[handlewanker]

Mac, I really think you are losing it a bit, perhaps old age does not become you, so on the grounds of good will I'll allow you to rant as much as you want....... I'm very considerate.

In the post that you have just quoted I DID specifically state that to measure the run out of a toothed or timing pulley you need to check it at the contact points and that is at the flanks of the teeth...... NOT NO EVER on top of the teeth or the bottom either and never on the flanges.......what part of that statement did you not understand????

The main point is.......if you have ANY run out on a timing pulley you cannot correct it once the teeth are cut.......you "could" rebore the pulley, but ten to one it will run out even worse.

The very real problem is, a pulley must be machined FIRST in the bore to allow it to be mounted on a true running mandrel in a mill or whatever...........this is the same operation as simple gear cutting practice.........bore and teeth MUST be true to one another or you'll get cyclic run out and that leads to serious vibration.

It's really only coincidental as the poster has not replied to either my suggestion or yours, so let it rest and stop being a grumpy old curmudgeon who just wants to make waves where there aren't any.......AND IF YOU WOULD KINDLY STOP MISQUOTING POSTS THAT ARE NOT APPLICABLE TO ANYONE EXCEPT THE POSTER, THE WORLD WILL BE A BETTER PLACE.
Ian.

.

[mactec54]

Mac, I really think you are losing it a bit, perhaps old age does not become you, so on the grounds of good will I'll allow you to rant as much as you want....... I'm very considerate.

In the post that you have just quoted I DID specifically state that to measure the run out of a toothed or timing pulley you need to check it at the contact points and that is at the flanks of the teeth...... NOT NO EVER on top of the teeth or the bottom either and never on the flanges.......what part of that statement did you not understand????

The main point is.......if you have ANY run out on a timing pulley you cannot correct it once the teeth are cut.......you "could" rebore the pulley, but ten to one it will run out even worse.

The very real problem is, a pulley must be machined FIRST in the bore to allow it to be mounted on a true running mandrel in a mill or whatever...........this is the same operation as simple gear cutting practice.........bore and teeth MUST be true to one another or you'll get cyclic run out and that leads to serious vibration.

It's really only coincidental as the poster has not replied to either my suggestion or yours, so let it rest and stop being a grumpy old curmudgeon who just wants to make waves where there aren't any.......AND IF YOU WOULD KINDLY STOP MISQUOTING POSTS THAT ARE NOT APPLICABLE TO ANYONE EXCEPT THE POSTER, THE WORLD WILL BE A BETTER PLACE.
Ian. .

Now that's more like it, except

I think the one that is not making much sense is what you are posting, post 169 you replied to using my post about the flanges

If there is any run out it is easy to correct, you just don't know how

It's very easy to remachine the bore of a timing pulley, if it needs it, or you have to change the bore diameter, I and many others do it all the time

[handlewanker]

Dear Mac....... sigh.........I realise you are not a practical trained engineering person.......perhaps you are heavily steeped with high end academic knowledge on many things, so the simple problems escape you in the real World......like cutting the teeth on a timing pulley and wondering why they run out.

First of all, your statement in the last post is untrue......YOU CANNOT REPAIR OR REMACHINE A TIMING PULLEY IF THE BORE/TOOTH RELATIONSHIP IS OUT OF WACK

You CAN only re-machine the bore to correct it's diam...... BUT if the teeth of the pulley run out to the bore you CANNOT remachine the bore to correct it.

Firstly, the bore will become bigger than the shaft it was designed to fit...... and with a keyway perhaps making perhaps a bush insert difficult or not practical.

Secondly by what magic would you apply to realign the teeth pitch circle to the bore to correct run out before boring?????

It is extremely difficult to detect the high point of a gear or toothed pulley pitch circle run out once the teeth are cut.....ask me how I know.......it can be done but is extremely tedious to set the gear or timing pulley teeth pitch circle exactly true to the bore.

If this does not clarify the situation, then I suggest you take a short course in gear cutting to establish the requirements or all your timing pulleys and gears will suffer from run out.
Ian.

[daniellyall]

Ian, CNC machine, touch probe decent probing cycle can find the center of almost anything.

A manual machine very time consuming

[handlewanker]

Sorry Dan, that is not the point........once you have the teeth of a gear or toothed timing pulley cut and bored you cannot set it up to repair it if the teeth run out to the bore......or in other words to be more precise for the nit pickers.......the pitch circle of a gear or timing pulley MUST be concentric to the bore or you get a cyclic run out as they rotate.

You CAN re-machine the bore as I stated if you set it running true, but you cannot ascertain the run out point to offset the pulley or gear before you machine the bore.....you have no datum to work from..

You "can" re-set a gear or timing pulley true to their pitch circles if you know how when you want to re-machine a bore.........I'll leave it open to anyone to make a guess as to how you achieve it......Mac no doubt, being a self proclaimed expert on all things that move, will eagerly enlighten you on that score.......WON'T YOU MAC?

BTW, it is cheaper to make a completely new timing pulley or gear than attempt to repair one that has the teeth running out.
Ian.

[mactec54]

Dear Mac....... sigh.........I realise you are not a practical trained engineering person.......perhaps you are heavily steeped with high end academic knowledge on many things, so the simple problems escape you in the real World......like cutting the teeth on a timing pulley and wondering why they run out.

First of all, your statement in the last post is untrue......YOU CANNOT REPAIR OR REMACHINE A TIMING PULLEY IF THE BORE/TOOTH RELATIONSHIP IS OUT OF WACK

You CAN only re-machine the bore to correct it's diam...... BUT if the teeth of the pulley run out to the bore you CANNOT remachine the bore to correct it.

Firstly, the bore will become bigger than the shaft it was designed to fit...... and with a keyway perhaps making perhaps a bush insert difficult or not practical.

Secondly by what magic would you apply to realign the teeth pitch circle to the bore to correct run out before boring?????

It is extremely difficult to detect the high point of a gear or toothed pulley pitch circle run out once the teeth are cut.....ask me how I know.......it can be done but is extremely tedious to set the gear or timing pulley teeth pitch circle exactly true to the bore.

If this does not clarify the situation, then I suggest you take a short course in gear cutting to establish the requirements or all your timing pulleys and gears will suffer from run out.
Ian.

You are talking to the trees out back again,

Anything is possible if you know how, to repair an out of true Bore like this, obvious you do not

I think we could almost feel sorry for you, that you have lead such a sheltered life, manufactures that use Timing Pulleys, and everyone that buy timing pulley stock, machine the bores every day, you can buy blanks and machine the bores to fit what ever you want some photos of Timing Pulley blanks below may help you get the feeling you don't know what you are talking about, the photos below are just a few of the possibilities

You can buy Timing Pulley stock from all timing pulley manufactures, any pitch and most tooth profiles, and machine your own to what ever you want them to fit, the hybrid special photo I made is an H series

[daniellyall]

Ian a decent CAD/CAM program the datum can be where ever you wont it to be, you can even move it around if you have a power fail, that is why you have touch probes you would probe around it to find the dead center then machine it and it will be to speck of what the machine can do.

Google it you will find 1000 of examples of useing probes to find a datum in some very strange shapes, and you can run the probing cycles at anytime before, during and after the program run some high end machines you can use the cutter to check for problems.

Your machine can even do it.

[Mmpie]

What are you all on about, gears and timing pullies are meteorites from outer space. You can't machine them.


Sent from my iPhone using Tapatalk

[handlewanker]

You are talking to the trees out back again,

Anything is possible if you know how, to repair an out of true Bore like this, obvious you do not

I think we could almost feel sorry for you, that you have lead such a sheltered life, manufactures that use Timing Pulleys, and everyone that buy timing pulley stock, machine the bores every day, you can buy blanks and machine the bores to fit what ever you want some photos of Timing Pulley blanks below may help you get the feeling you don't know what you are talking about, the photos below are just a few of the possibilities

You can buy Timing Pulley stock from all timing pulley manufactures, any pitch and most tooth profiles, and machine your own to what ever you want them to fit, the hybrid special photo I made is an H series

Oh Macko old chap.......I did say in my last post.........MAC IS GOING TO TELL US HOW YOU PICK UP A PITCH CIRCLE ON A GEAR OR TIMING PULLEY TO CORRECT THE OUT OF CONCENTRICITY BORE..........but you dodged the issue4 Mac as you don't know how........ so do tell us how you pick up the pitch circle to re-machine a bore.

BTW.......if you obtain an unbored timing pulley and due to your bad machine skills subsequently bore it and the bore is out to the pitch circle which means you have a cyclic event......BY WHAT MEANS DO YOU RE-SET UP THE TIMING PULLEY TO GET THE PITCH CIRCLE TRUE TO THE BORE?.....even a moron can understand that problem.
Ian.

[handlewanker]

Ian a decent CAD/CAM program the datum can be where ever you wont it to be, you can even move it around if you have a power fail, that is why you have touch probes you would probe around it to find the dead center then machine it and it will be to speck of what the machine can do.

Google it you will find 1000 of examples of useing probes to find a datum in some very strange shapes, and you can run the probing cycles at anytime before, during and after the program run some high end machines you can use the cutter to check for problems.

Your machine can even do it.

A CAD/CAM program can pick up the pitch circle of a gear after it's cut???????.........do tell me how it happens as that is impossible.

BTW......the pitch circle is the contact point that a gear makes when the tooth contacts a tooth on another gear as it rotates.

A gear is actually a roller that has teeth that extend beyond the rolling surface and below it to transmit motion without slipping.

The rolling surface is also called the pitch circle.

If the pitch circle is running out to the bore you have cyclic variations.
Ian.

[mactec54]

A CAD/CAM program can pick up the pitch circle of a gear after it's cut???????.........do tell me how it happens as that is impossible.

BTW......the pitch circle is the contact point that a gear makes when the tooth contacts a tooth on another gear as it rotates.

A gear is actually a roller that has teeth that extend beyond the rolling surface and below it to transmit motion without slipping.

The rolling surface is also called the pitch circle.

If the pitch circle is running out to the bore you have cyclic variations.
Ian.

And so it is easily corrected /setup by the method he described, simple probing, just one way it is done

[daniellyall]

Ian I said datum not pitch circle you know FA about cad/cam and I know what a gear is, as I said look up probing cycles.

If one wonted to they could probe the gear all the way around on every single surfaces and obtain the relative dead center to 0.01 in or less and it can then re probe all the surfaces again and check that the bore is dead center and it will be if not it will adjust the position in the machine it's self this is useing codes and macros that have been around since the first cnc machine was made.

And I would say that is 1/2 of what mactec54 was referring to since this is a post on a cnc machine.

[handlewanker]

I get the distinct impression that nobody has mastered the basic skills of engineering.

I do realise that you "could" do it that way.....highly improbable, extremely impractical, very time consuming and very costly if you have to go out and buy in a touch probe.

let me enlighten you to the most practical, the less costly and time consuming way .......Mac, being at a loss for words, has lost the plot as he just nodded to someone else's suggestion........he really hasn't a clue when it comes to basic engineering, a typical armchair academic.

For a start, ,the timing pulley has had the teeth cut accurately to the OD of the blank.......that means the pitch circle is true to the OD......but the bore can be out to the pitch circle if it was cut in a second op, and that is the problem.

All you have to do is set the pulley on the mill table and with a dial indicator sweep round the OD of each tooth...........once you have found the central point it's good to either bore it or re-bore it if a correction is needed.....it's as easy as that.

If you cannot get an accuracy of +- .02mm for centrality, you had better take a refresher course in basic engineering skills as I did this exercise as an apprentice back in the old days.

BTW.......how much would a timing pulley run out be to not be suitable for a drive train?.........you would not notice a run out of under .1mm.as the drive belt is quite resilient........but more than that and you could get vibration creeping in at high speed.
Ian.

[daniellyall]

Ian next time you are in town go to a machine shop with cnc equipment and ask them how hard or easy it is to probe something like a timing pulley to find the dead center of the timing pulley.


For a start, ,the timing pulley has had the teeth cut accurately to the OD of the blank.......that means the pitch circle is true to the OD......but the bore can be out to the pitch circle if it was cut in a second op, and that is the problem.

If the pulley is out in the bore and the pitch circle is correct to the OD then probing the pitch circle and haveing it update the the X and Y work zero or what ever G54 + is selected can be done very quickly and if the OD is correct to the pitch circle you can probe the OD.

Where the center hole of the pulley is means nothing to the cnc program at all, all that matters is you set where the material is and where the WCS is and if you are useing a probe where to probe that's all there is to it they have been doing this since the word go with cnc equipment.

[handlewanker]

Don't be a dill Dan.......back in the old days we did it like I said.......anyway, who in his right mind spends the time to do a correction when you can chuck it out and buy another one for less than it takes to correct it.

I have 3 timing pulleys for my mill......all in steel.......if any of them ran out to an unacceptable degree I'd chuck them out.

DIY correction is a different matter as you can piss fart about for as long as it takes and not notice the cost.

BTW.....how many DIY people have a Cad/Cam progrem and a touch probe too and would know how to use it?

As far as I have observed so far, many people ( not everybody) who resort to Cad/Cam are totally ignorant of basic machining and engineering set-ups......of course that is not a general summing up of the mass Cad/Cam users...

Even if I did have that equipment the way I stated is much quicker.........only a person who only works with CNC and has no basic engineering skills would attempt what you are saying.

Come down to Earth, no one would pay you for the time that it would take to do the job your way.

This has gone to the extremes of stupidity as the original poster did not actually have a run out ....he only thought so when he saw the flange guards were wobbly........LOL

It would have been a more exciting exercise if the thread had concentrated on the actual real problem of the spindle run out.

NOTHING MORE TO BE SAID ON NON EXISTANT WOBBLY TIMING GEARS......I hope..
Ian.

[daniellyall]

You have a program that can use probing Ian you have 3 of them.

[handlewanker]

As in......NOTHING MORE TO BE SAID ON NON EXISTANT WOBBLY TIMING GEARS.....sigh.

[handlewanker]

Lets get down to Earth and become more meaningful.........the prospect of a spindle bore taper run out is a bad dream to haunt anyone with a new mill....it just won't go away and MUST be fixed or you'll forever have a cutter sizing problem due to elliptical cutting paths.

So, what can you do to a spindle bore taper to correct it when there is run out?

The first recourse would be to send it back to the supplier under warranty.....at your shipping cost of course there and back.

There are other ways less costly, so I expect we'll have a plethora of examples from the experts in the next few posts.
Ian.

[daniellyall]

Ian I was saying probing what mach3 can do native and in the wizards, it's already there the 3rd one is you and your keyboard G codes man, M codes, Macros, CNC language - Fanuc 20i . Have a another coffee and turn the aircon up

[handlewanker]

Platform is all yours Dan........I've moved on to the next more important item.