Bearing Hole Wizard

Are there any bearing mounting hole wizards in the CAD programs? I couldn’t find it in Solidworks. I have opened up a discussion in Solidworks Forum. It would be useful if Solidworks adds bearing mounting hole selection to hole wizard. We can select holes for screws and bolts in the hole wizard. For example, f608zz OD 22mm , ID 8mm depth 6mm, Solidworks can make a mounting hole which diameter is 22mm and depth is 6mm.

bearing mounting hole

I can think of three ways to do this in Inventor (and I’m willing to bet SW has the same tricks). Using your dimensions of 22mm OD, 6mm Depth, 8mm ID…

  1. Extrude two cutouts using 1 or 2 sketches. One is 8mm through; the other is 22mm OD and 6mm down.
  2. Using the hole wizard, make 1 hole at 8mm OD through all, then use hole wizard again for a 22 mm OD hole 6 mm deep.
  3. Using the hole wizard, make 1 counterbored hole. Hole OD 8mm, counterbore 22mm OD and 6mm deep.

I would say that the main reason bearing holes aren’t included is that not all bearings are sunk into their parts. MANY uses of bearings involve the bearing being on a mount, and for those cases you’d use the mount’s hole pattern.

The other reason? There’s a LOT of bearing sizes and classes. Just off the top of my head: Flanged bearing, standard bearing, linear bearing, linear bearing with retaining rings, flanged sleeve bearing, sleeve bearing, needle bearing, cross-roller bearing (not the actual name but close enough), taper bearing, thrust bearing (in both ball and needle forms), thrust washer. Every single one of those will need some sort of model for this. I didn’t even get into sealing the bearings… Or some of the specialist linear bearings. I would say it’s just too much time and effort for SW to include that.

Two further notes:

  1. I have a similar frustration when dealing with belts in Inventor–they only have certain sizes. Predictably, I usually need a different size.
  2. I would explore SW for a bit and see if there’s a bearing generator–many CAD programs have various design assistants and that’s often one of them. I don’t expect it’ll generate the geometry for the bearing to fit into for you, but I could be surprised.
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You can make bearing holes through hole wizard using Legacy Holes (credit to @ido0546 for this trick), for any bearing size you want and you can you even use c-bored for flanged bearings. I’ve started doing this in my CADs and it’s actually a lot more convenient than using extrude cut.

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I am not expert but they can take it from toolbox. If they edited screws and bolts to make a hole, they can do it for bearing.

I’m going to say no on that.

Screws and bolts come in a bunch of standard sizes, both SAE and metric. Those are well defined. As an exercise, and I’m pretty sure you’re able to do this, make a model including threads of a screw such that you can come up with a correct metric screw size-thread-length combination with 3-4 inputs and adding a head.

Also, many CAD programs cheat. They’ll slap an image of threads when you put a threaded hole in, and they’ll just make the hole at the nominal threading size.

Now let’s take a bearing for a 6mm shaft. (I’m intentionally restricting the size here.) I’ve got no fewer than 12 options for an OD at a place that doesn’t exactly specialize in metric parts, across about 15 broad categories of bearings. Add in mount-included bearings, and I’ve got another 2-3 categories to worry about. If I expand that to NOT restrict the size… I count about 20 different categories of bearings. EACH of which has its own quirks–as a relatively trivial example, a 6mm shaft bearing, standard type, can have 7 different ODs, at least one of which has two different width options.

My guess is that the folks that do the work have bigger fish to fry, particularly if it’s a matter of “well, there’s a really easy way to do this already”. Yes, it’s more work for you…

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Bearings can be deceptively complex to use. In most FRC applications, they’re spinning at hundreds to low thousands of rev/min, for brief periods, for brief service lives. But industrially, the very same bearing can be called upon to run continuously for years at 10 times the speed. Under those more demanding conditions, the appropriate parameters of a bearing hole might be considerably different than a robot that just needs to survive 20 h intermittently.

To take an example, the fit of the hole and the bearing matter. Do you press the bearing in with a lot of force, a little force, or no force (and secure it with something else, like retaining compound)? In an FRC application, you can probably take your pick. In a particular industrial application, you might have a constraint on the amount of heat that the bearing can generate (and the assembly can reject to the surroundings)—you therefore might not want the tight press fit because this will increase friction on the balls unacceptably. How should the CAD tool account for this consideration?

Another example is mass production. Whereas in FRC, you want to get one particular bearing to fit one particular hole, in mass production it is generally desirable for every possible bearing (throughout the range of acceptable production variations specified) to fit every possible hole (which could be manufactured within the part specifications)—or at least something approaching that. You might therefore need to specify different tolerances on the hole to make it work at scale, and again, the CAD tool would have to be aware of this factor, or provide a method of working around it.

Your CAD software purports to work for all of these applications. They would need to make clear that their bearing hole program is only valid for certain assumptions. Perhaps the software developers believe that a bearing tool subject to these limitations wouldn’t be useful enough to justify the development effort.

Incidentally, for details on how to design bearing interfaces, check out the engineering literature published by the major worldwide bearing manufacturers (for example, SKF and Timken). There’s a lot of very detailed guidance for high-precision applications. Particularly with regard to tolerances, the manufacturers specify what they can supply, and what mating part tolerances they expect for best results. Some of this won’t be relevant now, but it may be instructive in general.

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