Disc Sander Runout and Vibration

[John Vorberger]

I purchased a Delta 12 inch disc sander from Amazon and it came yesterday. Based on advice I've read about online, I checked the runout of the wheel. I believe it is the axial runout, but you will get a better idea of it once I explain.

Basically, when I put a piece of wood against the disc near the outside edge of the disc and I spin the disc manually, I can hear and feel the disc sanding the piece of piece only at certain times. For example, I hear the disc sand the piece for maybe 1/4 of a rotation and then it doesn't sand it for 1/4 of a rotation, then it sands it again. I tried to measure runout based on the actual platter (not sure what the term is for the metal disc the sanding disc is glued to), and I got about 0.020, maybe slightly more. Is this acceptable or should I exchange this disc sander for a new one at no cost?

Also, there are slight vibrations whenever I turn on the sander. Not enough to slide the miter guide off the table like some have observed, but enough to be felt.

What do you thin I should do about these observations?

[Paul K. Johnson]

Are you sure it isn't the sandpaper? I've had problems with some sanding disks coming loose very quickly. I always clean my disk platter with acetone before adding a new disk. But the disks that are very curled and on heavy paper just won't stay stuck down.

As soon as I put a new disk on I press it in place with my hands and then turn the sander on and use a crepe cleaner to press it down better. That doesn't resolve the problems with curled disks so I just don't use those any more.

[glenn bradley]

Depending on how you plan to use it I'd return it. What I mean by that is that if you plan to dimension parts, adjust miters or anything that requires reasonable accuracy the runout will be a constant source of frustration. I have a Grizzly that I can do pretty trick things on and even Dad's Harbor Freight runs true (on the second one).

There are certain tools that are fine when operating sub-par depending on what you do with them. A disc sander that is a bit out can be used for rounding the ends of boards, hogging off an angle before heading to the shooting board and so forth. I don't have much room. This makes me a little demanding in what I expect from a machine. We all have thresholds of what we accept as reasonable.

[John Vorberger]

I thought that it might be the sandpaper, but I took a close up video of myself spinning the sander to check what was wobbling. It looks to me like both the metal and the sanding disc wobble. Also, the wobble of the platter could he the source of the vibration, right?

Also, when I tried the same technique I used to see if there was runout closer to the center of the disc (maybe 3 inches from the center), there were still periods of sanding and no sanding. That makes me think the disc is glued on properly, but today I can check just the platter because I need a finer grit paper anyways than what it comes with.

Can paper be put back on after being removed?


Thanks,

John

edited to add: I'm using the disc sander mainly to true up the edges of my segments for my segmented turning. The angles must be exact within a tenth of a degree.

[Paul K. Johnson]

I've never been able to re-use paper which kills me when I just put one on and need to change it. Those disks aren't cheap. In fact, I've very strongly considered getting a second sander so I can have two grits at all times. It still wears out but I almost never wear one out because I need to change to a different grit while the current one is still good.

Anyway, what normally happens is it tears or the glue rips away. A heat gun might make it come off intact but that hasn't worked for me either.

Sometimes I'll just look for random things to sand before changing so I don't feel like I've wasted a new disk.

[John Vorberger]

Ok, I think I will examine the outside of the disc and check if there are any spots that have uneven glue. But unfortunately I think the platter is uneven.

[John Vorberger]

What about the vibrations? Are they normal?

[michael langman]

John, Yes the vibration could be coming from the platter running out. If you can see the back corner of the platter and could put a pencil point up to it, and turn the platter by hand, then you could see if the platter has run out in relation to the pencil point.
I would send the sander back for a replacement, but the next sander you get may be the same. Maybe not.

[John Vorberger]

It's hard to explain, but the front of the platter is beveled, so I put a pencil point up to the top of the bevel and spun the wheel slowly by hand. The bevel moved in and out in relation to the pencil point, visibly, I didn't need any tool to measure what I could clearly see.

Do you think a replacement would have the same issue?

[John Vorberger]

Does anyone have one of the 12 inch disc sanders? Not necessarily a delta because they are all pretty similar. Anyway, if you have one, do you notice any runout or vibration?

[Joe Bradshaw]

John, I have a Grizz 12"sander and it runs pretty smooth.
Joe

[John Vorberger]

Thanks Joe. Hopefully my replacement will be smooth.

[John Vorberger]

Do you know if it is possible to true up a disc sander platter that has runout?

[andy bessette]

Of course you can true up the disc. But also check for shaft runout.

[Erik Manchester]

I have a Delta 12" disc 6x48" belt unit from 1989 and the outer edge of the Disc face has 0.003 variation in rotation. This is acceptable for my needs and it decreases toward center.

I have a Velcro pad on it for easy paper changing and it critical to get the paper centred on the disc or it will induce a vibration.