I'm ready, I'm steady, but I'm scared!

[Dave Bureau]

I am in the process of building my third segmented project. I dont have a lot of experience on the lathe so here is my problem. The project is bigger than what I have done in the past. It is 12" dia x 20" tall. I have spent over 40 hours so far making feature rings. I'm READY to mount the base on the lathe. I have built a STEADY rest for when the vessel gets longer. I'm SCARED that some how the mount will break off and I'll lose the piece and all the time spent. I have a beall tap and can make wooden mounts, I have a face plate but dont want to drill holes in the bottom of the vessel. and I have a stronghold chuck. Can I screw a piece of MDF to the faceplate and glue the base to that? Will the MDF hold? Should I put a tennon on the base itself and use the stronghold chuck? (BTW I have never done this. Do I just make the tennon straight or do I angle it like a dovetail?) Or should I just glue it to a wood mount? I would like to glue it to a peice of MDF first so it will be easier to part off later. What do you think the best way ot go is? The base is about 6" in dia.

[Dick Sowa]

For tall segmented vessels, I find it is easier to make them in sections that are shorter, and glue them together. I use solid wood waste blocks, screwed to a faceplate. For larger bowls, I assemble rings till the assembly is 6-10" tall.

MDF will not hold screws well, and can fail as a waste block. I only use it to temporarily mount a ring to flatten it, or for tiny parts...knobs and lids. I learned that the hard way.

For a bowl your size, I would make it in two halves. One starting at the base. The other starting at the top. You will need two faceplates. Or you could use your chuck with a solid wood waste block in the jaws for one half.

When all the rings are assembled, smooth and sand the mating surface, and dry fit them together. Keep one half mounted on your headstock, and the other half can be aligned by using a live center in your tailstock against the other faceplate.

Tighten the quill, and it should easily hold the two halves together so you can finish turn the outside profile as a single assembly. When you are happy with the profile, just back off the tailstock and turn the inside of each half down to the wall thickness you want, and completely finish the insides.

Then, all that is left is to glue the two halves together, do some cleanup on the outside at the glue line, finish turning the lip and foot, and you are done.

Here's one I actually did in three sections...tall and narrow made it hard to properly thin the walls otherwise.

http://www.digitalwinners.com/woodworking/bowls/images/1a-P1050257a.jpg

[Richard Madison]

Dave,
Do NOT use mdf. Suggest hardwood waste block firmly screwed to a faceplate, turn and sand flat and glue on the bottom piece of your vessel. Found an old picture, 15-3/4" x 25" tall, built entirely on the lathe. Not exactly a great piece of work, but you get the idea.

[Robert McGowen]

Another vote for a hardwood block screwed to a face plate. I have always built vases using a face plate and a steady rest, glueing and turning one ring at a time all the way to the end. Never had any problems doing it that way.

[Wally Dickerman]

Dave, since you say that you are quite new to woodturning, my suggestion to you is that you put this piece aside to be finished sometime in the future. A piece, segmented or otherwise, that is 12 x 20 is a lot for even an experienced turner to handle. Woodturning, if the rules of safety are observed is fairly safe, but a piece that size flying off the lathe could do serious damage.

MDF has NO structural strength. It should never be used for a glue block.

The piece is too large to consider using a glue block. If you feel that you must go ahead with it, a faceplate attached directly to the base is the only safe way to go. It should be at least 4 in. and 6 in. would be better. It should have at least 6 screw holes, and only panhead self tapping screws should be used. There is a lot of leverage in a piece that is 20 in. deep.

I hope that you use a faceshield and stay out of the line of fire.

Wally

[Richard Madison]

Bonded Joints

Edge-Grain Joints

Face-grain joints (wide surface of a board) are commonly seen
in structural laminated lumber products, where adhesive
bonds are stronger than the wood. Edge-grain joints (narrow
surface of a board) (Fig. 9–8) can be almost as strong as the
wood in shear parallel to the grain, tension across the grain,
and cleavage.

This from the Forest Products Laboratory "Wood Handbook", Chapter 9. There is other detailed data available from various sources. If the joint is as strong or stronger than the wood, then I feel ok about using a glue block. Just a thought.

[Brian D Wood]

I have done several vases in this size range and always use poplar as the waste block that the faceplate is screwed to. For several reasons, its cheap, strong enough, and it is an easy wood to part off through when the time comes. Be careful and good luck, that is a large vasel.

[Don Orr]

For anyone who does not know who Wally Dickerman is, he is a source of advice I ALWAYS listen to. He has been turning longer than a lot of us have been alive. He knows more about turning than most of us ever will. While I don't do segmented work yet, I would certainly listen to those who have given much good advice. Your title of this thread says a lot already. The questions you ask are good ones, but they say a lot about how hesitant you are with something this size. Trust your gut feelings.Everyone wants to "go big or go home". Think about developing your skills and confidence before tackling the big one. Most of all be safe !

Sorry if this sounds kind of negative.

[Robert McGowen]

The piece is too large to consider using a glue block. If you feel that you must go ahead with it, a faceplate attached directly to the base is the only safe way to go.
Wally

You have a face plate, then a glue block, then the base of the vase glued to the block, then a glued on ring, then a glued on ring, then a glued on ring, etc., etc. I don't really see where you are gaining anything by doubling the depth of the base and screwing into it, especially if it is an expensive piece of wood that you will just part off. :confused:

Also, a piece that size really needs a floating base, which is not glued to anything to allow for wood movement, so the first ring that the base is inside of HAS to be glued to a glue block, as there is nothing to attach a face plate to.