Ring gluing and disk flatting

[Robert Edington]

I am new to segmenting. I have a wedgie sled and wedgies. My rings look pretty good.
It's just when I start stacking them that I have problems.

I have one of those clamps with a 1" threaded rod that is in the middle of a frame. You stack the rings on the base, put some sort of a anti torque device on the top and tighten the rod down on the stack. I think you know what I'm trying to describe.

I do a rub fit to get the ring to suck down on the previous ring before tightening the rod. I recheck for centering.
I measure for centering from the flats to the the points on the next ring.
I always end up with out of round (leaning) glue ups. I lose alot of my "safety" that I built into the walls just trying to get the bowl round.

1. How do you center, and keep it centered, your glue ups?

I think my rings are centered, just leaning. I run the rings through a Performax after I unclamp the ring glue up (not the stack glue up).
I am just practicing with walnut. Making the same bowl over and over. Disk and six 3/4" rings. 16 segment. About 10" diameter.
I am trying not to hurry. I am learning with each bowl. But this leaning has got to be fixed. On a 1" top ring, I end up with maybe 3/8" or 1/4" wall once it is round.

2. How do you flatten a disk?

I turn it flat. I put a rule across the center and check for rocking or light. Then I put a flat board, with PSA sandpaper, on it. Because the tip speed of the disk is faster than the center, I end up with a hump in the center, due to less sanding, and have to get the gouge out again and try to sheer scrape it flat.

Am I holding the board wrong? How do you hold the board to keep from getting the hump? Or, is there a better way to flatten?

Thanks for taking the time to read this and respond. I'd like to get better at this.

RP

[Don Jarvie]

Here's how I do it and unfortunately I dont have a drum sander so its by hand. First I cut all my pieces and for each ring, ex 12 pieces, I glue up 2 at a time using the rub method on a piece of granite. Glue 2 together, etc until I get the ring done. Since my sled isnt as accurate as I would like it I trim each half so they make a circle. Before the next glue up I flatten each piece so when the ring is glued I have 1 fairly flat side.

To flatten the other side I rub the piece on a piece of glued sandpaper until its pretty flat. Once the rings are done I will stack them to see if I have any gaps between the rings and if so flatten some more until there are no gaps.

As for centering the rings. I tend to cut my wedges on the big size, usually 1 1/2 inch deep (outside to inside) so I have more room for error. I stack a few at a time and just use clamps. I try my best to keep them centered but if its off a bit no big deal. It wont make a difference when I turn the piece since my rings are deeper. The more important part is to make sure the rings line up so the spacing is even so you get a nice brick pattern. I only use the center rod if I have a big glue up like a lamp.

The only draw back is it takes longer since I only glue a few pieces at a time. I dont mind because I get a flatter ring so its less hand sanding.

Since you have a drum sander I would make sure I got one side fairly flat and then let the sander do the rest. If all of your pieces are the same thickness and glued flat then a few light passes with the sander should do the trick.

[Allan Ferguson]

You and I are using ring segment glueing by the rub and hold method. If my rings sit stable on a flat surface, I run them though the drum sander, when flat and glue cleaned up, flip and repeat. I have a press with 1/2" all thread in th center (needs to by 90degrees to the base). I have just started to use a rule with a hole in the end that fits over the center press screw to help center each ring. Try stacking 1-2 rings a time. No further flattening needed. No sure what disk your referring to. If it is to glue the rings to for turning, size to the ring, dish the center leaving outer area to be your glue surface. I have just finished my eight seg piece, all have been good.

[Justin Stephen]

I flatten rings with a drum sander. Before that I did it the hard way using a big sanding disc (on MDF w/ faceplate) running on my lathe and holding the ring against that, which sucks as it spews copious amounts of dust directly into your face...but it works.

I made a homemade clamping table using a 12" press screw and have used that for most of my segmented pieces. I measure each ring and make pencil marks where it should go in relation the one below it. For example, lets say I have I have the base and one ring on the faceplate already. I will measure the point to point length of the ring that is already glued on in two directions, always measuring in millimeters instead of English measurements. I figure out the orientation of how this ring will align with the one to be glued on next and then mark that orientation on each ring. I then measure this other ring flat side in the same two directions and subtract one ring's measurements from the other, divide by 2 and then make pencil marks that far in on the new ring so I know what center is. The reason for doing it in millimeters is to make the math easier (e.g., subtracting 86 millimeters from 112 millimeters is easier than subtracting 6 15/16" from 8 3/8"). I dry fit the two rings together, draw the outline of the smaller ring, apply glue within the outline and them clamp them together on the clamping table. Since fresh glue causes the rings to "swim" a little, I wait until the glue has started to tack up while continuing to apply more pressure and then get them centered at that point. Takes a little practice but it works well. This all probably makes no sense but its hard to describe.

An easier method is to use what is called the "Segment Stomper" and weights. I used this for my last segmented piece and it works pretty well.

[Grant Wilkinson]

Robert: I'm a bit confused by your description of your problem. I thought you were saying that your rings were not centered one on the other, but then you said that they were, but that they were "leaning". I don't know what "leaning" is.

If your rings are not centered one on the other, are you gluing them one at a time, or are you trying to glue all at once. If you are trying to glue them all at once, go to one at a time. Before putting them into your ring press, spread the glue you are using, center the top one over the bottom, then put a couple of dabs of hot melt on the edges to prevent the top ring from moving when you clamp it. (You can use popsicle stick pieces hot melted to the larger disk if you have room.) The hot melt will let the press do its job, but it will stop the rings from sliding around. (Go to http://www.dennyedwards.com to see this in action.)

To sand boards flat you can mount the ring on the lathe or mount a sandpaper disk on the lathe. Justin describes the sandpaper disk method. It works, but you can put too much pressure on one side or the other of the ring you are sanding and get a bit of a wedge shape. I use the sandpaper on a board method. The ring is mounted on the lathe. The board needs to be long enough to span the diameter of the ring. Putting pressure in the middle of the board ensures that you get a flat ring. It cannot "hump" since the board/sandpaper is as long as the ring's diameter.

[Justin Stephen]

I use the sandpaper on a board method. The ring is mounted on the lathe. The board needs to be long enough to span the diameter of the ring. Putting pressure in the middle of the board ensures that you get a flat ring. It cannot "hump" since the board/sandpaper is as long as the ring's diameter.

I've done this also. One trick I discovered was to add a couple of cheap Home Depot fence gate handles (galvanized pull handles, for example) at the appropriate angles to the back of the board to make it easier to hold onto.

[Robert Edington]

Thank you for all your replies. I'll put them into practice.

RP