Defective LM8UU bearings.

[neuroclast]

I don't see any section to report defective hardware, so I'm trying here. Also, only providing poorly categorized forums for customer problems seems like a pretty terrible customer service model. I also sent in a request via the form for missing/etc items in shipping to hopefully get help.

I ordered 6 of these LM8UU bearings, as you can see in my ticket. Unfortunately, all 6 I received are defective. Three of them even had ball bearings missing and laying loose in the bags they came in.







As well as the obvious fact that they were losing ball bearings from just being shipped, they fit horribly on 8mm polished stock. This is what they are designed for, so I'm a bit confused. As you can see from 1.jpg, the stock is well within tolerance, actually a bit smaller than 8mm. Even with this extra play, the bearings take a good deal of force to move up and down the rods. You can see in 3.jpg that they clearly don't act as bearings at all, and instead just sit wherever you put them unless you use a good bit of force to move them.

From the return section of your site, it looks like my only options are to ship these back at my cost, and only for store credit? I'm trying very hard to be understanding here, but to get this many defective items, and my only options are to pay to send them back, and then get credit to get more defective items, seems a bit absurd.

I am willing to work with you guys, so please let me know what to do here. And I'm sorry if my post seems a bit irritated, but from the struggle to find a way to report these issues to someone as well as the poor quality of the parts I received, and the fact that I might have to pay to send them back and only get store credit has my blood pressure up a bit!

Thanks.

[adafruit_support_bill]

Hi, CNC/Mechanical components are still new to our store and we do not have a forum section for them yet. I have moved this topic to "Other Adafruit Topics" for now. If the bearings are defective we will replace them or refund your purchase. You can contact support@adafruit.com with a link to this thread to arrange for that. Meanwhile, I will order some up from stock for further testing.

[adafruit]

We had these on some 8mm precision ground stock and while they're not ultra smooth (they are very low cost for hobby CNC/robotics use) they do allow for linear motion. we think they're intended for horizontal motion, driven by a stepper motor assembly. You may have to up your budget to $20-$30/bearing to get what you're looking for.

http://www.mcmaster.com/#standard-linea ... gs/=lgmpcs (# 60595K11 etc)

Let us know if you find any bearings < $3 that perform to your expectations, we'd love to check them out and stock them!

As you saw in our email to you (and your paypal account) we refunded your purchase.

[neuroclast]

Thanks for the quick response and refund. If you want me to send these back, just let me know. I have used many linear bearings in the past, mainly from VXB. The ones I have used the most are http://www.vxb.com/Merchant2/merchant.mvc?Screen=PROD&Store_Code=bearings&Product_Code=Kit262&Category_Code=8mmLinearMotionSystems. These break down to around $4.44 per bearing, so they are a bit more expensive. These do, however slide effortlessly on polished 8mm stock, have better bearing retainers, and will just "slide" down a vertical stock without any prompting.

As I see it, and this may just be my opinion, these linear bearings are supposed to reduce the linear motion friction/stiction. I've used various bronze bushings/etc that had way less of those than these bearings. I would just say maybe stock the bronze bushings or some better VXB bearings. I know the cost would be higher on you and the customer, but honestly I can't see anyone who is investing the money in bearings being happy with these.

Thanks again for the response and help though.

[electronloop]

Did adafruit test the remaining linear bearing products to ensure future shipments will be ok? I don't want to have to return this from europe, even a refund would be costly.
I may want to order some SC8LUU (PID: 1180) but if quality is as poor as reported by OP, I will pass...

[adafruit]

Hi, we're still testing all of our bearings - if you need a certain performance you may want to purchase them from a physical store where you can test the bearings. We have not heard any other reports or issues about these bearings and are still testing various models, thanks!