Observation and question about anchor points heights

Now that I have my M4 cruising around the frame, I’m noticing that depending on the position and height of the router, the belt entry angle into the arm is more or less aligned with the arm.

Of course, when the M4 is right in the middle of the frame and the Z is bottom out things look good and the belt angle coming into the arms is ok at around 2 to 4 degrees. (depending on which arm you look at)

But when we take the worst extreme case scenario which would be cruising towards the top left anchor at 20 inches from the anchor with 1.5" of material on the frame, the top left belt would be at about 23 degrees from horizontal.

This creates 2 situations

#1 The belt tends to twist (almost 90 degrees facing down) and may mis-align itself into the arm and add some unwanted wear.

#2 The closer we get to the corner, the bigger the angle and then the sled tends to tilt. (see clip)

.

Ok, enough with the observation, here are the questions.

What if I was to raise the anchor points to minimise that belt entry angle? Since the arms all have a 1" height difference,

I would:
add 4 inches to the top left anchor point
add 3 inches to the bottom right anchor point
add 2 inches to the top right anchor point
add 1 inches to the bottom left anchor point

This would normalize all the belt entry angles and the most extreme would be around12 degrees.

I think this would probably also help with the tilting. But how would this affect accuracy ? I understand that this would shorten the belts a little bit. Would this affect the calculation? Will calibration take care of the shorter belts? This is probably a @bar question.

Let me know if you think this is a good idea

Cheers

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I measured the arm thickness as 21.25mm, so that would be better spacing between
the anchors than 1"

There is a way to enter the height of each anchor, so the software is supposed
to take this into account.

I have been thinking from the beginning that it would be best to raise the
anchors from the default ‘against the frame’ height.

If you have a spoilboard and the workpiece, your angle at the corner is going to
be even worse.

I think we just don’t have enough people getting past the calibration to be
doing real work for the problems you call out to be significant yet.

David Lang

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I have not received my M4 yet, but I was thinking about this being an issue, as it is definitely an issue with my M2. Those same exact problems manifest themselves from old to new. Hopefully by the time I get my M4 this problem will be solved as I am planning on raising all my anchor points to meet the height they come out of the sled. Since my primary mission or purpose to own is working primarily with plexi, the depths have to be perfectly consistent all the way around due to the type of bit I have, its an issue that needs to be solved before I start using it for production work.

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Joseph wrote:

I have not received my M4 yet, but I was thinking about this being an issue,
as it is definitely an issue with my M2. Those same exact problems manifest
themselves from old to new. Hopefully by the time I get my M4 this problem
will be solved as I am planning on raising all my anchor points to meet the
height they come out of the sled. Since my primary mission or purpose to own
is working primarily with plexi, the depths have to be perfectly consistent
all the way around due to the type of bit I have, its an issue that needs to
be solved before I start using it for production work.

depths should not be a problem, it’s getting through calibration to get accurate
ancor point locations (and therefor accurate x/y cuts) that is the current
problem.

David Lang

Thanks for the exact measurement,

I understand the calibration issues and the priorities, I’m sure Bar and the crew will iron it out.
We can certainly bring this back into the conversation later on. I would not want to ease out the belt angle and compromise accuracy!

In the meantime, I did some scaled down cutting (under 24"x 24") over the week end on my modified M2 frame and M4 machine

Cutting rectangles, circles, 3D bowls at speeds between 60 to 80 inch per min.
Accuracy: It will come, but was not so bad, at ±1mm in most case (especially compare to the M2)
Duplication: is very good
Square: is spot on
Speed: is great
UI: minimalist but works (no worries there, I know things will tidy up, later)

Overall I’m happy with the results

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Great to hear you’re making good progress!
Please share some photos/videos of your cuts when you have an opportunity, we’re super excited to see what people make with M4.

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This would effect the calculation, but luckily it there is already a setting for it. In the settings you will see a that we have an X,Y, and Z coordinate for each anchor point. At the moment we’re pretty much ignoring the Z-component and using the defaults everywhere, but if you want to experiment and customize it that should be supported already

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Thanks for the answer,

I went and looked at it,

Seems like calibration is handling this and roughly adjusted it in the same increments and pattern as the motor heights. The anchor points height differences calculated at calibration are 20ish mm which is in line with the height difference of the arms. I will give a try to increase the anchor points when I get back next week!

Cheers

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