Help a newbie with a small part, tweaking settings and merging objects

[jade_thib76]

Ok, so I’ve been hacking away at a small project. I found a print I liked of a microscope pen holder. I work at a lab job where I use a microscope all day, and we use a special pen to dot our slides - so I wanted to modify this pen holder because it’s designed for like a ball point, where you can just let the pen slide through the “eyepiece” and rest on the “stage”. But I wanted to make it so that we could “cap” our dotting pens into the eyepiece and the eyepiece itself would be the pen’s cap. So it needs to be a pretty precise fit because they are felt tipped pins and they will dry out exposed to air. I’ve got it pretty well designed, though it’s an absolute hack job because I don’t have any cad software (or the knowledge of how to use them) and there are a few issues.

So, I found a pen cap that works well for the actual pen tip, its got a “cone” tapered tip that pretty much mirrors the pen’s original cop, it tapers down nice and small so the least amount of air is touching the tip. Then I basically made a slightly larger cylinder for past the tip until the pen’s larger circumference, and then that is attached to a slightly larger cylinder that holds this whole eyepiece in the microscope itself. This has a pretty tight tolerance so it stays in the microscope when you take the pen in and out.

At this point I’m giving lots of verbal detail, but I’ll now post pictures so it makes sense. Here is the whole print. (used transparent PLA here when getting the tip just right)

Here’s the “eyepiece pen cap” by itself (ignore the funky colors, it will be black)

My issue is finding the right combination of settings for the pen cap. It’s extremely thin in the middle section, so I understand why it has issues, and as the cap gets narrower basically it’s kind of printing in “mid air” and doesn’t have something underneath it to connect to, but I need the cap to get narrower.

Like I said it’s a hack job, and there are issues with the pieces “connecting “ to each other. If I do “classic” walls, I have to print it at 50% speed - which is fine I guess, but I also don’t like that you can’t really tell it to print at 50%, you have to wait for it to start and then go to the printer and I change it to silent mode. If I don’t change it to half speed it will likely mess up at the parts where the cylinder gets narrower.

I found that if I do Arachne walls I can print it at full speed, but then the pieces want to separate with little force.

I’m also finding that I’m getting this webbing inside where the pieces are joined.

I have the pieces merged and did the boolean thing, they are one piece in the slicer, but they still get funny where the connect. I’ve even tried to overlap the pieces a bit more, so it’s not just “right on top” of each other.

I’m uploading the 3mf too. I’d love some help, I want to create one of these for all my coworkers but I need to get the pen caps just right. Like I said the diameter of it all is perfect/ it fits the pen like a glove, it just has some leftover issues. There’s other parts on the plate but those are seeming ok, though some of the settings I’ve played with then might make the other parts not print as well …there’s another skinnier cylinder piece (makes the focus knobs for the scope) that seems to prefer being printed at regular speed. So many variables! I’ve done a bunch of googling and changed random things, but finding out that too many changes just makes you crazy. Perhaps someone can help me with something basic that I just don’t know about. Like I said Arachne walls seemed to help but caused another problem.

Using black basic PLA.

Here’s the .3mf

Microscope Pen Holder Mine upload.3mf (295.5 KB)

[MalcTheOracle]

I just noticed this before I try to sleep (it is 6:24am here).

My guess is your nib point is flat rather than a perfect cone. Thus cause the perennial problem that it prints in the air with nothing to support it.

I also note the external shake has changes in diameter that are not tapered to the next reduction.

You have choices:

1. Print in the same orientation but design the tip point to be a cone, just extend up from where it currently is by removing a cone with a starting diameter of the existing tip diameter and an end diameter of zero.

   This should form a suitable flat point where no material will fall or disconnect.

2. Print it in the same orientation but add supports.

   This will require no design changes, but may leave the very tip with support stick in it that cannot easily be removed due to where it is.

3. Print it upside down with supports.

   This will deal with the stepped external diameters and make the printing of the negative space easy.

4. Print upside down and slightly taper the stepped diameters to make the, printable without supports.

   This will make it easy to print and not require any supports. The model will be clean and easy to print as nothing is printed in the air.

---

Always consider printing things upside down when you have a problem print as thus often presents simpler answers.

If this doesn’t work I will look at the file when I wake.

[jade_thib76]

@MalcTheOracle

Print in the same orientation but design the tip point to be a cone…

Thanks for your reply! The top skinniest tip is actually my least problematic area. It is a nice cone inside that pretty perfectly mirrors my pen tip, and it prints well. In fact I’m at the point now where my only issues are right at the specific parts where the layers change into the skinnier cylinder. Is there a way to slow down to 50% but ONLY on a specific portion of a specific part? I know I can do a modifier, and have it change the speed exactly where I want it, but the problem is you can’t do a modifier that simply says “perform silent settings” - you have to create the modifier, and then you have to change ALLLLL those speed settings one by one, and as far as I have searched, I don’t know what the “DEFAULT” is for all of those values to 50% them. And for that matter, if those values are available somewhere, do we know that the Bambu silent mode literally halves the speed of everything? Am I making sense? lol I know I can also do the M220 S50 code thing at the layers I want, but my print contains another part that prints better at full speed.

[RocketSled]

If the thinnest section is less than 3 walls thick, you will never be able to successfully print it so it’s strong enough not to break the first time someone pulls a little sideways on the pen when removing it from the holder. FDM 3D prints are “anisotropic”, they are not as strong in Z as they are in XY.

I would make the hole in the base that accepts the cap a bit bigger in diameter, and then I’d increase the OD of the cap to use that additional space, so that the cap has much thicker walls but that thickness is achieved on the outside so the pen still fits on the inside.

Also, I’d get rid of the stepped taper on the cap, so that it’s just a smooth cylinder. You can glue it in to the holder, or add a simpler feature to “lock it” in place when inserted. But making this change would allow you to print the cap upside down from the current orientation and that would solve the internal “air print” problem you’re having.

[MalcTheOracle]

There is a way to change speed (or any settings) at one or more sections of height, but, the easy percentage speed option is only available on the printer of device tab of Bambu Studio, not prior to slicing.

• Select the Prepare Tab
• Select the model (or part)
• Right-click it (get the context menu)
• Select Layer Height Modifier
• The object list should now be selected, if not, select that option
• Under the selected model you will see a ‘Layers’ child option, select it if not already selected
• At the bottom of the screen you have a from and to text box set and a plus and minus pair of buttons
• If you only need one region, you do not need to add another
• Set the from and to boxes in millimetres
• Once set, you get a new entry under Layers child object for that range, select it
• You now get a set of parameters you can tweak for just that range.

You can also set the colour for the whole range by selecting the swatch to the right of each range.