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Zig Zag ornaments

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Don,
I see that my geometry isn’t what I thought it was, sorry about that! Glad you empirically arrived at the right angle
Ron
Not a problem, I still don't know if there is a mathematical solution and even if there is the cross slide angle etchings are to crude to really know the exact setting after the trial & error process.
 
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Yes the router is mounted at 45 degrees and on a Delta Rockwell cross slide with the top slide adjusted 7 degrees off perpendicular
Perfect. I’m doing the same. I’ve found also you never get a true 90 unless router is bolted down. Harvey Fein does awesome router work. I’ve also had trouble with the 1/4 inch shanks stuck out a little too far in the collet. I only buy the 1/2 inch shafted router bits now! It is amazing when you move a router by hand how bad or far out the cut can be through movement.
 
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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.

john, with all due respect, but what you're suggesting is not possible. The fact is the bits are dipped toward the center for clearance. It's sometimes called the primary end relief angle. Virtually all side-cutting cutters have the relief. When the bits are cutting vertical to a flat surface the cutter path is flat, the dip does not show. If you use your cutter as a drill with no side cutting, then you'll see the effect of the dipped center.

I don't know how you're measuring the 87 degrees. It doesn't surprise me that a filler block at cut 93 degrees would appear to fit nicely.
 
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Perfect. I’m doing the same. I’ve found also you never get a true 90 unless router is bolted down. Harvey Fein does awesome router work. I’ve also had trouble with the 1/4 inch shanks stuck out a little too far in the collet. I only buy the 1/2 inch shafted router bits now! It is amazing when you move a router by hand how bad or far out the cut can be through movement.
That is exactly my thought on the problems with having the router hand held on a wooden table.
Today I tried 12 steps or 30 degrees between Vs and I also cut all the way to the center to check the centering on the Vs. The center where the Vs should meet as viewed with my magnifying glasses look to be about .010" high so I lowered it and now it appears to be right on. The inside of the joint still appears to open up so I moved the top slide another half degree Now I just have to cut some Vs on 2 pieces with the same settings.
 
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John, mostly an end grain joint. What kind of glue are you using? What is your wall thickness?

Turned enough parts to make about a dozen. What fun! Thanks for posting and looking forward to the article.
 

john lucas

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My wall.thickeness after hollowing is usually about 1/8" or so. I use epoxy because of the tapered grooves you dont get a true wood to wood contact for more than a millimeter or so. It's a tapered joint with th fap.getting larger as.it goes deeper depending entirely upon how accurate the angle is that you routed. So if you shape the ornament and remove any wood at.all you can Cut into this gap. For that reason I use colored epoxy so the gap becomes a decorative element. My first experiments with this technique I routed straight across perpendicular to the side. As shaped the ornament i discovered this gap. That led to experiments of routing at different angles to try and get a perfect.wood to wood joint. So far my best attempt has only had wood to wood about 1/4". Even the. Its hit or miss. Probably because I am hand controlling the router. This isnt metal.lathe accuracy.
 
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The latest efforts are made with 12 Vs and the angle across the end has been increased to 7 1/2 degrees. The joints do not seam to open up on the inside now so that problem now seems to be solved. The one problem that there is no solution for is that when the points are cut to meet on the outside, as in diamonds verses zig zag, they spread apart toward the inside.
DSC00773.JPG DSC00775.JPG DSC00778.JPG
 
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Perfect. I’m doing the same. I’ve found also you never get a true 90 unless router is bolted down. Harvey Fein does awesome router work. I’ve also had trouble with the 1/4 inch shanks stuck out a little too far in the collet. I only buy the 1/2 inch shafted router bits now! It is amazing when you move a router by hand how bad or far out the cut can be through movement.
I looked up Harvey Fein and yes he does some awesome work and the router is rigidly mounted which makes it possible to do the piercing's, just imagine how jagged those long piecering's would be using a router with only a platform mount.
Note: The AAW symposium in Tacoma Washington I was there and brought the MWA challenge entry, which was a chandelier, and Harvey F purchased it at the banquet auction.
 

john lucas

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Don are you using a compound rest table to control the movement of the router. In your photo I only see the wooden part. If I ever get caught up on the other things I need to do I'm going to try and rig up a compound rest that has a rotary table to my lathe to control the movement of the router better. It just may be a while before I get around to that.
 
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Don are you using a compound rest table to control the movement of the router. In your photo I only see the wooden part. If I ever get caught up on the other things I need to do I'm going to try and rig up a compound rest that has a rotary table to my lathe to control the movement of the router better. It just may be a while before I get around to that.
Yes it is a Rockwell delta cross slide that they made in the 1960s to do light metal work on the wood lathe. The unit has 2 dovetailed slides, the first one is fixed on the Y axis that is it moves in and out perpendicular too the lathe bed and the second one is settable for any angle similar to the top slide on a metal working lathe.
DSC00770.JPG
 

john lucas

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Cool. I have 2 units that I'm going to play with. One I bought from MSC years ago to use on my drill press. It's really too massive to rig up on the lathe. The other one has a much smaller range of movement but has a rotary table on it and it's about 5" tall total so that's the one I'm looking at adding to the lathe. I will need to make a sort of course adjustment to get it roughly in position and then use the geared movements to control the feed and positioning of the router.
 
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Update: The angle that I previously thought was 7.5 degrees off perpendicular does work for 18 Vs however the switch to 12 Vs changes the angle so I tried 10 degrees and that seams to do the job. The larger Vs ( every 30 degrees verses every 20 degrees) changes the required cut angle to make the points match the groove I think.
 
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Follow up to the previous post:
I have been working on some double zig zag with diamond between for the middle of the globe using 12 Vs and 10 degree off perpendicular for the router travel. I verified that the 10 degrees made a near perfect joint inside and out in fact it seams a shame to hide the inside. The piece shown has a cheery base with walnut Zig Zag and the birch diamonds, while the other side has only the cherry base and walnut zig zag. Notice that all of the joints are tight inside and out so that when rounding the outside the joints will not open up as the diameter decreases. The cylinder for the turning is about 2 9/16" in diameter and will be turned down to a 2 1/2" sphere with the zig zag points on center and an inside diameter of about 2 1/8". The second photo is the final glue up of a walnut and birch one in the press.
DSC00798.JPGDSC00799.JPG
 

john lucas

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Glad to see your experiments. I hope 5o finish my crossfeed table in the next few weeks so I can work on more accuracy. Gotta.finish some lamps, some ornaments and an article on using index wheels but when i get that done i will.work on it.
 

john lucas

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You are doing a wonderful job larry. I'm working on building a router table that has a crossfeed and rotary table so I can try to answer some of the questions I have about router accuracy using my hand held table. It also might open up more avenues for decoration on turnings using a router. I would love to have an ornamental lathe but it's not in the option right now so I'll just keep playing with this system.
 
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Don W suggested I read this thread, and I watched the demo you did in Gwinnett also...and Larry the ornaments are gorgeous!
I feel confident the lathe I bought is a good one but outside of that I should probably just start over

what’s an ornamental lathe?
 
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