“Nib/dimple on Box Lid

[Ned Ladner]

When making lidded boxes, starting between centers, I’m having issues with the center of top of the lid. No matter how much I sand, and I do work through all grits ending with 600, I end up with either a small hump/point or a tiny hole/depression in the center. What am I missing? I am sanding on the lathe at about 500 RPM.

Thanks in in advance for any suggestions.

Ned

[Paul Williams]

I always take a few strokes across the center with each grit with the lathe turned off. Not sure if this is the cause of your hole, but I figure the very center doesn't get sanded because it is basically going around in the same place in relation to the sandpaper.

[Roger Chandler]

I make quite a few lidded boxes. You are probably not leaving yourself enough of the blank to get the lid finished off, especially if you are putting a knob on the lid for grip to remove the lid. Sanding to get the nib off isn’t a difficult thing, and what I do is move the abrasive back and forth with the lathe spinning....takes the nib off very well. Tools can make a difference, so a bowl gouge will be harder to use and finish the box than what I use most of the time, which is a detail gouge.

[John K Jordan]

When making lidded boxes, starting between centers, I’m having issues with the center of top of the lid. No matter how much I sand, and I do work through all grits ending with 600, I end up with either a small hump/point or a tiny hole/depression in the center. What am I missing? I am sanding on the lathe at about 500 RPM.

Thanks in in advance for any suggestions.

Ned,

When you say you are sanding with the lathe at 500 rpm are you holding the sandpaper still or power sanding? For the center of anything sanding with the lathe running can be a problem so I sand at least the center by hand.

Like many I used to have trouble making a perfect center of bowls, boxes, lids, etc. I finally solved that completely.

The secret for me is negative rake scrapers and hand scrapers. I'll turn the best I can, erring on the side of leaving a little extra wood in the center rather than a dimple. I next use appropriate negative rake scrapers with the lathe running to clean up as much as possible, then with the lathe off I use a hand scraper to make the surface perfectly flat, rounded, concave, whatever shape is needed. I have a variety of small curved hand scrapers that will work for almost any concave or flat shape. Flat scrapers are usually perfect for convex shapes.

These are some of the little negative rake scrapers I use to get it as close as I can before going to the hand scrapers. They are amazing on end grain.

scrapers_small_thompson.jpg

These are some of my hand scrapers. I grind new shapes as needed.

scrapers_.jpg

The effectiveness of the scrapers depends somewhat on the particular wood. If one thing doesn't work, I try another. Best to scrape "uphill" relative to the grain. (In some circumstances I use the hand scrapers with the lathe running, but not in the very center.) I sharpen the hand scrapers just like cabinet/card scrapers using a carbide rod but a tool shaft will also work.

In some situations I use the StewMac scapers, 1/8" thick tool steel, not the least flexible. (A freshly sharpened thin, flexible scraper is better for end grain.)

SCRAPERS_StewMac_IMG_20171019_081858_098.jpg

A big bonus of using the hand scrapers is they greatly reduce the need for sanding, especially with coarser grits. Sanding end grain not a fun way to spend an hour. After the shape is right, I end up doing much or most of my sanding by hand with the lathe off using a soft sanding block (an eraser).

sanding_soft_block.jpg

JKJ

[Kyle Iwamoto]

I also use a bowl scraper, the traditional kind, not the ones like JKJ. I'm also trying to learn the benefits of the fluteless gouge, which seems to work very well, except for the little nib.... More practice required. However, used as a traditional scraper , I can get that annoying nib off.
Option 2, leave the nib on purpose, and embellish the nib. I've made box lids with a scraper "spire" in the center. Making sanding extremely difficult and hardly worth the effort...

[John K Jordan]

I forgot to mention another thing I use to smooth the nub on a domed/convex lid - sanding sticks like these. I make several sizes, the most useful are smaller than these, about 1" wide.

sanding_blocks.jpg

As Kyle mentioned, leaving something in the middle and embellishing can work, maybe cut thin lines to visually break up the discontinuity (if the design agrees). Richard Raffan mentioned he uses a similar idea on the inside of lids since it is difficult to make a perfect concave surface in a small space.

Another thing people often do is just cut out the middle and glue in a little turned disk, cabachon, or other piece of contrasting complimentary wood or other material. Some people will use a texturing tool on the center but that is tricky to do it right and you usually only get one chance! Easier is to cut a little recess then texture the end of a cylinder and cut that off and glue it into the lid. This way I can make repeated tries with the texture tool until I get one I like.

Here are a couple of cocobolo boxes I did long ago where I experimented with pieces of ebony to fit shallow recesses in the lid. I tried several shape - I liked the small finial better with this oddly shaped box - I think the flatter one would have looked better a bit more domed, especially from the side view:

cocobolo_boxes.jpg cocobolobox_w.jpg

JKJ

[Reed Gray]

The dreaded nib/vortex in the center of bowls and boxes.... The slow feet/minute speed in the dead center of any turning project makes it difficult to get clean cuts in that last little bit. For boxes/end grain especially, and to maybe a little less so on bowls, this is where the NRS works best. You can clean up any minor tool marks with the NRS, and then sand. You can power sand most of them out if you have the space. Hand sanding while spinning doesn't work as well...

robo hippy

[John K Jordan]

I had a chance to get a few cell phone photos while turning a box lid today. Before scrapers I used to spend a lot longer on the centers of things like this. This is eastern red cedar, end grain. (This lid is for a glass container that had a glass lid until My Lovely Bride knocked it off the counter. This will make her happy. I turned the lid to reuse the silicone rubber seal that was on the glass lid. I'll get photos of the result later.)

This is a shallow concave inside the lid, first using a small curved negative rake scraper I ground from a round 3/8" Thompson steel rod.

scraper_box_IMG_20171220_113048_415-1.jpg

Then using a small oval hand scraper to remove the nub and clean up the bottom of the shallow concave center. (I like to do this off the lathe with the chuck in a carving stand - far easier to see and work)

scraper_box_IMG_20171220_113442_765.jpg

Sand a bit with the soft sanding block. I like the wild figure of this wood. Almost ready for the 800 grit paper.

scraper_box_IMG_20171220_113612_012-1.jpg scraper_box_IMG_20171220_115628_053.jpg

On the other side I did the same in the center of the knob: NRS on the lathe, hand scraper and sanding off the lathe. On the slightly convex wide area on the top of the lid I used this small negative rake scraper, ground almost straight across. It left the surface so smooth that 600 grit sandpaper couldn't improve the surface.

scraper_box_IMG_20171220_131022_453-1.jpg

I do much less sanding since I started using the negative rake and hand scrapers more. Almost all sanding is by hand with the lathe off.

JKJ