Aligning models to print dual color

[Chub]

I have 2 STL files that were made from each other. I created an extrude and then added a text cut. I then copied the text sketch and created as a new part. When I make an assembly of the two parts to verify alignment, all is good. When I drop them on the build plate and merge (doesn't matter software) they do not align. I know this isn't a printer question but would appreciate some help. I even used the same face and origin in the SolidWorks part files. This has worked in the past but can no longer get them to align

Thanks for any help

[TMeeks]

In most slicers, when a second part is dropped onto the printer plate, the first is repositioned out of the way before the second is laid down. This is normal.

But, a second step is usually available that repositions both parts to their originally design position. So, without knowing what slicer you are trying to use, we can't help you with that second step.

[Chub]

I am currently using Cura, but have tried others. I have actually been successful in the overlaying on other parts. I wanted to tweak them so I ended up overwriting because I thought I knew how to do it. Apparently I am not sure what really aligns them to be merged.
I thought they went by origin. I have tried to create just a circular slug on the front plane, cut another circle into it .100". All based off the origin in SOLIDWORKS. I then made a new part that was round and matched the exact cut geometry of the slug. Drop them into Cura, highlighted them both and merged. The merge happens but they don't align. See images.

Any suggestions would be greatly appreciated.

[TMeeks]

I will be gone most of this weekend. But, your topic is an important one because it has to do with an entire workflow, beginning with design and ending with the slicer.

We have been printing with 2, 3 or full-color for some years and each printer and slicer used a slightly different strategy. The strategy used by Cura is using a separate STL for each color. Other slicers, proprietary to the printer, allowed us to create STLs from non-joined parts and click on the parts to select the nozzle color to use. Voxelizer is a newer slicer and can even use material overlays, which is going to be very helpful.

When I get back Sunday evening I will create a short video showing how I would do two color using Cura. I don't have enough experience with the 2-color head of the Geeetech to know how well it deals with parts + water or alcohol soluable supports; but, I will also create a video demonstrating, in theory, how that should work.

All next week I will be exploring the A20M and anything I find should easily translate to the A10M. I will also begin exploring QuadFusion (4 color) strategies using a printer very similar to the Geeetech i3 concept; but, using the Maestro control board. Again, even though it is a completely different brand, the concepts, like mixing, should be helpful across all mixing heads.

I have created a Dropbox Folder for all my A10M and A20M test files. Attached is an image on the first dual print test, you can find the STL files here: https://www.dropbox.com/sh/oxeh08kx01s1 ... -aoya?dl=0

Hope this is helpful.

[Chub]

Your models merge perfectly. It appears that they were created with a center rectangle feature since the origin is at the center for each. I tried creating 2 squares with the center at the origin. When Cura merges them it mates the bottom left corners. When I create simple cylinders, it merges them off center from each other and keeps them both on the plate.
I made a plane on the same level as the face I want to merge them too and it still puts them off center. This doesn't make sense because I had one model (which like an idiot I overwrote) where one model was crated like 6 inches from the front plane and the other was on the front plane. They both merged perfectly. This is really driving me crazy because it seems so simple.

Another question would be how do I get them to import with the color assigned? Even the models that I downloaded from Tmeeks came in the same color. A Cura setting that I can't find. A true rookie here.

Thanks again

[TMeeks]

I don't believe that they can come in preassigned, unless it is support material.

I'll try some other shapes.

[Chub]

Have I been doing it wrong all this time? I took the hex parts and instead of Merging, I hit "Reset all Model Positions" or "Reset all model Transitions". That snapped them into the desired location. Then I grouped them. I assigned extruder 1 and 2 prior to grouping. Will this get me where I want to be? Small short lived victory. Are you merging parts or using Reset all positions?
Well, except everything seems to have to be on the plate. Even when I have my sketch plane offset to the height that I want the part to come in. No matter what I do, everything stays on the plate. See the pink model with the blue shading.

Thank you
Bound and determined

[Mike_27]

select the models you want to merge
right click
pick merge models
click prepare
choose layer view

see if it worked.

[Chub]

Thank you everyone for the help. My issue wasn't how to merge 2 parts as much as it was getting them to align when they merge. By chance I seen a YouTube video on exactly this. I had a couple Preference setting that were incorrect. Since I wanted one of my parts to not be on the bed, I had to uncheck both AUTOMATICALLY DROP MODEL TO BUILD PLATE and ENSURE PARTS ARE KEPT APART. I think I already had checked slice automatically. Here is what needed to happen: (I also attached a single screen shot that shows examples as I went)
1) drop the first model. Make sure the Z is set to zero because you have now told Cura not to automatically drop to the bed.
2) drop second model.
3) Assign colors/extruder to each part.
4) Right click the second part and select Center Selected Model
5) Now is when you need to know the Z distance the second model is going to be. Enter that in.
6) Control - A to select all models. Then Merge Models. They now become one.

This should do it. I spent a solid week and a lot of hours modeling different shapes and configurations. This process seems to be the fix. If anyone has a better way or see's an error let me know. I will say that at work I use a different slicer and had the same issue. I am concerned there is no Center Models on the Apex slicer. I had early success without changing heights or anything on the Apex software. It was short lived and I am still not sure how I got it to merge. It was my first time trying, so I have since overwritten the model thinking I would be able to do it effortlessly again. No suh luck.