Modeling Challenge - Trasmission between 3 shafts

[mfro]

Nice.

The housing fillets don't work because the transition between the ribs and the circumference of the flanges is not clean (rib rectangular, flange circular).

You can fix that with a pad that sticks out of the circumference and a final "peeling groove" that cuts it down to the OD. That will then accept refine and the fillets will work.

fillet.png (147.44 KiB) Viewed 1191 times

[jimmihenry]

Nice.

The housing fillets don't work because the transition between the ribs and the circumference of the flanges is not clean (rib rectangular, flange circular).

Thank you! Thought about that, but it seemed to be simpler to do the ribs the old fashion way. This is clear a mistake i made, i should cut it circular no matter what! That is why i could see the small line on top of the rib . And i ignored it duh, that was dumb! FreeCAD does the fillet after i refined the model.

Now i can not do the (PAD/ Grove/ Fillet1 and Fillet2) in a circular pattern... I did the rib pattern, made the circular cut so i can make 80 fillets to complete the model. I believe you can not pattern subtractive features if i remember correctly, not yet.

One side done file size 81,4MB yea... no upload. The file size is over 1.66MB without the fillet. Over 3MB with one rib complete.

[jimmihenry]

Here is the image of the completed assembly. The file is round about 229MB with the housing fins fillet. Aftermath as i already said the first part that i called "TCRD90 Remake.FCStd" has its trouble with the fillets. Maybe because of the way i made it, but it is pretty much 100 percent a match except the fillet. The housing end cover can also be remade exactly, it's a bit of a pain because i had to apply the fillet on both sides of the fin. That resulted in 80 fillets, a lot of work, time and a oversized file in regards to the MB. I am not uploading the entire assembly because of the size. Neither will i upload the assembly as single parts, the positioning is still demanding. If someone would like to have the entire model anyway there are some temporary file upload services (at least 229MB) i could make use of....

While adding the fillet to the housing end cover fins the RAM occupation grew up to 11,3GB usual it is around 4,7GB. I closed FreeCAD and reopened the model. The RAM stored 4,7GB of data as usual...

@Ufile.io the model will be available for about 30 days. Follow the link to the model: https://ufile.io/c3dnwil9

[mfro]

Your model of the crank arm (Body "Body" in your file) has similar problems like you had with the casing. The seams left at the outer surface prevent the fillets from working.
Here is my part (with a final "peeling groove" I also recommended for the casing that cleans up the seams thus allowing to apply the outer fillets later on). This also has an Additive Pipe in the section between the two conics instead of a simple pad as it IMO better resembles the original shape.

SpericalLink.png (77.8 KiB) Viewed 1006 times

[jimmihenry]

Your model of the crank arm (Body "Body" in your file) has similar problems like you had with the casing.

Hi Markus,

the crank and the body are two different parts i made a mistake making the housing, once again thank you for pointing this out. You made up the crank, it has a different shape you own creation and it looks nice. What is the point comparing two different shapes? The "challenge" is to recreate the device using FreeCAD. Creating exactly the same shape with a different program using different tools and features.

I would love to see your recreation and learn how to do this the proper way using FreeCAD.

Cheers.

Image below. Burgundy (red) is the original part.

[mfro]

It's entirely possible that I made mistakes by picking up the original measurements.

The shape of the crank is basically directly dependent of the diameter of the construction sphere or circle in the sketch attached to it, respectively (I didn't take the effort of cutting the cross sections for measurement as you did).

[jimmihenry]

I tried another approach creating the needed fillets. This time i created the connecting boss, the part connecting the two circular structures including the fillet 4x6mm radius. Than i made the circular bushings... But now FreeCAD does not wont to do the upper and lower fillet. I really should let it go now... This approach is labor intensive... However QD (quick&dirty) it is, from the beginning

Cheers

[Vincent B]

First step to try to animate the obelisk79 model. The yoke ball go inside the main shaft. Need to be adjusted.

phpBB [video]

[obelisk79]

First step to try to animate the obelisk79 model.

I was able to create an animation, I made a mistake by not linking two of the shafts to turn, but you can still get the idea of how the mechanism operates. I never fixed it since I ran out of patience screen-shotting each frame individually.

Also, of note, this was 100% modeled without using any drawings or the original step files as a reference. All I could get on my terrible internet was the screenshots from the grabcad page. Of particular note, the ball-joint cups would not work the way I designed them in the real world, but that would be easy to fix. I'm just glad I was able to quite effectively approximate the original model/mechanism.



EDIT:
If there's interest, I'd be willing to take a stab at modeling a housing and correcting some of the semi-impossible/impractical design aspects of my model. This was a fun challenge. I think we should look for more things like this.

[Vincent B]

eventually done.

phpBB [video]