Cut Accuracy..

[Force Reducer]

This is my first post. I hope I can relay the issue properly!

The person setting up the shopbot files to cut is using a 1/4" bit, but in order to get the part accurate, he had to enter the bit diameter as .005 rather
than .25.

I read a post that said it's a good idea to check the size of the bit with a caliper(?) because often the size is different than what the manufacturer states, but in this case .005 is way off from .25, could the bit really be that much smaller?

Are there other things we can check (other settings, the machine itself, etc.)?

Thank you for any help! :)

[adrianm]

Has he set the cuts up to be outside the vector lines or on/inside them? They need to be outside if you want the part to be the same size as drawn.

Try telling the machine to move a certain distance and then measure it actually has moved that distance.

If that works ok then I'd suspect the files aren't being created properly. If it doesn't then you may have the wrong units selected.

There are others here with more experience than me over the signs of that particular issue and how to fix it. I'm sure they'll be along soon.

[dlcw]

Could also be an issue with the setup values. Make sure you have run the proper setup file for your machine. This bit me in the derriere when I first set up my machine.

I forget where the setup files are located on the hard drive when you install the software for the first time. Maybe someone could chime in on this location?

[bleeth]

What software is he using to design the parts and create the toolpaths?

[Force Reducer]

He probes and the file is written in ShopBot 3xx. He then uses Aspire 3.5 to create the toolpaths.

[bleeth]

So these are 3d files abd he is then machining the model with a 1/4" ballnose?

[Force Reducer]

He's able to view the files in 3d view in Aspire, so I guess these are 3d files. It's non end cutting bit.

[Force Reducer]

It's not a ballnose.

[srwtlc]

Probably would be best to see the Aspire file. Sounds like some tool/toolpath settings could be wrong.

[Iceis]

Can I email that to you Scott?

[srwtlc]

Sure, check my profile for address.

[Force Reducer]

I wasn't able to directly upload the Aspire file (.crv3d), so I zipped it.

These are very simple carbon fiber shapes we're cutting.

Thank you for your help! :)

[jerry_stanek]

Here is a file that I downloaded from the forum I think Gary Campbell wroye it It is for squaring and getting the values correct.

[srwtlc]

Hmm, I'm not really making sense from the toolpaths. All of them are set to cut on the outside/right of the part which should give you the proper size part barring any bit deflection of which there should be none at the depths your showing. If cut with a 0.25" bit, the parts are coming out too large? Could it be a part probing variance that is giving the slight size difference? One of the toolpaths has an offset allowance of 0.050 to the outside with a 0.187" cutter. Not understanding the use of the 0.005 bit as it's cutting with the same outside strategy. Surely you're not cutting with a 0.25 bit while telling the software that you're using a 0.005 bit? That would make the part much smaller.

Maybe some more information is in order. What is the thickness of the material being cut? Considering the thickness of the material, what is your desired depth of cut per pass and final depth? Is the desired tool a 0.25" end mill of sorts (don't know what's recommended for carbon fiber)? There's definitely no problem with the shape that wouldn't allow you to use any size cutter you want. What is the size of the piece of material that this part is being cut from (seems like the job setup dimensions/datum location could be set up better)?

What Jerry's post is getting at, is the part not the right size/shape due to a misaligned machine.

I think we need to get your toolpath strategy figured out before we can go further.

Need some input from others on carbon fiber cutting recommendations too.

[jerry_stanek]

If his machine isn't set up right with the correct values he will not get the correct size in all directions.

[Force Reducer]

I will bring up everything mentioned in all the posts and talk with Lee. I'll post again on Monday. Thank you so much!

[bleeth]

I really think you and he should sit next to each other at the design computer and call SB support. At this point it would likely be the most efficient way to get it all solved at once.