Tinker CAD

[Brian Higgins]

Frustrated!
I keep trying to print a axel Circular shaft with my Dremel 3D45, the circle keeps coming out oval!
It takes five prints before I get any thing close.
Aaahhhh!!!!
Brian Higgins
VA Researcher for blind mobility “Laser enhanced Echolocation” ClearPath Navigation


Sent from my iPhone

[Chris Albertson]

What a lot of people do is print a 25mm cube, then measure it. Use the size error to calculate a calibration constant. for X, Y, and Z axes. But be warned, the calibration might change for large and for small objects and be different from different kinds of plastics and different temperatures.

For shafts, I use metal, take an 6mm metal rod and press-fit it into an 6mm hole. Or press-fit a ball bearing unit into a larger hole then place the metral shaft through the bearing.

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[Brian Higgins]

Thanks good info

Brian Higgins
VA Researcher for blind mobility “Laser enhanced Echolocation” ClearPath Navigation


Sent from my iPhone

> On Aug 16, 2025, at 3:36 PM, Chris Albertson <alberts...@gmail.com> wrote:
>
> What a lot of people do is print a 25mm cube, then measure it. Use the size error to calculate a calibration constant. for X, Y, and Z axes. But be warned, the calibration might change for large and for small objects and be different from different kinds of plastics and different temperatures.

> To view this discussion visit https://groups.google.com/d/msgid/hbrobotics/3F254509-53AB-456E-8B61-A4B1B73AD218%40gmail.com.

[Rafael Skodlar]

Brian,

Resizing the model might be your problem. This happens when one of the
axes is not selected when you are resizing the part. Assuming you
build the shaft along the Z axis, X and Y should be resized equally
for the circle. You can tell if the part is going to be circular on
the first layer. Check the layers in your slicer program especially if
you resized the model.

Another possibility is some kind of drag or motor step skipping on the
CNC machine in one axis.

That 3D printer was made by Flashforge I believe. The worst 3DP design
I've seen and repaired over the years.

CNC machines that build parts with stacking plastic in layers are not
printers! They are 3D plotters!!!

As Chris has said, it's better to use metal shafts in most cases.

Rafael

[Brian Higgins]

I think once it has become oval you have to delete it and start oval. I had a horizontal shaft for the wheels and a vertical shaft to go into the handle.

Brian Higgins
VA Researcher for blind mobility “Laser enhanced Echolocation” ClearPath Navigation


Sent from my iPhone

> On Aug 17, 2025, at 1:51 AM, Rafael Skodlar <kc6...@gmail.com> wrote:
>
> Brian,

> To view this discussion visit https://groups.google.com/d/msgid/hbrobotics/CAB4wyt1M3zogqS_wPXvqUHH%2BAazhTd1jwUUa_z_k7fATGi5S8g%40mail.gmail.com.

[Chris Albertson]

You might be overthinking this. The answer might be as simple as “crappy printer”.

You do everything just right and still the printer is just not the precision device you hoped it would be. The solution is to measure the error and then apply compensation in the slicer

I have been very impressed with my Voron 0.2 printer. The build volume is tiny but the printer is very fast and accurate. It works best with ABS plastic.

But even with a good printer, you just can not expect high precision. Tolerances on the 0.1mm range are considered “very good”. If you need better precision and strength, CNC metal is the way to go. Igt is unlikey that you could print every part you would need for a non-trivial robot., You'd need some metal and ball bearings

[Corey McGuire]

When you scale in tinkercad, make sure to hold the modifier key (Don't remember which, also don't know your OS) which allows you to scale uniformly.  Hold the key (Alt, Shift, Ctl, Option, Other Apple button... I still call them "Open Apple" and "Closed Apple") and then drag the handle.  This means when you tug on one of the scale handles, X, Y, and Z will scale uniformly.  You may not WANT all to scale...BUT... better to have the two axes you WANT to scale uniformly and have to adjust the third again than to make an oval.

On Sat, Aug 16, 2025 at 11:35 AM Brian Higgins <blind...@gmail.com> wrote:

[Brian Higgins]

I think what the issue is, in TinkerCAD on my laptop using my iPhone mobile hot spot I can create the initial sketch but can’t make alterations or change dimensions. So I have to get the size and shape the very first time.

Brian Higgins

VA Researcher for blind mobility “Laser enhanced Echolocation” ClearPath Navigation 

Sent from my iPhone

On Aug 18, 2025, at 3:49 AM, Corey McGuire <core...@coreyfro.com> wrote:



To view this discussion visit https://groups.google.com/d/msgid/hbrobotics/CAPyZGSWW4zo0Z4D633iNABRXL5CNOUua6V%3DLtoGHJom8JwAg9A%40mail.gmail.com.

[Marco Walther]

On 8/18/25 09:18, Brian Higgins wrote:
> I think what the issue is, in TinkerCAD on my laptop using my iPhone
> mobile hot spot I can create the initial sketch but can’t make
> alterations or change dimensions.

ThinkerCAD does not really care, how you get to the internet. Yes,
ThinkerCAD lets you change the dimensions and position of the shapes.
You can even type in numbers, if you prefer;-)

-- Marco

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[Tom Bertalan]

Heh, "start oval"

> delete it and start oval

[Brian Higgins]

Ha, ha, cute 

Brian Higgins

VA Researcher for blind mobility “Laser enhanced Echolocation” ClearPath Navigation 

Sent from my iPhone

On Aug 21, 2025, at 10:31 AM, 'Tom Bertalan' via HomeBrew Robotics Club <hbrob...@googlegroups.com> wrote:

Heh, "start oval"

> delete it and start oval

To view this discussion visit https://groups.google.com/d/msgid/hbrobotics/9a34b4b6-0792-4107-9758-3655b5022bc0n%40googlegroups.com.

<start_oval.png>