First cut from my 8520...what is this god awful noise coming from...

Someone had a procedure on rebuilding the head- if I can find the link I'll post it here
Mark
ps here you go:
 

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Someone had a procedure on rebuilding the head- if I can find the link I'll post it here
Mark
ps here you go:

Thanks Mark. I'm not interested in rebuilding the head at this point but it gives me a good idea of how the pulley assembly is removed. In this PDF he had to remove the pulley with a puller. Clearly mine is moveable up and down by hand....so somethings a miss and so I'll start there and assume, for now, that that is the source of the noise....
 
OK understood, good little mill even if it needs a little fixing, I don't own one but I like to stockpile information just in case
Hello my name is MARK and I'm an information hoarder :cool 2:
 
OK understood, good little mill even if it needs a little fixing, I don't own one but I like to stockpile information just in case
Hello my name is MARK and I'm an information hoarder :cool 2:
I'm with you, Mark, about "hoarding" information, at least about machines that I own or expect to own one day (and I do own an 8520). Not being one to want to reinvent the wheel when I can help it, I have created 3-ring binders for most of my machines where I put whatever manuals, brochures, parts lists, write-ups of procedures, etc. I come across in the cornucopia of information available to us on the internet (most of which couldn't have been found anywhere pre-internet). I can sleep a little better knowing that if and when I need to rebuild the head of my 8520 I will have an excellent step-by-step guide to doing it. Also, the next owners of these machines will probably be ecstatic to have access to these "books" after the big estate sale!

I'm reading this thread almost like a mystery serial and I can't wait to find out what the issue turns out to be. The answer may well end up immortalized (printed out and lodged in a page protector) in my 8520 book!

Bill
 
I'm with you, Mark, about "hoarding" information, at least about machines that I own or expect to own one day (and I do own an 8520). Not being one to want to reinvent the wheel when I can help it, I have created 3-ring binders for most of my machines where I put whatever manuals, brochures, parts lists, write-ups of procedures, etc. I come across in the cornucopia of information available to us on the internet (most of which couldn't have been found anywhere pre-internet). I can sleep a little better knowing that if and when I need to rebuild the head of my 8520 I will have an excellent step-by-step guide to doing it. Also, the next owners of these machines will probably be ecstatic to have access to these "books" after the big estate sale!

I'm reading this thread almost like a mystery serial and I can't wait to find out what the issue turns out to be. The answer may well end up immortalized (printed out and lodged in a page protector) in my 8520 book!

Bill

I'm hoping it's simply a broken retainer clip that's causing the pulley to vibrate up and down and slap against the head. Like I mentioned in an earlier post, I reduced the speed to 600 RPM from the 1900 RPM that I had before and the machine sounds way better. Of course I'd like it to sounds exactly the same regardless of the speed I have it at. Perhaps I'll have some down time to work on it tonight.
 
So I'm 90% sure my noise is coming from my pulley being loose. I can't seem to pinpoint any other problem. I completely removed the cover and the noise is still there. So it's not the brake handle. I then attempted to remove the pulley. I started by attempting to remove the drive plate. I removed the two hex screws and the side spring loaded set screws but the drive plate seems to be fused to the pulley pretty good. The document for rebuilding the 8520 head makes it seem like this drive plate should just come right off....it doesn't. I also found the two set screws to be excessively loose. More on this in a bit. The video below shows me trying to slide the pulley up and off of the shaft but' it's binding on something. Again, I don't know WTF. So I gave up, slid the pulley back down and tightened the set screws. The pulley tightened up ok until I went to cut something. The pulley slid back up a tiny bit and the noise continued. Took the thing apart again and the pulley moves up and down. Granted it requires some effort to move up and down but it's moving nonetheless. I'm not sure what's going on with this thing and I just want it to work. I sold my Rong-Fu to buy this mill in part because of it's cult following and right now I just feel pretty annoyed... :(

 
So I'm 90% sure my noise is coming from my pulley being loose. I can't seem to pinpoint any other problem. I completely removed the cover and the noise is still there. So it's not the brake handle. I then attempted to remove the pulley. I started by attempting to remove the drive plate. I removed the two hex screws and the side spring loaded set screws but the drive plate seems to be fused to the pulley pretty good. The document for rebuilding the 8520 head makes it seem like this drive plate should just come right off....it doesn't. I also found the two set screws to be excessively loose. More on this in a bit. The video below shows me trying to slide the pulley up and off of the shaft but' it's binding on something. Again, I don't know WTF. So I gave up, slid the pulley back down and tightened the set screws. The pulley tightened up ok until I went to cut something. The pulley slid back up a tiny bit and the noise continued. Took the thing apart again and the pulley moves up and down. Granted it requires some effort to move up and down but it's moving nonetheless. I'm not sure what's going on with this thing and I just want it to work. I sold my Rong-Fu to buy this mill in part because of it's cult following and right now I just feel pretty annoyed... :(


You'll get it figured out. Two socket head screws and two ground dowel pins hold and locate the plate on the top of the pulley. It's probably just old hardened oil glueing it together. Sharpen up a cold chisel and tap it into the seam between the plate and pulley, working all the way around the circumference. It should separate.

That's an interesting draw bar and threaded spindle you have there. I assume that you have the cap nut that screws onto the top of the spindle. I've heard of the mod, but not seen it. The flange on the draw bar is bigger than the depth of the splines, so the draw bar has to come all the way out. Your pulley sleeve has a much thicker flange than mine, and I hate to say it, but is that a break around the inside edge that I see? I'm afraid that the "sleeve" part has broken off from the flange, which would explain your whole issue. You will need to braze it back together or make a new one. Someone here can help you with that (maybe even me).

Don't give up. I had to deal with several issues on mine, including silver brazing the broken brake plate, but I've made it into a really nice machine.

-Jon
 
Thanks for the guidance Jon, I got it apart (mostly). Not sure why I didn't think to remove the draw bar first. I can see that the pulley sleeve assembly is broken. Looking at the pictures up close, it looks pretty clear that someone had it break on them before and they attempted a fix that didn't hold. If that's the case, I may just make a new one. So with that said, two questions.

1) What's the best way to remove the broken portion of the pulley sleeve from the pulley without damaging the pulley? Press it out? Will the bearings just slide off or will they have to be pressed out as well? In the diagram, I see that there are 2 retainer clips in between the bearings so I'm not sure what the best way to get these off would be.

2) Is the pulley sleeve pressed into the flange or is it all one piece? If it's pressed in, what's the best way to remove the broken off piece that remains in the flange?

Thanks in advance for any help!

pulley1.jpgpulley2.jpgpulley3.jpgpulley4.jpg
 
Now that you have the top clip off, press the sleeve out through the pulley from the top. It should push the bottom bearing out with it. Impossible to say how much trouble the bearings will give you. Sometimes the bearings just fall out/off (a good or bad thing depending on your point of view). The top bearing in the rear cone pulley on mine was wallowed out several thousandths, and had to be sleeved and re-bored. I also sleeved and re-bored the brake ring contact surface in the front cone pulley. The end result was a very quiet machine and a brake that locks things up with just a little pressure on the lever.

I recommend replacing all of the bearings while you have it apart. They're standard sizes, and inexpensive. The only ones that I re-used were the thrust bearing on the knee screw and the quill bearings (but I have spares anyway).

-Jon
 
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