# Clausing 8520 'chatters' when cutting



## Terrywerm (Jun 10, 2014)

First, let me describe what is in place on this particular machine. When I purchased it, the drawbar was a 3/8"-16 grade 8 bolt, 12" long. It works just fine, but the push out cap and drawbar were missing. Anyway, the drawbar issue is being addressed so that I will soon have the proper cap and drawbar so that the drawbar will eject collets as well as draw them in.  There is a small cone shaped washer under the head of the bolt, which tends to keep the top of the bolt centered in the spindle. 

The problem is this: Whenever I start a cut with an end mill, the machine makes a metallic, ringing, chattering noise. It literally sounds like the drawbar is vibrating and hitting the inside of the spindle. There is plenty of clearance inside the spindle, I don't see how vibration would cause the drawbar to flex enough to vibrate against the inside of the spindle. My new drawbar will be a bit more stout than the 3/8 bolt that is in there now just to be sure. When the machine is running, but not cutting, it is quiet. If I take the drive belt off and turn the spindle, it is smooth and free, it does not sound or feel like there are any bearing problems. The noise starts even with the lightest cut, and does get somewhat worse with a heavier cut. The chattering noise sounds nothing like a bearing that I've ever heard.

So my question is this: Have any of you other Clausing owners ever experienced this?  For that matter how about you owners of any kind of mill?

I am contemplating a complete disassembly of the headstock to clean everything up. If I do that, I will replace the bearings simply because I am already in there, but maybe that is not necessary at all. I must admit that I am baffled by this one.


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## JimDawson (Jun 11, 2014)

I had a similar problem on my mill.  It's a 2J2 type head, with a #30 taper spindle but does not use a drawbar.  It was driving me nuts, and was more prone to chatter when moving in the Y axis than the X axis, it didn't matter if I was climb or conventional milling.  I pulled the quill out and checked the bearings, everything seemed fine, very smooth.  I adjusted the bearings a bit tighter and put it back in.  Same problem.  I talked to a friend of mine who used to rebuild machine tools, and he suggested that the problem was the top spindle bearing, this is what he normally found.  Long story short, I needed to run the machine to get a job out the door so I adjusted the feed and speed to minimize the chatter and finished the job.

I sent the spindle over to the local rebuilder and had the 5 bearing upgrade done.  When I got the spindle back, the problem was gone.  I never did really diagnose the problem, but my friend may have been right, because I would swear that the bottom bearings were just fine.  It did sound like most of the noise was coming from up high in the head, rather than the lower part of the spindle.


PS.  I don't know if you remember my fork lift issue: http://www.hobby-machinist.com/showthread.php?t=20780&p=179552&viewfull=1#post179552  But I found the problem, one of the mast roller bearings had broken in half and was causing extra friction.  So when letting down a light load it would hang a bit.


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## 34_40 (Jun 11, 2014)

I haven't made a lot of chips with mine,  mostly alumininum too,  but there has been at least one small piece of steel..   but there wasn't any chatter in mine.

Could the sound be coming from the depth stop adjuster? (or whatever it's called! :lmao  Maybe the scale is bouncing? :thinking:

Grasping for straws I'm sure...  I just don't see how the drawbar,when tight, could bounce enough to rattle / chatter..


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## Bishop (Jun 11, 2014)

My 8520 is quiet when taking a cut in steel or aluminium. I wonder if it might have something to do with the step pulley's. If there was something loose there itight make a sound under load? Just another guess though. 

Shawn


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## Andre (Jun 11, 2014)

Are you sure it's not the splines of the spindle ratting? My BP M head does that a lot, I throw some motor oil in the splines and run the quill up and down a few times to spread the oil in the splines. It quiets it down for fifteen minutes or so. Just watch out when you turn it on because sometimes it will sling oil in your face!


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## John Hasler (Jun 11, 2014)

Andre said:


> Are you sure it's not the splines of the spindle ratting? My BP M head does that a lot, I throw some motor oil in the splines and run the quill up and down a few times to spread the oil in the splines. It quiets it down for fifteen minutes or so. Just watch out when you turn it on because sometimes it will sling oil in your face!



My Avey has a rattle that I've been worrying about: perhaps that's it.  I wonder if sticky way oil might be better on the splines than motor oil?


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## chips&more (Jun 11, 2014)

Have you tried the wooden dowel or similar tool trick to better pin point the noise? You take a length of dowel say 3/8” round, put one end up to your ear and with the other end, place it on various points of the mills head. You will be surprised at how directional that simple method can be…Good Luck.


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## Don B (Jun 11, 2014)

terrywerm said:


> The problem is this: Whenever I start a cut with an end mill, the machine makes a metallic, ringing, chattering noise. It literally sounds like the drawbar is vibrating and hitting the inside of the spindle. There is plenty of clearance inside the spindle, I don't see how vibration would cause the drawbar to flex enough to vibrate against the inside of the spindle. My new drawbar will be a bit more stout than the 3/8 bolt that is in there now just to be sure. When the machine is running, but not cutting, it is quiet. If I take the drive belt off and turn the spindle, it is smooth and free, it does not sound or feel like there are any bearing problems. The noise starts even with the lightest cut, and does get somewhat worse with a heavier cut. The chattering noise sounds nothing like a bearing that I've ever heard.
> 
> So my question is this: Have any of you other Clausing owners ever experienced this?  For that matter how about you owners of any kind of mill.



I had a Busy Bee Mill that was doing the exact same thing as your describing, spin the spindle by hand couldn't feel a thing, run all day with no load and was fine, I finally figured there just had to be something wrong with a bearing even though I couldn't feel it, it was a bearing in the end, when I removed them one bearing felt smooth until a little radial load was applied (by hand) then I could feel a slight roughness every few spins, replaced that bearing and the noise was gone, the machine was only about 4 months old.

Edit: Sorry should have added it turned out to be the top bearing (which was not the one I suspected) and the noise was far worse with the quill extended.


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## Terrywerm (Jun 11, 2014)

Thanks guys for all of the replies. I was running the mill earlier today, no load, no drawbar, no other noises going on, and I realized that it does make a little bit of noise near the top of the spindle, that I previously had thought was vee belt noise. A closer listen has me realizing that it sounds more like a dry bearing. Guess I know what's next.

Thanks again for the replies!


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## daveyscrap (Jun 11, 2014)

Hey terry I have a brand new still shiny press at work if you need help pressing bearings. I kind of bent our old one into a wishbone. But it's there if u need one 


Sent from my iPhone using Tapatalk


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## Ray C (Jun 12, 2014)

Terry,

I'm not familiar with that model of mill but, if it's similar to others I know of, the "problem" may be due to how the spline is being driven.   On the mills I'm most familiar with, the spindle is driven by a shaft and at the top of the shaft, it's a spline.  This allows it to move up or down and also be driven by a gear through which, the spline traverses (i.e. the center hole of the gear matches the spline).  Whenever any funny sounds start emanating from that area, it's usually a sign the spline is too dry or, the teeth of the gear are going dry.  Under heavy loads, the sound is more pronounced and it's due to the chattering of the fit between the spline and matching center hole of the driving gear.


Ray


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## Terrywerm (Jun 12, 2014)

Daveyscrap, thanks a million for the offer. I think I've got it all covered, but I will keep you in mind, just in case. It sounds like there may be an interesting story related to you reshaping the old one!

Ray, thanks for the info on the spline chatter.  This mill does not have any back gears, so there is no gear on the splines. Instead, this mill just uses belt reduction, and the pulley is attached to a drive plate that engages the splines on the spindle. It is possible that the noise may be from there. I will see what I can do to eliminate the noise from the spline by packing some temporary shims in there. If the noise disappears, then I know that the noise is being generated in the splines, but if it does not, then it may well be a bearing.

I will post back here once I have found the solution.


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## Metalflames (Nov 29, 2014)

Did you ever diagnose the problem? I noticed on mine if the Front belt cover is on it makes all kinds of noise.


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## Terrywerm (Nov 30, 2014)

Well, a few things have changed, and I forgot all about this thread and my promise to post my findings.  Too much going on I guess!

The front cover is not the problem, although it easily could be as it does not enjoy a tight, vibration free fit on the machine. However, I knew this early on, and simply placing a hand on the cover would identify it as the culprit if that were the case. Not that lucky though, as dampening the cover made no change to the sound.

My original drawbar was a 12" long 3/8"-16 grade 8 hex bolt; it is what came with the machine. When I discovered the chatter problem, I tried a couple of things to abate the problem, including making a centering bushing for the makeshift drawbar to bear against instead of the top of the spindle spline itself. This reduced the noise, eliminating it when not under load or when using a drill chuck, but when applying a side load during milling processes, the noise still occurred.

I had been interested in obtaining a factory style drawbar, and another member had an extra one that he was willing to part with, so I purchased it. Once it arrived, I made the retainer cap that keeps the drawbar captive in the spindle and also enables the 'self ejecting' capability where the drawbar will push collets out without having to resort to beating up the top of the drawbar with a hammer. 

Since that time I have not had much work for the mill, but I do not recall the spindle making any noise while working on any of the small projects that I have had since changing the drawbar. 

Do I think the drawbar was the problem??  No.  I am thinking that I just have not had any projects that applied any significant side load to the spindle and bearings. I will make an effort to get out into the garage and run a test cut on a piece of scrap to see if the problem still occurs. It has been cold out there and I have been ill since Wednesday evening. I am finally feeling human today so I will try to get out there and see what I can find out.


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