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IndustryArena Forum > Mechanical Engineering > Linear and Rotary Motion > Ball screw support bearing questions. Are $420 bearings necessary on this machine?
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  1. #1
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    Ball screw support bearing questions. Are $420 bearings necessary on this machine?

    I decided I want to get the backlash out of my 1978 Pratt & Whitney Tapemate C retrofit (Fanuc machine basically).

    It seems like the backlash is in the ball screws, but I wanted to replace the support bearings also.

    There is no info at Fanuc for the part number in the manual, so they said I need to pull the bearings to find the numbers.

    Well, I did that and they only have the generic 7204A then hand etched for the rest of the part number.

    The numbers look like
    7204A DBC9PK
    or
    7204A DBC9PX

    Not sure if that is an x or k?

    I gave this info and pics to a bearing house and I guess they sent it off to NSK.

    They came back with this part number:
    7204A5TRDUHP4Y

    When I look these up they are ABEC 7, P4 etc.

    https://www.motionindustries.com/pro...p?sku=00114980

    This seems like a lot of money for these 47mm bearings. I know bearings can be expensive, but is this reasonable for a 1978 machine? It has single nut NSK ball screws.

    I just want to make sure I am not paying too much for an over spec'd bearing. By the time I get done reconditioning two screws and replaced the support bearings I will be $2500 to $3000 in this old machine just for the XY screws and bearings (not including everything else).

    I have a lot of time and money in retrofitting it with all new AC motors, drives, full electronics, Mach4, programming time, etc etc, so I am too far into it not to get this backlash out. (~.0030 in Y and ~.0014 in X).

    I just want to make sure I need over $800 worth of bearings here.

    I am not even positive the old bearings are bad. They are old, but this machine was never in production (came from a university teaching NC programming). I have had it for 14 years myself and it was never really used during this time. I made a couple parts when I initially got it working with Mach 3, but recently I revived the interest again with getting it up on Mach 4 and upgrading the computer and some other stuff.
    Attached Thumbnails Attached Thumbnails 20191102_190426.jpg   20191103_200336.jpg  

  2. #2

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    Re: Ball screw support bearing questions. Are $420 bearings necessary on this machine

    Quote Originally Posted by jevs View Post
    I decided I want to get the backlash out of my 1978 Pratt & Whitney Tapemate C retrofit (Fanuc machine basically).

    It seems like the backlash is in the ball screws, but I wanted to replace the support bearings also.

    There is no info at Fanuc for the part number in the manual, so they said I need to pull the bearings to find the numbers.

    Well, I did that and they only have the generic 7204A then hand etched for the rest of the part number.

    The numbers look like
    7204A DBC9PK
    or
    7204A DBC9PX

    Not sure if that is an x or k?

    I gave this info and pics to a bearing house and I guess they sent it off to NSK.

    They came back with this part number:
    7204A5TRDUHP4Y

    When I look these up they are ABEC 7, P4 etc.

    https://www.motionindustries.com/pro...p?sku=00114980

    This seems like a lot of money for these 47mm bearings. I know bearings can be expensive, but is this reasonable for a 1978 machine? It has single nut NSK ball screws.

    I just want to make sure I am not paying too much for an over spec'd bearing. By the time I get done reconditioning two screws and replaced the support bearings I will be $2500 to $3000 in this old machine just for the XY screws and bearings (not including everything else).

    I have a lot of time and money in retrofitting it with all new AC motors, drives, full electronics, Mach4, programming time, etc etc, so I am too far into it not to get this backlash out. (~.0030 in Y and ~.0014 in X).

    I just want to make sure I need over $800 worth of bearings here.

    I am not even positive the old bearings are bad. They are old, but this machine was never in production (came from a university teaching NC programming). I have had it for 14 years myself and it was never really used during this time. I made a couple parts when I initially got it working with Mach 3, but recently I revived the interest again with getting it up on Mach 4 and upgrading the computer and some other stuff.
    I would clean up the old bearings and put them back in If it has done very little work why did you even take it apart most likely the Ballscrews where ok as well, you said it had backlash how did you check this
    Mactec54

  3. #3
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    Re: Ball screw support bearing questions. Are $420 bearings necessary on this machine

    Quote Originally Posted by mactec54 View Post
    I would clean up the old bearings and put them back in If it has done very little work why did you even take it apart most likely the Ballscrews where ok as well, you said it had backlash how did you check this
    I measured the backlash in several ways. First by just jogging the machine back and forth and measuring it (with a dial indicator). I also measured at the nut that adjusts the support bearing clearance and I could not get much of anything there. It did not appear to have any give there letting the screw move back and forth. Then I also measured how much I could rotate the ball screw by hand before any table movement occurred with the indicator. This amount of free play was about equal to the amount the motor had to rotate to move the distance of backlash I was getting with the first measures of machine movement. So, with that matching on easy to feel rotational slop and no movement of the support bearings, that left one culprit.

    I then removed the ball screw, mounted it in my lathe, clamped the tool post to the ball screw nut and put pressure on it in back and forth and measured backlash with an indicator. I was getting at least .001 or better, but I cannot apply near the force it takes to move the bed. I cannot even move the bed by hand it is so heavy and takes some force to break fee of the "suction" of the ways to get moving. I can only move it with a pry bar even though it seems easy to move with the screw by hand. I can also feel a tiny bit of side to side wiggle with the ball screw nut.

    The X axis is much less, but it is also moving less than half the mass of the bed that the Y is, so that kind of makes sense.
    There is certainly backlash, no doubt about that, and mostly if not all in the ball screw as far as I can tell. There is no play in the oldham couplers.

    I think they may have had the bearings over tightened as well. I ended up having to use an air hammer to get the nuts loose and these nuts are used to adjust the bearing backlash out, it should not be that tight. It has a slit and bolt to lock it to the threads once it is set correctly. It only has holes for a spanner and I couldn't get enough bite with that to loosen it. I even used a pipe wrench with no luck (which unfortunate marred the nut OD, but that is only cosmetic). I had to use a point on the air hammer in one of the spanner holes to break it free. Then it came undone pretty quick.
    I am not sure how the bearings should feel because I do not have a new one to compare too, but I don't trust them to be as good as new ones will be and I will be careful to tighten them properly. I cleaned out the Y set. With no grease they are not very smooth feeling, but maybe with grease they would be.
    I just think it would be a better idea to replace them along with the rebuilt ball screws? Then I know what I got.

    Is there a sure way for me to tell these bearings are good or bad? If they were over compressed that seams like it has potential to deform things or cause more wear that you might not feel, but could create more heat etc?

  4. #4

    Re: Ball screw support bearing questions. Are $420 bearings necessary on this machine

    The bearing price on that website seems retarded. Call Tull Bearing in Minneapolis, MN and see what they tell you. 612-588-1185. They've been selling spindle and ballscrew support bearings for decades. Plus all other types of drive stuff like belts and seals and such. I don't think they even have a website. They seem not to need one.

    One thou backlash isn't that much. Does your control have a backlash compensation function? Take care of it there if it does. If your machine is as tight as you say it is, you might double check your gibb adjustments. Or is this a linear rail machine? Wouldn't think so coming from the 70's.

    Not sure how you're going to remove backlash in a single nut ballscrew unless you can get yourself a set of oversize bearing balls of exactly the right diameter(s). Double nut you can grind the spacer and fit a modified tie bar. Never touched a single nut before.

    If you do replace those bearings, get the proper grease and don't over fill. You'd be surprised how little grease is the right amount. Many time the bearings will be pre- greased and save you the trouble.

    I must say an odd but kinda cool looking machine. Good luck with it. Call Tull. Cant hurt. They'll have the Klubber grease too. (Expensive-ish) But maybe the bearings will be pre-greased.

    Dave

  5. #5
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    Re: Ball screw support bearing questions. Are $420 bearings necessary on this machine

    I am not buying bearings from that website (it is way high on there), but I did get a better price from that same companies local location. That was mainly a link to show the bearing specs. The price I got quoted is $389.17 plus tax which comes to $419.28. However, still about $840 for two sets

    My control (Mach 4 with Ethernet Smooth Stepper) does have backlash compensation, but the Y is .0030" or a bit over backlash and the X is .0014". I have never been content with this and had planned to see what I can do about it. Now that I have everything else done on the machine, I want to address this. I figure I might as well fix them both at the same time and get them as low as possible. From that point forward I will know the machine and what the best it can be is and how it lasts going forward.

    The machine has ways, which appear to show no real wear that I can tell judging by the crosshatching on the sides. I did suspect the gibbs might be too tight also, but I checked them and even loose I can't budge it by hand without a bar to get it going I pulled the adjuster screws out to make sure there was no tension and moved the bed so the wedges came out some, so the pressure was low to none. It was still the same, so it is just hard to move by hand, and it is a heavy bed. Everything appears to be getting oiled nicely by the oiler. Even the X, which has lighter load on it, I could not budge by hand. However, they both move easily with the screw (twisting by hand). Overcoming the surface tension of the ways takes some force when not using a screw.

    The places that rebuild ball screws say they can get them to zero backlash. They preload the balls in the size to make this happen, but they also check the nut and screw and grind if needed. My understanding is that the single nuts are actually spaced in a way that the balls are pushed in each direction internally, which kind of acts like a double nut except you can never adjust it out, you get what you get on the build and that is it. I figured if I ever run the machine enough after this to get backlash again, then I may look into a double nut setup if it will fit. I think there may be enough room. However, this would add a bigger expense right now and they claim they can get them to zero backlash.

    I will still call around about the bearings though, thanks for the name of the business. I would kind of like to order them out of state and avoid the extra $60 in taxes if possible.

    Ultimately I am going to buy good bearings, and if these are the one it takes, then I will just have to bite the bullet. I was kinda hoping these would be cheaper or there was an alternative just as good, but I want the machine to be as good as it can be.
    Attached Thumbnails Attached Thumbnails 20191103_195944.jpg   20191103_200717.jpg  

  6. #6

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    Re: Ball screw support bearing questions. Are $420 bearings necessary on this machine

    Quote Originally Posted by jevs View Post
    I measured the backlash in several ways. First by just jogging the machine back and forth and measuring it (with a dial indicator). I also measured at the nut that adjusts the support bearing clearance and I could not get much of anything there. It did not appear to have any give there letting the screw move back and forth. Then I also measured how much I could rotate the ball screw by hand before any table movement occurred with the indicator. This amount of free play was about equal to the amount the motor had to rotate to move the distance of backlash I was getting with the first measures of machine movement. So, with that matching on easy to feel rotational slop and no movement of the support bearings, that left one culprit.

    I then removed the ball screw, mounted it in my lathe, clamped the tool post to the ball screw nut and put pressure on it in back and forth and measured backlash with an indicator. I was getting at least .001 or better, but I cannot apply near the force it takes to move the bed. I cannot even move the bed by hand it is so heavy and takes some force to break fee of the "suction" of the ways to get moving. I can only move it with a pry bar even though it seems easy to move with the screw by hand. I can also feel a tiny bit of side to side wiggle with the ball screw nut.

    The X axis is much less, but it is also moving less than half the mass of the bed that the Y is, so that kind of makes sense.
    There is certainly backlash, no doubt about that, and mostly if not all in the ball screw as far as I can tell. There is no play in the oldham couplers.

    I think they may have had the bearings over tightened as well. I ended up having to use an air hammer to get the nuts loose and these nuts are used to adjust the bearing backlash out, it should not be that tight. It has a slit and bolt to lock it to the threads once it is set correctly. It only has holes for a spanner and I couldn't get enough bite with that to loosen it. I even used a pipe wrench with no luck (which unfortunate marred the nut OD, but that is only cosmetic). I had to use a point on the air hammer in one of the spanner holes to break it free. Then it came undone pretty quick.
    I am not sure how the bearings should feel because I do not have a new one to compare too, but I don't trust them to be as good as new ones will be and I will be careful to tighten them properly. I cleaned out the Y set. With no grease they are not very smooth feeling, but maybe with grease they would be.
    I just think it would be a better idea to replace them along with the rebuilt ball screws? Then I know what I got.

    Is there a sure way for me to tell these bearings are good or bad? If they were over compressed that seams like it has potential to deform things or cause more wear that you might not feel, but could create more heat etc?
    Well did you ever try and check to see what the spec's where for the machine before you took it apart, I think you will find the old control controlled any backlash it had in the Ballscrews, which is what all machining centers do and use

    It seems like you have done some damage to the nut , which will need to be replaced, and yes they are meant to be that tight, they will have a Torque number for the nut to be set at you can not over torque these Bearings sets as they are a matched set, the preload is set from the manufacture of the Bearing so you can't over load them

    The Bearings you can take them apart and inspect the races, looking at your machine ways they are still as new as would of been the rest of the machine, this was a machine that needed to run not be taken apart

    The best thing you could do is add a high pressure oil pump to get oil into the slides this is why it is so hard move, they need to float on a film of oil, this may be why the Ballscrews have developed the backlash and wear .030 wear points to no lubrication on a machine that has done no real work
    Mactec54

  7. #7
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    Re: Ball screw support bearing questions. Are $420 bearings necessary on this machine

    Yes, there is no spec on backlash in any of the manuals unfortunately. I have no way to know how good it would have been new or what the allowable slop should be over time. There are specs on repeatability and accuracy as new, but the original accuracy spec is not great at .002"/12". Repeatability is .0005" though. Of course this is based on the original controls/motors/encoders which have all been replaced with much better stuff now.

    I will only know how good the backlash can be by reconditioning it with rebuilt ball screws, new bearings, and proper installation/adjustment.

    I do not believe and cannot find any reference to any backlash compensation either. This was one of the first Fanuc controls (programs manually entered with a single line LED display, or loaded by paper tape. Pretty archaic by today's standards.

    Backlash is bad regardless of compensation ability anyway. I think most people would agree once it gets over .003, that you might want to address it. The sloppier things get, the faster they are going to wear. Backlash compensation cannot work as good as actual low backlash.

    I have not done any damage to the nut, I am not sure why you way say that? As I said, I did not adjust anything. I only checked things, then pulled it apart so I can make it better. The way it is/was, is the way I got it. Unfortunately there is no torque value or any instructions on setting the bearing tension. See pic, that is the only mention of it in all the manuals (I have them all, even training manuals, schematics, parts manuals, operation manuals, university training courses etc). The bearing tension would not affect the wear of the nut anyway though, only the wear of the bearings.

    The ways stay wet with oil. The pump works. I also have it programmed to run with any moves of X and Y. You think this one is inadequate? All the fittings and plumbing are in great condition and like I said it keeps things wet. However, I cannot say how it worked before with the old controls or if they kept oil in it etc. I assume they did based on condition and the docs I see and the people watching over it.

    One thing to note is that the ball screws have to be manually lubricated (greased) as far as I can tell. There is also no wipers on the screw nut. This could be an area that shortens life of the ball screws if not meticulous.

    This is something I do need to figure out though. I am not sure where I am going to come up with a proper torque setting for the bearing nut?? I think I also need to modify the nut to make it easier to tighten/adjust. You cannot even get to the thread locking screw without removing the motor and oldham coupler. This is something that could be improved a little.

  8. #8

    Re: Ball screw support bearing questions. Are $420 bearings necessary on this machine

    Hello Jevs,

    I doubt that at this point anyone is going to change your mind, but I'm feeling like some of the others around here and think you should use what you have. This is as I said, a very cool looking machine. Surprising sort of as most the coolest stuff was built in the 60's, whereas in the 70's design aesthetics started heading south. So consider yourself lucky. Still this machine is from 78 which means 40 years old as it sits. The entire Z axis portion of this machine gives me doubts. The backlash you're concerned about could be taken care of for the most part buy the control. Does your control have pitch error compensation? If it does, maybe your money would be better spent having the thing laser shot and ballbar tested. But even that may be getting outside the bigger picture.

    I think this is a great machine for you to learn on. Programing, tool paths, setup, machining characteristics of different metals, tool choice, control functions and characteristics, all of it. You've already got your hands dirty by tearing it apart. Knowing what's under the sheet metal will never hurt. I've rebuilt many machine tools, and I know the process teaches you a lot of useful information that you can take with you forever.

    It's doubtful you're going to be making missile components for Boeing. Working to tenths is likely a once in a blue moon thing as well. You'd be surprised at how many dimensions on most things don't really matter at all. That is if they're designed correctly. This thing will likely, as it sits, do as much or more then you thought it could. It's weaknesses will become apparent soon enough, and you'll learn your own tricks to overcome them. Just like running an old worn out lathe or beater car. You learn what it does and doesn't do well and use your smarts to outsmart it. This skill is also useful and can be carried with you.

    You're actions at present remind me a bit of myself in the early days. Perfectionism creeps in and makes you do things that really aren't necessary. Oddly enough, getting into machining is what broke me of my own must-be-perfect nature. People don't want to pay for your perfectionism. Most parts don't need it either. Don't get me wrong. Set your own standards about what's acceptable to go out the door. Feel good about your work. But try not to be annul, or overdue what isn't necessary unless you like working for nearly nothing.

    Alright enough of that. I respect what you're after, but think this machine is not what deserves this much attention. Save your pennies for a machine that was built at the least in the 90's. But learn a ton on what you have for now.

    Besides... you never have to get rid of the old beauty if you don't want to.

    Dave

  9. #9

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    Re: Ball screw support bearing questions. Are $420 bearings necessary on this machine

    Quote Originally Posted by jevs View Post
    Yes, there is no spec on backlash in any of the manuals unfortunately. I have no way to know how good it would have been new or what the allowable slop should be over time. There are specs on repeatability and accuracy as new, but the original accuracy spec is not great at .002"/12". Repeatability is .0005" though. Of course this is based on the original controls/motors/encoders which have all been replaced with much better stuff now.

    I will only know how good the backlash can be by reconditioning it with rebuilt ball screws, new bearings, and proper installation/adjustment.

    I do not believe and cannot find any reference to any backlash compensation either. This was one of the first Fanuc controls (programs manually entered with a single line LED display, or loaded by paper tape. Pretty archaic by today's standards.

    Backlash is bad regardless of compensation ability anyway. I think most people would agree once it gets over .003, that you might want to address it. The sloppier things get, the faster they are going to wear. Backlash compensation cannot work as good as actual low backlash.

    I have not done any damage to the nut, I am not sure why you way say that? As I said, I did not adjust anything. I only checked things, then pulled it apart so I can make it better. The way it is/was, is the way I got it. Unfortunately there is no torque value or any instructions on setting the bearing tension. See pic, that is the only mention of it in all the manuals (I have them all, even training manuals, schematics, parts manuals, operation manuals, university training courses etc). The bearing tension would not affect the wear of the nut anyway though, only the wear of the bearings.

    This is something I do need to figure out though. I am not sure where I am going to come up with a proper torque setting for the bearing nut?? I think I also need to modify the nut to make it easier to tighten/adjust. You cannot even get to the thread locking screw without removing the motor and oldham coupler. This is something that could be improved a little.
    That gives you enough information .002"/12". Repeatability is .0005" and would of been very good back when this was first built, you need it to be in this spec's and is the standard that most machines still have today for the repeatability, the .002/12" though is not so good though which says the Ballscrews are not that great a quality, so if they regrind the screws you may be able to get even better than the .002/12" if the Ballscrew rebuilder is any good

    You said in your post that you damaged the nut any damage to the nut by removing it will have to be fixed or replaced, what size is the thread dia this will give you an idea of how much torque can be used on the nut, this would be quite high on your machine

    As I said these are not a nut that you adjust, you tighten to a Torque setting and that is it, you have matched bearings and they have to have the max you can tighten the Nut too
    Mactec54

  10. #10
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    Re: Ball screw support bearing questions. Are $420 bearings necessary on this machine

    Quote Originally Posted by the_gentlegiant View Post
    Hello Jevs,

    I doubt that at this point anyone is going to change your mind, but I'm feeling like some of the others around here and think you should use what you have. This is as I said, a very cool looking machine. Surprising sort of as most the coolest stuff was built in the 60's, whereas in the 70's design aesthetics started heading south. So consider yourself lucky. Still this machine is from 78 which means 40 years old as it sits. The entire Z axis portion of this machine gives me doubts. The backlash you're concerned about could be taken care of for the most part buy the control. Does your control have pitch error compensation? If it does, maybe your money would be better spent having the thing laser shot and ballbar tested. But even that may be getting outside the bigger picture.

    I think this is a great machine for you to learn on. Programing, tool paths, setup, machining characteristics of different metals, tool choice, control functions and characteristics, all of it. You've already got your hands dirty by tearing it apart. Knowing what's under the sheet metal will never hurt. I've rebuilt many machine tools, and I know the process teaches you a lot of useful information that you can take with you forever.

    It's doubtful you're going to be making missile components for Boeing. Working to tenths is likely a once in a blue moon thing as well. You'd be surprised at how many dimensions on most things don't really matter at all. That is if they're designed correctly. This thing will likely, as it sits, do as much or more then you thought it could. It's weaknesses will become apparent soon enough, and you'll learn your own tricks to overcome them. Just like running an old worn out lathe or beater car. You learn what it does and doesn't do well and use your smarts to outsmart it. This skill is also useful and can be carried with you.

    You're actions at present remind me a bit of myself in the early days. Perfectionism creeps in and makes you do things that really aren't necessary. Oddly enough, getting into machining is what broke me of my own must-be-perfect nature. People don't want to pay for your perfectionism. Most parts don't need it either. Don't get me wrong. Set your own standards about what's acceptable to go out the door. Feel good about your work. But try not to be annul, or overdue what isn't necessary unless you like working for nearly nothing.

    Alright enough of that. I respect what you're after, but think this machine is not what deserves this much attention. Save your pennies for a machine that was built at the least in the 90's. But learn a ton on what you have for now.

    Besides... you never have to get rid of the old beauty if you don't want to.

    Dave
    I appreciate and completely agree to what your saying here. And yes, at this point there is no turning back really. I could have just ran it as/is, but I have OCD and I am a perfectionist. This can be a curse as you may know, but once you got something dialed in and happy, then it is smooth sailing from there usually . I just want to make it is as good as it can be.

    I know what you mean about the Z, this is some old school archaic tool changing and the spindle can only do 4k, but I already have thoughts of some day upgrading/changing all that, but not sure I will. That becomes a tipping point for sure to just getting a new machine.

    At this point, this is just my personal hobby machine, but I do have hopes of someday offering some products for sale etc.

    The main thing about the money I spend on it, I justify it more by considering it an education at this point. This backlash chasing is somewhat an education too (expensive one), but I really want to know what it will be in the end and only one way to find out...spend some money. I was going to clean up and reball the screws myself, but quickly learned what it takes to do it right and decided to send them out.

    This is actually a very low time consuming part of the whole build considering what I put into the whole machine electronics and Mach4 programming etc. (and the Mach3 setup prior)

    Of course if I could go back in time, it seems like my time may have been better spent buying a brand new machine, but I would not have learned everything I learned on this one. Since I have had this I have done a lot of other things that all started from my interest in this machine. At one point in time I considered this machine done, but now that I decided to add 3D probing, auto tool height setting, Mach 4, new internal computer (more integrated), I decided I want to try to edge out all the backlash I can. I was chasing 3D probe vs edge finder differences and backlash kept coming into the thought process, so I decided to deal with it and make it as good as I can.

    I have learned a ton since I first dragged this machine home. I can now design a CNC machine from scratch and this machine started that learning for me. I now have several machine tools, four 3D printers, Laser cutter, etc However, I need this machine running to start building/machining parts for the CNC router I designed. That is where I will start getting deeper into the actual operations of the mill. I only made a few car parts with it on Mach3. Most of this machines life with me has been spent just sitting around waiting for me to find time to use it.

    With all that said, the main thing I made this post for was to source less expensive bearings or determine if these level of bearings are truly required in this application. I have no way on my own to decipher those original bearing numbers and relate them to a new bearing, so I am relying on NSK/Motion Industries so far to tell me. Possibly they are just quoting me the best they have to offer (ie most expensive)...dunno.

    Right now I will be waiting for the screws to get looked at and done, so I am spending a little time learning more about the bearings.

    Just some non related to this thread pics attached to show the transform of the electronics cabinet. Going from Mach3 to Mach4 was a significant process alos. Some of the hardware had already gone obsolete with no pokeys plugin support. Had to adapt a newer version to the Machmotion operator panel. Lots of programming involved with that too getting the tool changer working and other mods.

  11. #11

    Re: Ball screw support bearing questions. Are $420 bearings necessary on this machine

    Maybe you can find some less expensive bearings here https://www.vxb.com/searchresults.as...h=7204&Submit=
    Jim Dawson
    Sandy, Oregon, USA

  12. #12
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    Re: Ball screw support bearing questions. Are $420 bearings necessary on this machine

    Yeah, I do wonder if some of that accuracy is fudged in with no backlash compensation, encoder characteristics, original DC servos capability etc. as well though. Dunno.

    I sent the ball screws to Thread-Craft, Inc. based on a few peoples comments on the forums and talking to them. I also called a couple other places. One place I called pretty much let me know I didn't want to send them there.

    I am just hoping their price comes in line with what the other place that had a couple good references quoted me.

    The ball screws are NSK, they have a good reputation. However, I have no idea the original specs.

    Oh, about the nut, when I was talking about the nut, I meant the bearing backlash adjusting nut. I marred the OD of it trying to get it off (which has no affect on anything other than aesthetics). The function portion of it is still perfect (the parts that go against the bearings and it's threads etc). I will clean it up the OD surface. I would like to figure out a better way to get a wrench on it than the 3 holes for a spanner though. I could not get it off using the spanner I have, even once the coupler was out of the way. There is not enough room to even get the spanner I have in there with the coupler on. You also cannot loosen the thread locking bolt without taking the coupler off (and removing the motor most likely). Maybe if I made a custom hex wrench I could. The coupler has to be removed with a puller. This is not convenient for future checking/adjusting and is not going to work well for any kind of a real torque reading. The best I could do with it as it is would be to go by feel for tightening it.

    Couple simple parts I made with it before this last round of upgrades attached. I only made a few parts in all these years I had it.
    Attached Thumbnails Attached Thumbnails 20191102_175324.jpg  

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