Cut 3-d software question

[headhunter]

I'm just curious..If I load a program in cut 3-d..Lets say it says 2 hours roughing....When I run it through the control panel of the shark, it adds about 3 hours to the cut time. I was cutting a 3-d unicorn for a friend and the program said 2 1/2 hours for the rough and about 3 hours for the finishing...After loading I got 4 and half hours on the roughing and a little over 6 hours on the finishing...I've selected the new archs as the post processor...Anyone know why the cut time difference?

[sk8nmike]

If you look in the tool path section of Vcarve you will see an icon that looks like a clock called "Toolpaths Summery". In there you can tweek the setting so that Vcarve matches the time it really takes to carve something

[4DThinker]

In Cut3D the calculation is based on just the area of the object and a guess factor as it has no real info about the CNC you'll be cutting with.
In VCarve Pro there is also a guess factor, and it won't necessarily be the same as what Cut3D uses. These factors at best will only get you close some of the time as each CNC uses acceleration and deceleration from point to point along a cut, and may never get up to the set tool feed speed if the lines are all short. Projects with mostly long raster pockets and long profile lines will cut faster than projects with fewer things to cut but all with short line segments.

[Danwood]

I have a Question for you. Why are you doing a roughing cut and then a finish cut? A roughing cut will take from 1/3 to 1/2 the time of a finish cut. And the finish cut time will not be less because you did a roughing cut.
I use a 0.125 tapered ballnose cutter with 10% stepover. I go from blank board to finished in one operation.
You are wasting time. The bit I use comes from Cutting Tool Source.
http://WWW.cutingtoolsource.com. The part number is 3TB25015. It has three flutes A 1.25 inch LOC (Length of cut) A 1.5 Deg. taper and a .250 Dia. shank.
I have made many raster cuts up to 1 inch deep with no problems.
Most of my carvings are done in A dished out area and are from 1/2 to 5/8 inch deep. The first pass is very shallow and gets deeper as it progresses, but the most I take off 0.0125 at a time. even the weakest router can handle that.

If you have a situation where your first pass is deep I recommend you revise the Gcode to make the travel speed 30 or 40 inches per minute to reduce stress on the cutter and the router for the first pass only. Then bump it up to your normal cutting speed.
My normal cutting speed is 100 IPM at 22000 rpm and I get excellent results.
Good Luck
Dan1931.

[headhunter]

Thanks for the replies. I haven't been able to visit the forums much lately..But to answer your question, I do some fine detail carvings from stl files that I create, and normally use .0625 diameter bits. I didn't want to break too many and that is why I do a rough cut...I'm still new to this whole ball game, so in time with friendly advice from you people, I might be able to figure this stuff out...

[sk8nmike]

As a general rule it's best to do a rough pass first, cuts down on the wear and tear on the machine and reduces bit deflection. I normally use a 1/2" bit for my rough cuts then came back with the fine carving bits. Not sure how deep your pockets are, but 15 minutes of my time is worth a $40 bit.

[rsetina]

Dan makes a good point. I ran a 24 min cut tonight with a 1/8 in BN bit and by the time I got to the middle of the project I was cutting about 3/8 of an in deep and the finish was very good without a roughing cut. I did create a roughing cut tap file but didn't use it. Not using it saved quite a bit of time. No pun intended. LOL