# How about an X,Y,Z sensor on the Sled

I’ve been thinking over a complete Maslow make over. One of the things I’ve noticed is I keep my chain is very congruent to the tilt angle of the frame. I think people that are experiencing skips are dealing with slight deflection from a parallel plane. I have removed the standard chain guides, I am using bottom elastics and I can see the idler sprocket angle when there is any deflection so it is rotating counter to any deflection as the chain enters the drive gear from that side creating counter deflection if you will. It’s a very harmonious ballet. In my opinion you can try to force the chain to enter and exit a path over the sprocket but you are fighting high load forces. I’ve had my chain turn to a monkey fist while calibrating. It didn’t kill my set up because I was watching very closely and killed the power.

My thought is with an XYZ sensor you could calibrate the frame angle the off set out ward distance of the motors in Z, then the sensor on the router top (cap) could tell when the angle changes, a skip alert maybe. The data would be interesting. It even could be a separate Arduino. The data would pick up the rotation of the sled as well.

If your frame is as at a 15 degree angle but the sled is at a 13 degree angle something is going to happen and something not good is inevitable.

In software we build a model of what we thin will happen, there must be a way to use this data to compare what we think will happen and what actually happens and calculate the margin of error and make adjustments until the patterns match.

More musings on how to get more consistent performance.

Thank you

if the chain is not stright, you have a problem, but the sled angle when held in
mid-air vs the frame angle is not significant.

since the sled rides on workpiece. as long as the workpiece is a constant
thickness, the angle of the sled is going to match the angle of the frame.

pulling slightly above or below the Z center of gravity is only going to make a
very small amount of tilting force on the sled.

I’m not completely sure that pulling above the Z center of gravity (needed to
have it tilt forward) is really the right thing to do. When you are pulling
sideways, you are trying to tilt the sled sideways vs pulling the most effective
way on the sled.

pulling a little high may help keep you from tilting over the edges of the
workpiece compared to pulling low, but that’s the only advantage

if the sled is going to tilt, it will tilt different amounts if the angle
between the chains is low than when the angle between the chains is high

David Lang

I have been thinking about this for my frame as I am going to be varying the thickness of the cutting matertal quite a lot.

What I have come up with is this.

1. Make the top motors move in the Z axis

I will be using a lot of different thickness materials so the problem become worse as materials change

What I have come up with is

1. Make the top motors move in the z plane
To do this i am mounting them on a cheep z axis slide
The slides have a stepper so I can easily drive them into position

2. Mount a cheep laser pointer on the sled for alignment
This will need a target aligned on the motor mounts

So the idea is
After changing board thickness

1. Rotate the sled so that the laser pointer points at the target.
2. Move the first slide till the dot aligns with the target
3. Repeat for the second top motor

The plan is to mount them with the carriage underneath (ie upside down from the pic) and support.
As my frame is made from 50x50RHS steel this is not an in issue
I will just add a section of steel that support the entire length of the frame so it cant bend under the weight

That seemed to complicated for me on 0 \$. So I had to opt for having sled and motors precisely aligned and just changing the thickness of my backing material. What I have not done till now but is next to make the down beam adjustable so the sled can always ride over it.

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@34by151 , I don’t have a Maslow yet, but intuitively, it seems like it would be easier to:

• build your maslow adjusted for the thickest material you will cut,
and
• clip the appropriate thickness of slider plate to the bottom of the sled to keep it parallel to the motors.

Definitely more manual than the Motor-on-Z-slides, and you need to accumulate a library of Sled Sliders for each thickness of stock, but also seems like less to go wrong.

I’d like to play with a MEMS Gyro sensor to see if I can damp out the vibration of the working Router, and provide a real-time tilt sensor that way.

I’ll try to get some picts of my design solution for this problem next week. I have a unistrut frame, where the crossbar rides on 2 flat lengths of unistrut squared to the uprights of the frame.

The cross bar is clamped to the uprights using a simple plywood jig sized to ride behind and above the crossbar, keeping it in place when tight and referenced/offset to the uprights + Backing frame + Spoilboard depth. the jig is clamped to the flat lengths at the end of the uprights with appropriately long bolts and washers and scrap.

On either side of the machine, the jig-clamps are marked, that allows me to slide the entire crossbar forward or back nearly 5-6", but I’ve only marked the appropriate 1/4"-3/4" thicknesses I most commonly will use.

Like i said I’ll post some picts next week, but as long as you have a way to slide the cross bar back and forth on the frame, you’re 90% of the way there, just measure your offsets and frame ‘depth’ and make some marks for whatever stock you want.

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I like the sounds of this, @mrfugu .
I will be building my frame this weekend, so will be looking at a way to do something similar with my unistrut - Thanks!