Undercutting Tool

[Dennis Taylor]

Can someone provide some guidance on making a tool to under-cut the top of a spindle for a Xmas oranament, so that it fits the round globe..I am thinking maybe a HB Freight tool set and using the 1/2 Spear point to undercut the cap so that it will sit flush?..is that a good tool to work this problem with, or is there something simplier I am missing..turn the spindle between center on either a chuck or cup center, any guidance is greatly appreciated..making tons of globes, but the caps and finials don't sit well at all, and look bad.

Dennis

 

[Andrew]

Can someone provide some guidance on making a tool to under-cut the top of a spindle for a Xmas oranament, so that it fits the round globe..I am thinking maybe a HB Freight tool set and using the 1/2 Spear point to undercut the cap so that it will sit flush?..is that a good tool to work this problem with, or is there something simplier I am missing..turn the spindle between center on either a chuck or cup center, any guidance is greatly appreciated..making tons of globes, but the caps and finials don't sit well at all, and look bad.

Dennis

For things like this, and my ornaments to be specific, I just undercut a little with the parting tool. Very much like undercutting the base of a bowl or weedpot so it'll sit stable on a table. It doesn't normally take much of an undercut as the only portion that'll actually be touching the globe part is just the outter most rim of the spindle (drop finial or the "cap" on top). Just as long as you undercut enough for your globe roundness to miss it, then it should sit flush on that outter edge of the spindle.

I can take pictures or just show you realtime anytime this weekend on the webcam.

 

[Dennis Taylor]

Andrew, I tried to under cut the cap/finial with a parting tool, but my problem is the same, right at the base of the tenon it is fat,I lay the parting tool on it's side for a standard part, and the angle into the cap, it clears the material on the cap area, but not at the base of the tenon, and then the tenon don't fit into the hole, of course I could enlarge hole, then tennon to loose..pics might help..can't seem to get it...tried with a spindle gouge and don't have the clerance needed to get into the cap..Dennis

 

[Andrew]

Dennis,

Would you happen to have a picture of your or a similar ornament that you're talking about? I can picture at least a dozen variations on these ornaments in my head right now. I regularly make about 5 different ones myself although they about all use the same kind of cap - globe - finial attachment. I need to make up some of them anyway so I guess tomorrow will be as good a day as any. I'll make some and take pictures in the morning as I go. I'll let you know in the morning where to look.

Without seeing how you're doing it firsthand, would perhaps a modified parting tool or narrow skew do the trick? Basically, instead of grinding the parting tools' very tip (where the 2 bevels meet at the end) straight across; you could grind it so that it looks more like a skew with a heel and a toe (short point and a long point). That way, you can get more "reach" into that undercut and make your tenon the same diameter all along it while still performing a cutting action and not potentially damaging the outter edge of your cap or finial. Just a thought.

If you have some time tomorrow, we can get together online and I can show you it live. The webcam is setup to take pictures every 10 seconds and you can "chat" with me all on the same webpage. It's pretty easy and the pictures aren't large so it goes fairly quickly.

 

[C Edward Moore]

ornaments with an icicle

When I began making ornaments of the globe and icicle type, I tried to make a spherical globe. As I became more experienced and was more familiar with Bob Rosand's ornaments I realized that the globe should not be a sphere, but a sphere that has been "flattened" a little on the top and the bottom. So, I suggest that you consider this design feature. Check out Bob's article in the Fall 2004 American Woodworker.

Secondly, if you are flattening the globes, then the icicles can be undercut using a round 1/4" skew. On page 14 of the same American Woodworker, Bob writes about round skews and how to make them. They are fun to make and great to use.

 

[Andrew]

Dennis,


Here you go. Let me know if this isn't what you're looking for or it's not clear.

http://www.statelinewoodturners.org/ArticlesTips.htm

Look at the "Making a Globe Ornament" on that page.

 

[hockenbery]

use a peeling cut

I undercut with a 1/2 skew using a peeling cut I learned watching a raffin video.
first round the stock. Then lay a traditonal skew on its side on the tool rest with the cutting edge paralell to the cylinder with the bevel riding with the cutting edge just off the wood. To make the cut raise the tool handle until the tool begins to cut and just push it lightly over the tool rest as it peels the wood away. The angle of the skew point does a very nice under cut.

I hold the tool with one hand and the handle under my forearm so that I can hold a caliper or open end wrench in my other hand to size the tenon at the same time. If you need more undercut you can change the angle of skew to achieve it.

This takes surprisingly little time to master and it is a one step tenon and under cut. If you are doing just a few turn the ball first and fit the tenon to the ball.

After undercutting turn the finished edge in about a 1/4 inch or so. you'll want to turn this section to the a small dameter last. Having the this little bit turned early is a good plan since a slip with a tool here could ruin a whole finial.

Keeping the bevel riding make this a peeling cut and it will be quite smooth.
You can use the skew as a scraper and get a similar udercut shape but the tenon will bemuch more ragged.

happy turing,
AL

 

[Dennis Taylor]

thanks all....It works

I pictures Andrew really helped, and the advice of using the skew & parting tool worked, once I pieced the puzzle together, I am undercutting like a champ thanks to some great advice..thanks to all...great forum, due to great people...Dennis