cannot see anyway of uploading to the gallery/attachments

Hmn maybe we are both right! I confess I have never issued a G92 without a parameter, no idea what that does. I always issue a G92 with a Z parameter from my startup g-code to get the bed to nozzle distance right. I level without the glass plate in place and so if the G92 did not change the Z position there would be a big crash

Lol a man with my type of brain

Err, it WAS supported. If I remember rightly when the 1st release of the new software was released, i.e. following 1.5.something, it disappeared but I am sure it was subsequently re-instated. This may all have been before UM produced a dual extruder printer2.0 was released. I have always had a dual extrusion non UM printer and so have always had a custom definition with dual extruders that I can print one at a time with. Now, currently on 2.4, it has been quite a long time since I have printed with multiple models on the bed and it may be that it has disappeared again and I have not spotted it. It was about 10 months ago when I last used it and not sure if I was on 2.4 at that time or an earlier version.

Off at tangent maybe @kmanstudios but why is the Cura line width default 0.35. I always thought that a nozzle with a 0.40 opening always printed a line with a width of 0.40? Anyway as an Englishman I have always used line width of 0.40 and got excellent dimensional accuracy and strong models. Double lol,maybe that is why our Dutch friends keep having to put their fingers in the dykes.