32 replies to this topic

[MatsNorway]

I need a table with wedge or key? standards..

you know... those ****as that goes into the slot on a axle.

ISO, NS or DIN norm. or just the right word combo to search myself. Or both ;)

Edited by MatsNorway, 02 February 2011 - 13:55.

[Magoo]

Those are commonly known as Woodruff keys, although there are a number of combinations and trade names. They also come in English, metric, etc. dimensions. Don't use them on a race car if you can possibly avoid it. Terrible stress risers.

http://www.roymech.c...ff_keyways.html

[MatsNorway]

Those are commonly known as Woodruff keys, although there are a number of combinations and trade names. They also come in English, metric, etc. dimensions. Don't use them on a race car if you can possibly avoid it. Terrible stress risers.

http://www.roymech.c...ff_keyways.html

thank you.. its for a braking device on a platform that goes on rails. the handwheel goes on top of the woodruff key. Wierd name. But unice. in Norway its called a kile. same as tickling. so its kinda hard finding good info.
besides my boss was gone today.

Edited by MatsNorway, 02 February 2011 - 20:26.

[gruntguru]

thank you.. its for a braking device on a platform that goes on rails. the handwheel goes on top of the woodruff key. Wierd name. But unice. in Norway its called a kile. same as tickling. so its kinda hard finding good info.
besides my boss was gone today.

The keys in your photo are parallel whereas a Woodruff key has a crescent shape when viewed from the side. Woodruff keyways are cut by plunging a narrow "slab" milling cutter into the shaft whereas the conventional parallel keyway is made by running an end mill along the shaft. The Woodruff keyway introduces significantly less stress because of the large radius.

Edited by gruntguru, 02 February 2011 - 23:08.

[Ray Bell]

I would have thought that a typical Woodruff keyway was cut deeper, thereby creating a bigger stress raiser?

It also has square corners, whereas the ones illustrated above are rounded off.

[Lee Nicolle]

I am surprised that I still se a lot of taper and key set ups, mostly in equipment these days but I believe even in small machinery. I would have thought with the amount of decent spining equipment advailable these days it would have been a thing of the past.
On cars I have seen them strip the key and not drive, or conversely not want to come apart with the correct pullers.
Recently saw one on a slasher that would not come off, heat was used after the pullers stripped them selves. In the end it was cut off with an angle grinder and then the whole drive flange had to be replaced. All this to replace a seal that had failed prematurely on a machine with about 60 hours on it

[Magoo]

Types of keys (and keyways) include square or parallel; wedge aka ramped key; Woodruff aka half moon; Scotch key. A true square key is simply square stock cut to length -- good for a parallel way in a gear or hub but a disadvantage at the shaft part of the deal as the keyway must be carried through to the shoulder or there is no way to remove the key -- for example, in the photo above, the keyway would extend to the threads, producing a terrible sress riser. Wedge keys are similar except their upper and lower faces are tapered, allowing adjustment of the member on the shaft. Disadvantage: introduces inconcentricity. A Scotch key is similar to the square key except the shaft is drilled axially to accept a piece of round stock.

Hence the popularity of the Woodruff or half-moon key, which is designed to fit a way or slot that is a circle segment in aspect. The key is extracted by tapping one end downward, which walks the key up and out of its keyway at the other end. There is a variation known as a sled-runner key, a sort of cross -- a square key in the middle and a half moon key at the ends, if you will. There was a Woodruff for whom the key is named, forever memorialized as in catalogs, machinery handbooks, and at parts counters, you must often reference Woodruff keys to get any sort of key at all. Sort of like Kleenex or Crescent wrench. If, after devising a clever piece of equipment, machine shop staffers come up front and present you with a "Woodruff key award," accept it graciously but understand it is not really an honor.

[gruntguru]

I would have thought that a typical Woodruff keyway was cut deeper, thereby creating a bigger stress raiser?

It also has square corners, whereas the ones illustrated above are rounded off.

Although all stress raisers are bad, for a shaft in bending the worst kind are the ones you can see when looking perpedicular to the shaft axis (ie along the axis of the bending moment).

The corners shown as rounded off in the photo don't even exist on a Woodruff keyway - at least they are a long way from perpendicular to the shaft axis.

[MatsNorway]

Although all stress raisers are bad, for a shaft in bending the worst kind are the ones you can see when looking perpedicular to the shaft axis (ie along the axis of the bending moment).

The corners shown as rounded off in the photo don't even exist on a Woodruff keyway - at least they are a long way from perpendicular to the shaft axis.

Soo... half moon key god for bending, bad for rotasjon then..

Only chart i have found so far.
http://www.stanho.co...ages/gard1a.gif
http://www.stanho.co...mages/gard6.gif
I need square or parallel or whatever it is called.

Edited by MatsNorway, 03 February 2011 - 08:24.

[Lee Nicolle]

Types of keys (and keyways) include square or parallel; wedge aka ramped key; Woodruff aka half moon; Scotch key. A true square key is simply square stock cut to length -- good for a parallel way in a gear or hub but a disadvantage at the shaft part of the deal as the keyway must be carried through to the shoulder or there is no way to remove the key -- for example, in the photo above, the keyway would extend to the threads, producing a terrible sress riser. Wedge keys are similar except their upper and lower faces are tapered, allowing adjustment of the member on the shaft. Disadvantage: introduces inconcentricity. A Scotch key is similar to the square key except the shaft is drilled axially to accept a piece of round stock.

Hence the popularity of the Woodruff or half-moon key, which is designed to fit a way or slot that is a circle segment in aspect. The key is extracted by tapping one end downward, which walks the key up and out of its keyway at the other end. There is a variation known as a sled-runner key, a sort of cross -- a square key in the middle and a half moon key at the ends, if you will. There was a Woodruff for whom the key is named, forever memorialized as in catalogs, machinery handbooks, and at parts counters, you must often reference Woodruff keys to get any sort of key at all. Sort of like Kleenex or Crescent wrench. If, after devising a clever piece of equipment, machine shop staffers come up front and present you with a "Woodruff key award," accept it graciously but understand it is not really an honor.

While I know what you are talking about with a crescent wrench they really have never been known as that here. Usually an adjustable spanner or just a plain shifter.
Kleenex is very generic though

[Kelpiecross]

[quote name='Magoo' date='Feb 3 2011, 17:50' post='4816431']
Types of keys (and keyways) include square or parallel; wedge aka ramped key; Woodruff aka half moon; Scotch key. A true square key is simply square stock cut to length -- good for a parallel way in a gear or hub but a disadvantage at the shaft part of the deal as the keyway must be carried through to the shoulder or there is no way to remove the key -- for example, in the photo above, the keyway would extend to the threads, producing a terrible sress riser. Wedge keys are similar except their upper and lower faces are tapered, allowing adjustment of the member on the shaft. Disadvantage: introduces inconcentricity. A Scotch key is similar to the square key except the shaft is drilled axially to accept a piece of round stock.

Scotch keys I have seen (and used) are round etc. as you describe but are actually threaded/screwed into place.

[Garsted]

Try this:

http://www.roymech.c...ays/keyways.htm

if you search on "metric keyway standards" there are lots of leads

Steve

[Greg Locock]

In a properly designed joint the key transmits no torque. All the torque is transmitted via the taper.

This is better than a spline as concentricity is guaranteed and the fatigue life is better.

In the real world, not so much.

[Lee Nicolle]

In a properly designed joint the key transmits no torque. All the torque is transmitted via the taper.

This is better than a spline as concentricity is guaranteed and the fatigue life is better.

In the real world, not so much.

Real world often gets in the way of theory!! Thats why sometimes engineers have to get out in the world.

[Magoo]

R8 machine tool collets feature both a taper and a keyway. Almost never will you find a mill with the key installed in the spindle. All the drive is taken by the taper.

[Lee Nicolle]

R8 machine tool collets feature both a taper and a keyway. Almost never will you find a mill with the key installed in the spindle. All the drive is taken by the taper.

And in that application it is fine.And very efficient and accurate. [though I would use a key] But when driving something bigger not so fine. So many old cars with axles that wont drive when the key strips, and ag equipment too. And ofcourse that set up is totally intolerant of any misalignment and most bigger shafts flex

[fredeuce]

And in that application it is fine.And very efficient and accurate. [though I would use a key] But when driving something bigger not so fine. So many old cars with axles that wont drive when the key strips, and ag equipment too. And ofcourse that set up is totally intolerant of any misalignment and most bigger shafts flex

Lee ,
The problem with stripped keys is not an inherent design flaw but simple lack of maintenance. As Greg stated above the taper transmits the torque not the key. The older style axle with keyway and matching hub works well. If not maintained they will lose their ability to transmit torque and put it all through the keyway. The best way to fit these its to take the key out of the keyway and then apply lapping paste (valve grinding paste) to the tapered surface and then place the hub on the axle and lap the axle taper to the hub. Then rotate backwards and forwards to lap them together. That will ensure a perfect fit.

As for the lawnmower deck often a judiciously placed blow with hammer and drift whilst under tension with a puller usually gets them apart.

Edited by fredeuce, 15 February 2011 - 11:41.

[gruntguru]

The problem with stripped keys is not an inherent design flaw but simple lack of maintenance. As Greg stated above the taper transmits the torque not the key. The older style axle with keyway and matching hub works well. If not maintained they will lose their ability to transmit torque and put it all through the keyway. The best way to fit these its to take the key out of the keyway and then apply lapping paste (valve grinding paste) to the tapered surface and then place the hub on the axle and lap the axle taper to the hub. Then rotate backwards and forwards to lap them together. That will ensure a perfect fit.

As for the lawnmower deck often a judiciously placed blow with hammer and drift whilst under tension with a puller usually gets them apart.

The taper fitted flywheel on Minis is guaranteed to weld itself onto the crankshaft in engines making serious power. Tried everything from lapping to Loctiite. Still ended up bashing the flywheel through the starter hole - sometimes for what seemed like ages.

[Kelpiecross]

The taper fitted flywheel on Minis is guaranteed to weld itself onto the crankshaft in engines making serious power. Tried everything from lapping to Loctiite. Still ended up bashing the flywheel through the starter hole - sometimes for what seemed like ages.

Bashing through the starter hole while using a puller? - or just bashing?

[OfficeLinebacker]

Bashing through the starter hole while using a puller? - or just bashing?

Just bashing. It had nothing to do with trying to remove it. Simply angry.

[Greg Locock]

And in that application it is fine.And very efficient and accurate. [though I would use a key] But when driving something bigger not so fine. So many old cars with axles that wont drive when the key strips, and ag equipment too. And ofcourse that set up is totally intolerant of any misalignment and most bigger shafts flex

Well you can buy Fenner taperlocks for 400 hp machines, so at least some indutries don't think that tapers are inappropriate for big jobs(if you think about the size isn't really a problem). The real issue is that the designer is willing to sacrifice good joint design to make the thing cheaper etc, after all 'nobody' ever needs to disassemble that joint.

Having said that designing tapers for torque transmission is a surprisingly complex business, especially if either of the components is relatively thin walled, or has discontinuities such as a bolt hole in it. You can do it by hand, but it is iterative. When you pull a cheap tapered joint apart look for witness marks and see how much of the shafts are actually in contact. Typically you'll find one end or the other has been doing all the work.

[gruntguru]

Bashing through the starter hole while using a puller? - or just bashing?

With puller. Sometimes without, but to be honest when they are properly welded on, it doesn't make much difference (unles maybe you had a serious hydraulic puller).

[fredeuce]

With puller. Sometimes without, but to be honest when they are properly welded on, it doesn't make much difference (unles maybe you had a serious hydraulic puller).

As always use the right tool for the job. My recollection of that job when I played around with Minis is that there was a dedicated hydraulic puller as well as the standard screw type puller. The latter often required a bit of a tap on the side of the hub of the flywheel once under tension and they break free. Whereas the hydraulic would do it with out the need for the brute force.

[Kelpiecross]

As always use the right tool for the job. My recollection of that job when I played around with Minis is that there was a dedicated hydraulic puller as well as the standard screw type puller. The latter often required a bit of a tap on the side of the hub of the flywheel once under tension and they break free. Whereas the hydraulic would do it with out the need for the brute force.

I never managed to get a Mini flywheel off by bashing alone - but they came off OK with a home made puller.
The Mini flywheel is not held on by the taper only - there is a very hefty locking washer under the nut. You can get aftermarket locking washers in EN24, EN16 etc. so apparently attachment relies a lot on the locking washer and bolt.

[gruntguru]

I never managed to get a Mini flywheel off by bashing alone - but they came off OK with a home made puller. The Mini flywheel is not held on by the taper only - there is a very hefty locking washer under the nut. You can get aftermarket locking washers in EN24, EN16 etc. so apparently attachment relies a lot on the locking washer and bolt.

When you say "locking washer" are you referring to the key? (For those unfamiliar with Mini flywheel attachment, the key is transverse to the shaft and part of the thick washer under the retaining bolt.

Although every reference (and this thread) says the key is only there to locate and not to participate in the drive, is it possible that a high quality key is part of the solution to taper fretting on highly modified Minis?

[Kelpiecross]

When you say "locking washer" are you referring to the key? (For those unfamiliar with Mini flywheel attachment, the key is transverse to the shaft and part of the thick washer under the retaining bolt.

Although every reference (and this thread) says the key is only there to locate and not to participate in the drive, is it possible that a high quality key is part of the solution to taper fretting on highly modified Minis?

Yes - I should have written "keyplate" or "keyed washer" etc. "Locking washer" is often used (possibly incorrectly) instead of "keyplate" etc. I suppose "locking washer" would be the "bent tin" washer under the flywheel bolt.
You would have to think that the makers of the high quality steel keyplates do expect the key to participate in the drive - that it is not just for location. This is not to say they are correct - but if they have found that this cures the problem of the flywheel coming loose - maybe they are right.
If it is just for location why is the key so big?
Also - unless the flywheel/engine assembly has been balanced there is no need for any particular location - so why a key at all?

I don't really know, but contrary to what appears to be accepted wisdom, I think just about all keys take some part in the drive process.

[fredeuce]

If it is just for location why is the key so big?
Also - unless the flywheel/engine assembly has been balanced there is no need for any particular location - so why a key at all?

I don't really know, but contrary to what appears to be accepted wisdom, I think just about all keys take some part in the drive process.

Since the timing mark are on the flywheel, when you assemble the crank and flywheel you need the timing marks in the right place . That's all the "keyed" portion performs. You will also note the key is offset so that it goes on only one way. The balance of the washer is simply that a means of protecting the end of the flywheel and crank from being scored and applying the load by the bolt when being tensioned.

As for the key taking part in the drive only if the tapered joint is not doing its job.

Edited by fredeuce, 16 February 2011 - 20:32.

[Lee Nicolle]

Really a taper is a decent flywheel fitment, except for removal problems. But on an axle you are relying on the splines into the diff to take all the misalignment. Diff tubes flex and twist. This coupled with good traction and horsepower means they come loose and turn.
Anybody who has ever had these horrid things will know all about it. Early Holdens, Early Fords, Studebakers etc.
Everything on automotive driveshafts of any description these days is splined, and usualy fairly fine splined to increase the load capacity.

[Kelpiecross]

Since the timing mark are on the flywheel, when you assemble the crank and flywheel you need the timing marks in the right place . That's all the "keyed" portion performs. You will also note the key is offset so that it goes on only one way. The balance of the washer is simply that a means of protecting the end of the flywheel and crank from being scored and applying the load by the bolt when being tensioned.

As for the key taking part in the drive only if the tapered joint is not doing its job.

I forgot about the flywheel timing marks (and I have looked at Mini timing marks at least a million times). But I still get the impression from the size and strength of the key that it is not just for timing alignment purposes - it would seem to be intended for "backup" driving purposes at least if the taper started to fail.

[Greg Locock]

I forgot about the flywheel timing marks (and I have looked at Mini timing marks at least a million times). But I still get the impression from the size and strength of the key that it is not just for timing alignment purposes - it would seem to be intended for "backup" driving purposes at least if the taper started to fail.

Not getting at you, but what is the point of this backup drive? Presumably the key can't take the full torque for long, so it seems to me that even with a cluey driver the inevtiable is merely delayed by a few seconds.

When a taper loses it, it doesn't just go a bit soft, the driven end pops rearward and you lose ALL the drive via the taper.

Edited by Greg Locock, 17 February 2011 - 03:53.

[Kelpiecross]

Not getting at you, but what is the point of this backup drive? Presumably the key can't take the full torque for long, so it seems to me that even with a cluey driver the inevtiable is merely delayed by a few seconds.

I did say earlier that I didn't really know about the purpose of the key. I am just pointing out that the engine maker and the makers of the high-quality steel replacement keys certainly seem to be making them strong enough to share the drive loads (or act as a backup). It is hard to picture how the taper and key could share the drive load - but that seems to be the intention of the various key makers.
If you are not familiar with the key - here it is:

http://www.minisport....au/prod911.htm

As you can see this is not a key it's a KEY (with apologies to P. Hogan).

Edited by Kelpiecross, 17 February 2011 - 09:16.

[Catalina Park]

I did say earlier that I didn't really know about the purpose of the key. I am just pointing out that the engine maker and the makers of the high-quality steel replacement keys certainly seem to be making them strong enough to share the drive loads (or act as a backup). It is hard to picture how the taper and key could share the drive load - but that seems to be the intention of the various key makers.
If you are not familiar with the key - here it is:

http://www.minisport....au/prod911.htm

As you can see this is not a key it's a KEY (with apologies to P. Hogan).

There is two parts to the Mini flywheel key.
The washer part is to hold the flywheel tight on the taper when you do up the bolt.
The key part is there to align the timing marks (and the balance marks) while you try to crush the washer to lock the taper.
When you make the washer out of stronger material you are trying to keep the flywheel tight on the taper not to make it take the drive. They are trying to avoid the bolt from coming loose.

Did you ever use the locking washer under the bolt? Did you know that the locking washer is the main reason why they come loose? It is too soft and crushes under load.

For removal of the Mini flywheel I use a puller and a heat gun. Do up the puller tight and then hold the heat gun on the flywheel for about a minute then tighten the puller again. Easy peasy.

[OfficeLinebacker]

For removal of the Mini flywheel I use a puller and a heat gun. Do up the puller tight and then hold the heat gun on the flywheel for about a minute then tighten the puller again. Easy peasy.

Yeah but then what am I going to bash with a hammer when I get angry? The workbench?