Vcarve finishing pass

[PeachCraft]

Hi, I am beyond frustrated I have quite a few bit of wood with potentially awesome carves on but when ever I go to do the finishing file it goes nuts. My roughing is no problem but why oh why does my finishing go so bad. This is what happens I set it up have all the right bits on etc but when I start it it plunges in deep and/or just goes awol, pretty much ruins my roughing pass... what I really need is for someone to help me understand what I’m doing wrong as once I know I’ll be confident that I’m not going to be wasting wood and bits.

[Tex_Lawrence]

I sure that you will have to upload the saved files before anyone can see what is happening.

When I make a separate toolpath for finishing or final pass, I start by duplicating the successful roughing pass. Then I'll change a few things that make the copy the final pass.

[adze_cnc]

If the preview in VCarve looks good then it's pretty much assured to be a problem at the machine. Given that the only thing we know about your machine is "Sharp" it'll take much more information such as what post processor you're using?

[SteveNelson46]

I see this is your first post. You came to the right place for advice. If you can upload your file or post a link to it I think someone here should be able to help.

[PeachCraft]

Not sure if this worked or not.

[PeachCraft]

ok so i suck at this.. not sure how to open the file up and post it, the one i just posted is not the one i'm talking about but it did the same for that file as well

I get the roughing one done no worries but can't for the life of me get the finishing file done its a constant struggle and I'd like for someone to PLEASE help me

[gkas]

To start with, your endmills are WAYYY TOOOO LARGE. The 0.25 endmill for the profile does not do anything except the outside perimeter. It can't fit anywhere else. Also, the cutout should be done as the LAST step. The 3mm ball nose is way too large to cut any detail. There is nothing physically wrong with your setup.

You may not be setting the bit in your CNC to the top of material. Are you forgetting this step after a bit change? It must be done after every bit change.

Check the physical connections, setup of all the hardware. Check if you are using the correct post processor. Check your control software setup.

Your carve may not be pretty, but there is no reason for the bit to plunge.

[PeachCraft]

So the initial carve is great, get plenty of detail and maybe I’m using the wrong size in the file but that’s not my issue, my issue is the second finishing stage obviously I know about the final stage and the files are not saved in any particular order. I don’t really understand what you mean about the correct post processor? What I need is for someone to go through setting up a file one on one if possible so someone who knows the program well who could connect to my computer and also be on a voice call and go thru setting one up with me. If there is someone who could dedicate a little time to me I’d be so appreciative.

[Adrian]

Your feed rate and RPM's on the finishing toolpath don't make a lot of sense. I'm assuming you don't have RPM control on your router/spindle as you have it set to 1900rpm which isn't going to work so it must be running at a different speed in reality.

Your feed rate is set to the equivalent of 500ips which is very, very fast. It's doubtful that the machine is getting anywhere near that speed due to the way finishing toolpaths work but you should really slow that down in case it's causing issues with acceleration/deceleration in your control software etc.

Are you resetting the z-zero between bit changes?

The post processor is what you use to save the toolpaths. When you go to save the toolpaths you have to choose a post processor from the drop down list. That MUST be the correct one for your machine or nothing is going to work properly.

I really don't know what you mean about duplicated the roughing pass and turning it into a finishing pass. They are totally separate toolpaths. If you duplicate a roughing toolpath you get another roughing toolpath.

Have you been through the tutorials? There seem to be a lot of basic concepts that you're struggling with and it's only going to make your experience with CNC more troubling if you don't get a handle on those.

[PeachCraft]

My spindle has its own speed control. Yes resetting the z zero between bit changes. My post processor is correct. I am trying to ‘get a handle’ on things believe me, I’m watching videos and asking questions constantly. When I do the file I make the roughing stage first then I do the finishing one as per the videos. I am doing it just like the bloke in the video says and yet every time I’m getting the same outcome.

[Adrian]

I'm pretty sure it's the feed rate on the finishing pass that is tripping things up. On the other two toolpaths you're using mm/min but on the finishing toolpath you're using mm/sec so it's running 60 times faster than you're expecting.

It all depends on how your control software handles that but I would change that first and see if that sorts it.

[PeachCraft]

Ohhh I didn’t even realise that...

[sharkcutup]

This is the best I could get with the tools (bits) I have available! But now that is such a delicate piece I probably would not even attempt it with a CNC router. Maybe a CNC laser would be better for something that delicate!

Just my Opinion/Thoughts!!!

Sharkcutup

[martin54]

There is quite a steep learning curve if you are new to all of this. Why not start by working your way through some of the tutorials, not just watching them but downloading the files and actually running the jobs on the machine. The toolpath preview gives a very accurate preview of what the job will look like once cut & the file you have uploaded looks really bad with your choice of tooling, I would never have tried to cut it in that state
That's not meant to be negative, just pointing out that there is a lot you have to understand & that's where the tutorials come in & Vectric make it a bit easier to learn because they provide the files for most of them so you can actually work allong with the video rather than just watching.