I'm new at 3D Printing. I made a model of what I want to print using blender, but it's really small with a little system that must be very precise to work.

What I have is like a hollow cylinder with a diameter of 11mm, and a thickness of 1mm. This goes inside a counter part, that is carve with the cylinder shape, but with a little extra gap so it can rotate like an axis. Maybe this picture explains better:

enter image description here

And this should be the front view of the counter part:

enter image description here

So, I need to know if it's possible to print that cylinder hard enough to work as an axis. And what should be the gap size between the cylinder and the counter part's hole to rotate properly? If it's is like 0.05mm, can I print that level of detail with a 3D printer too?

What hardware and material should I use to do this?

Thanks in advance. Sorry for bad english, I hope you understand!


enter image description here

(6mm is the depth of the hole)

  • $\begingroup$ The tolarences for a extruder printing might vary from the accuracy of extrusion feed; you can have the values you are expecting, but a gap of 0.05 wont be enough to do a working assembly; in my case I´m using 0.15mm for one printer and 0.3 in other. Remember that is melting feed printing instead an injection molded (more controlled). $\endgroup$ Mar 22 '18 at 2:22
  • $\begingroup$ @FernandoBaltazar I can't add so much gap because I have really limited space. What could be the smallest amount of gap to get a nice rotation? $\endgroup$ Mar 22 '18 at 3:25
  • $\begingroup$ you need to test your printer. If you need to print 3, 5, 8 prints with different gaps to get the best choice then do it. Gaps can be as bigger than the part allows, or as narrow as the mind limits. $\endgroup$ Mar 22 '18 at 5:20
  • $\begingroup$ Do you have to use an extrusion printer? What about one of the light-curing resin layer printers? What's your budget, as spending 10X the money will get you a huge improvement in tolerances. $\endgroup$ Mar 22 '18 at 14:16

It is definitively possible to do what you want, but your questions are samewhat problematic:

So, I need to know if it's possible to print that cylinder hard enough to work as an axis.

"hard enough" is a mysterious quantity. What is the intended application? The load of the axis, the rotation speed, the medium in which the part will be in, its operating temperature... they all affect the answer.

And what should be the gap size between the cylinder and the counter part's hole to rotate properly?

Reading at the question and the comments, I think you may have the wrong representation model in your mind. There are four different concepts at work here:

  • Accuracy is the maximum dimensional variation between parts.
  • Tolerance is the amount of random deviation or variation permitted for a given dimension.
  • Allowance is a planned difference between a nominal or reference value and an exact value.
  • Clearance is the intentional space between two parts.

So: what you want to achieve for the object to rotate is to have at least some clearance once you have the parts printed. Therefore, you want to design your part with an allowance which is at least as much as the accuracy.

Note that a machine cannot produce parts with a tighter tolerance than its accuracy. So you must design your part with a tolerance equal or greater than your printer accuracy.

The correct number will therefore be entirely dependant from the specific printer you will be using. You can find out the specific accuracy of a printer by printing a tolerance test (I know, I know... why isn't it called "accuracy test"?)

See this unrelated answer - from wich I took the above definitions - for learning more about the above and a concrete example.

If it's is like 0.05mm, can I print that level of detail with a 3D printer too?

I hope it is now clear why this question makes no sense: clearance is a variable which depends from accuracy (and the application), not the other way around.

I can't add so much gap because I have really limited space

This comment too is incorrect: the "gap" (clearance) can be very very small. You have to have the correct allowance in your design, and allowance will not intrinsically make a part larger.

What hardware and material should I use to do this?

Again: this is entirely dependent from your application (load, operating temperature, orientation, speed...)

A consumer-grade FDM printer (easy accessible, cheap and cheap to operate) will allow you to print a rotating part, a SLA/DLP printer (less common, toxic resins, more expensive to operate) will allow to print the same part with different materials and tighter tolerances...

I don't worry about breaking, but it cannot be flexible

Again: without an explanaton of the intended use (or the numbers associated to it) it's impossible to answer this comment conclusively. Resins tend to harden to more rigid solids, but you have thrown around tolerances as small as 0.05mm in your writing, and over 12mm of axis, that is a deviation of less than 0.5% from "perfectly straight". I'm hard pressed to think you will find a printable material with such a rigidity.

  • $\begingroup$ First of all, thank you for the proper vocabulary lesson. I don't own a 3D printer, this is my first project. I was looking for some 3D printing service around my region, and found a SLA one, but when I asked them about their machine tolerance, they didn't know what I was talking about. The entire project is a little necklace, with a small system that allow it to rotate and make a new figure. So, about speed: manual rotation; and temperature: environment is fine I guess. It don't have to be "perfectly stright", just enough to keep all together. Should I ask this guys for a tolerance test? $\endgroup$ Mar 23 '18 at 4:25
  • $\begingroup$ @JuliánPera Many 3D printer owners has their own printer like a hobbie to print some stuff and make funny his projects, probably they don´t know about accuracy, tolerances and repeatibility. Why don´t you try to search a profesional printing service giving the specification you need to get. If you are asking a question is because you need to know how accurate can be your printer instead looking for someone do your homework or even playing to be a desing engineer. $\endgroup$ Mar 23 '18 at 5:39
  • $\begingroup$ @JuliánPera - no problem, I learnt the proper English words recently myself. The key is that you get the reasoning, not the words, though! :) Jewelry and dentistry are the typical cases where SLA/DLP are dominating the market: they typically have small volumes and very high accuracy, which is important tr get a fine level of detail. Typically jewelers print with a material called "castable resin", which is a resin that vaporises when touching liquid metal (so you put the print in silicon or other medium, pour liquid metal on top of it and voilá: "3D printed" metal! $\endgroup$
    – mac
    Mar 23 '18 at 6:26
  • $\begingroup$ So my suggestion: reach out to a goldsmith or jeweler that does this kind of stuff and ask if he could print/fabricate the thing with your own design. He will be probably able to guide you through a precise set of restraints for your design (allowances, overhang angles, minimum size of a detail...). $\endgroup$
    – mac
    Mar 23 '18 at 7:06
  • $\begingroup$ "3D printer" metal sounds cool, but expensive too, haha. I'm fine with plastic by now, but cannot find a place that offer the service I need. I was checking some 3d printing service online, like Sculpteo and Materialise, but they offer up to 0.4 of clearence, even using SLA. Am I missing something? Because I was waching people doing Tolerance Tests on Youtube, and they got nice results with 0.1 using FDM. $\endgroup$ Mar 24 '18 at 7:19

It is considered good practice to limit your post to one question at a time. The question about hardware and material is too broad to be a good question and I will set that aside.

Equally unfortunate, your drawing is ambiguous. I suppose if English is not your native language, I'm not helping things either.

The drawing has some errors that make it challenging to be certain of a correct answer, but I can provide you with some useful information as a direct result of a test print created today.

The test print for my printer creates a series of spool shapes within retainer shapes. More complex than a simply cylinder making the test that much more difficult.

My printer is able to print without problem parts that are 1.0 mm apart, 0.8 mm apart and 0.6 mm apart. The test failed at the 0.4 mm spacing and the 0.3 mm spacing, telling me that I need to perform some tuning.

Your question asks about 0.05 mm spacing. I think you will not find an FDM printer that will manage such separation without bonding together the individual components. FDM printers use filament.

You may also not find that an SLA or DLP printer can provide such tight tolerances. It is the most likely source of a success, however. I have only minimal exposure to tolerance in this type of printer. SLA/DLP printers use lasers/light and liquid resin. They can accomplish 0.05 mm layer thickness, even as small as 0.025 mm layers, but I do not know the figures for horizontal precision/accuracy/tolerance.

SLS printers use a nylon powder and a laser to fuse the powder together to form the model. My SLS printer uses 0.050 mm powder. To accomplish the separation you require would mean a single layer of powder will separate the individual segments of the model. This is not practical for this type of printer.

Your best bet would be to consult with a 3D printing service that uses SLA printers. SLA is likely to be more precise than DLP due to the method of exposing the resin, although that is not a universal truth.

  • $\begingroup$ By material and hardware I meant this, what kind of technique should I use, you answered what I wanted. SLA/DLP results are hard enough for 1mm of thickness? The piece must be rigid to work as an axis. I don't worry about breaking, but it cannot be flexible. I updated the original post with a 3D picture, maybe it can orient you better. $\endgroup$ Mar 22 '18 at 3:34
  • $\begingroup$ The updated image is excellent. SLA material, once cured, is quite hard. According to a comprehensive article: formlabs.com/blog/… you may see Shore hardness above 70 in the parts. Strength is subjective, however. SLA is going to be no stronger than any plastic with 1 mm wall. SLA will create well at that resolution. $\endgroup$
    – fred_dot_u
    Mar 22 '18 at 9:56

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