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Holey Calibration Issue - Top middle hole higher than the other top holes

Good morning! I’ve got an ORIGINAL Maslow setup (no ring/ no z-axis) that I’m trying to get calibrated. I’m using WebControl and have gone through the Quick Config and have the chains all set and the sled attached. When I started the calibration, the first hole it cut was SUPER high, only 1/2" from the top, but the other top holes (left and right) weren’t that high, more like the calibration picture shows.

I’m not even sure where to begin with this issue, I’d appreciate any tips or advice (or a thread that already has this information!)

Thanks everyone.

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the original L bracket approach cannot be made accurate with any current

you need to replace the L brackets with a ring or linkage setup that makes it so
the ends of the chain are a constant distance from the bit with the chains
always in line with the bit.

Only after you do that will you have a chance of an accurate machine.

David Lang

Thanks for the quick reply dlang!

Oh, so this was best used with Ground Control? I actually have a M2 Classic Bundle kit on the way that will have the ring and z-axis motor. I purchased this setup a few years ago and we just kept getting other projects stacked in front of it, so the ring wasn’t even released yet.

What I find interesting is that the other holes were all pretty much in line with each other, horizontally and vertically…it was just the center hold that was off.

So, with the L-brackets, it’s not even worth continuing until the new setup gets here?

GroundControl is also not going to be accurate, but it’s calibration routine is
old enough (before we really understood things) that it may not show the
problems, but they will show up when you get to cutting.

If you have the machine working at all, you can use it to cut your own linkage
kit. I’ve wanted to do (or help someone do) a video on how to use an inaccurate
maslow to cut the linkage to make it accurate for quite a while now. If you
areinterested, we can work through this together (and if you can film it, or at
least take pictures for a post, it would be very nice)

People were having horrid problems trying to get accurate with the L brackets,
adn Bar could not understand why, until he took his machine apart to move it and
couldn’t get it accurate after it was reassembled. Then we did a dive into the
math needed to make it accurate and found there were just too many unknowns to
make it work in practice. The tilt of the sled turns out to be a critical thing,
and that’s affected by the torque of the router and the resistance the bit is
running into. The ring/linkage approach eliminates that factor and significantly
simplified the math in other ways, and from there we’ve been able to do much

David Lang

Ah, I understand better now. Thanks!

I’m in the middle of trying to get the Maslow cutting accurately for a project that I’m doing and I need it working in a week or so. I’ve got the newer M2 setup coming in, so I’ll be working on that when it gets here. BUT, I’m down to work on that with you. The only downside, I don’t have the material to get two different complete setups working. So, if I can get it setup elsewhere, that would be a fun project to work on.

With the current holey calibration I have, can I attempt to cut the sled? The M1 and M2 distances aren’t just horizontal, but they’re at an angle. I didn’t know if I should try another calibration to see if it cleaned up any?

Well, that sounds interesting! How quickly did the ring end up becoming part of the preferred setup? I’m currently using the 4th hole back (from the workspace) so that the sled sits with as little tilt as possible, but I keep getting the “sled not keeping up error”.

slow your ma feed rate and check that your power supply can keep up (that it’s
voltage isn’t sagging under load)

these instructions make a ‘45 degree’ kit (so you can look on the forum and see
other examples that were laser cut)

to make you own linkage kit, you will need

  1. plywood to make a new sled (not absolutly required, but makes things much

  2. plywood to make the links (1/4" plywood or so, you want it stiff, so not the
    super cheap stuff)

  3. wood to make standoffs to get the linkages the right height from the sled.
    This can be done with stacked and glued plywood pieces, but if you have other
    tools (drill press, bandsaw, etc) it can be done stronger and easier with solid

First get the machine to a state where you can move around and define a home
(center position that is repeatable). Make sure that at the end of setup, when
you extend the chains, you mark which link is at the 12 o’clock position on the
sprockets so that you can reset to this point when things go wrong.

I would suggest using a 1/4" bit, but the size doesn’t matter, what matters is
that you have a bit and bolts that are a snug, but not tight fit (you need to
have piecees able to rotate on the bolts)

The key to doing this is to recognize that while the existing maslow is not
accurate, it is precise (repeatable), so we need to do things where we are
moving to a fixed number of points and move the workpieces around to make
multiple cuts. We will work with the center hole, moving only straight up and
down from there for the critical holes.

Parts we are creating

  1. a new sled with mounting holes for the linkages in approximately an X pattern
  2. two links with three holes (center plus one at each end that match the X
  3. four links the same size to move the 3-hole links clear of the router (they
    connect the ends of the 3-hole links to the mounting holes in the sled)

If you are very confident in your accuracy, you can do this all without the
maslow, but personally I trust the repeatability of the maslow over
measurement/marking :slight_smile:

the four two hole links just need to have identical spacing of the holes, so if
you have a drill press, it’s best to make them without the maslow, cut 3/4" to
1" wide strips 8-10" long, clamp them together and drill holes in each end
(drilling through all four at the same time) The exact distance doesn’t matter,
what matters is that the distance between the holes is exactly the same on all
of them.

for the sled and the 3 hole links, what you will do is drill a hole in the
center of your machine, and the center hole of the sled and the links. bolt the
piece to the machine tell the maslow to move up (Y axis) to +5" and then drill a
hole in the part, then move to -5" and drill a hole in the part. It won’t matter
if the maslow moves exactly that distance, as long as it moves to the same point
each time.

For the sled, you will cut one set of holes, then rotate the sled ~90 degrees to
cut the other set of holes (this way it doesn’t matter if the maslow isn’t
moveing the same distance in X as Y, you never rely on it)

You can use the maslow as a complicted circle cutting jig and move the bit to
~9" up or down from the center and rotate your stock on the center pin to cut a
circle. do not cut out the center hole yet.

remove the sled from the maslow, put a bit in the router you will mount on it,
put that bit in the center hold on the sled. mark and drill the mounting holes
for the router so that you know it will be centered on that hole, then cut out a
larger center hole for clearance (this can be done like you did the outside of
the sled on the maslow, with a hole saw, with a jigsaw, whatever. it doesn’t
need to be precise or clean, just give you space for the shavings to get out and
clear of the bit.

Then you want to mount a long standoff on the sled, mount the router and bricks
(with the router set to a reasonable height for cutting) and then get a piece of
angle iron or similar and hang the sled from the standoff. you want to find the
point where the sled hangs vertially (moving the balance point on the angle iron
towards or away from the sled) That is the height you want the 3-hole linkage to
be at. So you want to make one standoff of each pair shorter than this by 1.5
linkage thickness, and the other taller by 1.5 linkage thickness.

does this explination help? or do I need to try for images of each step?

David Lang

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Wow!! The level of detail here is awesome, thank you! I wish I had asked this question BEFORE I ordered the ring in…haha

These instructions make sense, and I think I will be trying this so that my original setup will be more precise (and then maybe I can have 2 setups running :laughing:). I’ll check the forum for examples of the actual pieces. I don’t have a drill press handy, but I think it might be good practice to build the “part” and then have the Maslow cut it? I’ve noticed so far in my testing is that it cuts vertically and horizontally just fine…but it struggles with the arcs, so I think I can cut the strips out pretty easily. Thanks for going to the trouble to write this all out, I’ve never had this kind of support on a forum.

I was able to get a sled cut, though it’s a little oblong because when I followed the original instructions, the temporary sled didn’t have bricks on it, so the lack of weight made some parts of the circle a little longer than needed. I also only have a 1/4" bit so the circles for the lag bolts were massive and the head of the bolt would have fit through without washers. I’ll add a picture or two.

In your opinion, is the ring or linkage more precise?