X axis spring back on vice squaring ?

[handlewanker]

Hi....ultimately, any backlash will appear at the tool point no matter where it originates from.....this could be from flex in the system, oil film thickness or warm up from cold as the machine works.

A job that takes an hour to go through will produce a warming in the components and that means expansion etc.......where you start off from is not where you end up at when the metal expands, so in the end you have to compromise and assume the part you make is going to be as good as it's ever going to get.

I would only worry if the part being made showed dimensional errors....like a hole that was cut by circular interpolation and was not round etc.
Ian.

[handlewanker]

Steel shim would be best, you should be able to get this from a local industrial supply, sometimes Bearing suppliers will also have shim they may even have some already the right size for your bearings, .05mm should be enough

Yes C Ratings have always been used for Ballscrews, and correct the smaller the number the better the Ballscrew Pitch Lead error is

Yes correct ABEC ratings, but C ratings are a little confusing in the SKF page as well, the bearing ratings are not only about the radial clearances as for AC Bearings this is adjustable, no matter what the grade is, the ratings are about the whole Bearing

Bearings rated with the ABEC rating system typically have five ratings in the class scale that range from the widest tolerances to the tightest tolerances of the bearings with rating numbers of 1, 3, 5, 7, and 9. Each number corresponds to a degree of roundness in the outer and inner races of a bearing. The higher the rating number of bearings, the tighter the component parts for tolerance, meaning that a higher ABEC grade is assigned to a ball bearing manufactured against a higher standard of precision. For instance, a ball bearing rated at a grade of 9 provides the highest precision and efficiency.

Quite right Mac.......but you forget one thing (apparently old age does not become you).......when that high tolerance bearing gets pressed into a bore it takes on a different characteristic.....same as when it gets pressed onto a shaft the characteristic of the tight dimensions varies too.

I'm talking about radial bearings as Ang cons are in a different category of application, fit and running characteristics.........most of which are unquantifiable by the layman.

In this case common radial bearings are not in the picture as thrust loads are being catered for............having highly rated ang con bearings for ball screw needs is a minimal gain situation due to, as you say, any mismatched pair of bearings can be set up with shims to produce any characteristic you need.

This would not be a factor for a spindle where the running loads are more severe than just a ball screw thrust force.
Ian. .

[mactec54]

Quite right Mac.......but you forget one thing (apparently old age does not become you).......when that high tolerance bearing gets pressed into a bore it takes on a different characteristic.....same as when it gets pressed onto a shaft the characteristic of the tight dimensions varies too.

I'm talking about radial bearings as Ang cons are in a different category of application, fit and running characteristics.........most of which are unquantifiable by the layman.

In this case common radial bearings are not in the picture as thrust loads are being catered for............having highly rated ang con bearings for ball screw needs is a minimal gain situation due to, as you say, any mismatched pair of bearings can be set up with shims to produce any characteristic you need.

This would not be a factor for a spindle where the running loads are more severe than just a ball screw thrust force.
Ian. .

Another rant, with no substance, who is taking about Radial Bearings, turn the page AC Bearings are on the next page

Stop thinking that you are better than a Layman, nobody has the right to compare

All Bearings are fitted by what ever Grade of Bearing they are, Bearings from name brand manufacturer's all have a fitting Tolerance listed for the ID and the OD of the Bearings, no matter what the Grade is, even someone like yourself should understand and know this, even a layman as you word it, can read and understand this

Ballscrew thrust Bearings see a much higher loading than, Spindle Bearings, you have that back to front, just your lack of knowledge on the subject , that is why on real machining centers, the thrust Bearing have at least 5 times the load rating than what spindle bearings do, most Ballscrew thrust Bearings are special in some way, and can not be compared to Spindle Bearings, they are totally different in there construction ( Heavy Duty ) and how they are used

Hobby level is a different story, for Bearing selection it's what ever works to get the job done, with your way of thinking though, nothing would even get done

This is what a Ballscrew Thrust Bearing looks like

[handlewanker]

Mac...I did say that the high tolerance bearings are only as good as the bore and shaft they are fitted too........or didn't you understand that part?

If the housing is not perfectly round then it doesn't really matter how good the tolerance on the bearing is if the housing is a thou oval.......which can happen if the user is slack with their machining ability.

I really think you're so far up in the clouds with talk of extreme conditions when really we are talking hobby talk not heavy industry and magic machining centres.

BTW......I doubt that most if any hobbyist would have access to or have knowledge to surface grind angular contact bearings accurately enough to make them a matched pair.........but your head is in the clouds so that aspect escaped you.,,,,.......stay with the shimming as that is probably what most hobbyists would relate to.

Incidently..........as the thrust bearing housing(s) in this case is brand new and a Taiwanese "better quality" make....they DO specifically state NOT to strip them down as they are factory preloaded.

Are you now saying that the thrust bearing(s) fitted on this machine in question are faulty and need shimming......shock horror....is there no end to your nonsense?

Also.....I doubt that the ballscrew A/C thrust bearings on this machine will ever be loaded more heavily than the spindle bearings......it's going to be used for HOBBY PURPOSES.

A high RPM will do more damage to a bearing than relatively low speed loading that ballscrews do most of the time......in the hobby world that is....which is where we are at, not on some machining centre you mentioned that goes hell for leather just to break even at the end of the day and is exposed to more extreme conditions than any hobby mill ever would have.
Ian.

[mactec54]

If the housing is not perfectly round then it doesn't really matter how good the tolerance on the bearing is if the housing is a thou oval.......which can happen if the user is slack with their machining ability.

The only one talking about bearing fits and housings is you, how about a reality check

BTW......I doubt that most if any hobbyist would have access to or have knowledge to surface grind angular contact bearings accurately enough to make them a matched pair.........but your head is in the clouds so that aspect escaped you

I just stated what I do, with no aspect that others could do the same, I think if you read which seems to be a problem for you that I did also say that most use shims

Incidently..........as the thrust bearing housing(s) in this case is brand new and a Taiwanese "better quality" make....they DO specifically state NOT to strip them down as they are factory preloaded.

Are you now saying that the thrust bearing(s) fitted on this machine in question are faulty and need shimming......shock horror....is there no end to your nonsense?.

Another reality check for you do some reading the web site say's that they may need shimming

Also.....I doubt that the ballscrew A/C thrust bearings on this machine will ever be loaded more heavily than the spindle bearings......it's going to be used for HOBBY PURPOSES.

( I Doubt ) Again more BS, and lack of knowledge on the subject

A high RPM will do more damage to a bearing than relatively low speed loading that ballscrews do most of the time......in the hobby world that is....which is where we are at, not on some machining centre you mentioned that goes hell for leather just to break even at the end of the day and is exposed to more extreme conditions than any hobby mill ever would have.
Ian.

That's not what you said in the last post on the subject, you are also incorrect at the Hobby level, the same applies ,Again your answer and Posts shows your lack of knowledge on the subject

[handlewanker]

So Mac......how thick a shim do you recommend fitting to one of these Taiwanese thrust housings to "correct them" ?..........001"......002" more ???....I'm quite sure a hobbyist has material of that variety just laying about to attempt to cut shims from............have you ever worked with that thin a material?

We are talking about the "better quality" Taiwanese offerings aren't we, not some exotic stuff that you won't find for a hobby machine.

If you fit a thicker shim you will end up with preload allright.....lots of it...... just how much you actually need is a debatable point.

BTW.....the housing for any ball race is THE most important factor, in case you aren't aware, as it will distort a ball race outer race otherwise making a high tolerance ball race scrap in a short while.

BTW once again.......the suppliers of the Tawanese thrust housings....AS FITTED TO THIS MACHINE........ state specifically that the housing should NOT be stripped down as the preload is applied at the factory...........what part of that statement don't you grasp or are you only aware of industry standard thrust housings.....like the one you posted in post #63......totally out of context to this thread.

Get real Mac, this is a hobby situation and always will be, not an industrial application.

If it were an industrial situation there would be a service guy doing the trouble shooting as that's what the warranty would cater for.

THIS is a DIY CNC retrofit on a hitherto manual machine, and as you are apparently not aware of such matters, at the DIY level, without too much engineering skill, anything can go out of wack with just the turn of a screw etc.

I'll stress this point for the last time........this is a hobby world scenario where the game play is off the shelf plug and play components where the old methods of fitting, filing and scraping have no place.

No one wants to mess around with the components like you suggested if they are suspect......when you buy ready made for a purpose you shouldn't have to under any circumstances.
Ian.

[mactec54]

So Mac......how thick a shim do you recommend fitting to one of these Taiwanese thrust housings to "correct them" ?..........001"......002" more ???....I'm quite sure a hobbyist has material of that variety just laying about to attempt to cut shims from............have you ever worked with that thin a material? .

You can get the shims needed already made from a Bearing supplier, but you all ready know this

We are talking about the "better quality" Taiwanese offerings aren't we, not some exotic stuff that you won't find for a hobby machine...

The housing and Bearings is Just more of the same, with a little more cost, at 54 Euros what do you expect to get

If you fit a thicker shim you will end up with preload allright.....lots of it...... just how much you actually need is a debatable point..

It is then adjustable, to remove any backlash he has, as they quote on there web site, Adjustable

BTW once again.......the suppliers of the Tawanese thrust housings....AS FITTED TO THIS MACHINE........ state specifically that the housing should NOT be stripped down as the preload is applied at the factory...........what part of that statement don't you grasp or are you only aware of industry standard thrust housings.....like the one you posted in post #63......totally out of context to this thread.

What part can't you understand or read, this is from there web site

There are many FK blocks on the market, and the problem is, they all look the same. Prices differ greatly. We have chosen to buy/sell only the highest quality bearings (P5 Taiwan) suitable for ballscrews in quality class C3 through-C10. The blocks we have in stock with the high quality bearings is the type that can be made backlash free, by adjusting the pre-load on the angular contact bearings.

They don't say how to adjust them to make them Backlash Free, and the only way to do this is to add a shim which is the normal thing most Hobby users have to do

If it were an industrial situation there would be a service guy doing the trouble shooting as that's what the warranty would cater for..

If you have a machine that is still under warranty, why would you mess with it, what's your point, when there is no warranty every machine owner does what ever they have to do, to keep there machines running

THIS is a DIY CNC retrofit on a hitherto manual machine, and as you are apparently not aware of such matters, at the DIY level, without too much engineering skill, anything can go out of wack with just the turn of a screw etc. I'll stress this point for the last time........this is a hobby world scenario where the game play is off the shelf plug and play components where the old methods of fitting, filing and scraping have no place...

What's your point, the OP built this machine, and wants to improve it, that's more than you can do, or have ever done he knows his machine inside out, so for him to adjust something is not a problem, with the right guidance the Hobby guy can achieve anything he wants to, they don't have to be an Engineer or a machinist, most of all they just need to try something, that's what most do

No one wants to mess around with the components like you suggested if they are suspect......when you buy ready made for a purpose you shouldn't have to under any circumstances...

Then you would send the faulty part back to Taiwan at your cost, which would cost you more then the part is worth, the problem is they don't want the part back and they will tell the OP the same add a shim to fix the problem

[handlewanker]

Mac....old bean.....before you have a seizure from banging away at the keys like crazy and being obnoxious in the process......consider this FACT........if you have 2 angular contact bearings that you would like to use in a thrust resisting design and when you apply them face to face, that is with the cups facing inwards, you will find that almost any unmatched pair will be just about good enough to be backlash free when in a static mode.

They may not be suitable as an unmatched pair to do the job for thrust resistance without some preload.....hence the application of a shim or grinding.....we all know that.

The problem is if you stick a .001" thick shim between the 2 inner races and apply pressure from the retaining thingy against the outer race......you "might" get a good thrust resisting thrust bearing set-up........but what if you can't get .001" shims from your local dealer?......,001" is 1/4 the thickness of a Human hair or 1/4 the thickness of a piece of copy paper.

On the DIY level, where we are at........supposing the inner race bore of the AC bearings is 16mm diam and the maximum outer diam of the shim needs to be 25mm at most........HOW DO YOU PIERCE A HOLE 16MM DIAM IN A PIECE OF .001" SHIM STOCK AND THEN CUT IT TO 25MM DIAM without crinkling it up?

I think you have glibly suggested what is required without realising the ramifications of making and handling such flimsy material.

BTW......when I have to shim a pair of AC bearings I use 2 shims of at leas6t 2mm thickness....one against the inner race and another against the outer race.

II can then rub the inner race one down to minus a thou or more for the preload required as this is so very easy to do.....at the DIY level where we/I am at.

I should mention that I also have a surface grinder for the purpose, but most do not.

I have also cut thin washers on my lathe for just such a purpose too.

I'll say no more on this topic...... even if you feel obliged to make more caustic comments in an attempt to have the last word or bolster your own ego complex.

I look forward to the final outcome that cures the problem that started this thread.
Ian.

[mactec54]

Mac....old bean.....before you have a seizure from banging away at the keys like crazy and being obnoxious in the process......consider this FACT........if you have 2 angular contact bearings that you would like to use in a thrust resisting design and when you apply them face to face, that is with the cups facing inwards, you will find that almost any unmatched pair will be just about good enough to be backlash free when in a static mode.

They may not be suitable as an unmatched pair to do the job for thrust resistance without some preload.....hence the application of a shim or grinding.....we all know that....

So it has taken you this long to get it now you are saying the same thing as I have been

The problem is if you stick a .001" thick shim between the 2 inner races and apply pressure from the retaining thingy against the outer race......you "might" get a good thrust resisting thrust bearing set-up........but what if you can't get .001" shims from your local dealer?......,001" is 1/4 the thickness of a Human hair or 1/4 the thickness of a piece of copy paper....

Then you make one

On the DIY level, where we are at........supposing the inner race bore of the AC bearings is 16mm diam and the maximum outer diam of the shim needs to be 25mm at most........HOW DO YOU PIERCE A HOLE 16MM DIAM IN A PIECE OF .001" SHIM STOCK AND THEN CUT IT TO 25MM DIAM without crinkling it up? I think you have glibly suggested what is required without realising the ramifications of making and handling such flimsy material...

You are a Fitter and Turner ( journeyman ) and don't know how to do this

BTW......when I have to shim a pair of AC bearings I use 2 shims of at leas6t 2mm thickness....one against the inner race and another against the outer race.
I can then rub the inner race one down to minus a thou or more for the preload required as this is so very easy to do.....at the DIY level where we/I am at
I have also cut thin washers on my lathe for just such a purpose too...

Now you are saying that you have done this, but when I say something similar, it is bad not right can't do this, with what you describe you would be know in the industry as a Hack

It's good I think you are starting to get the picture, now you are starting to say the same thing as me that I have already said in other posts

There is my be hope for you yet

Just think back when you had the problem with the failed electric Drawbar on your $10,000 Baby CNC Mill, did you send it back to China to get it fixed, or try and come up with a fix yourself, what was your end fix we all know the magnetic dream was a failure, you never did say what the final outcome was, or is this just another thing / project that has never been fixed

[handlewanker]

Nope no failure as yet,,,,,,the magnetic solution is just a design that I think will work.....amongst the other designs I think will also work........I have many irons in the fire and they all take a priority as the occasion arises.

BTW.....I do think the shim idea will work if it needs to be shimmed ....never said it wouldn't ............actually said it shouldn't be as the maker of the thrust bock stated that it should not be stripped down due to it having been preloaded at the factory..........preloading means it shouldn't have any backlash and if in your infinite wisdom you apply more preload.............well, that's your prerogative once you've bought it........just how you think more preload will help is way beyond my understanding.

I did say I would make thicker shims, actually spacer washers, of 2 different thicknesses which is totally doable by even the rawest noob to turning etc......do I also have to explain how 2 spacer washers are easier to make than a thin shim?.

To sum up....the preloading, as applied to the type, size and quality of the AC bearings in the thrust block needs to be sufficient to do the job.....excessive preloading will prematurely wear the bearings out and that is a total failure situation.

By your reckoning, if there is still backlash after fitting a shim ...well then, add some more.....more is better than none you say......LOL....you're kidding aren't you?

On the subject of shim manufacture.......I don't fit shims....never had to.....I've always used matched AC pairs for when I had to replace bearings that showed wear etc......this was in the industry for which I was trained to apply my skills etc.

IF......I had to make shims, then I would use my 1 ton press and a press tool to cut the shims out cleanly........the dies for a .001" thick steel shim need to have practically zero clearance to prevent burring of the cut edge.......making such dies is not a job for the amateur.

My last post on this subject.....having said what needs to be said, even you can glean from the explanation(s) how it works.....NO MORE TO BE SAID........let's get on with the show.
Ian.

[handlewanker]

So it has taken you this long to get it now you are saying the same thing as I have been




Then you make one




You are a Fitter and Turner ( journeyman ) and don't know how to do this



Now you are saying that you have done this, but when I say something similar, it is bad not right can't do this, with what you describe you would be know in the industry as a Hack

It's good I think you are starting to get the picture, now you are starting to say the same thing as me that I have already said in other posts

There is my be hope for you yet

Just think back when you had the problem with the failed electric Drawbar on your $10,000 Baby CNC Mill, did you send it back to China to get it fixed, or try and come up with a fix yourself, what was your end fix we all know the magnetic dream was a failure, you never did say what the final outcome was, or is this just another thing / project that has never been fixed

For your information.......the electro draw bar as fitted did fail due to overvoltage burning the brush mounting plate.....other than that it worked perfectly.......the temporary fix, as noted on the Skyfire thread now closed, consisted of a hex bolt in a bar across the top of the housing that works even if only as a manual temp fix......off topic, but it answers your digression.
Ian.

[mactec54]

For your information.......the electro draw bar as fitted did fail due to overvoltage burning the brush mounting plate.....other than that it worked perfectly.......the temporary fix, as noted on the Skyfire thread now closed, consisted of a hex bolt in a bar across the top of the housing that works even if only as a manual temp fix......off topic, but it answers your digression.
Ian.

Not really off topic, this relates to what you said in your post that the OP Hobbyist, should not do what he was going to do to the Bearings Etc , did you get a replacement from China NO you did not, did you fix the failed part NO, yes we remember what happened to the original part, which was any easy fix for someone like you, but you chose to try something ridiculous, ( There's nothing wrong with " trying" something different as you did ) But this did not fix the problem, I was not talking about your temporary fix either, which is still in place now more than 2 years later, this was not new information to me, as I did read what you had posted, I just wondered if you had actually fixed it recently

So this was all about did you get a replacement part from China, for the faulty part, or try and fix it your self, and we now know this answer

[handlewanker]

On the return to China topic.....no I did not contemplate a send back option as that would probably be a return as the same as before fix.....it needs a different approach.

The unit that was fitted to the machine was rated at 24 volts and the rectified voltage of the transformer was up at 36 volts.....this was probably a ploy to get more current flow for a short while as the down thrust was only a 3 sec move duration.

It firstl burned through the wire to the brushes and after fixing that it melted the brush carrier itself.

I could fix that too but it might go on to burn out the armature itself.....a redesign was the best option in my opinion......when I get a round tooit

Back to the thread......do you still consider that more preload is needed?.....Taiwan will not be pleased to honour a warranty claim on that score.......they did specifically state NOT to mess with the dang thing......adding more preload above the manufacturer's recommendation will not cure backlash........especially if backlash is only really a problem on the finishing cut when the drive train is lightly loaded.

BTW....so far all I've seen is a test to determine that backlash is present when the drive train is not under a load.

Heaven forbid that it will get worse once the spindle is working and a cutter is engaged.........that tells me the thrust housing are totally inferior and not up to the task of resisting the cutter loading.

Before they get opened I would suggest a return to sender for a refund and a buy in option with another supplier for better quality.

Too bad if the supplier tests them and can find no fault with their preload settings......quite frankly I think you're barking up the wrong tree.

How about an acid test........put a piece of aluminium in the vice....about 70mm X 70mm x 20mm...... and do some hand coding to make a cut across one end face and then the other end about 5mm deep to a specific length dimension.

This will test the accuracy of the X axis balls crew.....do a cut on the other 2 faces to test the Y axis ball screw too........this will also test the X and Y axes for squareness.

With a known cutter diam, If you get the sizes right on both dimensions you have no backlash in the X or Y ball screws.

CNC is all about accuracy built into the machine via the ball screw pitches.....and their attachment points too.
Ian.

[mactec54]

Back to the thread......do you still consider that more preload is needed?.....Taiwan will not be pleased to honour a warranty claim on that score.......they did specifically state NOT to mess with the dang thing......adding more preload above the manufacturer's recommendation will not cure backlash........especially if backlash is only really a problem on the finishing cut when the drive train is lightly loaded....

You must be in a dream, of some kind, if you think there is any kind of warranty

Before they get opened I would suggest a return to sender for a refund and a buy in option with another supplier for better quality...

You must of missed the part about sending something back for a replacement, it would cost the OP more than the part cost to send it back, there is nothing wrong with the Housing, the Bearings just need adjusting, they are only P5 grade Bearings, and are not a matched set, so it is expected to have to make some adjustment's, if needed, even the supplier says adjustment may be needed

CNC is all about accuracy built into the machine via the ball screw pitches.....and their attachment points too..

You have a lot to learn, you are not even close


Another good Rant though with no substance, your acid test method would not show if there was any backlash, your uneducated approach would be fruitless

[ti5m]

I have sent an email to the supplier of the bearing housings and they said the preload is adjusted by tightening the nut on the ballscrew to press the angular contacts together. Only i dont see how that can be possible with the bearings face to face as in there picture of them ? Unless they are not the same as in the picture and are actually back to back. I shall have to ask them. They do seem like they are interested in helping out though requesting pictures of my setup and how i am measuring backlash. They also said "the shaft couplers are pre-loaded, they dont have backlash" when i asked them if the backlash could be there.

They also said "it could be that you have 0 backlash.but are seeing stickslip. that is more difficult to solve."

I did the steps-per setup in Mach3 again this time with backlash comp turned off. Restarted Mach3. And things do seem better. Then i adjusted gibs and measured backlash again and got some better numbers. 0.016mm X axis, 0.025mm Y axis, 0.03mm Z axis. Popped those numbers into Mach3 backlash comp and set 50% acceleration setting. Restarted Mach3. And it looks to be working normally from my dial gauge readings.

Sometimes Mach3 dose something funny as when i set it to step in 0.01mm amounts the first step from 0 will be 0.0075mm on the DRO and the table will hardly move. Then the second step will be 0.0175mm and the table will move 0.02mm. All other steps will be in 0.01 from then on till it gets back to 0 on the DRO then the first step from 0 will be back to 0.0075.

So i think you are correct in Mach3 is also playing a part in my backlash problem making things difficult.

[mactec54]

I have sent an email to the supplier of the bearing housings and they said the preload is adjusted by tightening the nut on the ballscrew to press the angular contacts together. Only i dont see how that can be possible with the bearings face to face as in there picture of them ? Unless they are not the same as in the picture and are actually back to back. I shall have to ask them. They do seem like they are interested in helping out though requesting pictures of my setup and how i am measuring backlash. They also said "the shaft couplers are pre-loaded, they dont have backlash" when i asked them if the backlash could be there.

They also said "it could be that you have 0 backlash.but are seeing stickslip. that is more difficult to solve."

I did the steps-per setup in Mach3 again this time with backlash comp turned off. Restarted Mach3. And things do seem better. Then i adjusted gibs and measured backlash again and got some better numbers. 0.016mm X axis, 0.025mm Y axis, 0.03mm Z axis. Popped those numbers into Mach3 backlash comp and set 50% acceleration setting. Restarted Mach3. And it looks to be working normally from my dial gauge readings.

Sometimes Mach3 dose something funny as when i set it to step in 0.01mm amounts the first step from 0 will be 0.0075mm on the DRO and the table will hardly move. Then the second step will be 0.0175mm and the table will move 0.02mm. All other steps will be in 0.01 from then on till it gets back to 0 on the DRO then the first step from 0 will be back to 0.0075.

So I think you are correct in Mach3 is also playing a part in my backlash problem making things difficult.

Yes that is the normal problem that you see with Mach3 Backlash comp, and when 2 axes change direction it will do it all over again

You have this figured out quite well, the Ballscrew locking nut can only do so much with the bearings being Face to Face, so you are correct with that, and they are not, they don't know what they are selling, as well, the Bearings for a Ballscrew like this should be assembled Back to Back, Face to Face can work for a machine like yours, but what I have been saying will have to be done to correct any Backlash with your Bearing assembles, once the Ballscrew lock nut is locked then the adjustment would be with the front clamping plate, this would need a shim in front of it as I showed, if this is not enough, then you would need the shim in between the 2 inner Bearing Faces

Stick Slip is a normal component of all solid way machines, this does not cause backlash, this is just there uneducated excuse, which is a poor one, your small light machine would see very little Stick Slip

[handlewanker]

You must be in a dream, of some kind, if you think there is any kind of warranty




You must of missed the part about sending something back for a replacement, it would cost the OP more than the part cost to send it back, there is nothing wrong with the Housing, the Bearings just need adjusting, they are only P5 grade Bearings, and are not a matched set, so it is expected to have to make some adjustment's, if needed, even the supplier says adjustment may be needed




You have a lot to learn, you are not even close


Another good Rant though with no substance, your acid test method would not show if there was any backlash, your uneducated approach would be fruitless

Well Mac....if you have backlash (or stick slip) you WON'T get any accurate sizes like I suggested....that is interpreted as lost motion on the reversal of the screw(s)......something you have no control over as it's purely mechanical and guesstimating how much compensation is needed is a shot in the dark.

ADJUSTING the nut on the ball screw to take up the slack is a lot different to just adding more preload......adjustment is a definite action......preloading is a guesstimation of what you think a cutter will exert on the ball screw and the counter force required to resist it.

BTW....if you tighten the dovetail gibs more to attempt to reduce slide wander, you WILL get lots of stick slip, of that you can be sure.......this will also impact on the ball nut and thrust bearings.

AND Mac, in your infinite wisdom..... which I doubt..... pray do tell us what results you would get if you applied the acid test I suggested......ranting and disputing the method is not a valid answer.

As you "probably" know, once you hit the green button to start the wheels turning you are in the lap of the gods until the job is finished.......the G code values will determine where the cutter starts and stops .....not you.

If the outcome is not as expected due to backlash, then you won't get accurate results......preloading will not give you an accurate outcome.if it's not the cause of the problem....otherwise the test I suggested will come out good if the preload is sufficient for the needs.
Ian.

[mactec54]

ADJUSTING the nut on the ball screw to take up the slack is a lot different to just adding more preload......adjustment is a definite action......preloading is a guesstimation of what you think a cutter will exert on the ball screw and the counter force required to resist it. .

It does not matter what he does with the Nut on the Ballscrew, it won't help with any of the Backlash he has, so why are you even talking about it, you have no idea or concept of what is happening with his Face to Face Bearing configuration

As you "probably" know, once you hit the green button to start the wheels turning you are in the lap of the gods until the job is finished.......the G code values will determine where the cutter starts and stops .....not you. Ian.

Your Rants get more and more of the same all the time, it just shows your inexperience, and lack of education with CNC machines and there building, just remember you have never run a CNC machine to make anything, and never built one either, but you can tell someone how it should be done

When you get experienced, if ever, you will find you can make changes after you have press the green start button, you can make any offset changes you want on the fly, while the machine is running, changing the part being machined

The proof will be when he adds a shim and removes the backlash he has

[handlewanker]

LOL.....oh Mac, you are so uptight with your thinking......once you have run a program and the part is finished it is.....FINISHED.......what part of that don't you understand?.......if, due to lost motion, your part is undersize it is.....SCRAP......metal taken off can't be put back on, unless you have an inbuilt putting on machine....LOL

Of course, if you have to keep stopping the machine in the middle of a run and have to constantly measure the work piece because you have the fear that the outcome will not be to your liking...........that's a manual mode, and I would be doing that on my manual mill not messing with the vagueries of a CNC mill that is unreliable.

It gets worse......if you are running with a CAM program.....at what part of the program do you butt in and do a measurement?

It has been said many times that once you close the door the part is made in there not with your God like hand hovering over the throttle.......and pray, do tell me where you would make an offset change when you find that a hole is oval instead of round?.....on the next part after you scrap the first one?

I think you should desist from insisting that anything anyone says is contrary to how you would like it......go with the flow.......by all means offer your advice, it can be valuable occasionally, but keep your hands in your pockets.

I will state definitely that you are raving and don't remember what you are saying.....in post # 78 you DID state that............"it does not matter what he does with the nut on the balls crew, it won't help with any backlash he has"'

Strange, I thought the whole point of the exercise was about the supposed possible backlash from loose bearings in the thrust housing and the method of possibly fitting a shim and tightening the nut was the whole solution to curing the backlash effect.

Tightening the nut with the shim fitted....if it's really needed....... DOES give you the reduction in backlash by preloading the bearings....... PROVIDED it isn't caused from some other area.

BTW...CNC machines are only machines, made by Man, not Heavenly bodies that you worship reverently.....and they do have feet of clay.....they cannot think for themselves and even I with my small knowledge can make one sing.
Ian.

[mactec54]

LOL.....oh Mac, you are so uptight with your thinking......once you have run a program and the part is finished it is.....FINISHED.......what part of that don't you understand?.......if, due to lost motion, your part is undersize it is.....SCRAP......metal taken off can't be put back on, unless you have an inbuilt putting on machine....LOL

Of course, if you have to keep stopping the machine in the middle of a run and have to constantly measure the work piece because you have the fear that the outcome will not be to your liking...........that's a manual mode, and I would be doing that on my manual mill not messing with the vagueries of a CNC mill that is unreliable.

It gets worse......if you are running with a CAM program.....at what part of the program do you butt in and do a measurement?

It has been said many times that once you close the door the part is made in there not with your God like hand hovering over the throttle.......and pray, do tell me where you would make an offset change when you find that a hole is oval instead of round?.....on the next part after you scrap the first one?

I think you should desist from insisting that anything anyone says is contrary to how you would like it......go with the flow.......by all means offer your advice, it can be valuable occasionally, but keep your hands in your pockets.

I will state definitely that you are raving and don't remember what you are saying.....in post # 78 you DID state that............"it does not matter what he does with the nut on the balls crew, it won't help with any backlash he has"'

Strange, I thought the whole point of the exercise was about the supposed possible backlash from loose bearings in the thrust housing and the method of possibly fitting a shim and tightening the nut was the whole solution to curing the backlash effect.

Tightening the nut with the shim fitted....if it's really needed....... DOES give you the reduction in backlash by preloading the bearings....... PROVIDED it isn't caused from some other area.

BTW...CNC machines are only machines, made by Man, not Heavenly bodies that you worship reverently.....and they do have feet of clay.....they cannot think for themselves and even I with my small knowledge can make one sing.
Ian.

I don't think you have had enough sleep, your Rants are getting worse, and if I said that back in post #78 and you are repeating it that is correct, it does not matter how much he tightens the clamping nut on the Ballscrew it won't help anything, the OP already knows this, as I said you have no concept how this works, with a bearing arrangement like this

You are sounding like a broken record, once you have had a few years running a CNC you will lean about changing tool offsets and tool wear comp on the fly, it has nothing to do with if you have a machine that machines an oval hole, if you want a perfect hole you would be boring it even on a CNC