Is there a specific height the ring system is supposed to be adjusted at?
Should it be higher up like the first pictures or lower like the second? Also should I tighten the small nut and bolt to where it can’t move up and down?
The ring should be positioned above the center of gravity of the sled. This will ensure that it stays stable near the edge of the workpiece. You can figure out where the center of gravity is by placing some sort of fulcrum underneath the body of the router. It may take some trial and error to get it right.
Are you referring to the mounting bolts for the ring? Yes, those should be nice and tight, otherwise the ring could shift during cutting.
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Not the mounting bolt, the small black hex screws that attaches the ring to the mounting L bracket
Tie a piece of string to the ring and hold it up in the air
Adjust the height until it is balanced perfectly and then raise it a tiny bit so it is just above the center of gravity
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When I built my system I did not see any instructions to tell how to set this so I just “best guessed” the height and installed the ring on the sled. After a number of really bad test cuts, while trying to figure out what I did wrong, I happened to look at the frame (from the side) and noticed that the chains were not at all parallel to the plywood I was cutting and this was allowing my sled to lean out at the top.
The sled was at center of the plywood at this point and since I was significantly off from where the ring position needed to be, I adjusted the height of the ring ( by adjusting the center screws of the ring brackets, keeping the ring parallel to the sled) until the chains were “visually” parallel to the plywood (working surface).
Once the chains “looked” level with the plywood, I lowered the sled to the bottom center edge of the plywood using GC and used a stiff metal ruler to measure the distance from chain to plywood (both near the sled and at top edge of my plywood). FYI, I have a support rim around the entire working surface of my frame to support the sled at the edges. I used the averages of those measurements to determine how much to change the vertical position of the ring.
I adjusted the ring height based on these measurements so that the chains distance to the plywood was slightly more (~1/8") near the sled then at the top of the plywood. I chose to have the bottom chains further away from the plywood so that the bottom corners of the plywood (working surface) would have added force pulling the sled into the plywood (at the top of the sled). This length bias causes the opposite result at the top of the work piece (not as much force pulling the sled into the plywood), but I figured that the benefits at the bottom outweighed the loss at the top edges.
I then moved the sled to the top of the plywood and did a visual check of chain parallelism and verified that the top of the sled remained firmly against the working surface. As expected, the pulling force on the sled (at top of sled) was lower at the top center of the plywood (compared to what I felt at the bottom center of the plywood) but the sled was still firm against the plywood.
I then moved the sled all around the plywood’s outside edges and corners using GC to check for consistent contacting between the sled and plywood. I was satisfied with the contact I saw.
I hope this makes sense. It was much easier to do then to write down.
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James, you have the right idea in keeping the chains ‘level’ with the plywood,
but you are correcting things incorrectly.
you should find the sled balance point as people described above (note that the
balance point is going to be different depending on the Z position of the router
at the time)
Then once the ring is locked down, you should look at the chain angles and
adjust the frame (or add wasteboards below your workpiece) until the chains are
close to parallel with the workpiece.
David Lang
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Tie a piece of string to the ring and hold it up in the air
Does it refer to the entire sled?
Yes, the entire sled.
My unconfirmed opinion is that you move the sled to the middle hor/vert and balance there by just pulling the attached chains away from the sheet. This way you can see when the top of the sled is slightly tipping towards the sheet and that’s where you are good to go (if you have your motor-sprockets ~ same distance as 2).
My superstition is that you get a difference ‘balance point’ compared to tie a string at the middle top of the ring.
(Credit for the picture to @ruaridhmac)