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Marc Sitkin

PRO Member
Hi folks-
I'm turning a large vase from SPP, 25 rings about 18x13 finished size. The base is a nice smooth convex curve. I've cut and assembled the rings for rows 1-10, and have started stacking them on the base (I glue up on the lathe using a longworth chuck on the tailstock to align concentrically). Things were going fine until I went to glue up ring 6 to ring 5. Not enough wood on the inside of ring 6 to match the angle and width of ring 5. Dimensions of the rings are matching expected internal/external diameters on my summary and cut sheet, so am I right in assuming the problem is the profile of the curve I'm turning to as I proceed? If so, can I print out a profile to follow as a guide during assembly?

I've just made a new ring to go between 5 and 6, which required jumping the board width up to 2" from 1.3". This seems to fit, but not convinced the rest will follow without problems.

I selected the option to round the board widths in my summary report. This seems like it might be part of the problem, in that I have a lot of wood to turn away.

I usually work from hand drawn plans, and don't have as much wood to cut while turning. I do well by cutting off my segment corners and fairing my curves. This is a first time project with SPP, so if anyone can offer guidance I'd appreciate it. Thanks!
 

mfisher

Super Moderator
Staff member
Hi Marc.
- It would be helpful if you would attach the .json file for us to take a look your design.
Load your project and do a (share / export).

- In SP looking at the cutaway view. If you look at the 2nd dot counting up from the base. You can left click and hold on the dot and drag it up the profile. By doing so will increase the inside diameter of some of the lower rings.

- Do you have WoodTurnerPro (WTP) software? If you don't you can download WTP and use it for 30 days. The reason I ask is WTP has a glue line function that will tell you based on the inside/outside diameter of the rings how much glue surface you have between rings.
It is pretty easy to rebuild your project based on your summary list and entering the inside/outside diameters of each ring. Easy to make adjustments to board width for each ring by adjusting the inside diameter.

- As far as optimizing board width. What it does is come up with a common width of a board for multiple rings. Example. rings with boards width of 0.59, 0.56, 0.54 would be optimized to 0.60 So you can cut pieces for 3 rings out of the same width board.

As far as turning as you go. I do that from time to time. An outside diameter caliper is what I use. Set to caliper to the ring diameter. Make a cut and see if you have turned down enough.
 

Marc Sitkin

PRO Member
Thanks Lloyd. Attached is the .json file as well as the spreadsheet. Appreciate your looking at this, and look forward to your insights. The idea of moving it to WTP sounds good. I do have the software.
 

Attachments

  • 2021-1-16-9-29-55.json
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  • Cherry, Maple Mahog vase.xlsx
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mfisher

Super Moderator
Staff member
Thanks Lloyd. Attached is the .json file as well as the spreadsheet. Appreciate your looking at this, and look forward to your insights. The idea of moving it to WTP sounds good. I do have the software.
I will look at it today.

It is Mike.
 

mfisher

Super Moderator
Staff member
Hi Marc.
- I quickly did rings 1 (disk) through 8 in WTP using the inside and outside diameter from the summary sheet SP/excel.
- The glue surface between ring 5 and 6 is 0.8 inches. which seems adequate.
- If the rings are not round but more of an oval, they can be turned round on the lathe. The result can be one side has thinner wall that the walls 90 degrees from the thin wall.
- While your method sounds like it should work it makes me think your vessel as you added rings were getting off centered or
- Did you turn the rings round between adding rings? If so are you sure that ring 5 OD is what the plan calls for?


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Besides building round rings. It is important the the rings get centered. When adding rings similar to what you are doing I sometimes will mount the ring on the longworth chuck, bring the vessel and the new ring together, draw a line around the ring on the chuck , pull the two halves apart and see if it looks centered. (hope that make sense.

As far as your project, You could increase the board width. Keep the SEL the same. It just changes the inside diameter and results in more waste wood. I know I still tend to overbuild. That is use more wood than what is needed.

Is it possible you glued up ring 7 thinking it was ring 6?
 
Last edited:

Marc Sitkin

PRO Member
Hi Mike-
Thanks for checking on this for me.

I'll double check ring 5 od to verify. I've been checking them as I go, and haven't found one off yet. I'll also double check 6/7 to look for a mistaken swap. I've stopped the glueup at ring 5, after double checking the ring 6 overlap and finding it lacking wood on the ID.

I mount each new ring on the longworth tailstock and mark the OD of the previous ring to get a glue line before gluing the two together, so ring 6 never got added. I've made a new ring 6 with a larger ID to compensate. I'm not sure that this will be a fix, as ring 7 etc might still be off. I'm not turning the rings round before mounting.

The segments are producing round rings, and it seems like the alignment of ring to ring in glue up is pretty accurate. I've been turning them as I build the stack, and haven't seen any strange eccentricity as I knock of the corners.

I'm going to add the new ring 6 to the stack today, and then check the fit of 7 before glueup in the hopes I can recover. If not, I'll look at other options.

I think I'm going to move the dimensions to WTP before cutting any more wood fo the next batch of rings.

Will be in touch!
 
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