Can this gear be modeled on freeCAD easily

[JoshuaNicoll]

So I've been trying for a few days to model this gear and it just doesn't seem to be working out, I'd rather not have to do down the completely modeling it from scratch as that's not really my forte but if no alternatives are there I sort of have to, either that or find someone else to do it. The drawing is mostly tranlated from chinese into the following which is why the language feels a little clunky, I did consider making it a little more readable but I didn't wanna mess with it too much.

Chinese Drawing translation.jpg (102 KiB) Viewed 1491 times

As you can see there are a couple of slightly odd features that FC gear can't really make, or let me change, so am I to assume this gear has to be using sketches and other more manual methods or are there hidden settings I can't see.

Screenshot (4276).png (257.89 KiB) Viewed 1491 times

This is where the translated section came from, which includes the drawing of the gear in question.
I'm really not used to drawing complex gears like these and never really did it before so I'm a bit in over my depth here.

[heda]

don't get why you ever would want to model it in detail...
afaik there is only one pseudo use-case for modelling a gear in detail
cant imagine that 3d print will not swallow what fc does now (maybe someone that actually prints will know for sure)

in any case, you could dig into the equations in the underlying workbench and modify them to your needs,
if you hardcode it for this specific gear as a one-time thing... no need to bother about gui-things...

[JoshuaNicoll]

don't get why you ever would want to model it in detail...
afaik there is only one pseudo use-case for modelling a gear in detail
cant imagine that 3d print will not swallow what fc does now (maybe someone that actually prints will know for sure)

in any case, you could dig into the equations in the underlying workbench and modify them to your needs,
if you hardcode it for this specific gear as a one-time thing... no need to bother about gui-things...

I'm modeling it in exact detail as it gets exported as a step file and machined by a company in china, this gear is part of two mitre gears and a larger assembly. The drawing calls for SNCM220 steel, seems to be a common steel though in Europe I've never encountered it (though I have encountered the EU version) , it's US equivilent is 8620.

[heda]

right, so this is for real and not a toy.

I cannot tell if you know what you are about to getting yourself into or not,
but am leaning towards that you do not.

If you feel a bit out of depth here, the recommendation is to find someone that is not out of depth and simply pay up,
assuming that you want to end up with something that has a chance to work.

a 32 inch pinion, at least for me means that it is expected to last for decades...

is it really the manufacturer that has explicitly asked you to model this in detail?
if so find another manufacturer / speaking partner...

and then again, maybe you know exactly what you are doing - but then why post a general question on this forum...

[looo]

So I've been trying for a few days to model this gear and it just doesn't seem to be working out, I'd rather not have to do down the completely modeling it from scratch as that's not really my forte but if no alternatives are there I sort of have to, either that or find someone else to do it. The drawing is mostly tranlated from chinese into the following which is why the language feels a little clunky, I did consider making it a little more readable but I didn't wanna mess with it too much.

Chinese Drawing translation.jpg

As you can see there are a couple of slightly odd features that FC gear can't really make, or let me change, so am I to assume this gear has to be using sketches and other more manual methods or are there hidden settings I can't see.

Screenshot (4276).png

This is where the translated section came from, which includes the drawing of the gear in question.
I'm really not used to drawing complex gears like these and never really did it before so I'm a bit in over my depth here.

I tried to model the gear with the bevel gear from the gear-workbench. This uses a spherical involute profile and is not the Gleason profile type. Also I am not sure about the helix angle. In the table it's 0° but in the drawing the gear is shown with a (beta) helix-angle.

https://www.dropbox.com/scl/fo/im131ly7 ... 4c9p093p6i

Bildschirmfoto 2022-05-01 um 14.28.37.png (961.91 KiB) Viewed 1233 times

[JoshuaNicoll]

So I've been trying for a few days to model this gear and it just doesn't seem to be working out, I'd rather not have to do down the completely modeling it from scratch as that's not really my forte but if no alternatives are there I sort of have to, either that or find someone else to do it. The drawing is mostly tranlated from chinese into the following which is why the language feels a little clunky, I did consider making it a little more readable but I didn't wanna mess with it too much.

Chinese Drawing translation.jpg

As you can see there are a couple of slightly odd features that FC gear can't really make, or let me change, so am I to assume this gear has to be using sketches and other more manual methods or are there hidden settings I can't see.

Screenshot (4276).png

This is where the translated section came from, which includes the drawing of the gear in question.
I'm really not used to drawing complex gears like these and never really did it before so I'm a bit in over my depth here.

I tried to model the gear with the bevel gear from the gear-workbench. This uses a spherical involute profile and is not the Gleason profile type. Also I am not sure about the helix angle. In the table it's 0° but in the drawing the gear is shown with a (beta) helix-angle.

https://www.dropbox.com/scl/fo/im131ly7 ... 4c9p093p6i

Bildschirmfoto 2022-05-01 um 14.28.37.png

Yes I noted the gear shown had a helix angle but the drawing says 0° which is something I'm still trying to work out, the current gears clearly have a very very slight angle but this newer design seems to have a more substantial angle, the very first drawings dating from 2013 have no angle at all, so there might have been changed made and the angle was not updated. I wish these gears had a clear lineage of who designed but the design dates back decades and there have been at least 15 different companies (or more accurately 15 different iterations made by different companies) and this whole project has been somewhat of a nightmare, these gears are tiny as shown and have a huge load on them so that's why so many people have tried to improve on them, and from what I can tell no one has done it economally yet so the newest design seems to be the strongest.
You can even see the wear on this gear, the teeth are worn over.

20220501_221743.jpg (292.18 KiB) Viewed 1120 times

[JoshuaNicoll]

right, so this is for real and not a toy.

I cannot tell if you know what you are about to getting yourself into or not,
but am leaning towards that you do not.

If you feel a bit out of depth here, the recommendation is to find someone that is not out of depth and simply pay up,
assuming that you want to end up with something that has a chance to work.

a 32 inch pinion, at least for me means that it is expected to last for decades...

is it really the manufacturer that has explicitly asked you to model this in detail?
if so find another manufacturer / speaking partner...

and then again, maybe you know exactly what you are doing - but then why post a general question on this forum...

I definitely know I don't know much about gears, it's not really my area of expertise yes, you got that right. As you said, I made this post before out sourcing this model to see if I was I was just dumb and didn't see something obvious but it does seem this is the kind of gear that has to be modeled from the ground up, that's not going to be fun. I previously modeled a normal involute version of this gear and they worked but the wear was excessive, it now makes snese why as these gears use the gleason tooth profile that makes a lot more sense. I posted a picture of one of the versions of these gears (they're a mitre pair, the other gear is similar but has different features). The gear is only 13mm or so in size so certainly not 32 inches. They can operate at up to 26,000 rpm which is very fast for a slopply held gear. I would personally prefer to see tapered roller bearing races ground potentially directly onto these gears, or at least interfearance fit but the bearings are so small there is no room. Angular contact would also be fine but again I couldn't find any in the size needed, quite frankly these have been a headache from day one.

[heda]

aha, so the real thing but toy-like

should have said that why listen to a random voice on internet in the earlier post,
not capable of reading carefully enough to get inch vs mm
anyhow this scale is out of my depth...

hm, wear - would be inclined to say downright failed, rather than wear...
too high load, not well lubricated/cooled - any guess is as good as the other

not surprised that you do not make it when you model gears by hand and "machine to 3d"
not really how it works for the bigger stuff, micron matters there, no reason to think it is different on smaller scale

still think you need to find the proper speaking partner/manufacturer,
bearing in mind that there are plenty of shops out there that simply do not have the proper tool chain and or knowledge to deal with things.
imho opinion, noone will get gears right if they are not really into it.

if people really have worked on this for decades, it kinda sounds like time to go to g or k directly...
assuming that you actually want to know if it is fixable or not (might not be...)

in any case, intriguing issue at hand and good luck, which ever way you choose going forward.

[M4x]

Please let us know how it goes!