[nivlek]

I am hoping that someone can steer me in the right direction on this problem, that I'm having

I am running version 25 of BobCad

I have a 4 sided figure which I use a indexing system to rough out the four sides. These four sides of indexing are pretty simple and no problems

I then proceed to a 4th axis rotary finish cut. This is where the trouble is causing me a headache.

I have a 2mm diameter ball end mill with a flute length of 3mm, overall length of 50mm and a protrusion length of 20mm

With these tool dimensions, I would have assumed BobCad, would have diverted away from areas that didn't allow further cutting with the above tool.

When I start the simulation, I get a lot of red colour which illustrates the tool fouling. I can see it in the simulation.

So my question is, why does the program allow this ?

I cannot put the whole BobCad file up here as it is too big, but I have posted a screen shot of the red colour.

Any help would be appreciated

Kel

Attachment 260234

[JEST]

DO NOT EVER ASSUME IN MACHINING!

Bob (most CAM), does not "learn. It must be guided or limited. One thing is certain. Bob "thinks" it is doing what you want....

You probably are missing a boundary definition. Without the file, it will be a guessing game for help.

[nivlek]

Jest
I guess that's where I was wrong in assuming.

Any idea on how I can put up the BobCad file when it is 74mb ??

Kel

[jrmach]

When you get in Multiple Machine Set-ups,,,notice all the different colors your model is.
In this example there is 4 machine set-ups with roughing and finishing in each set-up.
Notice the last tool used is defaulted to red ? Go to analysis and make sure you are not seeing just another color for cutting tool.
But you may got a violation of tool path.Don't know for sure,but check analysis anyways.
In my example,the black is what you get when there are machine set-ups machining over the previous machine set-ups.And the red was Equal Distance,,4th machine set-up
This was V25....
This project is screaming for V26 or V27.
These newer versions you can run 1st machine set-up,simulate,then save the simulated model as a .stl file.SO,,machine set-up #2 you use the saved .stl as your stock,,and so on and so on.
Can you see the huge advancement in being able to do this ?? Absolutely worth it.
Let me know if you want to know more on saving .stl from simulation in the newer versions.Absolutely perfect for this kind of work.

[nivlek]

jrmach
Thank you for the reply
I have checked the analysis and the colour for the tool path is close to green. (not red). So I think the violation of tool path is correct.

Kel

[SBC Cycle]

In your screenshot I can just see the gouge report. The collision appears to be the shank of the cutter with the workpiece. Try a temporary tool swap, changing the flute length to almost full length of the protrusion and see if you get the same gouging.

You may have left too much rough material for the 3mm flute length to machine. The toolpath has no way to check that, it's just going to guide the tool around the part and keep the tip out of places it can't machine. That doesn't mean it's not going to rub if the flute length is not long enough.

I'm taking a big guess at this point but that's the direction I would start based on just your screenshot. I have a few other ideas of what might be causing this but it is really hard to tell without a file. I understand your upload predicament but try an imaginary extra long tool first and post another screenshot if necessary.

[nivlek]

SBC Cycle
Thank you for your reply and I think you have the same thoughts as me.

I changed the flute length to 20mm and didn't get a tool foul. The tool foul, on the original program, did foul on the shank.

So, back to the original question.

If I only have a flute length of 3mm, why does BobCad allow it to foul. I was assuming that it would simply not machine that area.

In this screen shot, you can see the extended flute length to 20mm

Attachment 260356

Kel

[nivlek]

SBC Cycle
Could you please advise how I can take more material away with the roughing 3mm tool ?

Sorry to be a pain, but I think that it is my ignorance rather than BobCad program.
Kel

[mmoe]

SBC Cycle
Thank you for your reply and I think you have the same thoughts as me.

I changed the flute length to 20mm and didn't get a tool foul. The tool foul, on the original program, did foul on the shank.

So, back to the original question.

If I only have a flute length of 3mm, why does BobCad allow it to foul. I was assuming that it would simply not machine that area.

In this screen shot, you can see the extended flute length to 20mm

Attachment 260356Attachment 260356

Kel

The short answer is because you told it to. There are some cases where a "collision" would not be a collision in the real world, such as where it's just rubbing the shank (and perhaps you have a undersized shank that would not actually rub). The application should not do the thinking for you because if it did, you would be more limited in what you can do with it. The simulation is where you can determine if you made a mistake, and the software appropriately showed you that what you want to do is not going to work the way you hoped. It would work out that way in real life as well, so you can choose to change the toolpath or change the tool in order to get the correct result. Or, if you are in one of those special cases where you have a custom tool that would not have the problem shown, you can ignore the warning since you know it's not applicable. By allowing the user to do things that aren't necessarily ideal, Bobcad is giving you more options in how you do things.

As you do this more and more, you'll know before you even get to the simulation that you need to select certain tools, and you'll find that you have these sorts of collisions less and less just from experience. I think what you really have shown is the power of the simulation package. I recently made a short comparison video to show a sample part being cut out in simulation vs. the real machine, and it really is very close. There are a few things I'd like to see made available in our tool definitions, which could make it even more accurate, but it's very good. Here's a link:

https://www.youtube.com/watch?v=VSqCyrpZkPw

[nivlek]

MMOE
I agree with you about the simulation. I would rather break a fictitious tool on the simulator rather then the real tool.

So where have I gone wrong.

I cannot seem to find a cutting tool at 2mm diameter with 20mm long cutting flute

Kel

[jrmach]

MMOE
I agree with you about the simulation. I would rather break a fictitious tool on the simulator rather then the real tool.

So where have I gone wrong.

I cannot seem to find a cutting tool at 2mm diameter with 20mm long cutting flute



Kel

MAKE ONE,,,add tool from library,,,

[nivlek]

jrmach
sorry I should have written that better.

I mean, I could not find a real ball end mill at 2mm diameter and 20mm cutting surface.

It's easy to make a pretend tool.

Kel

[jrmach]

jrmach
sorry I should have written that better.

I mean, I could not find a real ball end mill at 2mm diameter and 20mm cutting surface.

It's easy to make a pretend tool.



Kel

Geez Mate,,Tool length 10X the diameter.That small likely to snap.

Found some Flea Bay,but dang,your in Oz.

2mm R1 x 35mm HRC40 Cutting Solid Carbide Ball Endmill 10 PC | eBay

[nivlek]

jrmach lol
if you look at that ebay listing, the picture maybe deceiving,

the description maybe more accurate

2MM (R1) X 35MM SOLID CARBIDE BALL ENDMILL 10 PC IN ONE BOX

TWO FLUTES

TOTAL LENGTH : 35MM

SHANK DIAMETER : 2MM

It would be nice to have a tool ten times the diameter !!!!!! :banana::banana::banana:

Kel

[nivlek]

ok back to the original problem.......

How can I either take more material away with the 3mm diameter tool or teach BobCad (or me) not to machine an area that the tool cannot reach or where the tool fouls.

Kel

[jrmach]

Well,you can edit your solid model,not ideal
You can Lie to BoB about your 3mm tool and tell it is a 2.5mm tool.that well cut more off,but it will affect the model
5axis machine and software..Sweet!!
I would Not try grinding down a relief,,too small diameter
Get the right tool.There are quite a few members at PM (I can't mention name here,but I can message if you need) that are from OZ,you could ask there for a source.Here in the States without even looking,I would be willing to bet Harvey tool has it.

[nivlek]

Thank you again jrmach

I doubt whether I would find a 2mm diameter ball end mill with a 20mm cutting surface and 40 to 50 mm overall length.

Also after looking further into the collision report (thankyou SBC Cycle) I can see the arbor collides also. so it must be my ability to do this.

Just thinking, what if I put up here the gcode ? Can someone work out what I'm doing wrong from the gcode ?

The file is 85mb so is simply to large to put here

Kel

[jrmach]

I don't have 4 axis but, your part simply looks like a 5 or more axis part,,depending on the detail you want to cut.

[nivlek]

jrmach
I think that I would disagree with you that it is not 4th axis, cause I think that it is...maybe I am wrong !!!

but

if it is 4th or 5th axis machining, I think, the tool should not foul if you put the parameters into the program.

I am thinking this because the first four sides of the figure are done by indexing. And there is no problem with that.

The problem starts when the program starts to do the final cut in a rotary motion and tries to push the tool further then what the tool parameters, that I put in, should allow it to.

I guess what I'm trying to say, is, shouldn't BobCad stay within the parameters given by me ??

for example
The tool is 20mm long.....why does BobCad want to reach 30mm (assuming)
The tool has a cutting surface of 3mm but it will try and shave off a piece at 10-15mm (assuming)

I'm pretty sure this is my ability and not a BobCad
Kel

[jrmach]

I agree the tool should not foul,IF everything is set-up right.At least in 3 axis it wouldn't.Should only cut with the ball.The flutes and shank should never touch anything.This also means parts of the model will not be cut(Detail) if it would violate the model
My 5th axis or more comment is how I visualize the model being cut with ALL the detail cut.as shown in the solid model.Being cut with just indexing gets so far,4th a little more detail...All depends on the model.Yours to get in all the nooks and cranny's and cut exactly as the solid model shows,is going to take more positioning.That's what I see.
I don't have 4th,so I don't know the tool paths.Something looks way off though.How are you holding the part?And you using a center or what?Surely this tool path cannot do the end of these parts with a rotary motion.
Sure don't help that file is so big.
Maybe someone with 4th can help.Upload some snips of your "wizard" pages of the tool path you used.

A 6 index 3axis tool path would work somewhat.
The bad thing in V25 is you can't save the .stl from simulation to use on next index.

Off topic a little,I do understand your want of the 4th axis,but,here is a 2 index 3 axis part I did and the model.Notice it is not exactly cut like the model,but pretty close.There is detail that was not cut and cavities that tool did not go all the way in.I also 2D machined the base.I also sanded where the 2 indexes meet.Then lightly buffed.