Top
WC logo MENU
Post ResponseReturn to IndexRead Prev MsgRead Next Msg
Turning
Simplifying Offset Turned Doughnut and Bocote observations
Posted By Craig Daymon
Date Monday, 6 June 2022, at 11:43 a.m.

I've attempted this (February 2014 issue of AW Journal, Neil Scobie) with great success on the last one. Not the first time I've made these, but not to the point where it was mastered.

These are useful for making horns, palm tree trunks and as I intend this time, both handle and spout for a teapot from one turning. Probably good for those making bangles/bracelets/other jewelry items.

It is an eccentric turning. 3 axes. And there is some sanding and shaping to finish it up.

So take a square of stock about as thick as you intend the thick end of the hoop to be. The offset as specified by Neil (his was about 5.5" diameter and I think 1.75" thick. Draw a center line on both sides of the square in the direction of the grain and make sure these lines are measured from the same side for both sides. Mark a center point on one side and wrap it around to put a properly aligned center point on the other side as well. (This will be your first axes.)

Neil offset his by 3/16" from center on his 5.5" square. There are 2 offsets marked on each side. He marked the center as 1 and the others as 2 and 3. 2 and 3 are flipped on the opposite side. So if 2 is above center on one side, it is below center on the other.

First turn the square to a circle and round over the edge to a half circle.

Now mount the circle on the #2 marks. (Check your tool rest is as close as possible, but doesn't hit the piece when it turns.) On the tailstock end, turn away the shadow. Stop and start a few times. You are trying to turn away the shadow without going past the halfway point on the edge. You can do some sanding before switching axes, but I'm not sure it is really necessary as there is sanding after it is done.

OK, now mount on the #3 marks and repeat the steps above.

Here is the key change I have done to the procedure from what Neil described. And there is, I suspect some difference in the result, but I don't see it for looking when I'm done. Instead of building a holder on jumbo jaws for holding the hoop to turn away the center, I simply remounted on the center points again. The idea is to turn away the center and turning to the radius you turned on the first edge turning of the circle. You WILL be breaking through, or coming very close in this procedure and it is probably best to go  back and forth on both sides, approaching that break through point.

If you get your curve right, you should be trying to break through at the same point from each side. I've found this is fairly easy to do without issue, and since it is a hoop, even if you do break through more aggressively than intended, the result should be your hoop spinning around between centers. Probably recoverable, even at that point. (Just watch your speed as you approach that breaking through point.)

Maybe some carving away with a sharp knife to remove any "unturned" remains from the inside of the hoop. The narrower end of the hoop will come more to an edge than rounded over, but sanding down is fairly easy to do by hand. Just wrap, say 150 or 180 grit, doubled up (provides grip so the paper is easier to control) around the hoop and turn it with your other hand, working toward a smooth, rounded shape.

One challenge was that the eccentric turning and the closeness of the turning points made it a little challenging to find the proper points as a previous positioning flared the wood enough to hide the proper mark a bit. Probably not helped by my overly aggressive tightening of the tailstock.

OK, if anyone is still reading this, I have been using Bocote for this. I know it eventually darkens, but when initially turned, it is pretty bright yellow, with those dark streaks. Because I failed to properly align the grain on my first attempt, I saved some  of it before it was lost and turned a small dish. It is sitting next to me now. It is getting darker, but in the most interesting way. I honestly think it is showing more and more dark lines. Wish there was some miracle way to stop it at just the right point, because I think in another day or so it will have a really great look to it

This Bocote hoop is intended to serve as the spout and handle for the teapot. I believe if I cut centered at narrow end of the hoop, along the grain and cut again at the 1/3 - 2/3 mark, I will have the 2/3 of the hoop to use as a handle and the 1/3 as the spout. Fingers crossed.

 

Post Response

Your Name
Your E-Mail Address
Subject
Message
If you'd like to have the option of deleting your post later, please provide a password (CASE SENSITIVE!):
Password
 If you'd like e-mail notification of responses, please check this box
Accept Terms of Service

 
Post ResponseReturn to IndexRead Prev MsgRead Next Msg

faq
Frequently Asked Questions on using forums




Oneway Manufacturing - Superor Design, Legendary Quality

Messages Hand Tools Turning Classifieds Feedback SANDBOX
Copyright © 1998-2022 by Ellis Walentine. All rights reserved.
No parts of this web site may be reproduced in any form or by any meanswithout the written permission of the publisher.

WOODCENTRAL, P.O. BOX 274, COOPERSBURG, PA 18036