[Gary Wiant]

I just noticed this occurring on a job I just finished. I routed a total of 6 signs all had this type of finish on the edges.

Router is CNC Router Parts Pro4896 with Nema 34's & their spindle.

Material is kiln dried Maple.

Bit is a new Onsrud 40-112 1/4" downcut

Any help is greatly appreciated
Gary

 

[OCEdesigns]

What was your spindle speed and feed rate? Was it climb cutting or conventional?

I had something similar on a profile cut in yellow pine 1/4" EM but up cut. I was getting some chatter and changed to a conventional cut and it was better.

 

[Gary Wiant]

I think it was 150 feed rate cant remember the spindle speed. I'm pretty sure it was climb cut. I can check later when I get back to the shop

Thanks
Gary

 

[difalkner]

About a year ago I began leaving 0.005" on profile cuts (climb) and follow with the clean up cut in conventional, full depth. This has allowed me to eliminate sanding edges, in most cases.

Give that a try, Gary.

David

 

[Gary Wiant]

David I really like the sound of that. So you climb cut initially and leave .005 and finish pass it with a conventional cut?

 

[difalkner]

Yes sir, just like that. The climb cut takes me all the way down to the spoilboard in steps and then the finish cut is conventional at full depth to clean up the final 0.005". Works like a champ! I keep the same feed/speed about 90% of the time. Occasionally I'll slow the feed slightly, depending on the piece and the wood type. For me that's mostly Walnut but Maple and Cherry sometimes respond differently and I'll keep the feed at the same rate as the climb cut - in the 150 ipm to 250 ipm range, again depending on what I'm cutting.

On my Longworth chucks, which are cut from 1/2" BB, I have the final pass remove the tabs because the center piece is screwed to the spoilboard. This saves me from having to trim and sand the tabs flush. But most pieces aren't screwed to the spoilboard and I can't do that.

David

 

[ger21]

Personally, I almost never climb cut wood, as it will almost always result in a poorer finish.
The only time I climb cut is when cutting rabbets along the grain, or other similar cuts that will tear out with conventional cuts.

 

[Gary Wiant]

I tried a job with conventional cut, & the final pass allowance & let it take .02" & it worked great.
I reversed direction on the final pass. Is that correct?

thanks guys

 

[difalkner]

I do climb cut on the profile and conventional on the final, Gerry does conventional most of the time. I think as long as the final is conventional you'll be ok, even if the rough cut was conventional. To keep down the opportunity for chatter I would drop the final pass to below 0.010". I do my final pass at 0.005" so it's just taking a light shaving all the way around.

David

 

[Gary Wiant]

I use Aspire, How do you change the type of cut between the regular cut & final cut? Do you run them as seperate toolpaths?

Also when setting up the profile toolpath there is a check box for allowance distance. If n the next box down I'm taking a final pass of .01" do I want to leave .01 in the initial profile toolpass setup?

Thank you
Gary

 

[ger21]

Under Separate Last Pass, there's a "Reverse Direction" option.
If you are using "Separate Last Pass, then set the Allowance there.

Allowance under "Set Vectors" defines the finished part size.
Allowance under "Separate Last Pass" defines the offset between the last pass and first passes.

 

[Gary Wiant]

Ok thanks. So I've been doing some reading about climb & conventional & I have a question i cant seem to find the answer for.

Please correct me if I'm wrong.

1. When routing wood I'll be using down cut bits. And conventional would be clockwise around the part. If I would change to an up cut bit and calling it conventional (clockwise around part) would that be the same as doing a climb cut with an down cut?

2. If using a downcut bit cutting conventional (clockwise) and I select final pass in opposite direction does that make my final pass a climb cut?

3. Do I want to do the final full depth cut in the opposite direction or doesn't it really matter?

Thanks

 

[ger21]

1) regardless of the type of tool, conventional is always conventional and climb is always climb.

Conventional cutting is CW on the outside, CCW on the inside.
Climb is CCW on the outside, and CW on the inside.

2) Yes

3) IMO, it makes no difference. And my preference would be conventional (for wood).

The main reason that people climb cut first is due to a lack of machine rigidity. Conventional cutting will pull the tool into the workpiece, while Climb pushes it away.

If you use conventional cutting for both the rough and finish passes, if the finish pass is small, the rouging passes could gouge your part if your machine has a lot of flex.
So many people climb cut the first pass, which actually can leave slightly more material for the finish pass.

From my experience, conventional cutting almost always gives a better finish.

 

[Gary Wiant]

Gerry in your experience are the CNCRP Routers rigid enough for conventional cuts?

Thank you
Gary

 

[ger21]

They're a lot more rigid than my machine, and I always make conventional cuts.
Feedrate and depth of cut play a big role in cut quality.

I do a cleanup pass on our big machine at work as well, and it's a $150K machine that weighs 8000 lbs.