1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.
  2. The forum migration is complete. We had some issues with the hosting provider and I had to restore the server a 2nd time so if you happened to post from about 9:30pm - 11pm PST your post may have been removed. Please double check to see if its still there. If you have any issues post them in the technical support forum or email the AAW Forum Staff at forum_moderator@aawforum.org. Thanks!
    Dismiss Notice
  3. Welcome new registering member. Your username must be your real First and Last name (for example: John Doe). "Screen names" and "handles" are not allowed and your registration will be deleted if you don't use your real name. Also, do not use all caps nor all lower case.

Zig Zag ornaments

Discussion in 'Woodturning Discussion Forum' started by john lucas, Oct 26, 2020.

  1. john lucas

    john lucas AAW Forum Expert

    Joined:
    Apr 26, 2004
    Messages:
    7,417
    Location (City & State):
    Cookeville TN USA
    I'm having fun making these again. Had some new ideas. I'm doing a demo for the TAW and decided to use my Midi lathe. I needed to make or modify some router attachments to fit that lathe. That's what got me started on this batch. Well that and M Milliput has come out with some new colors so I had to try them out. They now have turquoise, Black, White, Silver gray, and Terracota. The silver gray isn't really all that silver. The turquoise is more or less that color. I like the black, White and Terracota. Here are some photos.
     

    Attached Files:

  2. Chris Edwards

    Chris Edwards

    Joined:
    Mar 1, 2020
    Messages:
    85
    Location (City & State):
    Lebanon, TN
    Can't wait for the demo.
     
  3. Don Wattenhofer

    Don Wattenhofer

    Joined:
    Jul 19, 2018
    Messages:
    686
    Location (City & State):
    Ponsford, MN
    A few questions:
    1. Do you use a 90 degree V bit?
    2. Do you use the indexing on the lathe?
    3. Does the midi lathe have indexing?
     
  4. john lucas

    john lucas AAW Forum Expert

    Joined:
    Apr 26, 2004
    Messages:
    7,417
    Location (City & State):
    Cookeville TN USA
    My midi has indexing but I wanted 16 slots and my midi has 24 so there isnt any way to get 16. I use an ironfire index wheel. You could use a 90 degree cutter but i prefer to use a 1/2" straight bit and mount the router at 45 degrees. It cuts the V with the outer edge and leaves a cleaner cut.
     
    Bill Boehme likes this.
  5. Dean Center

    Dean Center

    Joined:
    May 4, 2010
    Messages:
    1,065
    Location (City & State):
    Bozeman, MT
    Very striking and holiday festive. Those are some really nice finials, too.
     
  6. Don Wattenhofer

    Don Wattenhofer

    Joined:
    Jul 19, 2018
    Messages:
    686
    Location (City & State):
    Ponsford, MN
    I agree the the v bits have a definite problem at the point where as the straight bit at 45 degrees is a guaranteed 90 degrees.
     
  7. Tom De Winter

    Tom De Winter

    Joined:
    Apr 30, 2020
    Messages:
    79
    Location (City & State):
    Quad Cities, IL
    How can I see this demo?
     
  8. john lucas

    john lucas AAW Forum Expert

    Joined:
    Apr 26, 2004
    Messages:
    7,417
    Location (City & State):
    Cookeville TN USA
    The demo is an online zoom demo sponsored by the TAW. However there is an article on how to do these coming out in the next issue of American Woodturner. If your just interested in how I use the router on the lathe go to YouTube and type in john lucas Router demo. The demo I did for the Gwinnet woodworkers will.come up.
     
    Chris Edwards likes this.
  9. Dan Stromberg

    Dan Stromberg

    Joined:
    May 25, 2010
    Messages:
    55
    Location (City & State):
    Prince Frederick, MD
    John, I hope you and AAW will consider doing a live demo like last weekend's David Ellsworth demonstration. I think your work is incredible, and I for one would love to watch something live.
     
  10. john lucas

    john lucas AAW Forum Expert

    Joined:
    Apr 26, 2004
    Messages:
    7,417
    Location (City & State):
    Cookeville TN USA
    Would love to do a live demo but just don't have the computer equipment to do it. I'm looking into it but like everything else it takes money that I don't have.
     
  11. john lucas

    john lucas AAW Forum Expert

    Joined:
    Apr 26, 2004
    Messages:
    7,417
    Location (City & State):
    Cookeville TN USA
    Actually the straight bits don't cut 90 either. About 87 degrees. I have only found one 90 degree cutter that is actually 90 degrees and that was the freud. V cutters leave a very sloppy bottom of the V due to that part having almost no surface speed. That's why I went to straight cutters at 45 degrees. The bottom of the cut is very clean because your using the outer edge of the cutter that has a lot of surface speed in comparison to the middle of a V cutter.
    Here is my new toy. I needed to be more accurate for some of the experiments I'm working on so I built this adjustable router stand. It has an adjustable height so you can really get accurate on the centering of the cutter. It has a screw thread depth adjustment to move the fence in and out to change how deep you cut. The table will swing about 30 degrees in either direction so you can get very accurate angles. In the one photo you can see the test i'm running to try and get more wood to wood glue surface. It's looking like 5 degrees is pretty close to dead on.
     

    Attached Files:

    Bill Boehme likes this.
  12. Tom De Winter

    Tom De Winter

    Joined:
    Apr 30, 2020
    Messages:
    79
    Location (City & State):
    Quad Cities, IL
    John, I watched the video you suggested of the program presented to GWW. Very informative to this beginning turner. Thanks
     
  13. Don Wattenhofer

    Don Wattenhofer

    Joined:
    Jul 19, 2018
    Messages:
    686
    Location (City & State):
    Ponsford, MN
    I sure hope this is a typo you had to mean the 90 degree V bits not straight bits.
     
  14. john lucas

    john lucas AAW Forum Expert

    Joined:
    Apr 26, 2004
    Messages:
    7,417
    Location (City & State):
    Cookeville TN USA
    Not it is accurate. A straight bit has a slight cant to the bottom of the cutter to help it shear cut and make the cut cleaner. So when I use the bit at 45 degrees I am cutting with the side and the bottom. Both of my 1/2" bits from different companies leave a V cut that is 93 degrees. So I did make a mistake when I said 87. I was thinking about the tilt of the table saw blade when cutting square pieces to fit into the V notch.
     
  15. Don Wattenhofer

    Don Wattenhofer

    Joined:
    Jul 19, 2018
    Messages:
    686
    Location (City & State):
    Ponsford, MN
    I have been using a router for many years and have several straight bits that all make a square sided accurate groove so it follows that if you come in at a 45 degree angle you are going to get a 90 degree V.
    DSC00757.JPG This photo is of my attempt to duplicate your process. The small machinist square sitting there is to indicate that the V groves are 90 degrees and in line across. The router bit I used is a hinge mortising bit because it is the only straight bit that I have with a 1/4" shank. The original reason for the photo is to get your comments on the phenomenon where the points of the Vs angle toward the center and if you have any solution. Note the spin index fixture that I use has only 360 whole degree steps so I went with 18 Vs 20 degrees apart.
     
    hockenbery likes this.
  16. john lucas

    john lucas AAW Forum Expert

    Joined:
    Apr 26, 2004
    Messages:
    7,417
    Location (City & State):
    Cookeville TN USA
    Here is a photo of what I'm talking about. you can see how the cutters are dipped toward the middle of the bit. This leaves an 87 degree V groove so I cut my filler blocks to 93 degrees. I tested all 3 router bits I have in that size and all have roughly the same shear angle. I even checked some of my milling cutters and they are also lowered in the middle of the bit. I will have to look at Hing mortising bits and get one and see if it cuts flat.
     

    Attached Files:

  17. Don Wattenhofer

    Don Wattenhofer

    Joined:
    Jul 19, 2018
    Messages:
    686
    Location (City & State):
    Ponsford, MN
    The flute on your example is a moderate spiral but it is still ground to produce a 90 degree cut think about a standard twist drill it will drill the same size hole no matter how deep. I have a similar bit in a 1/2" piloted trim bit and there is no taper on it.
    DSC00762.JPG Th cut on the left is a solid carbide upcut spiral bit, the cut on the right is a straight flute bit and both cuts are perfectly square therefore if brought in at a 45 degree angle will produce a guaranteed 90 degree V. The spiral does give a shearing cut which of course is a better finish.
    For more info on straight router bits google router bits and you will see that only two dimensions are given - width and depth of cut - regardless of flute style.
     
  18. Ron Solfest

    Ron Solfest

    Joined:
    Jan 22, 2009
    Messages:
    108
    Location (City & State):
    TN
    John - what I think is causing confusion here is forgetting about the fact the outside point at the bottom of the cutter cuts the entire “bottom” of your groove. The center of the cutter could be 3deg up, or 30deg up; it doesn’t matter. The wing point making a complete circle (at 20k rpm or whatever) cuts the whole bottom while the side cutter cuts the side.

    As long as the center of the bit is raised from the outside, it will always make a 90deg cut as long as the cutter is straight parallel with the shaft. The only way to have something other than 90deg is for the cutting side to not be parallel with the shaft, or the bottom to have a cutter across it that goes down deeper toward the center.

    BTW - I like your cleverness at turning the straight bit 45deg to get a cleaner cut than a V bit - great idea
     
    Bill Boehme and Timothy White like this.
  19. Don Wattenhofer

    Don Wattenhofer

    Joined:
    Jul 19, 2018
    Messages:
    686
    Location (City & State):
    Ponsford, MN
    Thanks Ron you said it the best.
     
  20. john lucas

    john lucas AAW Forum Expert

    Joined:
    Apr 26, 2004
    Messages:
    7,417
    Location (City & State):
    Cookeville TN USA
    You are dead on Ron. I havent done it yet but there isnt any reason you cant do this same thing with a ball end bit.
     
  21. Don Wattenhofer

    Don Wattenhofer

    Joined:
    Jul 19, 2018
    Messages:
    686
    Location (City & State):
    Ponsford, MN
    Note my previous post on this thread with a photo of the setup I am using. The first try with the router traveling at 90 degrees to the lathe bed produced an accurate fit on the outside, however when looking at the joint on the inside as viewed thru the hole in the contrast wood the joint opens up. The bottom of the Vs are at 90 degrees but the points between Vs are at a 10 degree or 80 degree angle, which is understandable due to the decreasing radius. The next try I used the top slide set at a 5 degree angle but the joint was still open on the inside so then I changed the angle to 7 degrees and as near as I could tell the fit was good.
    The question I have for the math geniuses is there a way to calculate the angle needed to get an accurate fit?
     
  22. john lucas

    john lucas AAW Forum Expert

    Joined:
    Apr 26, 2004
    Messages:
    7,417
    Location (City & State):
    Cookeville TN USA
    I did a test the other day and 5 seemed to be right for me. It does depend on how wide of an area you want wood to wood contact. With about 5/16" it was pretty close. 6 degrees gave.me.a larger gap on the inside. I did discover that if the cutter or bottom of the V is. Ot dead center it throws it off.
     
  23. Glenn Lefley

    Glenn Lefley

    Joined:
    Jul 10, 2017
    Messages:
    537
    Location (City & State):
    Invermere, British Columbia
    To me that doesn’t make sense. Your logic is off I think. When the bit is spinning the outside edge which is 90 degrees to bit is spinning all the way round there for even if the inside was tapered at 45 degrees the outside would cut a 90 degree slot. I even tested one in my shop and measured after and it was 90 degrees.

    I can see a person have to cut a bigger than 90 degree piece to fill cut out as router in a sled always moves a smidge more and you never really get a true 90 when turned it on it’s side . it usually cuts a little bigger groove needing a larger angle block to fill void.

    F28F2CFE-E9A9-46FD-ABE9-10C1D8E25989.jpeg As per picture this bit with a 45 degree inside will cut a perfect 90 when turned on and a perfect 90 when turned on its side. If there is no play in router, your work or sled.
     
    Last edited: Nov 5, 2020
  24. john lucas

    john lucas AAW Forum Expert

    Joined:
    Apr 26, 2004
    Messages:
    7,417
    Location (City & State):
    Cookeville TN USA
    Glen What I'm doing is cutting a V with the outside and the inside of the bit. The outside cuts one side of the V and the inside cuts the other. The V takes the shape of the cutter. The outside of the bit is giving me a perfectly flat surface on the one side of the V. the other side of the V is being cut by the sloping portion of the bit. Trust me, I've cut hundreds of these cuts. If you cut a V and put a square in the the slot you will see. When I rip a piece of wood 90 degrees it will rock in the slot. If I rip it so one side is 93 degrees (with my bit) it will not rock and fit perfectly. I first discovered this using standard 90 degree V bits. I found out the slot was not 90 degrees on all but one brand. So then i though hey if I use a the corner of a straight bit it would give me a 90 degree angle, just like you are thinking. It doesn't. It's because you are only using half the bit.
     
  25. Don Wattenhofer

    Don Wattenhofer

    Joined:
    Jul 19, 2018
    Messages:
    686
    Location (City & State):
    Ponsford, MN
    Although I have never used the sled method I did feel that it had some problems as I doubted a person could hold a router steady enough to get a consistent cut. The cross slide I use provides steady movement as can be seen in the photo showing a machinist square firmly seated in two Vs. The only inaccuracy I have detected I think is caused by the spin index fixture where at some of the positions the locating pin does not seat properly.
     
  26. john lucas

    john lucas AAW Forum Expert

    Joined:
    Apr 26, 2004
    Messages:
    7,417
    Location (City & State):
    Cookeville TN USA
    A sled does have problems at times. Your cutting with both sides of the bit on some cuts and the router will try to rise. When your cutting with the router at 45 degrees like I do on many things now it doesn't do that and if you make a couple of passes to make sure you get the full depth it is quite accurate. Not dead on of course. I plan to make a better system in the future with a cross feed sled and rotary table. Might even build a cutter like they use on ornamental lathes. Then I could achieve whatever angle I want on the bit and it would be accurate.
     
  27. Ron Solfest

    Ron Solfest

    Joined:
    Jan 22, 2009
    Messages:
    108
    Location (City & State):
    TN
    Don Wattenhofer - I think you hit on the root of the question about the 90deg bit not cutting at 90deg that John Lucas has.

    The bit does cut at 90deg, it has to, that’s physics or math depending on how you look at it :)

    What is throwing people off is the radius of the piece is decreasing as you cut towards center, hence an orthogonal cut to the lathe shaft will be removing a larger and larger arc of the piece as you cut towards center.

    Best way to visualize I believe is to think about a solid cylinder mounted in the lathe. The router travel will need to be canted slightly instead of straight across the ways. The point the bit enters the outside of the cylinder is determined by the depth and width of the V you want to make (to match up around 360deg as you go around etc). The amount of “canting” needs to be set such that the very point of the corner of the router bit will cut *exactly* no wood at the *exact* center of this mounted cylinder.

    That would allow the proud point of the zig zag to have it’s interior and exterior points to be in the same orthogonal plane to the center of the cylinder. This will also cause the deepest point of the zig zag to get progressively shallower as you approach center, which allows the amount removed to be proportional to the decreasing circumference.

    I believe that is the issue John has been compensating for, and just confusing it with thinking the bit wasn’t cutting at 90.

    That’s my foggy thoughts as I wake up this morning...still think I might not have fully thought through the deepest point canting orthogonal plane very well...
     
    Last edited: Nov 6, 2020
    Bill Boehme likes this.
  28. Ron Solfest

    Ron Solfest

    Joined:
    Jan 22, 2009
    Messages:
    108
    Location (City & State):
    TN
    The fog is starting to clear. I recognize what I missed in the earlier reply.

    As you approach the center of our solid cylinder, ALL points of the zig zag need to approach 0. Therefore the orthogonal plane I was referring to needs to be at the center of the zig zag, not the proud point as I previously suggested.

    That means the cant angle needs to be half of what I previously suggested such that the deepest part of the V would form a cone (not plane, around the cylinder) which would angle up (removing less and less wood as you approached center). And the proud part of the zig zag would form an opposing cone (going in) as you approach center.

    The nice part about wood is that we don’t have to work in angstroms though and a little “fudge factor” is allowed :)

    I think this makes sense now, not sure if I’ve communicated it well...
     
    Bill Boehme and hockenbery like this.
  29. Glenn Lefley

    Glenn Lefley

    Joined:
    Jul 10, 2017
    Messages:
    537
    Location (City & State):
    Invermere, British Columbia
    Is this what you say is happening? Sorry trying to understand. 15AFE32B-0034-44C1-BAC5-0E68F0880461.jpeg
     
  30. Don Wattenhofer

    Don Wattenhofer

    Joined:
    Jul 19, 2018
    Messages:
    686
    Location (City & State):
    Ponsford, MN
    I think you have it right some what however the angle as I measured it was 10 degrees so as I stated my next try was setting my cross slide at 5 degrees so if 1/2 is the correct value then even with my crude angle measurement the fit should be closer then it was. I do believe that in this application a little fudge factor isn't good enough since I used a press to glue it up but could not overcome very slight miss fit, maybe if I was using softer woods it wood work.
     
  31. Ron Solfest

    Ron Solfest

    Joined:
    Jan 22, 2009
    Messages:
    108
    Location (City & State):
    TN
    Don,
    I think the problem becomes understandable after your observation about the circumference becoming smaller as you go towards the center. Coupling this understanding with the concept of thinking of the turning as a solid cylinder reduces everything to relatively straight-forward geometry and trig.

    The crux of the issue lies in the reduced circumference of the inside of the turning relative to the outside. Because of this something has to change between the two surfaces.

    In a “perfect” world the outside of the cut would be at 90deg, and the inside of the cut would be at a smaller angle depending on the thickness of the turning. This would allow the depth of the V to remain constant, and keep the arc of the circumference it removed constant. Given we don’t have a “modulating angle” router bit, it will *always* cut 90deg; therefore we have to compromise something.

    By canting the angle of the router track the compromise we choose is to modulate is to reduce the depth of the V, this allows the arc it removes to still be the same proportion of the 360deg circumference. This will raise a square shaft of wood slightly on the inside and two adjacent pieces will need to be trimmed (towards the inside) to provide a perfect fit.

    Again, fortunately, wood is a forgiving medium so we can get away splitting the difference, or other inexactitudes.

    If you draw the angles out recognizing that all radial lines come to a point at the center of the cylinder, and remember a little trig (opposite/side of a triangle = tangent) you can compute finer angles than the wood will care about.

    Thanks for motivating me to think of schooling from 40yrs ago :)
     
  32. Don Wattenhofer

    Don Wattenhofer

    Joined:
    Jul 19, 2018
    Messages:
    686
    Location (City & State):
    Ponsford, MN
    Think about the problem from the standpoint that the 2 mating surfaces will be offset from each other by 10 degrees which puts the point of the outer V into the the bottom of the opposite V therefore the the angle of the top must match the bottom of the V.
     
  33. Ron Solfest

    Ron Solfest

    Joined:
    Jan 22, 2009
    Messages:
    108
    Location (City & State):
    TN
    Don - I originally was pulled into this thread by the discussion of the 90deg bit not cutting at 90deg. I haven't watched John's demo, and his discussion of tablesaw cutting angles mislead me as to what was trying to be accomplished. Your last comment (and a picture that I can't find now?) helps me to understand. Sorry my learning path has been incremental.

    I get, and agree, with the fundamental issue now: Because the router bit always cuts at 90deg as it approaches the center you can not have the bottom of the V and the top of the V be in parallel planes due to the decreasing circumference, and therefore have to match the cone created by the points of the V on one surface to the cone created by the bottom of the V on the other.
    * If you cut straight, the bottom of the Vs will be orthogonal and the top of the Vs will be a cone and all diameters less than the original cylinder will have a gap.
    * If you cut at the angle I previously suggested such that the depth of the V goes to zero exactly at the center you'll have the opposite problem; namely the tops of the Vs will be orthogonal, and the bottom of the Vs will form a cone. Trying to mate these will leave a gap around the outside when you try and glue the two surfaces together.

    I think I'm just restating what you already know (to make sure of my understanding).

    I don't think cutting this angle in half is just "splitting the difference", I believe it is an exact solution so that the two cones mate.

    Given this, the formula you're looking for is simple. You need to determine the depth of the V based on how many integral V's you want to cut around the circumference. Once you have that depth, you divide it in half and then divide it again by the radius of the cylinder; put this number into your calculator and push the arctangent button and it will give you the precise angle you desire. Since diameter is 2 x radius, this simplifies further to:
    ANGLE = arctangent(V/D) where V is the depth of the V and D is the diameter of the cylinder.

    For example: 1/4" V depth on a 2.5" diameter cylinder would require and angle of 5.71deg = arctangent (.25/2.5)

    I shouldn't have read your reply just before going to bed last night, I woke up early thinking about this. Sorry again I didn't fully comprehend the problem before I started shooting my mouth off (my wife will tell you it's a bad habit I have). I think I have this correct now and might try to go back to bed for an hour or two :)
     
  34. john lucas

    john lucas AAW Forum Expert

    Joined:
    Apr 26, 2004
    Messages:
    7,417
    Location (City & State):
    Cookeville TN USA
    I hear a lot of theory about why the tool should cut a 90 degree angle but have any of you done it. I have done 100's of these V cuts. I've been doing it for many many years. I've tried all sorts of cutters, but definitely not all that there are. All I have tried do not cut a 90 degree V. They cut a flat bottom groove if you use them like they were designed because I have done many inlays this way as well as the v. Set up a router and cut and if it cuts 90 degrees send me the info on that bit so I can buy one. Would greatly simplify my life.
     
  35. Don Wattenhofer

    Don Wattenhofer

    Joined:
    Jul 19, 2018
    Messages:
    686
    Location (City & State):
    Ponsford, MN
    The circle I am using is 2.5" diameter which has a circumference of 7.854" / 18 ( Vs 20degrees apart) = .436" / 2 = .218 for the depth so please check my math ( my last formal education in math was about 1964) then apply to your equation.
    Thanks
     
  36. Glenn Lefley

    Glenn Lefley

    Joined:
    Jul 10, 2017
    Messages:
    537
    Location (City & State):
    Invermere, British Columbia
    I talked to a router rep and he said when a router is turned on it’s side and presented on a 45 degree angle it causes lift as both sides of the bit are not in the wood. Also a small amount of torque on the shaft this will cause the bit to NOT cut on 90 degrees, it is a combination of factors that are sort of out of our control unless we could some how eliminate that. As he said this small amount of movement and torque would cause a deviation. He said he would take a router bit and sharpen the long side in a way to reduce the angle a few degrees to cut at say 87 degrees and then with the movement you probably would end up with 90. But as he said in a perfect Environment the bit will cut a perfect 90 . And why would you do it in that situation when you can cut the filler to fit.
     
    Mark Jundanian likes this.
  37. Ron Solfest

    Ron Solfest

    Joined:
    Jan 22, 2009
    Messages:
    108
    Location (City & State):
    TN
    Don, it's been close to 40yrs since I got my EE so you may not want to trust my math either :)

    I agree with your math (although judging by your segmented turnings you need NO help with math). Therefore, arctan(0.218/2.5) = 4.98deg, and I'm pretty sure with wood a 5.0 deg angle should cause the surfaces to mate well.
     
  38. Don Wattenhofer

    Don Wattenhofer

    Joined:
    Jul 19, 2018
    Messages:
    686
    Location (City & State):
    Ponsford, MN
    Those are just verifying the need for a rigid mounting of the router and the work piece. The cross slide holding and driving the router along with a rigid indexing system eliminates all of those problems, that is why I rejected the wooden mount and sled.
     
  39. Don Wattenhofer

    Don Wattenhofer

    Joined:
    Jul 19, 2018
    Messages:
    686
    Location (City & State):
    Ponsford, MN
    1. DSC00765.jpg This is the latest try:
    2. The1st step was to turn the top piece to 2 1/2" OD and 2 1/8" half ID
    3. The 2nd step cut 18 90 degree Vs every 20 degrees and at 7 degrees
    4. The 3rd step turn a birch to 2 1/2" OD and bore out all the way at 2 1/8" ID
    5. The 4th step see second step
    6. The 5th step glue to the top piece
    7. The 6th step cut off about a 1/2" ring of birch on the top piece
    8. The 7th step (with the top piece remounted) cut the 18 Vs at 10 30 50 70 etc. degrees
    9. The 8th step is similar to steps 1 & 2 & 5 but for the bottom piece
    10. The 9th step is to round off the outside
    11. The 10th step do the hanging eye, the finial and finish
     
  40. Glenn Lefley

    Glenn Lefley

    Joined:
    Jul 10, 2017
    Messages:
    537
    Location (City & State):
    Invermere, British Columbia
    Was your router mounted at 45 degrees?
     

Share This Page