Originally posted by holmqer
I just did a poor job of sanding I think. I sanded 180 to 400, them MM 3200 to 12000, but never was able to get rid of the scratches from the 180. I sanded like I do for wood, with lathe spinning, then turn off lathe and hand sand perpendicular.
I don't seem to have as bad a scratch problem with wood.
I noticed the scratches on the purple one, too. Here's the long version of how I finish sand:
With resin, you have to be really careful how much pressure you put on the sandpaper, especially with the coarser stuff. It's like when you fall off your bike into gravel - if you land light, you'll get a bunch of little scrapes, but if you land heavy, you'll end up with a bunch of little scrapes
and 3 or 4 that may need stitches. [B)]
When I finish with the skew, if things are a bit rough, I start with 320 dry paper, and go really light, most of the time with the lathe turned off. I only use 320 to hit any tough spots or chatter marks, being careful not to 'target' less than 1/4 of the the radius of the tube. I hold little hunks of sandpaper between my index finger and thumb with both hands and lightly scuff the areas that need it. As far as I'm concerned, if you're using 180 grit on your resins, then you're not allowing your tools to do enough cutting for you. There are many times I go straight to MM1800 or 2400 right after skewing for both resin and wood. 80% of the time, the only thing I use 320 for is to wet sand with CA to slurry-seal open grains.
Mostly, when working with resin, I don't even turn the lathe on until I get up to MM2400 or MM3200. I just lightly 'shoeshine' buff the top 1/3 of the tube on about a 45 degree angle (halfway between 'cross' grain and 'with' grain), then turn the lathe a little, and do it again, usually takes about 4 twists of the lathe spindle to get good overlap on the one-third radius sanding patterns that I do. Once I get that angle scuff (remember, all lightly, just barely touching the sandpaper to the tube), I then go long-wise using my right thumb (LIGHTLY!) on the paper back and forth while I turn the spindle hand wheel with my left hand really slow. Once I get to at least 32MM, then I'll turn on the lathe and lightly sand like normal, being very careful with the pressure, then 'shoeshine' again, then the back and forth thing.
When I get to MM6K, I sand with the lathe on, and then 'shoeshine' with a little more pressure, watching the reflection on the tube, keeping an eye out for deeper scratches. If I find one that got by, I'll go back a couple grits and 'shoeshine' it out, then start again from the next grit.
The 'shoeshine' method really works well at 8K and 12K, and many times I'll do it without the lathe on.
I don't wetsand because of the mess, and I'm too lazy to go get and manage a water cup, so after MM12K, I'll inspect the tube for scratches and if there's tiny ones still in there, out comes the white diamond buffing wheel, which I use most of the time on resins anyways, there's just no substitute for the shine depth you can get with a buffer.
I usually just leave the tube right on the mandrel when I buff, it gives you some handles to hold. As for buffer wheels, you don't need to spend a fortune on a Beall system or anything. After swapping out my mandrel for a drill chuck, I just use the Ryobi mandrel, Ryobi buffing wheel and Ryobi white compound that I got from HD for less than $20. I just bump my tailstock up to the end of the mandrel to support it. When I'm not using it, I keep my buffing wheel wrapped in a piece of thick felt that I drape over the lathe bed to protect the workpiece when I 'oops' and bump it where the lathe bed would have boogered it up. I really only ever use the one wheel, although I've got 4 different ones that I use from time to time, mainly on beads and profiles.
Anyways, once I'm done with the final buff, I assemble the pen. Then, I use a coat or two of Ren wax, waiting about 10 minutes between coats, and it's done.
I hope this helps, let me know if anything was unclear. It's really not as time consuming as it sounds...matter of fact it took me longer to type out the steps than it does to actually do them, and I'm no slouch on the keyboard.
Nice casts, by the way! Looking very good. Isn't it fun?! [
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