Sanding the inside of a goblet or other hollow form?

[Texfire]

I was sanding down a wooden goblet that I've had for years. I had managed to ruin the finish on it a couple years ago by running it through the dishwasher, I should have known better but didn't. So the resulting finish was mottled and resistant to sanding. Now that I have the lathe, I thought I'd chuck it up, and was making okay time with using sanding strips on the exterior. It seemed to have a little wobble no matter how I shifted it in the chuck, I suspect after a couple of years it's not quite round, but I was able to use a finishing tool to remove the remainder of the old finish off the exterior and modify the profile a little. But when I got to the interior surface progress ground to a halt.

The inside was a total disaster. I started off trying to use sandpaper, which worked okay with finger pressure, but only as far as I could reach. I was also a little nervous that a catch could mean a broken finger. Then I tried using a finishing tool on the interior to remove the finish and get a smooth surface and ran into some extreme grain tearout, not sure why. Sandpaper was able to clear it out, but once again, the bottom two inches of the cup aren't sanded because I can't figure out how to get the sandpaper in there supported without doing something stupid. I also tried one of those angled bearing disks that you put sandpaper on, but it can't angle over far enough.

So how do you safely sand the interior of a 4" diameter goblet with a deep cup? Make a curved form and glue sandpaper to it? What have you done?

[iSawitFirst]

Maybe it would be better to not turn it while sanding. I'm not a turner so I'm trying to think of ways I'd do it. Maybe a sanding mop on an extension.

[Texfire]

Saw where someone used a slotted dowel to hold the paper. I think I'll give that a try. If that doesn't work then by hand will probably be the answer.

[Roger T]

Saw where someone used a slotted dowel to hold the paper. I think I'll give that a try. If that doesn't work then by hand will probably be the answer.

Hi Tex,

They make little velcro pads that will chuck up in a drill. 1",2" and 3". The 1" will more than likely let you get the inside done. Here is a link. You may need an extension to reach the bottom, but I think a phillips bit holder would get that done for you. Dont forget to order sanding discs also.

http://www.woodturnerscatalog.com/store/Abrasives___Hook_and_Loop___Apprentice_Disc_Holder___artisan_disc_holders?Args=

Hope this helps.

Roger

[Texfire]

Excellent, thanks for the assistance.

[Lawrence Brown]

If you have a rounded bottom on that goblet, you also may want to look into one of these that use these.

It's going to be hard to get that bottom smooth because of the angles, but with enough work you may be able to do it.

How are you chucking this up in the lathe? If it's a goblet, I'm assuming it's got a stem. One of the rules of turning is that on hollow vessels and things with narrow bases, you have to turn it in such a way as to maintain support towards the headstock. Once you finish a section, you can't go back, so in the case of a goblet you would actually want to completely finish the inside first, including sanding, before moving on to the stem. You would then add a jam chuck to the tailstock that fits inside to support it. Otherwise it's just going to snap off.

You definitely can't go back and use any turning tools on it again because, as you guessed, the wood will have moved. Sanding is about all you can do, and you want to do that at a very slow speed. have you looked into using foam-backed sandpaper, like sanding blocks? That will deform with the shape of the wood better than flat paper and should give you a better finish.

You going to post a pic once it's done?

[Texfire]

Thanks, that's exactly what I ended up going with. I actually got the whole package Guinevere system, and I think it's going to be useful. Of course the bottom of the goblet is too sharp an angle for the rounded form.

I'm not going to post a photo, unless someone needs one on how not to sand a previously goblet, it was already ruined so I can chalk that one up to the learning curve.