Computer, or control countour toolpaths

[Larry1958]

Hey,

 

I just started a new job and they are creating there programs using control feature for contouring toolpaths I.E. values for geom as drawn on print vs. using center-line toolpath. I am trying to convince them to go to centerline toolpath creation due to many error we get when making smaller moves. How many of you use the control vs computer toolpaths. I have worked in a half dozen shops and have never seen this before exept when creating simple profiles at the machine. I just want to get some pros and cons prior to convincing managment. Thanks.

[mcpgmr]

I use Wear or Computer. Never Control. Offsetting at the control does have some advantages at times but not enough to convince me to change the way I program. From the Mastercam Help.......

 

¨ Wear – combines compensation in computer and control. Mastercam calculates the compensated positions based on the tool diameter stored in the tool library, and codes them into the position and feed moves in the NC program. It also inserts the G40/G41/G42 codes to turn cutter compensation on and off. In effect, the tool moves are compensated twice.

 

Wear allows for a wear offset (the difference between the original tool size and the reground tool size) to be applied at the control. The wear offset is a negative number entered into the tool diameter register

[Larry1958]

That is pretty much my view also. I see a huge disavantage to using control because of the lead-in. If you use too much it will gouge and not verify it in Mastercam. It is going to be difficult to convince my peers however, they have been doing it this way for years. I just need some feedback from y'all so I can go to management prepared. Thanks.

 

P.S., Paul, does negative compensation work on all controllers? I think we have a Cincinatti that has problems with it, but I am pretty sure there are paramaters that can be set to fix it, also I am being told that the Fadals may have problems.

 

[ 01-25-2007, 01:34 PM: Message edited by: Larry1958 ]

[Charlie Pierson]

CC in computer + wear here. The reasons have been mentioned above.

 

Our Fanucs are using comp C; Height (Geo & Wear) + Dia.(Geo & Wear). +or- offsets are acceptable in any of the 4 registers for the tool. Methinks the Fanuc just adds the Geo & Wear together to obtain a final offset figure. At least they behave that way.

 

cp

[gcode]

Control Comp is old school.. People do that

standing in front of a machine punching code into the control with a blueprint in thier hand.

Its easier to do, but its foolish to do it that way with a Cam system.

Forcing your Cam system to output code this way

just opens you up for all kinds of trouble.

There is no way the Cam software can keep track of all the vaiables and how every control will behave in every situation.

 

For example, an operator tries to use a 3/4 endmill on a Control comp toolpath writen for a 3/8 tool.

There is no way to know what the control will do with that .750 value in the D offset, but its probably going to be ugly

[chris m]

WEAR

[mcpgmr]

Larry1958, I've never seen a control that wouldn't take a - comp value. Could be that the machine had the problem when the - value was too large and the move was mathematically impossible.

 

Funny how this topic comes up when I'm getting ready to release an old program (sHartCram) to the shop. No time to reprogram and process is locked in. Can't change the program unless we call for another 1st article inspection from the customer. The nit wit who programmed it used to do everything by programming tool c/l. When the guys on the floor get these programs they cringe. I print a hard copy and highlight the comments that say (TOOL RAD=0.XXX) so they remember to put the value in at the machine. Get's ugly when they forget. Covered my butt!

[ROB]

wear also.

[Jack Neelands™]

computer if its a one or two off ...wear if its more than that....or a hole with tight tolerances then I use wear.....

[Guest CNC Apps Guy 1]

WEAR without a doubt!

[chris m]

Our Okumas didn't like negative comp values very much with the original software; you can use REVERSE wear if you can't use negative values

[Mcam Nut]

I always use wear

[jeff]

Wear if I need to hold a tighter tolerance.

Computer if it's +/- .005" or greater.

HTH

[J Coulston]

I always use wear

[Tinny]

I must be in the minority cos I always use control. I was "brought up that way" and so were the 120 or so operators in my factory. Maybe its just the way you do things in America as opposed to the UK. No-one has ever had a problem with it in any way whatso ever.

[Camdude®]

+1 to wear

best of both worlds.

[Kannon]

computer and wear here

[pip]

Control here, that's the way I was taught in UK.

Then again, uptil the last ten year I had to write all my programs at the machine, and trig it all out by hand with a pocket calculator.

[Span]

Wear always.

[Mgrenier]

Control here. Makes it easier for the operator to check the NC code and know where they are going. Very useful for a custom shop.

[#Rekd™]

Hi,

 

Same as Jeff, wear on tight tolerances and computer for +/- .005".

 

John

[specv]

computer & wear here

[G Caputo]

Nothing but control here. All of our machines like it and so do the machinists. Trying to convert them over would be a waste of time.

quote:

---

I see a huge disavantage to using control because of the lead-in.

---

All you do differently is add 1/2 the cutter diameter to what you want your lead in to actually be. Being a job shop we can't write every program, so some of the guys will write there own and it is much easier to use comp on the machine and just duplicate that for them when we program them in mcam.

[heeler]

We use wear here, but personally I like control better. It lets me double check the gcode when I have issues on the machine when something doesn't work. We also have had several programs that was programmed with wear comp that wasn't applied correctly. They were run for 6 months or so and all of the sudden, they quit making acceptable parts. The problem was that we had new cutters when the program was created, and now we have resharps. Some of them would alarm out, some would apply comp to only one axis. So when you use full, you know that the program will always be good after your first part tryout.

 

Glenn

[Matthew]

Always computer or wear, never control. Having to put the value in at the control is one more thing to be messed up on a setup. If everything is programmed to nominal, all values should be "0". If there happens to be a small offset in the register already from the last setup (-.002" for example) there is less of a chance that it would affect the output of the current setup. Plus all the other reasons mentioned above, programming cutter centerline allows you to accurately verify, account for lead in/lead out and you know exactly where that tool is going. I used to program with CC in control when I was programming directly from a printed drawing into the controls keypad (9 years ago). But now it is old school.