BelfrySCAD
ball_bearings.scad, can we have a "rounding" argument?
Ball bearings have rounded edges on both the OD edges and ID edges. Can we have the option to specify the rounding value? According to the ball bearings spec sheets I looked at today, the interior and exterior rounding is always the same, so a single value should be adequate.
Thanks!
So you're asking for fillets at the bottom of the race (2 edges) and roundovers on the top? Do we have any plausible defaults?
I'm asking for round-overs on ID and OD edges. In the specs I reviewed this morning, the roundover varied depending on mfr and bearing size, so I would not suggest using a default value.
On Thu, Sep 26, 2024, 2:16 PM adrianVmariano @.***> wrote:
So you're asking for fillets at the bottom of the race (2 edges) and roundovers on the top? Do we have any plausible defaults?
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So as I see it, the ball bearing has 8 circular edges, 4 on the top and 4 on the bottom. It appears from looking at a McMaster diagram that all 8 are rounded or maybe chamfered. In the case of the flange there is a 9th edge. (In the shielded case it looks like only 4 edges.)
Are you asking that only some of these edges get treated?
I pulled this out of NSK bearing catalog https://www.nsk.com/content/dam/nsk/common/catalogs/ctrgPdf/bearings/e1103b.pdf, page 176: They only specify the two radii (assuming left-right symmetry), and this is what I was looking for. I guess the other two edges you're referring to are at the opening where the seal will be located? As you can see in the table, the value varies by bearing size.
To be honest, this is a low priority for me. If you want to decline this enhancement request, I won't be disappointed. If I really need the radii, I know how to do it using cyl() with rounding argument. Regards, Dan
[image: image.png]
On Mon, Oct 14, 2024 at 8:59 PM adrianVmariano @.***> wrote:
So as I see it, the ball bearing has 8 circular edges, 4 on the top and 4 on the bottom. It appears from looking at a McMaster diagram that all 8 are rounded or maybe chamfered. In the case of the flange there is a 9th edge. (In the shielded case it looks like only 4 edges.)
Are you asking that only some of these edges get treated?
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So if I understand that drawing then all 8 edges get the "r" rounding? And in principle that rounding radius should get added to the dimensional tables for the bearings.
The obvious (from p197 of the same doc): [image: image.png]
On Mon, Oct 14, 2024 at 10:52 PM adrianVmariano @.***> wrote:
What happens to the flange for rounding?
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Weird how the flange has a concave circular rounding instead of a fillet. Is it supposed to snap onto something?
Since there is no spec/dimension associated with that undercut, it couldn't be reliably used mechanically. I believe it's a byproduct of the metal forming. I have a flanged bearing down in the garage and I never noticed the undercut. Dan
On Tue, Oct 15, 2024 at 11:31 AM adrianVmariano @.***> wrote:
Weird how the flange has a concave circular rounding instead of a fillet. Is it supposed to snap onto something?
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This has been open for a while and I'm not feeling motivated to go modify Revar's code to add it. So I'm going to pass this off to him to either implement or decline to implement. @revarbat what do you think?
@dan-p3rry is this what you had in mind? The one on the left is what BOSL2 does now, the one on the right is with a slight modification to ball_bearings.scad to add an edge_r parameter to round the edges of the outer ring.
Rounding doesn't work well for 3D printing the bottom layer though. A chamfer would be better.
Yes, that's fine. The rounding isn't for printing, it's more for accuracy when difference'ing.
Thanks & regards, Dan
On Wed, Dec 11, 2024, 8:14 PM Alex Matulich @.***> wrote:
@dan-p3rry https://github.com/dan-p3rry is this what you had in mind? The one on the left is what BOSL2 does now, the one on the right is with a slight modification to ball_bearings.scad to add an edge_r parameter to round the edges of the outer ring.
image.png (view on web) https://github.com/user-attachments/assets/a1b4d7d3-9de9-4b72-9f0b-f7586c5babec
Rounding doesn't work well for 3D printing the bottom layer though. A chamfer would be better.
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This isn't really printable given the balls in there, right?
What about rounding of internal hole? Also, there are the cases of flange and shield.
Looking at the spec sheet @dan-p3rry referenced, I see I did it wrong. On the outer ring, only the outer edge has any significant rounding, not the inner edge where the race is. And the inner hole is also rounded.
In BOSL2 it would be like this:
With a flange, that spec document also shows one edge of the flange has rounding:
It works the same way with a shield too.
If that's acceptable, I can raise a PR with this change.
If @dan-p3rry says you got it right then raise the PR. But I think change edge_r to just rounding which is more consistent with other modules in the library.
Done, changed edge_r to rounding. @dan-p3rry do the most recent screenshots look OK to you? It's one additional parameter, as you requested.