Using temporary sled, does not cut

I tired to cut out the final sled as my first cut. This was too ambitious so I created a 4 in. by 4 in. square with 1/2 in. fillets at the corners. I’m using Fusion 360, which I familiar with from my Shapoko 2 that I also have.

I have tried both climb milling and conventional milling, but you can see that all of my attempts are non-square failures. I think the initial “squiggle” where the bit enters the shape is due to fusion 360, but with this temporary sled I just can’t get it to work. The failures are three parts:

  1. when the bit enters into the shape on the middle left side, it is like the bit jumps, so that side is not straight.
  2. After the first few times around the shape it appears like the sled slips and no-longer stays over the previous cuts. This causes the sled to develop a gap between the sled and the plywood, failing the cut
  3. The square is supposed to be 4 in., but it is 3-3/4" in one direction and 3-7/8" in the other

I have tried 0.25", 0.20", and 0.10" step downs, I have tired 40 ipm and 30 ipm. My temporary frame is angled a 20 degrees. I’m using a straight fluted 0.25 in. dia. bit. Firmware and Groundcontrol v1.06, also tried 1.04 and 0.99, no luck.

One side note, when i ran the calibration test shapes they never lined up and when I hit the button that should have changed where they cut, the shapes did not change, they just moved around.

Here is the g-code (30 ipm, 0.10" stepdown, conventional milling) RoundedRec100MilsStepDown30ipmRateConventMilling.nc (2.6 KB)
:
%
(1001)
(T1 D=0.25 CR=0 - ZMIN=-0.8 - flat end mill)
G90 G94
G17
G20
G28 G91 Z0
G90

(2D Contour2)

G0 X0.475 Y-0.2
Z0.4
Z0.2
G1 Z0.1394 F13.12
Z-0.075
G19 G3 Y-0.175 Z-0.1 J0.025
G1 Y-0.15 F39.37
G17 G2 X0.5 Y-0.125 I0.025
G1 X3.5 F30
G3 X4.125 Y0.5 J0.625
G1 Y3.5
G3 X3.5 Y4.125 I-0.625
G1 X0.5
G3 X-0.125 Y3.5 J-0.625
G1 Y0.5
G3 X0.5 Y-0.125 I0.625
G2 X0.525 Y-0.15 J-0.025 F39.37
G1 Y-0.175
G19 G2 Y-0.2 Z-0.075 K0.025
G1 X0.475 F30
Z-0.175 F13.12
G3 Y-0.175 Z-0.2 J0.025
G1 Y-0.15 F39.37
G17 G2 X0.5 Y-0.125 I0.025
G1 X3.5 F30
G3 X4.125 Y0.5 J0.625
G1 Y3.5
G3 X3.5 Y4.125 I-0.625
G1 X0.5
G3 X-0.125 Y3.5 J-0.625
G1 Y0.5
G3 X0.5 Y-0.125 I0.625
G2 X0.525 Y-0.15 J-0.025 F39.37
G1 Y-0.175
G19 G2 Y-0.2 Z-0.175 K0.025
G1 X0.475 F30
Z-0.275 F13.12
G3 Y-0.175 Z-0.3 J0.025
G1 Y-0.15 F39.37
G17 G2 X0.5 Y-0.125 I0.025
G1 X3.5 F30
G3 X4.125 Y0.5 J0.625
G1 Y3.5
G3 X3.5 Y4.125 I-0.625
G1 X0.5
G3 X-0.125 Y3.5 J-0.625
G1 Y0.5
G3 X0.5 Y-0.125 I0.625
G2 X0.525 Y-0.15 J-0.025 F39.37
G1 Y-0.175
G19 G2 Y-0.2 Z-0.275 K0.025
G1 X0.475 F30
Z-0.375 F13.12
G3 Y-0.175 Z-0.4 J0.025
G1 Y-0.15 F39.37
G17 G2 X0.5 Y-0.125 I0.025
G1 X3.5 F30
G3 X4.125 Y0.5 J0.625
G1 Y3.5
G3 X3.5 Y4.125 I-0.625
G1 X0.5
G3 X-0.125 Y3.5 J-0.625
G1 Y0.5
G3 X0.5 Y-0.125 I0.625
G2 X0.525 Y-0.15 J-0.025 F39.37
G1 Y-0.175
G19 G2 Y-0.2 Z-0.375 K0.025
G1 X0.475 F30
Z-0.475 F13.12
G3 Y-0.175 Z-0.5 J0.025
G1 Y-0.15 F39.37
G17 G2 X0.5 Y-0.125 I0.025
G1 X3.5 F30
G3 X4.125 Y0.5 J0.625
G1 Y3.5
G3 X3.5 Y4.125 I-0.625
G1 X0.5
G3 X-0.125 Y3.5 J-0.625
G1 Y0.5
G3 X0.5 Y-0.125 I0.625
G2 X0.525 Y-0.15 J-0.025 F39.37
G1 Y-0.175
G19 G2 Y-0.2 Z-0.475 K0.025
G1 X0.475 F30
Z-0.575 F13.12
G3 Y-0.175 Z-0.6 J0.025
G1 Y-0.15 F39.37
G17 G2 X0.5 Y-0.125 I0.025
G1 X3.5 F30
G3 X4.125 Y0.5 J0.625
G1 Y3.5
G3 X3.5 Y4.125 I-0.625
G1 X0.5
G3 X-0.125 Y3.5 J-0.625
G1 Y0.5
G3 X0.5 Y-0.125 I0.625
G2 X0.525 Y-0.15 J-0.025 F39.37
G1 Y-0.175
G19 G2 Y-0.2 Z-0.575 K0.025
G1 X0.475 F30
Z-0.675 F13.12
G3 Y-0.175 Z-0.7 J0.025
G1 Y-0.15 F39.37
G17 G2 X0.5 Y-0.125 I0.025
G1 X3.5 F30
G3 X4.125 Y0.5 J0.625
G1 Y3.5
G3 X3.5 Y4.125 I-0.625
G1 X0.5
G3 X-0.125 Y3.5 J-0.625
G1 Y0.5
G3 X0.5 Y-0.125 I0.625
G2 X0.525 Y-0.15 J-0.025 F39.37
G1 Y-0.175
G19 G2 Y-0.2 Z-0.675 K0.025
G1 X0.475 F30
Z-0.775 F13.12
G3 Y-0.175 Z-0.8 J0.025
G1 Y-0.15 F39.37
G17 G2 X0.5 Y-0.125 I0.025
G1 X3.5 F30
G3 X4.125 Y0.5 J0.625
G1 Y3.5
G3 X3.5 Y4.125 I-0.625
G1 X0.5
G3 X-0.125 Y3.5 J-0.625
G1 Y0.5
G3 X0.5 Y-0.125 I0.625
G2 X0.525 Y-0.15 J-0.025 F39.37
G1 Y-0.175
G19 G2 Y-0.2 Z-0.775 K0.025
G0 Z0.4
G17
M9
G28 G91 Z0
G28 X0 Y0
M30
%

Do you hear a pop? Perhaps the chain is skipping. Do you have a linkage kit? If so, one thing you might want to consider is building the final sled by hand as your cuts will be greater improved using it.

These are all issues I saw as well when cutting with the temp sled. Because there is no weight pulling down on the sled, the sled will angle away from the plywood during the cuts. I was able to cut all the pieces, but each of them was off by a certain measurement as you’re seeing. I would highly recommend cutting the final sled by hand or with your shapeoko and then you can even recut all the final parts after you have this new frame. I have a video series on this here: https://youtu.be/vsZJ0Y8rQDM

1 Like

No pop, the chain seems to be fine.

George,

Do you think I am having unique problems or is this something everybody has problems with? Thanks for the videos.

I remember somewhere in the instructions for cutting with the temp frame there was an advice to carefully and gently support the router by pushing slightly on it. Did you try that? From the pictures you are at a steep angle, did you try to increase that?
On what FW/GC are you cutting?

P.S. On a side note, It does not matter if you are the only one having this problem. It automaticity become a community issue until it’s solved. Thank you for posting. It helps to show where the instructions can be improved.

2 Likes

I definitely had very similar problems. One thing that helps A LOT was cleaning the chains with an old toothbrush. I found some pockets of sawdust getting trapped that caused the chain to get caught causing a lot of issues. The squares aren’t coming out as squares most likely do to this being a temp frame and no weight to balance the sled and make it accurate so don’t worry on that. The missing weights (which cause the sled to angle during cuts) also led to the dimensions being way off for the cuts. You should find a lot of this resolved once you use the final sled and frame , which is mainly why I suggest to cut it all by hand.

I am using V1.06. This is what my first test cut looks like from the calibration routine.

It is 1 in. long and moves left to right by ~0.25"

George,

When cutting the final sled by hand, i think the hardest part would be making sure that the holes through the frame for the router and the bolts are in the right place. That layout seems really hard.

Can you measure the angle of the frame tilt?
On the firm- and software side you could try 1.03. (I guess new calibration would be required)
From the pictures? Weight, put some stretch on the chains by adding weight on the bottom.
There is 1 setting with this setup that you can tune, if cuts are higher or wider. It is the distance of where the chain is attached on the sled.

So for cutting the holes on the sled, for the router holes I just placed the router with the bit in the center and marked where the holes lined up with the screws. For the brackets I just measured the distance from the center of the sled to each of the holes in the drawing file and measured those out - same thing for the brick holes. This worked out pretty well for me. Something to realize is that dimensioning it out yourself and making the cuts will be more accurate then relying on the temp frame, especially if you’re seeing it cutting different dimensions from what you told it

The frame tilt was at 70 degrees, i just tiled it back another 5 degrees so it is now 65.

I have switched to a 3" by 3" square and it is 2.5" wide by 2-5/8" tall when i cut it on my machine.

How do i edit the setting to try and get my machine to cut right?

Any idea how I can correct it.

@George_Lehaf I want to see if I can even get the machine to be close to correct before I dedicate the time to cutting the frame parts by hand. I can do it, but it seems so much harder. But I completely see where you are coming from. I guess I want to understand why so many people can get it to work, but I cant.

The standard frame has (or was) 15° tilt. I guess that would be 75° the way you measure.
So the pictures fooled me and you might be to flat and friction needs to be considered.
The setting for tuning width and hight of a square was


Click ‘Settings’ on the main screen.
Sadly I don’t remember the direction. 2 cuts, 1 25% up and 1 25% down will show.

1 Like

My temporary sled had really bad accuracy. I cut a few of the A-frame braces for the original frame design just as a learning experience (they all came our with about 0.25" accuracy; good enough for what they need to do but thats about it). I was able to get it to cut the circle for the stock sled (it was within 0.5" - 1" of being round) good enough for a little clean up with a belt sander and then assembly.

I did all this with GC and firmware versions 1.03.

All I can say if after I recalibrated with the new sled; the accuracy was MUCH improved! I’m using that to cut the rest of the frame parts. Accuracy is now about 1/16" and that is on the temp frame leaning on sawhorses. If I could give anyone advice now; it would be build the sled as soon as possible or even use other tools to build it.

This is not just an issue that you are seeing. The temporary sled is just not very good and I think we can do better. We’re moving away from the whole temporary frame/sled idea in the instructions we’re re-writing now. The plan is that the frame design can be easily built by hand. The sled still needs to be cut my the machine, but the temporary sled re-design makes it much bigger and adds the bricks.

I haven’t finished the write-up, but you can read what I’ve got so far here:

2 Likes

why make a square sled to start with, make a circle cutter (for one-time-use it
could be cardboard) and make the initial sled round.

examples of fancy circle cutting jigs are at:


in our case, we don’e need adjustability, so instead of a slot or multiple holes
or other adjustment, the jig can be simplified

after you have marked the center hole on the sled, but before you cut it:

take a piece of card stock/heavy paper about a foot long, place the clear
plastic base of the router on it at one end, mark out the center hole, cut out
the marked hole, sandwich the card stockbetween the clear base and the router,
put a nail through the card stock about 9" from the bit into the plywood.

cut out the sled by running the router around the center.

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Bar is the size of this new sled design the same as the previous final frame sled? If so, that’ll make it easier so I won’t have to recut anything for this and can just connect the new rail.

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yes, the final sleds are the same size.

2 Likes

This write-up would work, but I don’t have the ring. I bought mine before this upgrade. Hopefully the ring will be in the store soon.

I’ll try other peoples recommendation to try and cut the final sled by hand, from the original design.

2 Likes