Loft face of involute gear works, loft 2d offset of same face doesn't
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Loft face of involute gear works, loft 2d offset of same face doesn't
Somewhere else somebody did post a solution to loft an involute gear. (https://forum.freecadweb.org/viewtopic. ... 06#p101106 ).
This works for just two involute gear faces. When I make a 2D offset of these faces in part WB freeCAD starts hanging.
I tried different options and orders of following functions to create a pair of offset gears and loft them.
Wire to Face (Part WB)
Upgrade (draft WB)
2D offset (Part WB)
Loft (Part WB)
3D offset (Part WB)
So what is different between a face made from an involute gear, and the face made of an offset involute gear?
You can find my file here: https://drive.google.com/open?id=18vdh4 ... b0fmDEA7s9
as I have trouble uploading the file to the forum.
Thanks in advance
This works for just two involute gear faces. When I make a 2D offset of these faces in part WB freeCAD starts hanging.
I tried different options and orders of following functions to create a pair of offset gears and loft them.
Wire to Face (Part WB)
Upgrade (draft WB)
2D offset (Part WB)
Loft (Part WB)
3D offset (Part WB)
So what is different between a face made from an involute gear, and the face made of an offset involute gear?
You can find my file here: https://drive.google.com/open?id=18vdh4 ... b0fmDEA7s9
as I have trouble uploading the file to the forum.
Thanks in advance
- DeepSOIC
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- Joined: Fri Aug 29, 2014 12:45 am
- Location: used to be Saint-Petersburg, Russia
Re: Loft face of involute gear works, loft 2d offset of same face doesn't
Lofting between two gears with unequal teeth count is a pretty bad idea, because OCC will slice them up to make their edge counts equal. That will double an already high segment count, and generate a lot of extremely short edges that have a potential to be shorter than their tolerance. I have tried adding a circle in between your gears, and make two lofts. But the loft is self-intersecting, looks like an occ bug to me.
I assume you are making gears for 3d printing. Then, fill up the space between them with a simple revolution, in your example just a cylinder is enough.
I assume you are making gears for 3d printing. Then, fill up the space between them with a simple revolution, in your example just a cylinder is enough.
Re: Loft face of involute gear works, loft 2d offset of same face doesn't
But with just the two gear profiles without the offset it works.
I'm trying to recreate these gears as in the picture:
from this design: https://www.thingiverse.com/thing:2220506
I would like to recreate this gear reduction, but parametric and with more tolerance than the original one because it's not going smooth.
- DeepSOIC
- Veteran
- Posts: 7896
- Joined: Fri Aug 29, 2014 12:45 am
- Location: used to be Saint-Petersburg, Russia
Re: Loft face of involute gear works, loft 2d offset of same face doesn't
Then you'll have to do the transition manually, tooth by tooth. No FreeCAD operation as far as I know will give you a transition like on these thingiverse gears.
Re: Loft face of involute gear works, loft 2d offset of same face doesn't
Ok I tried this and now I have more or less a result I can be happy with. (still not as nice as the loft from one gear to another).
But now the next problem is freeCAD won't let me union or connect the objects. Sometimes it works and sometimes it doesn't, If I change a parameter in the spreadsheet it takes very long to recalculate if it ever finishes.
The file: https://drive.google.com/open?id=1Ws4bc ... iL5FN7XX0D
- Attachments
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- loft.png (67.23 KiB) Viewed 925 times
Re: Loft face of involute gear works, loft 2d offset of same face doesn't
why not put a cylinder in between the two gears? Does the connection-section have any functionality?
Re: Loft face of involute gear works, loft 2d offset of same face doesn't
Is there any mecahnical advantage in this quintuple helical gear over the double or herringbone gear?
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Re: Loft face of involute gear works, loft 2d offset of same face doesn't
These are used for a specific kind of planetary gear where which you can achieve a very high reduction in this case 1379 to 1.
I just would like to get a better understanding of this gear and use it for a custom application if everything goes well.
- DeepSOIC
- Veteran
- Posts: 7896
- Joined: Fri Aug 29, 2014 12:45 am
- Location: used to be Saint-Petersburg, Russia
Re: Loft face of involute gear works, loft 2d offset of same face doesn't
Laying a circle between two teeth is not an overhang, it's a bridge. Usually prints very well, with only minor visual artefacts. IMO your transition is much more of an artefact than a bridge would be.