Multi Species segmented ring question

[Tom DiBiasio]

Hi All

Im new to segmented turning and have what may be considered a super basic question (I learned long time ago not to consider my questions as "dumb" so I use the word basic instead), I am making my first painted bowl design with a combination of Maple, walnut, and Padauk. I have milled the stock to the correct width and thickness, then did the typical marking of the top and one edge so that when assembling the ring I can alternate the pieces to make up for any inconsistencies in the pieces. Since the ring is made up of three different pieces of stock, I cut the required number for each species all at once - all the maple, all the walnut, and then the Padauk. Now when I am assembling the ring in the required order or combination I am not able to maintain the "alternating" pattern of pieces like I do when I cut all segments from the same board or species. So my question is should I worry so much about this and perhaps make the cuts on the sled species by species following the ring pattern I have to make. This seems like it would add a level of complexity on top of something this already mildly complex to keep track of. Am I over thinking things here and should not worry so much about this alternating pattern?

Thanks in advance

TomD

[Steve Engelschall]

Curious timing on your question as I ran into this situation today. I always run a line down the stock so I can flip every other piece, figuring it "cancels out" any deviation from 90 degrees on my saw. Today I used two separate sticks of wood to make one segmented ring. I marked one piece with a line and forgot to mark the other one. Now I have 6 pieces marked and 6 pieces unmarked for a 12-segment ring. I spent a few minutes trying to figure out the order of the unmarked wedges based on the grain, but gave up. I decided to just dry-fit the ring in random order and it closed up perfectly. If you take the time to make sure your blade is dead-on 90 degrees, I personally don't think it matters if you flip every other piece. If the cuts aren't 90, then it matters.

So to answer your question, I'd just dry fit the pieces - if they close up flat you're good to go.

[Sam Force]

I've done hundreds of various rings with different woods. What I do is I count the segments as I cut them, from front fence is always an odd number and back fence an even number. When cutting a different wood I go back to the same sequence, if you are off by a couple segments (front to back fence) it makes very little difference. If you are unsure like Steve mentioned, do a dry run first.

[Zachary Hoyt]

I make a lot of segmented rings when building banjo rims, and just let them fall randomly into a bucket, only keeping them separated by species and size. If the bandsaw or whatever saw you use is set up right it won't matter about flipping them or not.

[Tom DiBiasio]

I am determined to crack this code called Segmented turning - so far it is winning but I will stay at it !!!! Today I glued up a 48 seg ring (mixed species as discussed above). Due to the small size of the segments and the many glue surfaces (48*2) I decided to try out the rub joint technique as the hose clamp routine was giving me fits. Well as you can see from the pics below this did not turn out well at all.... The half rings dont even come close to aligning and I have no clue why??? I went back and checked the angles on both sled fences as well as the Segment edge stop measurement - all was set perfectly. In terms of my rub joint method I did the typical - two by two, then four by four...etc until I got to the full 24 seg ring. I checked the SEL on each piece of the half ring and they seem to very close so im kind of at a loss for what could have happened? I double checked the angles and SEL stop again and re-cut all new pieces - does anyone have any suggestions for me based on the disaster of a first attempt before I start to glue up attempt #2 ???

TomD

[Jim Morgan]

That is way off!

Can you tell us about your cutting setup? That might help in diagnosing where error is creeping in.

[Tom DiBiasio]

Thanks Jim for the fast response - I am using a home made wedgie sled with segeasy wedgies. I counted over and over again the segments as it seemed like maybe I was one short by the way it was lining up but it seems that I have the right number of segments.

[Jim Morgan]

The diameters of your two half rings don't match; there is some discrepancy (despite your measurements) in SEL. Over 48 segments, small errors can add up. To minimize this problem, I added a couple of small toggle clamps to my wedgie sled so the stock won't shift during cutting.


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Perhaps a house call is in order. Where are you in RI?

[Sam Force]

Looking closer at your segments, it does not look like they are of the same angles, it could be the angle of the camera but they definitely look off kilter

[Tom DiBiasio]

Ok so you know the old saying for the definition of insanity (doing the same thing over and over again expecting different results) well I can say I now feel INSANE. I took a second attempt at this 48 segment ring, this time I was super cautious when cutting the segments to ensure that the stock was tight against the fence, and that my push through the blade was smooth and at least to the mid point of the blade arc, well past the cut point. I even did a dry fit in a large hose clamp first for a sanity check and it seemed pretty good. When glueing this time I really took my time to ensure each progressive glue up was tight on the joint and flat to the table. Well as you can see from the pics below I have the exact same issue with the second ring !!!!

I took a few pics of my cutting setup, you can see the seg plate is tight to the fences, and the stop is dead on the .700" mark, I checked for "slop" in the miter bar slot and dont seem to detect any.

Jim I have ordered a few toggle clamps to try but honestly this time was making sure that I held the stock tight to the fence as well as maintain the SEL..... At this point im not sure I want to keep wasting stock and may have to take you up on your generous offer to come by my shop. In located in Kingston near the university.

Any further thoughts from the group?

TomD

[Steve Engelschall]

Some thoughts...

1. Are you keeping the same side of your stock against the wedgie sled fences for every cut as you move back and forth between the two fences? Or are you using only one fence and flipping the stock for each cut? You shouldn't flip the stock as you cut the wedges, otherwise minor variations in stock width can change the angle ever so slightly.

2. When you rub-glue the wedges, are you keeping the OUTSIDE points/edges aligned? Here's a dry-fit example of two half-rings of a 12-segment ring. Note the outside points are aligned and the two halfs line up perfectly.

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In the following example, I purposely misaligned the outside points on two of the joints. Note how the two halfs don't line up. Small variations could have a large effect over 48 segments. This doesn't explain how you are getting half-circles with different radii, but something to watch out for anyways.

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3. You should consider starting with 12 (or maybe 16) segment rings before moving up to 48. You can also practice with wide stock, like maybe 2 inches, where errors will be magnified. Also, softer wood (e.g., walnut, soft maple) have "fuzzier" cuts and can mask errors. Harder woods (e.g. hard maple) have cleaner cuts and will expose errors in the setup.

Don't know if any of this helps, but this is what comes to mind...

[Brian Tymchak]

.... At this point im not sure I want to keep wasting stock...

I haven't done a lot of segmenting yet, but in watching Malcom Tibbets videos, I learned to dial in angle settings using cheap mdf, then cutting with the project stock when I was happy.

[Dave Mount]

Coming from a turner that has done a lot of flat work but no segmented turning. . .even if your pieces are cut perfectly, you have two things working against you for a freehand glue-up: 1) a very large number of segments in the ring; and 2) fairly narrow widths on your segments. Both contribute a lot of potential for variation in your glue-up, the former because very small errors in the orientation of individual joints can add up to big errors because there are so many pieces, and the latter because there is less registration between pieces and therefor harder to make sure the resulting angle is perfect.

My suggestion would be to cut a circle of ply equal to the nominal inner diameter and lay the pieces along it as you glue up; this will ensure that your ends meet, and if you have gaposus between pieces it will tell you your angles aren't right/consistent. In addition, after you do this you can put a band around the whole thing, remove the ply and cinch the perimeter. Or as someone else suggested, start with rings with fewer segments.

My advice, worth what you paid for it,

Dave

[Zachary Hoyt]

I always flip my strips between each cut, if the angle is correct and the saw is set up accurately they will fit fine. I don't think rub joints are a very feasible approach, especially with so many pieces. Clamping the ring equalizes the pressure on all the blocks. I lay out a strip of masking tape on my table, sticky side up, apply glue to one end of each piece of wood and stick them to the tape in a row, butted up tight against each other. When they're all in place I grab both ends of the masking tape and quickly pick them up and bring them together at the top of the circle. If you do this slowly the blocks will fall off the tape, so move fast. Then I lay the ring flat and put a band clamp around it. I always do 18 segments per ring, which is easier than 48, I imagine. To make the gluing easier I grab as many blocks as I can hold, usually 6, and hold them all in a stack so I can apply a double line of glue to one end of all 6 in one movement, using a glue bottle (or a mustard bottle in my case, since I am a cheapskate). This rim is one I glued last night and turned today for a customer who comes up with the pattern he wants.

[Steve Engelschall]

And another thought...Is there any slop in the fit of the wedgie sled into the miter slot? I think any wiggle at all would cause the angles to vary enough to show up in a 48 segment ring.

[Tom DiBiasio]

OK so first off thank you all for your suggestions and help. I am happy to report that I have had a successful glue up now and I thought to post my outcoming in case it helps someone else in the future.

So with the exact same sled and stop settings (no change at all to the setup from the previous failures) I made a 3rd set of segments. This time however I did several dry fits with different clamping methods to finally settle on one that worked. I decided to glue with a half ring method (24 segments each) with a small section of stir stick between the sections to compensate for any irregularities. With this approach I only attempted to glue half the ring at a time but used the full ring of segments to ensure alignment and shape. the hose clamps I have were not working so well for me - I purchased a kit from Amazon that is like 20' of band with 6-8 connectors where you make your own sizes. These clamps seem to be ok but for a ring of 48 segments that are 1/2" thick and only .70 SEL the clip portion was consistently pushing those segments way out alignment and would collapse the ring under pressure. So I decided to use one of my "Earl rope" clamps instead, this was a little challenging with a 1/2" think segments as well but absolutely doable if you are cautious and take your time to ensure the rope is always in the mid point of the segments as it wraps around. Once I got the dry fit routine down, practiced several times, I decided to give it go. To my surprise it went reasonably smooth and I was able to get the 1/2 ring glued up\ wiped off both sides and set flat to the glue table before the glue set up. I weighted down the 1/2 segment that was glued to ensure it was reasonably flat. Once the glue set up I was able to easily do the second half of the ring using the same method. After both sections dried I was amazed how close the half rings lined up and with a simple sanding of the half ring ends on my 14" lathe disc sander making sure to flip one of the rings over to compensate for any inconsistency in the sanding disc to the platform, I was ready to do the final glue up the half rings. Well from the pic below you can see that perseverance paid off and infact 100% of my issues were caused from the glue method I was trying to use. A few lessons learned here - first and foremost "dont give up" if something does not work right the first try or even the second try in my case, just keep on trying and eventually you will gain the necessary skills to succeed. Secondly with a large ring of small segments the rub joint technique is not one I will try again as it just did not work for me. Third and final lesson is that there is several ways to clamp a ring and no one size fits all - try different ways of clamping and gluing if you face challenges like I did.

Thanks again for all your suggestions - each one contributed to my problem solving leading me to a successful conclusion.

TomD

[Pat Scott]

I like your lathe sanding platform, what does the bottom look like? What kind of post did you use?

[Tom DiBiasio]

Hi Pat

Sure Im happy to share the details of my ring sanding platform. I built it due to always being frustrated with the vibration and extreme speed of my disc sander for sanding the end of half rings. The disc is just over 14" in diameter and mounted to the lathe with a 5" face plate (total of 12 attachment screws in this plate). As for the platform I started with a nova 8" post, it is part of their modular rest system. At the top of the post is 5/8 threaded stud, so I took a piece of 5/4 hard wood and made recess the same shape as a heavy duty 5/8 nut. This was a combination of routing and chiseling to get a good snug fit, once it was hollowed out I simply epoxied the nut in place taking care not to fill the threads of the nut with epoxy. This got a little messy but I managed to get it cleaned out well enough before setting up. Once set up I was able to screw the small hardwood platform to the post and test it out and check for square. Of course it was not perfectly square to the disc so when I mounted the larger mdf platform I had to insert some shims to square the platform. It is relatively new setup so I dont know how well it will hold square in the long run but overall I am super happy with how it is working for my intended purpose and in the end cost me less than $50 to have a fully speed controlled 14" disc sander. One "odd" thing I noticed is that for my purpose of sanding half rings and more delicate things I find running the lathe in reverse and about 400 rpms works very well and seems to be the sweet spot for this setup.

Here is a pic showing what I describe above - hope you find it helpful. I tried several times to rotate the pic but could not get it to work.... in the original pic on my pc it is the correct orientation.

TomD

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[Zachary Hoyt]

Your lathe sanding setup is very nice, good for you. I use a ShopSmith with a 12" disc sander, and can turn it down to 700 RPM or so for end grain sanding, which works pretty well. If I ever get a real lathe I may try something similar to your design to get a bigger disc and lower speed.