Undercutting gears?

[gatch]

This took me by surprise a little.. I just finished my 3rd year block course (fitting/machining) at Ucol in Palmy. Funny that they would send you all the way up to Auckland for 2 weeks. The one here was 3 weeks but definately did not need to be that long.. I agree with what you say about the competenz material looking like it was written by people with no industry experience, to the point even where it would seem the notes were written by one person who has copy pasted off the internet, the assignment book written by another dude who may have read the notes once, and the assessment written by some other dude who hasn't looked at the other books at all..

The bit that pissed me off the most was the performance criteria, "demonstrate and apply knowledge".. Ie pass the paper test, manufacture one demo piece and you are considered competent. Bullshit, if I was asked to program our works only cnc machine I wouldn't have a clue, as all we went over was g-code basics, if it came to making some small changes to a program it wouldn't be an issue, but NOONE is going to write an entire program by hand for anything except the simplest of jobs.

New Zealand is already missing a generation of skilled tradesman, the way competenz is going to miss another.. Luckily I work with a bunch of guys who have a broad range of experiences and am learning all the time. In saying that though one of the company owners is the most infuriating person I have ever met, like you said before sketchy if I don't receive a substantial pay increase once my time is up, I won't be able to throw in the towel fast enough..

[Sketchy_Racer]

Simon.

I have a meeting with CompeteNZ this friday, its going to be a little stormy....

He wasn't in my class. Have fun with the meeting with (in)competenz

This took me by surprise a little.. I just finished my 3rd year block course (fitting/machining) at Ucol in Palmy. Funny that they would send you all the way up to Auckland for 2 weeks. The one here was 3 weeks but definately did not need to be that long.. I agree with what you say about the competenz material looking like it was written by people with no industry experience, to the point even where it would seem the notes were written by one person who has copy pasted off the internet, the assignment book written by another dude who may have read the notes once, and the assessment written by some other dude who hasn't looked at the other books at all..

The bit that pissed me off the most was the performance criteria, "demonstrate and apply knowledge".. Ie pass the paper test, manufacture one demo piece and you are considered competent. Bullshit, if I was asked to program our works only cnc machine I wouldn't have a clue, as all we went over was g-code basics, if it came to making some small changes to a program it wouldn't be an issue, but NOONE is going to write an entire program by hand for anything except the simplest of jobs.

New Zealand is already missing a generation of skilled tradesman, the way competenz is going to miss another.. Luckily I work with a bunch of guys who have a broad range of experiences and am learning all the time. In saying that though one of the company owners is the most infuriating person I have ever met, like you said before sketchy if I don't receive a substantial pay increase once my time is up, I won't be able to throw in the towel fast enough..

I did my year one block course at ucol in palmy. It was shit there. We got to do toss all machining, most of it was paper work.

Where did you do your year two?

My block course up at MIT made sure we could write a program out by hand, and then we had to run it on a simulator, once it worked there we got to run them on the machines if you had enough time.
I don't know how you could have passed the units without being able to write a complete program, unless Ucol and MIT have different criteria?

The whole apprenticeship was blatantly designed by a pen pusher, and for a mechanical trade it is seriously way to paper work dependent!

[Deano]

I don't know how you could have passed the units without being able to write a complete program, unless Ucol and MIT have different criteria?

The whole apprenticeship was blatantly designed by a pen pusher, and for a mechanical trade it is seriously way to paper work dependent!

It's known as the dumbing down of society bro.

[gatch]

He wasn't in my class. Have fun with the meeting with (in)competenz



I did my year one block course at ucol in palmy. It was shit there. We got to do toss all machining, most of it was paper work.

Where did you do your year two?

My block course up at MIT made sure we could write a program out by hand, and then we had to run it on a simulator, once it worked there we got to run them on the machines if you had enough time.
I don't know how you could have passed the units without being able to write a complete program, unless Ucol and MIT have different criteria?

The whole apprenticeship was blatantly designed by a pen pusher, and for a mechanical trade it is seriously way to paper work dependent!

I did a pre-apprenticeship and my year 2 at Ucol, you are right, they are not that informative, sticking rigidly to the bare minimum they have to instruct on. I didn't learn a single useful thing on my yr 2.. There was guys who were supposed to be fitter/turners there who didn't even know that lathe tools have to be set at centre height. I think if I didn't have previous engineering experience and some clued up dudes at work, I would really be struggling even after the hours were finished..

Are you training solely as a machinist ? If so I think your cnc units may be alot more in depth than mine..

[Biggles08]

So....sorry to interupt the facinating conversation on apprenticeships, but just to fill you all in on what has been done.

Tonight I went over east to my mates workshop and we used a carbide cutter to shave off just over 1mm off the leading edge of the dog gears. This was done flat to get rid of the rounded edges first and then he put on a smaller cutter (3mm I think) and angled the dividing head to 3 1/2 degrees undercut (the dog gears come undercut by 2 deg from factory already apparently) and chopped it 90% of the way up the face from the base. He said he would leave about 10% of the face perpendicular to make it easy to engage the gears initially and make the edge more robust to the hammering I obviously give me gears :-). This was done rather than undercutting all the way from the base to the edge and leaving a small, sharp edge at the top that would be more suceptable to rounding or dulling quicker.

I took some video footage of before, as we were doing it and after that I will put on youtube sometime soon.

Overall I'm pretty positive that this will have fixed my problems and Snowy (my mate who did it) made a lot of sense in his reasoning.

Whats your thoughts on all of this peoples?

Biggles08

[Ozzy27]

So....sorry to interupt the facinating conversation on apprenticeships, but just to fill you all in on what has been done.

Tonight I went over east to my mates workshop and we used a carbide cutter to shave off just over 1mm off the leading edge of the dog gears. This was done flat to get rid of the rounded edges first and then he put on a smaller cutter (3mm I think) and angled the dividing head to 3 1/2 degrees undercut (the dog gears come undercut by 2 deg from factory already apparently) and chopped it 90% of the way up the face from the base. He said he would leave about 10% of the face perpendicular to make it easy to engage the gears initially and make the edge more robust to the hammering I obviously give me gears :-). This was done rather than undercutting all the way from the base to the edge and leaving a small, sharp edge at the top that would be more suceptable to rounding or dulling quicker.

I took some video footage of before, as we were doing it and after that I will put on youtube sometime soon.

Overall I'm pretty positive that this will have fixed my problems and Snowy (my mate who did it) made a lot of sense in his reasoning.

Whats your thoughts on all of this peoples?

Biggles08

Hi Marcus,
From Reading what you have said it sounds like you hve missed some of the key parts.
Have you also undercut the mating gear? (the hole the dog slides into)
Have you indexed the dogs? (made sure all the dogs touch the mating gear at the same point so the load is spread over all of the dogs)
The under cut should go all the way to the top od the dog with a very small taper lead. This is so when the dog is only partially engaeged and load is reapplied (you open the throttle)the dog is pulled into the mating gear completeing the change not pushing it out (missed change).
These are all thing someone with experience under cutting gears would have known. Hopefully it all works ok for you.
Cheers
Ozzy

[Biggles08]

Hey Ozzy27...see below:

Hi Marcus,
From Reading what you have said it sounds like you hve missed some of the key parts.
Have you also undercut the mating gear? (the hole the dog slides into)

yeah....it was another dog gear with 'male' dogs that it engaged with....this was also undercut at 3 1/5 deg.

Have you indexed the dogs? (made sure all the dogs touch the mating gear at the same point so the load is spread over all of the dogs)

He 'blued' the gears to check for this....all was sweeeeeeeet :-)

The under cut should go all the way to the top od the dog with a very small taper lead. This is so when the dog is only partially engaeged and load is reapplied (you open the throttle)the dog is pulled into the mating gear completeing the change not pushing it out (missed change).

This is what I was trying to explain with the 90% undercutting and the 10% being the 'taper' lead....although, he has made this straight and not on any angle.

These are all thing someone with experience under cutting gears would have known. Hopefully it all works ok for you.
Cheers
Ozzy

This was snowys first go at actually undercutting motorcycles gears....he has been involved with undercutting a BMW K1 gearbox before but he was only helping and they didn't actually undercut them, just re-machined them flat. He is a toolmaker by trade though so knows a thing or two....hopefully its fixed!!!! fingers crossed

[Biggles08]

heres the video:

[YOUTUBE]http://www.youtube.com/watch?v=2gFXvgSsAJc[/YOUTUBE]

[Biggles08]

HELP!!!!!!! still having issues with 4th gear! Can't seem to engage it properly! Anyone have a spare gearbox they want to donate to biggles racing team!?!? We seemed to have sorted out 2nd to 3rd but 3rd to 4th is still randomly hard to engage!

[Sketchy_Racer]

Tonight I went over east to my mates workshop and we used a carbide cutter to shave off just over 1mm off the leading edge of the dog gears. This was done flat to get rid of the rounded edges first and then he put on a smaller cutter (3mm I think) and angled the dividing head to 3 1/2 degrees undercut (the dog gears come undercut by 2 deg from factory already apparently) and chopped it 90% of the way up the face from the base. He said he would leave about 10% of the face perpendicular to make it easy to engage the gears initially and make the edge more robust to the hammering I obviously give me gears :-). This was done rather than undercutting all the way from the base to the edge and leaving a small, sharp edge at the top that would be more suceptable to rounding or dulling quicker.

I took some video footage of before, as we were doing it and after that I will put on youtube sometime soon.

Overall I'm pretty positive that this will have fixed my problems and Snowy (my mate who did it) made a lot of sense in his reasoning.

Whats your thoughts on all of this peoples?

Biggles08

HELP!!!!!!! still having issues with 4th gear! Can't seem to engage it properly! Anyone have a spare gearbox they want to donate to biggles racing team!?!? We seemed to have sorted out 2nd to 3rd but 3rd to 4th is still randomly hard to engage!

Hey ya Biggles,

That's a real bugger to hear about your 4th gear not responding.
One thing i did notice about your explanation, was the fact that your mate removed 1.00mm of material from your gear! That is a huge amount, far more than the depth of the case hardening of the gear, so now what you will have is a very soft dog which will deteriorate very quickly.

Usually undercutting a already hardened gear is done by grinding, where the amounts of material coming off the gear are around the 0.10mm figure, so that the hard surface of the gear is not removed.

One other thing to point out, is shimming of the gearbox. If the gears aren't shimmed right, it is possible for the gear to hit a stop on the shaft (circlip, or shoulder) and not be able to 100% engage.

Good luck with it all, I hope you get it sorted for round 3. I bet your glad that the Kawasaki has a cassette style gearbox!

Cheers,

-Glen

[Biggles08]

Hey ya Biggles,

That's a real bugger to hear about your 4th gear not responding.
One thing i did notice about your explanation, was the fact that your mate removed 1.00mm of material from your gear! That is a huge amount, far more than the depth of the case hardening of the gear, so now what you will have is a very soft dog which will deteriorate very quickly.

Usually undercutting a already hardened gear is done by grinding, where the amounts of material coming off the gear are around the 0.10mm figure, so that the hard surface of the gear is not removed.

One other thing to point out, is shimming of the gearbox. If the gears aren't shimmed right, it is possible for the gear to hit a stop on the shaft (circlip, or shoulder) and not be able to 100% engage.

Good luck with it all, I hope you get it sorted for round 3. I bet your glad that the Kawasaki has a cassette style gearbox!

Cheers,

-Glen

hey Glen,

I think we have found another problem that originally was over looked when we first removed the gears. It appears that the needle bearings on the end of the main shaft are a tad worn and damaged. There was a lot of play in the fixed gears right next to the bearings up to about 3mm. I will order the replacement bearing tomorrow and the washer and see it that removes the play. This will also eliminate any chance of the bearing ceasing.

Also, it seems the spring on the star shifter gear is not strong enough to pull the gear in completely and hold it. When the dogs don't engage completely because the faces of the dogs come together, when they rotate further the gear still doesn't engage properly. We are looking for a stronger spring too.

All this is great but I'm really cutting it fine to get it all ready by thursday morning to leave for Manfield.

[Pussy]

Hey Marcus, would it be worth giving one of these a bash?


http://www.factorypro.com/products/F...Pro_shift.html

[Biggles08]

Hey Marcus, would it be worth giving one of these a bash?


http://www.factorypro.com/products/F...Pro_shift.html

Funny you suggested that cause I was talking to John from triple zee today about exactly that! The problem is they don't list a star shifter for my model bike 07/08 ZX6R.

[Sketchy_Racer]

How ya getting on Biggles? Any luck with getting the bearings etc sorted?

[Biggles08]

How ya getting on Biggles? Any luck with getting the bearings etc sorted?

got the bearings to my mechanic this morning. He is putting it all back together this evening and trying to ensure that I'm going to have my gears sorted for this weekend...I'm leaving for manfield tomorrow morning at 6am...cutting it fine but hey not much choice. I'll find out on friday morning at the first practice session how it is....fingers crossed!