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  1. #1
    Hi everybody,
    I am new in building diy cnc and was trying to build my first cnc with about 1000mmx1600 work area.
    To make long story short I purchased kit from linearmotionbearings2008 on eBay with all rails and ball nuts. The order arrived two days ago and as soon as I have seen the box that my stuff was shipped in, my heart sank and I thought Iím going to have a hart attack. 1600mm ball screws and 1700mm rails were shipped in the cardboard box with no support of any kind. I knew before opening the box that there is no way that this stuff is not bent. At minimum I assumed that this would be strapped on the flat wooden board if not in the wooden box.
    Rails were ok.

    You can see ball screws here


    I have exchanged few emails with the seller and initiated return on eBay, he didnít seem to care, offered me 50$ on 750$ order.
    Is there anything I can do? Will going to eBay resolution solve anything, what about calling my credit card company?
    If this is how this stuff is shipped how does he maintain 100% positive review on eBay. I canít imagine this happened only to me.

    I apologize for my broken English, Iím a foreigner living in US.
    Any suggestions
    Help ☹

  2. #2
    Bugger. Those look bad.

    Perhaps you might be better buying them through AliExpress. That way, you don't release the funds unless you are happy with the delivered goods. I've not had to use that system in anger but it may be better than the ebay system. That seems to be how they allay fears when buying from unknown buyers in China - otherwise most buyers would be very reluctant to even think of buying through them.

    My understanding of ebay is that they almost always side with the purchaser, so you would be very likely to get your money back. For that, you would probably have to reject his "offer". And in the US, I assume the credit card company is also liable for bum purchases? That sounds like the backup plan if ebay don't play ball.

  3. #3
    It has been many years since I bought my ballscrews (and they were from linearmotionbearings). Mine were maximum 120 0mm and arrived in a simple cardboard box like yours.

    They were bent but not as much as yours. Probably helped that they were shorter. The worst one I sent off to a local company and they straightened them (~£40). The other one could do with straightening but was not too bad so I have left it. The $50 refund doesn't cover that but it is one option if you can find someone in Raleigh. He might budge a bit more if you get a straightening quote for all of them and he pays a fair portion (or 100%!) to save shipping costs and hassle.

    A 'small' amount of bend is actually OK as the ballscrews are flexible and will be forced into line slightly by the ballnut. But I'm talking a few tenths of a mm or less. Obviously the more bent they are the more the ballnut will wear out. They are also noisy when even mildly bent.

    As for the 'offset' machining. They might be accidentally machined with an offset - however you are measuring on the crest of the thread Vs the center line. Just to confirm it is better to put the nut on and measure on the outside of the nut as the balls will run along the bottom of the grooves, which is where they should be ground true. Or find a way to indicate to the bottom of the groove. That might be the same answer as your method, but worth a quick check to be sure.

    I've since bought from Fred at Aliexpress and found a better quality of parts, plus better packaging. I've not bought long ballscrews from Fred though so can't be sure how he sends those out but in general his packaging has been good.
    Building a CNC machine to make a better one since 2010 . . .
    MK1 (1st photo), MK2, MK3, MK4

  4. #4
    Quote Originally Posted by routercnc View Post
    I've since bought from Fred at Aliexpress and found a better quality of parts, plus better packaging. I've not bought long ballscrews from Fred though so can't be sure how he sends those out but in general his packaging has been good.
    I've had up to 3500mm screws from Fred and never had a bent one yet. To be honest this is why I stopped dealing with Chai at linear motion bearing and went with Fred because his shipping and packaging was much better.
    If the screws are relatively long (1500mm+) they come in a wooden packing crate, if say under 1500mm they come in a cardboard box. However, usually it's a very strong thick-wall box and if the screws are over say 1000mm they are supported in the box with Cardboard braces to stop them bending.
    Also, Fred wouldn't hesitate to replace or refund if they were bent and wouldn't ask for the old ones returning.

    Edit: I will clarify this in that usually when I order from Fred it's for more than one machine worth of parts and often has linear rails etc so my packaging might be made slightly stronger than for say a single machine worth of screws etc. However, I have in the past had small rushed orders and the packaging as been good and strong.

  5. #5
    Thanks for the reply.

    I was not aware that if you purchase on AliExpress your funds are not released before you receive your shipment. I will definitely keep this in mind for my next purchase. Will try to take this with eBay and with my CC if possible
    I did not think anybody would send this stuff wrapped in the carboard. It just did not cross my mind.


  6. #6
    I know this is an old thread but I want to put my comments about it.

    I have been using linearmotionbearings2008 (Mr.Chai) for the last 10-12 years and have been most happy with the service, product quality, packaging and price. Iím very surprised because every year since I place one order per year for a complete set of rails, ballscrews, bearings etc. for a 4 axes cnc approx. 32Ēx42Ē and all arrive in excellent shape (ship by FedEx). My last order is about a week ago but it looks like the area where they are located in China is locked due to Covid19 and my order is now delayed. The only explanation I can give is if the order was NOT shipped by a well know carrier like FedEx, DHL, UPS etc. Mr. Chai had told me if not using a carrier he canít guaranty the delivery. From China to Canada FedEx is charging $75.00 for my order but on an order of about $700.00 for my package the $75 is well deserved and I get them in Canada in 4-6 days.


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