Very slow

[Butcherman]

So, I set up a Moutnain Scene that I purchased from Vector Art 3D, I was given some info about my step over and reduced it to 10% at 100 IPM (I also adjust the FRO to 85) and the turnout is outstanding. With that being said, this took forever and a day to carve. A carving that is 10" x 12" it took me a total of 10 hours, and this is includes roughing. What can I do to increase my speed? Each job will cost an arm and a leg, this goes without mentioning the wear and tear due to excess cutting time. Any help out there?

[BillK]

You are right, that does seem excessive. What was the time split between the roughing tool path and the finish tool path?
Also what tools and size are you using or both?

I find that you can greatly reduce roughing time by using an end mill and even further reduce it by using Z level roughing. I usually leave .020" for finish cutting. I just 3D carved a 9 by 18 oval and it was done in under 3 hours.

There are a lot of posts about this that you can look at, but you are right about the wear and tear. At 20,000 rpm, your router bearings turned 12,000,000 revolutions in 10 hours.

[Butcherman]

@ BillK I used a 1/4 4 flute end mill for roughing @ 16,500 (FRO @ 85) and finishing with an 1/8" at the same RPM's and 100 IPM (FRO @ 85).

Roughing was about 1.25 hours.
Finishing was about 9.5 hours.

[BillK]

The roughing sounds about right, but probably would have been faster with Z level, maybe by as much as half.

The finish doesn't compute right. With a 10% step over (.0125) on a 1/8 ball, it takes 80 passes to cover one square inch. You were running at 85 ipm (100 ipm x 85%) so a square inch would take less than a minute, 120 square inches should take 113 minutes, a little under 2 hours. Granted there are a lot of up and down movements which could in effect double or even triple the square inches being cut, but still that is 6 hours. So either you cut a very deep model, or your step over percentage was not what you thought it was. Either way it's all math.

[Butcherman]

BillK It is during the finish is when things go to hell for me. It absolutely crawls during the finishing cut which is set at 45 degree. Cuts fast during Roughing, its a race against father time when finishing. So, in essence, if I change it to a Z level I should be able to decrease my cutting time. I still cant figure out why it slows down like it does. Anything else that may cause this problem?

[BillK]

Which post processor did you use?

[Eagle55]

When you say it "slows down", are you talking about the rate of the travel of the router slows down? If so maybe you are having a problem with getting the feed rate set properly. Also step over can effect the progress of the finishing too. Both of these settings are in the tool database for that particular tool. Just some ideas. Also something else to consider, depending on the fine detail you are looking to cut, sometimes you can get away with going up to a 1/4" round nose bit to do the finish carving, however much of my carves take 1/8" and some of the smaller carves I use a 1/16" tapered ball nose because of the small details that I don't want to loose.

Roger

[Butcherman]

@billk, when I got home I went back through my set up. I do not howmit happened, and it did, I identified that my feed rate had 40 ipm's. Blew me away, explains a lot. All that o have seen and read, not too mention everyone's help and advice really comes in handy.

I want to thank billk and roger, who have aided me in my time of Cnc need. Thank you both.

[BillK]

You're welcome. So at 85% of 40ipm you were at about a third of where you thought you were. So about 3-4 hours for that 9 hour cut.

Told ya, it's all math. Glad you figured it out.

[Consultingwoodworker]

Remember, these things will do what you TELL them to do, not what you WANT them to do!

Ralph