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Defective LM8UU bearings.
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Defective LM8UU bearings.

by neuroclast on Tue Feb 12, 2013 11:53 pm

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.

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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.
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Re: Defective LM8UU bearings.

by adafruit_support_bill on Wed Feb 13, 2013 7:00 am

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.
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Re: Defective LM8UU bearings.

by adafruit on Wed Feb 13, 2013 12:21 pm

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.
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Re: Defective LM8UU bearings.

by neuroclast on Wed Feb 13, 2013 2:10 pm

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.
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Re: Defective LM8UU bearings.

by electronloop on Sat Mar 16, 2013 12:13 am

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...
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Re: Defective LM8UU bearings.

by adafruit on Sat Mar 16, 2013 12:33 pm

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!
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Re: Defective LM8UU bearings.

by Bunsen on Sat Jun 29, 2013 10:29 pm

The first set of bearings I ordered a month or two ago were fabulous. The ones I just received a week ago do not have Zerk fittings and also seem to be pre-lubricated with some type of sticky grease. Is this what is now to be expected? Should I soak them in an organic solvent? If so, what type do you recommend that would remove the sticky grease? They don't work the way they are as the ball bearings jam and they don't slide well at all. The first batch, like I said, were fabulous.

Thanks
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Re: Defective LM8UU bearings.

by adafruit on Sun Jun 30, 2013 10:36 pm

We recently changed to a supplier that tested better than the previous one - it could be you got a bad set. the grease is to keep them from rusting you can clean them out and oil with whatever you prefer. email support@adafruit and we can get you a new set of bearings
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Re: Defective LM8UU bearings.

by adafruit_support_bill on Mon Jul 01, 2013 6:07 am

WD-40 works well for removing the sticky cosmoline.
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Re: Defective LM8UU bearings.

by Bunsen on Mon Jul 01, 2013 7:57 pm

WD-40 worked great! The issue seems to be the "cosmoine," which is a new word for me.

Thanks!
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Re: Defective LM8UU bearings.

by SeislGnaup on Thu Aug 29, 2013 4:56 pm

Hello,
I'm having some trouble with a LM8UU linear bearing and one of the SC8UU linear learing platforms I purchased earlier this month.

The bearing in one platform appears to be defective (it take a significant amount of force to move and is leaving scratches in the rail) and a different platform has two untapped mounting holes (see photos).

Any chance of getting refunds or replacements for these parts?
Attachments
unthreaded.jpg
Unthreaded mounting hole in linear bearing platform
unthreaded.jpg (217.91 KiB) Viewed 1261 times
badbearing.jpg
Scratches in linear rail
badbearing.jpg (286.74 KiB) Viewed 1261 times
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Re: Defective LM8UU bearings.

by adafruit_support_bill on Fri Aug 30, 2013 8:13 am

@SeislGnaup - Please contact support@adafruit.com with a link to this thread to arrange for replacements.
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