Thumb design is changed!

[Tetsuya KonishiKeymaster]

hi I’m Tetsuya. I’m designer of exiii.
I updated the design of HACKberry’s thumb.

View post on imgur.com

please check the data from the following link.

http://a360.co/23scK37

• This topic was modified 7 years, 2 months ago by  Tetsuya Konishi.
• This topic was modified 7 years, 2 months ago by  Tetsuya Konishi.
• This topic was modified 7 years, 2 months ago by  Tetsuya Konishi.

[Александр АнтоновParticipant]

I wish you good health. very beautiful design . it is fragile and could break. can be strengthened. I could not = (

[Hiroshi YamauraKeymaster]

Hi Alexander,
I guess you want to connect the parts which is surrounded by red frame.

View post on imgur.com

However, this gap is necessary for disassembling the thumb parts without removing the servo motor from the PCB.
Is it so fragile? I think it is enough for standard use.

• This reply was modified 7 years, 1 month ago by  Hiroshi Yamaura.

[Александр АнтоновParticipant]

Привет Хироши какую программу вы используете для конструирования деталей ?(можешь скрин шот рабочего стола сделать?)

(following translation is added by exiii)
Hi Hiroshi, what kind of CAD do you use for designing the parts? (Could you give me your desktop screenshot?)

• This reply was modified 7 years, 1 month ago by  Hiroshi Yamaura.

[Александр АнтоновParticipant]

красивый дизайн

[Tetsuya KonishiKeymaster]

Oh thumb!!
good job!

[Tetsuya KonishiKeymaster]

I use Fusion360 & CATIA.

View post on imgur.com

I use Fusion 360 for rendering

View post on imgur.com

and CATIA is used for modeling.

[Александр АнтоновParticipant]

Спасибо!!! просто хочу укрепить детали

[Satima AnankitpaiboonParticipant]

Hi Александр,

I think the problem is the material you use. You mentioned in another post that you used PLA.
PLA seems harder but it actually brittle. It has only a tiny bit of give (elasticity).

I heard some people use carburetor cleaner vapor or warm water (70°C or around 160°F) to treat PLA parts to make them softer. I haven’t tried it so I don’t know how long you should treat them. You can try it if you’d like.
They might be too soft if you do it too long.

[Satima AnankitpaiboonParticipant]

Hi Tetsuya and Hiroshi,

The new thumb looks really nice!

• This reply was modified 7 years, 1 month ago by  Satima Anankitpaiboon.

[Satima AnankitpaiboonParticipant]

Hi Tetsuya,

The connection between HbThumbProximalPhalanx02 and HbThumbProximalPhalanxBase02 seems to be loose and they would have to rely on a screw or a pin to stay connected, which is probably fine. However, I thought that might be a week point for daily use.

I wonder why you didn’t make the fitting between the two a little tighter.

I used a tighter tolerance on the last thumb and it didn’t need an extra part to connect them together. The insert is 3X10mm and the hole is 3.20X10.20mm. I thought I posted my parts here in case you’re interested. https://www.dropbox.com/s/eysoinbic3q9bd7/Separated%20thumb%20-%20Tima.zip?dl=0

For what I had, the worse is I would glue them with acetone (for ABS only) or superglue for PLA but it didn’t seem necessary.

Anyway, you must have a reason for having the new thumb the way it is. I wonder what that is.

• This reply was modified 7 years, 1 month ago by  Satima Anankitpaiboon.

[Hiroshi YamauraKeymaster]

Hi Tima,

I don’t want to use glue since HACKberry doesn’t need it for other assemblies.
If we use it for thumb, people have to provide glue only for this part.

I also don’t want to use press fit because it is very affected by the accuracy of the 3d printer.
Therefore, we decided to connect them using a screw.

[Satima AnankitpaiboonParticipant]

Hi Hiroshi,

Hmmm… you have good points there. That is very thoughtful to keep the list of materials required as little as possible.

Keeping the parts separate is probably more beneficial as opposed to gluing them anyway. In case if one breaks, we wouldn’t have to reprint both of them.

Speaking of the accuracy of the 3d printed parts, I did have that problem in the beginning. With the printer default setting or the quick print setting, the printed parts wouldn’t fit well. They seem to be too big and too thick to fit together.

Tweaking some printer settings like the printing speed, the filament feed/flow and temperature seems to help. The parts dimensions seem to be very accurate and fit well together without a whole lot of extra work (like sanding and filing to make them fit). It makes the assembly a lot more pleasant. However, now I wonder if this causes my parts to be really really loose with these settings.

[Hiroshi YamauraKeymaster]

Tima,

Sorry, I can’t understand why you care about looseness so much.
HbThumbProximalPhalanx02 is tightly fixed to HbThumbProximalPhalanxBase02 by the screw.
There is no looseness regardless of the clearance.

[Kyle SeleskiParticipant]

Woohoo CATIA V5. That’s what I use at work! =)

Sorry to spam

[Hiroshi YamauraKeymaster]

Hi Kyle,
haha, no problem.
Tetsuya is also CATIA V5 enthusiast.

[Satima AnankitpaiboonParticipant]

Hi Hiroshi,

Sorry I wasn’t clear. You’re right, the parts tightly fit with the screw.

I had some abs plastic failed around the screw thread before so I was just concerned about the material fatigue at this location where it’s subject to repeated loading and unloading. However, it might not be the case here. Maybe I worried too much.

About the printer accuracy, I didn’t realize that this would be an issue when I made my parts. But you’re right again. I have had people who got the HACKberry kits from me told me they had trouble fitting parts together. I thought I just shared how I fixed that but apparently it wasn’t the right place or timing to share. Sorry for the confusion 🙂

Thank you for the video.

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