Cutting quarter of circle problem

[boet]

I would appreciate advice on this. I am cutting a quarter circle inside radius 1000mm width of cutout 50mm. The problem I have is that the one side of the cutout is 50.4mm wide and the other side is 49.6mm so a difference of 0.8mm This would not really be a problem but I have to turn one of them round (mirror end to end) because I need the top and bottom veneered. Now it is a problem because 49.6 and 50.4 do not fit.

The vectors are created in Artcam and measured exactly to 50mm wide on both sides. But when I cut them I get the above result. This happen to every one I cut they are all identical and fit exactly if place one on top the other (just don't try and turn them around)
I have to cut 540 of these of which half will go upside down. Any advice I must be missing something.

8574
8575

[Brady Watson]

Posting an EPS or DXF of your vectors would be helpful.

Question: If you mirror one of the vectors about it's own axis (horizontally) do the parts line up exactly, or do you see a deviation in ArtCAM?

-B

[boet]

Brady thanks for looking at this attache the DXF of my test run. I will try to mirror one and see what the result is.



8576 (4.7 k)

[boet]

Brady If I mirror it in artcam I can line it up exaxtly with the other vectors.

[Brady Watson]

If your vectors mirror over exactly, then the issue is in the machine. The 1st thing that comes to mind is that your gantry is tweaked/racked a bit to one side. That is to say, one side of the gantry is further away from X0 than the other.

If you set your ShopBot up correctly, you should have placed your motor stops exactly where both X motor pinions touch at the same time while the gantry is perfectly perpendicular to the X axis. If you did this, just turn off your control box, manually pull the gantry in the middle of the Y axis against both stops. Hold it there and turn the control box back on. Now it *should* be square. If it is too far out of line or that method doesn work, take the time to square it up and make any adjustments necessary so that you know the tool is square every time you go to use it.

-B

[fleinbach]

Boet,


Is the longer axis of your arcs following the X or the Y axis?

[boet]

Frank

The longer axis are following the x axis end points are are about 1.5m apart to long to run on Y axis

[fleinbach]

Boet,

I noticed your start point is directly on one corner. Try moving it to a different location using the node edit tool. Also you didn't say how deep or fast you where cutting. What are these settings?

[boet]

Frank
I moved the start point. Cutting with 8mm cutter 8mm deep speed 75mm/sec. I created the vectors as follow: Draw circle r=1000 offset it to the outside 50mm then deleted so I was left with quarter circle to cut the circle was created using arc. Would it be better to create 2 circles one with r=1000 and the next r=1050. What would be best for the circle creation arc or bezier.

[fleinbach]

Boet

You can use the node edit to0l to place a point anywhere you want it. Select Node edit tool then right click where you want to insert a new node. The hover over the new node and right click again and select start point. The node will turn green. This will be where your cut path will start.

Also try cutting at around 5 or 6mm deep instead of 8

[daski]

The first thing you should do is isolate that the problem is with the bot not the software. Take one of your 1/4 circles and mirror it in the software, then cut both the original and the mirror at the same time. Mark them carefully so you know which one is which and how they were oriented on the table. If you end up with both of them being off in the same direction and amount when they are oriented the same way on the table then it's the machine. If you have to mirror them to get them to match then the problem is in the sofware. I doubt that is the case but you need to prove it. We did a bunch of cutting for kayaks and found that the material had tension in it and the sprang once we cut it.