If I wanted to work on a small piece, say something really small like 1’ x 1’, what’s the smallest possible frame I could get away with? For example, could I just put some bolts at the corners of my workbench, or make a small table top frame?
we are working to figure that out in the min/max angles thread
right now we are still figuring out what the limiting factors are.
David Lang
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it looks like a 48’ square frame can handle a 24.5 square work area
for a 12" square work area, the angles let you get down below a 30" square
frame, but that would require that you have the belt anchors at the same height
as the sled, and you are within an inch or so of the sled hitting the edge of
the frame.
but it does sound like this can be turned into a tabletop system
If you try it, please let us know how it works
David Lang
I think it might be tricky to get a good calibration?
How does the calibration algorithm work? Because on the big frames it seems like the router will only pull itself to the edge of the 4x8 sheet of plywood, even though the frame is much bigger. But on a smaller frame it seems like it will try to pull itself almost up to the anchors in the corner.
Is there some kind of max area that can be set, or an offset or something?
I also noticed that the anchor points have a Z axis as well. I assume the calibration algorithm takes anchor height, and the height of each spool in to account?
I think it might be tricky to get a good calibration?
How does the calibration algorithm work? Because on the big frames it seems like the router will only pull itself to the edge of the 4x8 sheet of plywood, even though the frame is much bigger. But on a smaller frame it seems like it will try to pull itself almost up to the anchors in the corner.
you can specify how large an area to do calibration in, and how far apart the
calibration points are (as of this week’s firmware update).
I also noticed that the anchor points have a Z axis as well. I assume the calibration algorithm takes anchor height, and the height of each spool in to account?
yes, but if the angles are too steep, youwill risk breaking the arms. the
expectation was that you would never get closer to ~2’ from an anchor, and even
then the angle could be an issue.
David Lang
I made a quick frame that was 4’ x 8’, which is only a little bigger than my workbench. And calibrated an area about 2’ x 4’. I just did 30 points so it would be quick, but got an .85 fitness. Unfortunately I was still getting big movement errors.
I’ll try again with a 9 x 10 grid for the calibration. Are there any other hints for getting a good calibration? For example, does the frame have to be really stiff? Is there anything we should do to help the sled be positioned well, or is not touching it better?
I punched the numbers in to David’s spreadsheet calculating min/max angles, and I think I needed a slightly smaller work area.
I did another calibration with the same frame size and a 18" x 36" area and more points and got a 1.15 fitness.
The sled seems to move around well, but I’m noticing that often one of the belts seems to have some slack in it? Is it supposed to look like that?
48” square workspace with 8” H offset and 9” V Offset will give you a working space of 32” x 24” but it’s really tight
as @dlang says - any smaller and your angles are goosed. Think the minimum offset you can achieve is 8” comfortably. A 36” square will only process 16x16 with a 10” offset
I made a quick frame that was 4’ x 8’, which is only a little bigger than my workbench. And calibrated an area about 2’ x 4’. I just did 30 points so it would be quick, but got an .85 fitness. Unfortunately I was still getting big movement errors.
so a 4x8 frame gives you a 12" x 64" cutting area, it’s just too long for the
angles
a 4x5 frame will give you a 20" x 30" cutting area.
play around with the spreadsheet and see what works.
I’ll try again with a 9 x 10 grid for the calibration. Are there any other
hints for getting a good calibration? For example, does the frame have to be
really stiff? Is there anything we should do to help the sled be positioned
well, or is not touching it better?
if the frame/anchor flexes when the belts pull tight, that is a very bad thing.
you should not need to touch anything during calibration.
David Lang
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during calibration or after? during calibration belts may have some slack, after
calibration when you are moving around they should not.
what is the height of your anchors?
David Lang
Pete Whitlam wrote:
48” square workspace with 8” H offset and 9” V Offset will give you a working space of 32” x 24” but it’s really tight
as @dlang says - any smaller and your angles are goosed. Think the minimum offset you can achieve is 8” comfortably. A 36” square will only process 16x16 with a 10” offset
The sled is 16" diameter, 8" puts the edge of the sled at the frame when you are
at the edge of the workpiece, that may or may not work, but I’m sure that would
require the belt anchor be raised, not at the edge of the frame (and raised
anchors are more likely to flex)
David Lang
After calibration. I think my anchors might be too low, I just used some heavy duty screws. I’ll re-do it with some longer bolts and see if that helps.
with the older maslows, some people made standoffs by glueing plywood disks
together to stack to the right height and still be very rigid.
David Lang
Dlang
I appreciate your help. I have built 4 stackable boxes that when placed together comes to 4x8 ft. Have been considering cutting 2x2" steel like used in trailer hitches for extending the arms. Also how much can the arms length be reduced by makung bolt point as close to horizontal as possible.
Martha
Martha Montgomery wrote:
Have been considering cutting 2x2" steel like used in trailer hitches for
extending the arms.
I have thought about that, but the problem is eliminating all possible movement
in the anchor points. you could have bolts into the side/bottom of the steel to
tighten down to prevent the arms from moving, but how repeatable is the
positioning?
Also how much can the arms length be reduced by makung bolt point as close to
horizontal as possible.
we don’t know. right now it’s speculation on my part that that helps.
having the anchors down at/below the spoilboard makes it easy to have them very
solid and not as likely to flex as if they are taller, but it pulls the sled
down to the workpiece in general (increasing friction and we have seen some
people posting videos that look like they have a problem with friction), and if
you get really close to the corners, the angle of the belt to the arms could
damage the belt (but it turns out that on most frames, you can’t get that close
to the corners anyway, so this is less of an issue than I expected)
David Lang
Thank you. Very informative. My boxes are 1x4 sides with 1/2" plywood on top. Figured I would place t nuts where needed and color code the corners. I was thinking of using aluminum 4040 extrusion but found it can twist. Maybe 2x2 steel with HD bracing ro tie points. And maybe some steel angle for added bracing. Trying to figure best means.
Original thought was to have spacing between boxes with maybe mini traffic cones for height support. Health has not been good and have not made it outside in over a week. So it is getting to where I need to complete something to try
Martha
I’m finalising my mobile work bench currently and it’s looking around the 1800/900 dimension which means with some slot on / in extensions of 300mm each side I will get a cut area of 1250/840 which is perfect as I have access to large quantities of ply off cuts that are 1/3rd sheet. Using the link from @dlang it’s easy to play around and see what will work and the add ons for the bench won’t be huge.
My vision has changed since joining kickstarter. I wanted to work on cabinets and i was thinking about making avalanche more like an RV. passing out on the freeway ended all that. No longer safe for me to drive. Walking distance very limited. Using powerchair and metro to get around. That sizing seems ideal for me. Likely would need to cut 4x8 sheets down for storage anyway . So dealing with how large a frame i really need.