Cutter Comp ?

[Chap54]

Hi all,

 

I am in a new company, and I am wondering about how most people use cutter comp. Here they program using the "control" feature, as opposed to "wear" in the cutter comp window. Every where else I have worke we've used wear, so this seems odd to me. When the head programmer programs a circle toolpath, you have to use a very limited selection of values in the lead in, lead out section in order to get a useable toolpath. It results in cutting a lot of air from what I can see. With wear I can dial in my lead in, lead out to almost any path I could want. There are 3 of us here using mastercam, and only the head guy whose been here over 20 years has used this way of cutter comp. The other fellow and myself have only programmed using wear.

 

The head prog. does use wear when programming thread mills, I guess because control won't work.

 

Is it me, or are they in the dark ages here?

[cunder]

Here wear is used. But I have used control once in a while. Some controls will adjust the feed rate based on the cutter size when cutting circles. Maybe that is why it may be used.

[Henk]

Hi Chap,

 

Do a search and you'll find many discussions about this.

Here in europe the "control" is uesd very often.

Some controls don't like wear.

 

It's very important to use one style within a company, otherwise everyone gets confused

[Mgrenier]

We use control here. Lead in/out distance is tool radius + length of move you need. The machine only moves by the amount you need since the tool rad will be compensated.

[gcode]

There are dozens of thread on eMC on this subject

use the search engine and search for "wear comp" and "control comp"

Some of the thread are sure to pop up.

Many people use control comp, but the majority here use wear comp.

Both camps feel very strongly about it and the arguments can get lively

Back in the days before computers and CAD/CAM I wrote my programs with control comp.. now I use wear.

No matter how good the software, control comp is dangerous in my opinion.

For simple geometry it's pretty safe, but when you get into tight corners of places where

ramp on/off motion is restricted, control comp is very dangerous. What you see in backplot

is only an estimation of what the software thinks the machine will do at comp on and comp off

and has no idea what value the operator will actually enter in the work offset page

I've never worked any place that used control comp, in fact most places expressly forbid it's use.

[Chap54]

I certainly don't like the control style. It appears initially to be very limiting. For now I will have to get used to it I suppose, I'm the new guy

[Josh T™]

3 Customers use Wear. 1 Customer demands Control. Just a matter of taste meh guesses

[shazam/TPP]

i use control but stock model does not work in "control". i have been oscillating between the two as well. Tom do you guys not use re ground end mills? we do and it would seem there is a greater chance of the wrong offset entered if an operator had to measure a tool then figure out how much under it is, as opposed to just entering the actual diameter. (we use diameter offsets).

[djstedman]

The real difference between the two is that a tool that is comp'd with wear comp is programmed on part centerline and a tool that is comp'd in the control is programmed to actual part geometry.

 

There are cases where control comp is beneficial, because if your tool is a significant amount different in size that what was programmed you will still maintain part geometry so long as the control is able to comp the tool to create the geometry that was programmed without cause a fault in the control (from not being able to work out how to comp the tool)

 

This being said I think most people would agree if you program something to use a 1/2 inch endmill you probably shouldn't just throw a 3/8 or 1/4 in there in its place.. however on tight tolerance stuff with reground cutters it might make a difference.

 

Anyhow for me the easiest way to do lead in / lead out on a control comp program is to simply plug in the amounts as if you were doing wear comp, then simply add 50% of the cutter diameter in the percent window on the lead in lead out screen.

 

The other thing we always do here is use a perpendicular line rather than a tangential line for our entry.

 

So for instance you have a half inch cutter making a cut.. you want a .05 radial lead in.. just make the radius .05 and then add 50% to whatever value is in the cutter percentage box (should have been 10%)

 

Do the same thing for your linear lead in.. and make sure to set your linear entry to perpendicular rather than tangent

 

Doing this will basically make your cutter go in exactly where it needs to at the beginning of the cut as if you were using wear then it will 'comp' half the tool however the tool wont move at all.

 

This drove me nuts when I first started having to use control comp being in the same situation in a new shop, once I figured these simple techniques out.. its basically no different now.

[hot_chip]

I am trying to adjust to a new shop. I always used to program in wear. If I understood you correctly I need to remove all arc on from my lead ins and only go perpendicular. Do you have a way to cutter comp on a threadmill toolpath? And I take it you have an arc sweep of zero for your circular toolpaths?

[djstedman]

No .. you can still use an arc value.. just make the line in and line out perpendicular.. and all values need to be at least 50% of the cutter to account for that in your lead in / lead out

 

Arc sweep can be whatever you want it to be as well ..

 

You can modify things to see how they work by watching in backplot

 

As for threadmilling I never use mastercam for it.. I use code generated by Vardex TMGen program since it has better ability to adjust feedrates on lead in lead out