two side machining error

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IslaWW
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Re: two side machining error

Post by IslaWW »

Ahhhh… the joys of recalibrating Chinese machines! :x
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martin54
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Re: two side machining error

Post by martin54 »

As Michael says if something works for you then stick with it but it might be worth you watching the Tutorial Rebacca linked to covering the asymmetrical dowel hole method, from your post with the illustration it looks like you may be doing something wrong which could give the misalignment in the dowel locations.

There is nothing mirrored with the latest versions of the software by the user as there may have been with earlier versions of the software, create your artwork on one side of the material select what needs to go on the other side & then using the right click menu select copy to other side, the software handles the mirroring & placement of the selected artwork so both sides align properly.
When you come to machine the job you only set your x y zero position once. Position your material, clamp, set your x y z zeros, machine first side. Move gantry out of the way, machine holes for dowels in spoilboard DO NOT touch your x y zero move gantry out of the way if needed to & replace your material for cutting the other side. Again do not alter your x y zero even if you have to do a tool change & reset your z zero. Machine second side, remove from machine & feel proud of yourself for perfect alignment :lol: :lol: :lol:

More than one way to do lots of different jobs so stick to what works best for yourself :lol: :lol: :lol:

roydant
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Re: two side machining error

Post by roydant »

I am having this error of being off in the x-direction. Vcarve v11. Drawing is in attachement
Speaker backbox test pieces.pdf
(4.63 KiB) Downloaded 59 times
I am flipping the piece horizontal. The one box is a recess and goes pass the 0 point so the cutter can provide a clean cut.

Is the program shifting this bottom over to get the piece into the positive realm?

I have used this single sided with no issues.

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SteveNelson46
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Re: two side machining error

Post by SteveNelson46 »

It looks like you are having problems understanding the 2-sided concept. There have been many posts on this and the procedures vary, depending mostly on user preference. To me, Becki's marlin video explains it the best.

https://www.vectric.com/support/tutoria ... ded-marlin

If you are not importing an stl then you can ignore that part but the concept is still the same. Here's how I do it.

I almost always use screws to mount the board to the spoilboard.

1. Make three circles on the top side. It really doesn't make any difference where but, I usually put 2 along one edge of the board and one on the other edge. Size them to fit your dowels.
2. Copy the circles to the other side.
3. Using the circles on the top side, create a pocket or inside profile toolpath, to a depth of about 3/8"
4. On the back side, create a toolpath for the circles the same as the top side only make the depth 3/8" PLUS THE THICKNESS OF YOUR MATERIAL This toolpath will not drill into your material, only the spoilboard. The idea is to make the dowel holes in the spoilboard only. Run it after cutting the top side and un-mounting it from the spoilboard and before mounting the flipped board.

It took me a little while to get my head wrapped around this procedure but, after using it a few times, it seems simple now.
Steve

roydant
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Re: two side machining error

Post by roydant »

This is a square piece. I set the piece against the lower left corner. I flip it left/right no dowels. The part is register left and down.

When I start cutting it appears that the software is shifting to the right so the bit does not go negative to the through cut for my slot.

When I preview the code it looks correct.

I watched the 2 sided tutorials and no reference to how this changes on the bottom versus the top surface.

Charlie_l
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Re: two side machining error

Post by Charlie_l »

Are the dimensions of the square piece exactly what you have set in the software? If the x is off by 0.010 inches, then when you flip it will be off center by 0.020 inches, or whatever your dimension is off times two. Using dowels eliminates the need to have your material dimensions exact.
Charlie
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roydant
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Re: two side machining error

Post by roydant »

It is square within .003 .
The error is .25 inches in x direction only.

I am going to check on machine and see if I can manually move the x zero point and then report back here.

Odd that the software shows perfect alignment but machining does not match.

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martin54
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Re: two side machining error

Post by martin54 »

If the software is showing the correct alignment then the error is almost certainly with the machine. How do you home the machine if you are working using a jig or fixture? My machine uses magnetic homing switches which are not 100% accurate so if I am using jigs or fixtures I have to watch out for that. Have you checked the calibration on the machine? As has already been mentioned the stock size will also make a difference. Any any one of those on it's own may not give a large error but add the 3 together & it can lead to larger errors. :lol: :lol:
I generally use asymmetric dowels when going 2 sided machining simply because I don't need to worry about the possible homing errors or the size of the stock :lol: :lol: :lol:

Charlie_l
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Re: two side machining error

Post by Charlie_l »

Targeting machine issues I would try an idea. After carving side 1 and then side 2, which is off by about 1/4 inch, then carve side 1 a second time and note if something has changed.
Charlie
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roydant
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Re: two side machining error

Post by roydant »

The Zero X and Y use optical sensors.

If I do the cuts strictly from the top side with two files instead of one everything aligns.

The cuts are with a whiteside RU4700.

What is very interesting is the Y axis does not have this issue.

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adze_cnc
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Re: two side machining error

Post by adze_cnc »

Does this mean that your workdlow is:
  1. set x,y,z zero
  2. run side a
  3. flip over material
  4. set x,y,z zero again
  5. run side b
If so why the reset of x,y,z in step 4?

roydant
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Re: two side machining error

Post by roydant »

I do not do step 4
Jig is fixed location

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SteveNelson46
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Re: two side machining error

Post by SteveNelson46 »

I'm sure I'll get a lot of flack by saying this but, IMHO, using a jig for 2-sided projects is okay if absolute alignment of both sides isn't imperative. Otherwise, you are just asking for trouble. That's why I use and swear by the dowel method suggested by Vectric.
Steve

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adze_cnc
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Re: two side machining error

Post by adze_cnc »

Another benefit of the "dowel method" is that after you've run one side you can put it away and do other jobs in between as necessary.

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adze_cnc
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Re: two side machining error

Post by adze_cnc »

roydant wrote:
Fri Mar 25, 2022 6:47 pm
I do not do step 4
The question then becomes: aside from flipping the material over and getting the g-code from a "double-sided" job how does your procedure differ when running g-code from two "single-sided" jobs?

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