Thread: Keyway in shaft

Originally Posted by Chrism3

I don't think that will work, for 2 reasons:
1 the nut is only a 'half nut' - quite narrow
2 the nut is entirely recessed inside the pulley - no room to get an allen key in to tighten a grub screw.

But thanks for the thought!
Chris

only needs to be 2.5mm or 3mm grubscrews
certainly looks like a short hex allen key will get in there....hard to tell by the pics

Originally Posted by Chrism3

It's still a puzzle to me as to why a left hand thread would come undone.

All threaded fasteners are meant to come undone - otherwise you may as well weld them. As to why this particular nut came undone, one of the reasons I suggested the design change to the pulley that I did was that I think the design is flawed. As soon as the bore on the pulley gets stretched, the pulley can flop around and any torque on the nut disappears. When that happens the nut will do what it likes.

Michael

Originally Posted by Michael G

All threaded fasteners are meant to come undone - otherwise you may as well weld them. As to why this particular nut came undone, one of the reasons I suggested the design change to the pulley that I did was that I think the design is flawed. As soon as the bore on the pulley gets stretched, the pulley can flop around and any torque on the nut disappears. When that happens the nut will do what it likes.

Michael

Ok. While the pulley is aluminium, it has a steel insert that fits onto the shaft. So if you think that deformed then the stresses must be large.

Originally Posted by Chrism3

While the pulley is aluminium, it has a steel insert that fits onto the shaft. So if you think that deformed then the stresses must be large.

Strictly speaking until it is measured you can't say definitively but it does not strike me as being terribly robust (I know that sometimes designers only have a "less bad" choice, but still...). Reading some of the posts in one of links you provided it sounds like some people have loctited the nut in place and still have to go back and re-secure it a year or so later. That suggests to me that the fix (locking the nut in place) is a symptom and not the root cause.

That's my WAG anyway.

Michael

It is done. New keyway, 3 grubs in the new pulley, one on the key and 2 into dimples in the shaft. Add a splash of retaining compound and locktight the nut and grubs in place.
The pulley is made of alloy X, too heavy to be aluminium but non magnetic, but the wrong colour and too easily drilled to be stainless.
I think the biggest issue is the pitch of the nut, it is a standard M14x2mm, way too course for the application.

Cheers,
Ew.

Yes, my thanks to Ueee - it is now back together.
I noticed that after running it for about a minute the end of the shaft, plus the end of the motor shaft were both quite hot - uncomfortable to touch. Heat that might have played some part in the catastrophe.
The pulleys however were not as hot, and neither was the belt, which claims to be heat resistant. So perhaps the alloy they are made from is a good conductor that transfers heat to the steel shafts.
Would others know whether this would be down to belt friction? I can't think of another reason. The belt is not overly tight, and has some give when compressed between finger and thumb.
regards
Chris

First I would check the spindel and motor bearings......
If there is ANY noise coming from the motor bearings without the belt on, replace them BOTH and also replace any seals on the motor shaft.
Spin the cutter spindle by hand and listen to any bearing noise. If there is any, replace the bearings.
Thaese are about the only things that can make the spindles/shafts hot without the pulley getting equally hot.

Spindle bearings are new Joe, but the old one i took off still felt fine.

I really think Chris needs to get someone else with the same unit to check the heat of theirs. If they do get hot normally then the locktight is not going to last as a fix.

Hmmmm
What is causing the heating? My planer and thicknesser shafts don't get hot even after long sessions. Barely warm. Somthing is not quite right. Does the belt get hot?
I had a similar prolem with an old motor. It woud get a hot shaft just running free. It turned out to be a hard and rubing rease seal at one end. Replaced it. Prolem gone. I would never have thought that a rubber lip on a seal could heat up a shaft, but it did.....

I just removed the belt and confirmed that the motor shaft doesn't generate any heat.
Then i put the belt back on and tightened it to see if that made any difference. I would say not - but after a minute or so the motor pulley is very hot, as is the cutter shaft and pulley and the belt is decidedly warm.

The cutterhead pulley is presumably hard up against the inner face of the bearing, since there is nothing to stop it when tightening the nut. But that shouldn't generate friction because the bearing will be turning with the pulley. And the rubber seal is recessed below the bearing edge.
I can only suspect it's the belt friction. I'll see if I can find the specs of the old belt and the new belt (which is certainly sold as a direct replacement).

Have you considered a " Dutch" key? Which is a allen screw drilled in from the end of the shaft through the nut and shaft. Do it up and it prevents the nut movement.

I'm confident Ueee's fix has already solved the nut issue - that's not generating the heat problem.

I found the tensioning specs for the new belt, and found that I needed to loosen it from the tight setting that I had moved it to.

I found the spot where I could hear an initial squeak as it slipped on startup, and tightened it a bit from there until I had no more squeak.

I then tried things out on a few pieces of timber, and it works great. In fact during the dismantling i discovered that the cutterhead lock was not adjusted correctly, and it now is, which has completely eliminated the snipe I was getting. Not that the Delta instructions tell you how to make this adjustment - I stumbled upon the Delta patent document, which describes in great detail how it works and how to adjust. This info is not on their FAQ site, neither is the detail of how to adjust the belt.

So I'll have to live with the heating - I've left the outer cover off so that I can see if anything goes awry.

[QUOTE=jhovel;1891587]Hmmmm
What is causing the heating? My planer and thicknesser shafts don't get hot even after long sessions. Barely warm.

Is your thicknesser a Delta?