Time estimate ?

[Uzumati]

When finishing up a design after doing the toolpaths I look at the time estimate and it says 27 hours or so but when I cut it it is done in 2-3 hours. I have checked all the feedrates on the bits and looked at the rapid rates but I am at a loss as to why the software overestimates so badly. Anyone have any tip on what setting I have off that causes this?

[Rcnewcomb]

See this FAQ: How can I get an estimate of how long the toolpath will take to actually cut?

[Uzumati]

Reduced the scale to 1 but unless I triple the feed rate for the bit the time estimate is grossly overestimated.

Ex. Finish 3D pass that was done in 6 hours was estimated at 23hr 45m only way to get the software to get a close estimate was to triple the feed rate from 30inches/min to 90

Is the time estimator just junk?

[mtylerfl]

It's up to you to set the appropriate Scale Factor for the particular job (3D, 2D, or combinations thereof)

This topic has been covered many times. Rather than re-telling all the "how-to's", try doing a forum search to find older posts that will be helpful for you.

[Adrian]

I've never heard of the estimate being way too slow when using a scale factor of 1. Normally it needs a scale factor of 3 to get it close on 3D work.

Are you sure the feed rate units you're using are correct? The more complex the job (3D work, lots of small parts etc) that stop the machine reaching the programmed speeds the more out the estimate will be (hence the scale factor) but, as I say, it's the other way around from what you seem to be saying.

[LittleGreyMan]

Most CAM simply calculate the estimated time by dividing the length of the toolpath by the speed. They simply distinguish the type of move (cutting, plunge, quick move).

As they don't take into account accelerations, decelerations and the fact the machine can't reach the theoretical speed on short moves, the time calculation is by definition ALWAYS smaller than reality.

If it is not, there is a glitch somewhere. A unit error as Adrian suggested or some parameter in your control software which makes the machine go faster than you asked.

[martin54]

You have used the max rapid rates from your control software (what ever that is) when you set the estimator up the first time haven't you ?
For 3D work mine is normally set about 2 or 3 depending on the job, have to be honest though & say I don't both to check a lot of the time as machining time is not a factor for me with what I do with the machine most of the time

[Rcnewcomb]

I've never heard of the estimate being way too slow when using a scale factor of 1

If the Rapid Rate is set incorrectly that can cause the estimates to be too long.

Here is the estimate with the rapid rate of 6 inches per second: 01:36:07

And here is the estimate with the Rapid Rate set to 6 millimeters per minute: 11:01:45