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Discussion Starter · #1 ·
Hello,
Does anybody have any experience making mouldings and trim longer than your machine using the Vectric moulding toolpath function? I have made a few test runs and I always wind up with a step where the two parts overlap. What am I doing wrong? I have made sure the material is consistent, the table has been surfaced and the jigging has been machined to ensure it is parallel with the axis. Thanks in advance for any help.
 

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can you show a picture of it? how big/deep is the step? is it consistent or repeatable? are you using the same toolpath for both cuts, bit direction? have you checked for play in the x and y axis movement? things may need tightened up... my guess is that the wood is moving, either at the end of the first cut or beginning of the next...

you may consider using lead-ins and lead-outs to smooth them out. or, if the step is repeatable, compensate for it by offsetting the wood by the step amount in the other direction.
 

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tuff, how are you registering the wood for the second cut, or follow on cut? the wood which has been machined, appears to have rough edges. and it is fairly important to have some way to register or align the wood in order for the second cut to be accurate. typically it is done with pins in the table, a laser, or a cleat screwed to the table, something like that. you could probably even draw a (very accurate) line on the table to align an edge to...
 

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Discussion Starter · #8 ·
The reference edge of the board was planed on a jointer. The stick was much longer and I ran tests on both sides, that is why the edges are messed up. A 30" long cleat was fasten to the spoilboard and the I routed along that edge on the cnc to ensure it was parallel to the axis.
 

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What bit did you use? I'd suspect a loose collet. I've seen collets get jammed with sawdust and prevent a bit from being clamped in tight. Upcut or downcut spiral bits can be moved, particularly in hardwoods. The move in the collet can be a small amount over time, which means when you restart a job cut depth can be different between the jobs, showing up as a step between them in your situation. The only other situation where I've seen that happen was when the wood bowed up after material was removed and as such the following cut left a a step between them.
4D
 

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Discussion Starter · #10 ·
What bit did you use? I'd suspect a loose collet. I've seen collets get jammed with sawdust and prevent a bit from being clamped in tight. Upcut or downcut spiral bits can be moved, particularly in hardwoods. The move in the collet can be a small amount over time, which means when you restart a job cut depth can be different between the jobs, showing up as a step between them in your situation. The only other situation where I've seen that happen was when the wood bowed up after material was removed and as such the following cut left a a step between them.
4D
Hello, I used a 1/4" ballnose bit. The collets are cleaned with a brush between each tool change and replaced after I see signs of wear or slippage. The wood was glued the spoilboard with
3M Super 77 Multi Purpose Spray where I can clamp and screwed down where I can.
 

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If your spoilboard is MDF and the project board is hardwood then the hardwood may have warped the MDF if it was fully held down to it. I've had this very same happen a few times with hardwood on my MDF spoil board with t-tracks every 4". I finally gave up on MDF and now use BB plywood t-shaped bridges that span my CNC frame rails to clamp projects to:
 

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Hello,
Does anybody have any experience making mouldings and trim longer than your machine using the Vectric moulding toolpath function? I have made a few test runs and I always wind up with a step where the two parts overlap. What am I doing wrong? I have made sure the material is consistent, the table has been surfaced and the jigging has been machined to ensure it is parallel with the axis. Thanks in advance for any help.
That is a curious problem. Can you upload a picture of you setup?

From your description it sounds like you thought of everything, but from the photo it is clear that something is moving. One photo is off in the X(?) axis, and the other is off in the Z axis. (I assume the material is oriented along the Y axis.)

From this first description, I assumed the step you found was a few thousandths. But in the photo it seems to be nearly the diameter of the cutter, which I believe you said is 1/4". That's a lot!

It seems to me that there's something about what you're doing that is different that what we are expecting. What you are doing should work without any issue, so there must be some variable in the works that we aren't expecting. The photo of the problem seems to contradict what you are explaining, so I'm a little confused.

But a photo that shows the big picture, the router, the fixture, and the stock, that will likely go a long way toward getting an answer to what is going on.
 

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I went over all of the bearing blocks, ball screws, guide bearings, etc. Everything is tight.
The part is machined out of the centre. The piece is oversized.
It sounded like you knew what you were talking about, and it sure looks like you know what you're doing. And I'm sure there isn't a mechanical issue at play that could explain the issue...so it must be something in the software.

Is VCarve trying to cut your desired profile in 2 passes? Maybe an oddball thought, but....if you repositioned the work piece inbetween the first and second passes, that would explain the photos you posted. It seems unlikely, but I suppose it could happen.

I don't have all that much experience with VCarve, but I have seen it default to multiple shallow passes when a single pass is perfectly adequate.. Like I was cutting out some 1/2" plywood, and VCarve's default setting was like 5 passes. I manually changed it to a single pass. The multiple passes was probably due to a setting in the tool setup.

Beyond that, maybe I could set up a similar project and see what VCarve does? I'm curious, because this kind of operation should just work.
 

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In a tiling job with varying results sometimes changing your typical strategy is required. For example I don't know where you zeroed the job, or if each tile you reset Z before starting it. The seam between tiles is where I'd zero each half. Reset Z at seam at the beginning of each tile job. Then at least that point should have a clean transition with no unexpected step. It sounds like you've checked all the other possible variables.
4D
 

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Here is program I used.
Are you using Aspire? My VCarve Pro (10.5) doesn't recognize the *.crv3d file. I tried changing the extension to *.crv, and got the warning "this program can't open Aspire files." Rhino doesn't recognize it either.

Have you tried to repeat the program a couple times without advancing the work piece? That is a troubleshooting step to isolate variables. If a second and third pass just touches the work piece, then the program is running correctly. But if there is a problem with the program itself, I expect you'll see it right away.
 
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