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17-06-2021 #1
I am not saying that there are no lemons, but that most are OK for hobby use and there is no reason to rush or assume that everything is bad. Of course if one is replacing the bearings one might as well do it right and get the proper ones. But you can't say that just because some people have issues all are having them. In my experience there was a huge quality improvement in these things the last few years, can't compare with how things were like ten years ago. Yes, they do use these simple bearings, but unless it is specified otherwise, there is nothing wrong with that, they didn't fool you. It's not for industrial use, if it was then I'd be more critical about them.
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Yes, they do use these simple bearings, but unless it is specified otherwise, there is nothing wrong with that, they didn't fool you. It's not for industrial use, if it was then I'd be more critical about them.
Quote Originally Posted by Clive S View Post
Have you checked what bearings are in the BK end bearings
Originally Posted by A_Camera
...for that price...? I mean, seriously, if the bearings are crap you buy some SKF quality bearings and replace them. It's a 5 minute job. Mine are so far perfectly OK. I just bought another kit. This one:
..Clive
The more you know, The better you know, How little you know
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18-06-2021 #3
As I made it clear, there is no such thing as "should be" unless it is specified. You can wish for anything, unless it is specified, it's just wishful thinking, and if it is as you wish then it is bonus. The only contract between you and the dealer is that what the specification is saying. That's the way things work. Expectations can be set very high, nobody can stop you from that, but it is naive to believe that something as cheap as these are, are the same in every aspect as the much more expensive ones. The OP is an adult, I am sure the OP understand this as well.
That's why it is important to point out not only the fact that your expectations are too high, but also that there is a set of bearings (the OP did not even expect any) and that those bearings may work for HOBBY use, so there is no reason to hurry changing those, unless he experience issues. Non of that did you or anyone else mentioned. You are so hang up on the AC bearings that that you lost focus from the subject, or target, building a CNC for HOBBY use. Your comment to him:
...is totally pointless and is what muddying the waters here because it says absolutely NOTHING except ridiculing him for his decision of buying those things. You are not saying ANYTHING about what to expect to see, or which sort you think is the acceptable bearing. NOTHING in that sentence is of any help to the OP or anyone visiting this thread. You didn't even bother to put a question mark after your sentence. The OP did not even expect any bearings in those seats, so the way I see it, any bearing is better than nothing.
In fact, you are so hang up on the AC bearings that you did not mention the most important parts of a ball screw, the screw and the nut. Those can actually cause a much more serious headache than bearings in those seatings. If the screw is bent or damaged there is nothing he can do, other than buying a new. Same for the nut, if something wrong with it and a cleaning does not solve it, then it's a case of biting the bullet and buying a new. Changing the support bearings is peanuts, easy to fix. Never the less, it can be an expensive thing to do for someone on a limited budget, especially if the current ones work well enough. What is "well enough" is not for you (or me) to define. It is up to him, the OP. Now, THAT is help for a newbie starting a new hobby activity. Just saying "Have you checked what bearings are in the BK end bearings" is pointless muddying. It would have been different if you had said more about how things should be according to your opinion, and explained the difference between bearings, but you did NOT do that, not before I chipped in with my opinion, which I have right to express also, without you telling me to shut up.
Are you always this rude or just today and only here? I think you should stop eating barbed wire for breakfast and take a cold shower in the morning.
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18-06-2021 #4
Ok, I didn't really want to take time out of my day to do this or bash heads with you but this needs to be done for the sake of those we are watching or will see this thread in months or years to come because what you are saying is totally wrong.
It's a simple fact, which if you don't believe me you can go ask SKF or any other bearing manufacturer is that deep groove bearings are completely the wrong bearing for the application these BK bearings are sold for. The whole point of the END fixing is to reduce axial movement and handle the linear forces and to do this then either Thrust bearings or angular contact bearings are the correct choices.
To say otherwise is WRONG and MISLEADING and no amount of arguing over a poor buying decision to save face will change this.
I didn't say that at all so please don't put words into my mouth.! I said that many on this forum had issues, which is true, and if you had been around long enough you would know this.
Well, that's exactly the problem here I think.? What experience do you have.? 1 set possibly 2 sets of BK bearings which if they are the same as these how could you know any difference.?
To say "in my experience" should actually mean you have experience of more than a couple of sets and actually experienced the difference between current and old components. If you had the experience then you wouldn't be making desperate face-saving comments like that and know that the current budget BK bearings are indeed worse and unfit for the purpose intended for the reasons I stated above.
You have the right to your opinions and I respect that, but I have the right to point out BULLSHIT when I see it and for the sake of others reading this now and the many 100's or 1000's that will read it in months and years to come I'm calling you out as pedaling BULLSHIT to save face for buying inferior components.
Whether you like it or not, the simple TRUTH is that DEEP GROOVE bearings are wrong for the application of end fixings for ball screws. It's not about AC are the best or the only ones which should be used, far from it, cheaper thrust bearings will work and are correct for the application also but AC is the better type and are what should be fit to the BK type bearings.
It's a simple financial fact that to produce these kits at such stupidly low prices that something must give and it's 99.9% nailed on most will come with DEEP Groove bearings for this very reason.
Now back to work.!-use common sense, if you lack it, there is no software to help that.
Email: [email protected]
Web site: www.jazzcnc.co.uk
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18-06-2021 #5
Relax Jazz, I am not exactly disagreeing about the differences with you or others, but as you say, it's about costs, so it is a compromise.
Regarding experience, I should actually ask the same... because honestly, if you have such low views on those BK/BF bearings then I have to assume that you don't use them. On the other hand, I am waiting for the 10th, so yes, I must claim that I have some experience with them, more than you think. OK, only for 1605 and 1204 screws, but none the less... I was not born yesterday just because I ask some questions occasionally.
Anyway, I am NOT saying that those bearings are as good as AC bearings. What made you believe that? All I am saying is that he should wait and see and decide on his own for the final decision. Of course it's good that the alternatives are clear and drawbacks are highlighted, but as been said before, replacing the bearings is easy and can wait. But then again, if replacing means complete redesign of bearing seats to fit AC bearings then it is a huge job for an amateur and also a large one for a pro. It's also a hobby machine, so aiming for something reachable is better than aiming at the stars and never get there.
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18-06-2021 #6
I'm 100% relaxed Camera but this isn't about costs at all, it's about what is suitable and what's not and those BK bearings with deep groove bearings are not suitable for a CNC machine because they are not designed to handle the loads in an axial direction. It completely defeats the point of fitting ball-screws if the end fixings are allowing the screw to float which they will with these deep grove bearings unless they are highly preloaded and it's this high preloading they are not designed to handle so they quickly wear excessively which in turn put stress on other parts of the machine. It quickly becomes a vicious circle of wear and stickiness.!
You are correct that I don't use these and never would, but I do have lots of experience of replacing them and helping other people who have unwittingly bought these, and the number is far more than your measly ten.!
In terms of experience fitting BK/BF bearings in general then I buy them by the 100 and just today I've fit 8 sets so you could say I know a little about them.!!
First of all, I didn't think you thought they were as good and never implied that you did. My objection to your comments is solely based on the fact that you advised the OP and advocate to others the use of Deep grove bearings for BK bearings was perfectly fine, they are NOT.
The other thing I don't agree with or understand is why anyone would buy these knowing they are poor quality or in this case plainly wrong and pay again to make good.? Crazy to me when for not much more you can buy the correct BK bearings.
On another note, I also feel you owe Clive S an apology because his comment was a valid one, even if it was short and to the point, your attack on him personally was unjustified and out of order in my opinion.!..-use common sense, if you lack it, there is no software to help that.
Email: [email protected]
Web site: www.jazzcnc.co.uk
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23-06-2021 #7
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