# Clunking / Knocking / Vibration Problem '88 Series I, Variable Speed



## middle.road (Sep 13, 2015)

I'm in need of some trouble-shooting input - again. Seems all my machines like to clunk...

Finally got the beast running, it's been sitting since we brought it home in May.
I sounded great at the auction, but now there is a definite clunk/knocking and a slight vibration when running.
Sound's like it's coming from the upper top area of the housing.
Mostly occurs in the lower RPM range and then evens out and dissipates at 1600+ RPMs.
Head was rotated 180° for transport. I'm wondering if something foreign has gotten into it or if it is
just the fact that it sat for almost (4) months.
She is all lubed up. I put ~50cc of #105 into the 5/16 set screw and the cups are full.

Searching around I see that it can be a whole bunch of different things, but I'm holding out hope that
it is something simple that I have not found reference to yet.

Thanks, _Dan


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## Tony Wells (Sep 13, 2015)

If it is a Reeves drive, expect trouble sooner or later. It is possible that sitting in one position could have given the belt a flat spot. If that's the case, in time it will disappear. Just let it run, unloaded, for a while, then change the speeds up and down a few times. You are aware that you should not change the speed settings with it not running, I suppose. 

It's also possible that there is a worn spot on the belt, giving it a "knock", but that seems less likely since it sounded fine when you first saw it. 

Also possible is the bushing in the movable pulley in the Reeves drive is worn, but again, not as likely since you heard it normally at one time.

Bottom line, let it run for a few hours. See if it quietens down.


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## middle.road (Sep 13, 2015)

How's about some rust? I noticed that you can see into the drive looking in just over the plastic housing above 'Series 1'.
The pulley is all rusted. Gotta love the climate control in my shop.
Up around the 2000RPM range it's silver, you can see the where it turns to rust on lower R's.
Belt must have been sitting @ ~ 1300RPM position.
Some good news possibly, the belt looks in very good shape from what I can see. The Gates lettering is nice and bright white.


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## sanddan (Sep 14, 2015)

I have a similar noise in my head that is related to the position of the belt in the pulleys. It only occurs at low RPM's and disappears as the RPM increases. Happens in both low gear and high gear, same position on the pulley. I can change the speed using the VFD and doesn't change the noise. Only changes when the belt moves. Rust isn't an issue on mine so probably not the issue with yours either. A flat spot on the belt is the easiest to fix, replacing the plastic sleeve requires a lot more disassembly.


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## JimDawson (Sep 14, 2015)

Mine is noisy also when first started in the morning, it gets better as the machine warms up.  I normally run for about 10 minutes at about 500 RPM just to get things warmed up a bit before I start cutting.  If it sits for a few days, it's worse.  It's like the belt takes a set.  

As a side note, there was a post a while back wondering about the temperature of the vari-speed belt system.  After running at about 3000 RPM for a couple of hours mine was 125 degrees at the housing, and the spindle nose was 115, the ambient temperature was about 88 at the time.


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## sanddan (Sep 14, 2015)

Running warm like that helped loosen up my quill a little. Moral of the story, run your machines more. LOL


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## middle.road (Sep 15, 2015)

First Part! Lathe compound Tee nut for the Dumore grinder I bought (4) years ago. Machine felt good.
Noise is dissipating a tad.
Got the DRO hooked up today, 'X'-axis innards are toast. (see other post) At least the 'Y' works.


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## derf (Oct 5, 2015)

The clunking, chatterery noise is most probably coming from the upper spindle hub and the splined gear hub. These parts have a limited life span, and need replaced when the radial splines bottom out. A broken down belt will also make lots of noise, coupled with worn bushings in the drive sheave.


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## sanddan (Oct 5, 2015)

Why would it only make noise in one belt position? In my case it only makes noise in the slowest belt speed position. Move it 50-100 RPM faster and noise goes away. It seems to have gotten less as I've used it. Maybe the belt took a set sitting in the same position? In my case it's 850-900 rpm in high gear. 850 is slowest in that gear.


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## derf (Oct 5, 2015)

When the belt wears away, and /or it gets broken down on the outside edges, it will ride closer to the center of the sheaves. At lowest and highest speed the belt will actually ride the shaft, not the sheaves. The clunking sound is made by the inside of the belt where it is corregated(for the lack of a better term). A worn or damaged belt will also run the spindle faster than what your speed dial says.
 I just did a conversion on my mill to a vfd and solid pulleys to eliminate all that . I checked the rpm with a digital tach, and with a broken down belt the top speed was 5500 rpm...quite a bit more than the 4200 that the speed dial said. Even on the bottom end of hi-range, the speed was over 900.


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## sanddan (Oct 6, 2015)

Thanks derf, that makes sense to me. Looks like a belt change to me. How do you determine the speeds with your conversion? I also have a VFD on my mill but the display shows the electrical Hz, not motor speed. Did you add a digital tach to the head?


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## derf (Oct 7, 2015)

Yes, I did indeed add a digital tach that I bought off ebay for 16.00. It will be a little tougher to mount one with the variable speed pulleys and such taking up all that space. Once I got all the vari-speed stuff off, I made poly v-belt pulleys from aluminum. The spindle pulley is 3". I mounted a 4" lexan disc (1/2" thick) to the bottom of the pulley, and used a flat head machine screw for the sensor flag.
Since all the speed control is now out of the way, I had plenty of room to mount the pick up sensor.


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## middle.road (Oct 7, 2015)

Derf is that a custom or kit pulley/belt mod to a Series I Variable speed head? -Details?


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## derf (Oct 7, 2015)

I had to make all that from scratch. You might have noticed the motor pulley has fan blades for spokes. The reason for that is the motor fan will run slower below 60 hz, so an auxiliary fan is suggested for cooling. I added a 6" muffin fan on the top cover, but it is hard to push air through a 7" pulley that is only 1/2" away from the fan. By fashioning the spokes in the pulley like a fan blade, it allows the air to be suctioned through instead of being deflected.


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## sanddan (Oct 7, 2015)

derf, was the work on the pulley (fan blades) done on a CNC? Nice install overall.

My noise issue might not be due to the belt hitting the pulley shaft. I put it into low range and ran it up to max speed and quiet as can be. I then lowered the speed back down but it didn't seem as loud as before. When I put it back into high gear the noise was back but only loud at the lowest speed. It seems to make a difference whether it is in low gear or high gear. I am back to thinking it might be the plastic sleeve in the upper pulley assembly above the spindle. I still plan on replacing the belt first in case that is the issue. Since I have a VFD to run the 3 ph motor another option I guess would be to do a conversion similar to yours. Is your VFD a standard one or different to enable your setup to work?


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## derf (Oct 7, 2015)

I machined the pulley on that very machine before I gutted it, yes it is CNC.


I believe I would install a new belt and the plastic bushings in both pulleys and see if that cures it. If that doesn't, it would tell me that the spindle pulley hub and the splined gear hub need replaced(that's about $500).
 The VFD is a AB 523, and is probably no different than any other vfd. The forward/reverse/stop control is wired into the cnc control. I use remote pot and built a dial around it for ease of operation. I also incorporated 2 adjustable limit stops for the pot. This makes it easy to run 2 different tools at different speeds just by flipping the dial one way or another.


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