For a similar reason that BP should be responsible if there’s something peculiar about their gasoline that makes it not work in, say, Toyotas.
Or, let’s say you go to Home Depot and buy a bag of #8-32 screws. You take them home and discover that they’re left-twist instead of right-twist, and the packaging doesn’t say anything about that.
Or, you go to Staples and buy a ream of printer paper, only to discover that it doesn’t work in any of the most popular printers on the market.
It’s the implied warranty of merchantibility.
Note that I’m not saying that it’s Andymark’s responsibility to make sure that their bearings work with VEX’s hex shaft. But (and, again this is all theoretical) let’s say that the bearings advertised as 1/2" hex and marketed to FRC teams were actually .4988, and that made a difference with respect to the common hex shafts used in FRC. If that were the case (and I have no idea if it is), then that would probably be a breach of the implied warranty.
The implied warranty can be overcome by things like Vex saying ‘by the way, our 18" shafts are a bit oversized’ on their product page.
I think one needs to remember that there is a difference between “must” and “should”. What you’ve described is a “should” more than a “must”. I’d think it would be better for sales to have one’s selection of parts be compatible with the rest of the market (since many customers are not strongly loyal)… but there’s no law requiring such unless there’s a claim made by the company in question that X is compatible with Y…
I’m an a engineer, not a business owner or marketing guru so take what say with a grain of salt.
…but there’s no law requiring such unless there’s a claim made by the company in question that X is compatible with Y
Actually, there is a law. In Indiana, it’s found at Section 26-1-2-314 of the Indiana code:
… a warranty that the goods shall be merchantable is implied in a contract for their sale if the seller is a merchant with respect to goods of that kind…
Goods to be merchantable must at least be such as:
(a) pass without objection in the trade under the contract description; and…
( c ) are fit for the ordinary purposes for which such goods are used; and …
(f) conform to the promises or affirmations of fact made on the container or label if any.
Undersize bearings (assuming that’s what’s going on, which could easily not be true) would have problems in all three of those areas.
Thunderhex is the best brand you could ever get for it’s purposes, our team ordered a few 36" rods but overall, stick with the 36" rods because you may need multiple pieces but as far as hex shafts it should be alright for us it fits like a glove when the ends are rounded properly. however it may be different in your case.
They are clearly designed to interface with a 1/2" hex bore. That’s the bore that essentially any product the shaft is installed on has. I agree that they should not fit 1/2" round bearings, but I don’t think that’s what the OP is asking.
No comment on this strange discussion of warranty, other than that I hope teams actually try contacting AndyMark for assistance before going on long diatribes about whether or not AndyMark parts are under a legal warranty.
If the AndyMark FR8ZZ-Hex bearing is under size, please let us know by contacting AndyMark directly. Assuming and speculating about this is not good.
AndyMark was the first company to offer this unique invention of a steel, flanged, hex bore 1/2" bearing. Maybe we should have pursued a patent at that time. Maybe not.
Implying that this bearing needs to meet the spec of a shaft that was developed many years later is absurd.
I would like to point out the original hex bearing was $10.00 and would have to be individually accounted for on the robots BOM. Thanks to AnyMark and Vex for providing innovative and cost competitive solutions to the robot market place.
Ok I measured the thunderhex to be .499” and the bearing to be .489. Is this enough to account for our struggles? Also, I didn’t mean to imply AM needs to change their bearing, just saying that the issue came up which was unexpected.
I am going to venture and say either your measurement isn’t perfectly parallel, and your number is off, or your calipers are broken, because I measured a bunch of them with some digital mititoyo internal mics, and they were all within + 1 ten-thousandths to -4 ten-thousandths, perfectly acceptable for a bearing of that caliber.
It’s certainly not out of the realm of possibility that his bearing is not in the exact same condition as yours. I really wouldn’t assume he is doing something wrong just because you don’t have a defective bearing on hand.
In any case, if the OP just contacts AndyMark I’m sure they can get it exchanged for a known good bearing.
just for reference 11 thou is about 3 pieces of paper, while it is possible that OP has worn a bearing down that much I highly doubt it, you would need to be intentionally filing it almost to see that much wear. also coming from a machinist, if it is defective from the manufacturer and is off by 11 thou, i can guarantee their hex broach is also destroyed entirely from over abuse and andymark should be very worried about their supply chain. I mean no hate by saying that he possibly measured wrong, or has a broken caliper I am just saying 11 thou is a whole heck of a lot for something as small and precise as a bearing.
While it’s not completely impossible, it’s highly unlikely. -.011 isn’t a press fit, it’s an extremely heavy interference fit if you can get it to fit at all. If @risho900 can fit a 0.499" shaft through with a few swings of a mallet as he said, it’s practically impossible for that measurement to be correct.
In any case, I would have someone else with experience using calipers to take a second look, using a different calipers if possible. If they agree that the bearing bore is severely undersized, then AndyMark might be interested in taking a look at it to confirm your measurement.
Edit:
That’s 11 thou undersized, meaning he would have had to add material to get there. No offense meant, but I agree that the most likely option is just an inaccurate measurement.
He is saying the bearing is 11 thou too small. You can’t “wear down” a bore smaller. Additionally, a crooked measurement would report a hex width larger than the true value in most cases, not smaller.
you are right about the smaller thing, that is my bad for not catching that, duh, but as far as parallel measurement, remember the hands of the calipers have thickness, if you measure at an angle where the opposite edges of the caliper hands are touching the sides of the bearings at an angle less than or equal to the inverse tangent of the width of the caliper divided by the width of the bore, but greater than 0 the measurement will in fact be smaller