[lance-ftw]

So,

I need some help.

I'm working on a piece that has some pretty fine detail in a few places, I want to rough with one tool then finish with another. I have a couple of issues.

first let me tell you what I did and how it failed.

I opened the project and set the roughing segment to the proper size for my material, basically the full project. For the finishing operation I set a sub segment just over the areas I needed the detail work to be done.

The last line of my Roughing operation just lifted the tool to my safe height and stops so I set a line of code to take the tool back to 0,0,0 assuming my second operation started from 0,0,0 and not from the 'end' line of the first operation (probably a mistake?).

The second operation uses a smaller end mill, when I started it, it moved to what looked like a completely random location on my material and started executing.

So first question: does the second operation start based on the relative position of the last operation intelligently or does it assume the same 0 position that the first operation started from? Does it intelligently compensate for tool length in some way or do I need to re-0 my Z axis?

Also, I noticed on my machine that when it executed the 0,0,0 position my X axis in the controller software was not 0 but the tool was in the original start position.

If I sub segment for the second operation does it need a new 0 position? If I set my 0 position to be bottom left of the material for the first operation does it assume my 0 is bottom left of the subsegment or of the actual segment?

I'm very new to CNC/Cad/Cam so alot of what I said is probably stupid sounding and I've probably left out pertinent information... if anyone can help though it'd be great! Thanks in advance.

[Lennings]

Hi Lance,

When you have made these two operations (Roughing and Finishing) in the same part (so one part with two operations), then DeskProto uses the same coordinate system for both NC files that are made. The last tool position of the roughing operation and the first one of the finishing will be on a different location: that does not matter at all, as DeskProto knows where to continue. Moving the cutter to (0,0,0) first is not needed, still when it is done it should not cause a problem either.

After changing cutters you do indeed need to reset the Z=0 position: at Z=0 the tip of the new cutter should be at exactly the same height as for the old cutter. X=0 and Y=0 remain the same.

I hope that this will help you understand what happens.

Lex.

[lance-ftw]

that's kin of what I assumed but the behaviour didn't match what I expected.

I'm pretty sure this is just user error but let me ask another question.


You say it uses the same coordinates as the previous job so if finishes at 4, 5, 10 and the first plunge in the second operation is at 1, 1, -1 then it will just move to 1, 1, -1 when I start the operation?

So lets say I run a job. I 0 out the machine before it starts, run the job and put an after movement to go back to 0,0,0. I raise up the tool, put in a new tool, drop it back down, re 0 my Z then start the second operation it should work just fine?

Does sub-segment matter? if the first job uses the entire wizard defined segment but the second operation uses a sub-segment (a circle around a specific area or a freeform box around a specific area) are all the co-ordinates still absolute and it recognizes the 'full segment' just knows to only cut within the new sub-segment?

[Lennings]

Hi Lance,

Correct on point one: the machine will automatically move to the position mentioned in the NC program file. So if the first position of the second file is (1, 1, -1) it will move to 1,1,-1.

Also correct on point 2: this is exactly what you need to do after a toolchange. So you need to have some horizontal surface that you can use to set the Z=0 for both cutters: when you use the top of the block for the first cutter, that surface may no longer be present for the second cutter (removed during roughing). So take care which horizontal surface you use.

Using a subsegment does not change this: the coordinates are absolute.
On the DeskProto screen the blue "orientator" cube indicates the position of point (0,0,0). You can see that for a subsegment this is further away than for the part segment.

Lex.

[lance-ftw]

that's what I thought...

This might be related to some of the other complications I've had with my particular machine.

I've got a sherline model 2000 with inch lead screws but I program in metric.

I got the incriments working appropriately but there are certain fields in the pre-programed machine in Deskproto that get confused... for 1, it's limit of Inches Per Minute instead of MM per minute. I fixed that by just changing the definition in the machine library to 500mm per minute max (the sherlines max speed is like 20ipm) so I have to basically lie to the code and tell it that I'm going 400ipm when in reality I'm going 400mmpm. it's only a minor issue. The other issue is that my model 2000 is an 8 directional mill in that I can rotate the head on the collumn vertically, horizontally and latterally, I'd love to be able to code that but it's not really that big a deal. I honestly don't think I"ll be using that feature set on the mill anyway. I've got the 4th axis controller and rotary table so I'll be messing with that. Hopefully when I get there the Deskproto software recognizes my A axis is on a 90 degree mount and not just a horizontal rotary table

Ultimately I'm really pleased with the software, I managed to make my first accurate cuts within a day of using it and I've never even 'seen' CAM software before.. that's either a testament to it's ease of use or the face that I'm a bloody genius... I'm guessin the former lol.

[Lennings]

Hi Lance,

About the units: in DeskProto the units for the NC file that is written are set in the postprocessor (Options > Library of postprocessors). These settings are independent from the unit selection in the preferences, allowing inch users to work with a metric machine and vice versa.

So in the postprocessor you can set units for the coordinates (tab Movement) and for the speed (tab Feedrate). Also see the Help on each of these pages.

Note that DeskProto handles the feedrate pretty basic: it just copies the number that you enter to the NC file. So the speed units are there only to guide the user, the program does not actually use them to convert to a different unit.

Lex

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