With the grain

[Larry Cessna]

I am running a large 3d carving. I am using a .5 inch up cut for my ruffing pass. it is splintering the maple? Should I use a down cut?? Also when I run my finishing pass should I go with the grain?? Thanks

[mtylerfl]

Hi Larry,

Opinions will vary. Sometimes by quite a lot!

I’ll tell you what I personally prefer...

- Downcut EM for Roughing. I usually do a Raster Roughing strategy (with the grain and a 0.04” Allowance and large stepover between 40% to 70%) but sometimes choose Z Level with radius of the Bit as my Pass setting

- Usually use either a 0.125” Tapered Ballnose at 8% Stepover with the grain. Smaller detailed projects, I use a 0.0625” TBN @ 8% stepover

Going across the grain or at an angle can leave “lines” that are next to impossible to completely eliminate in some cases. Going with the grain makes it easier to sand out any “lines”, if they are noticeable at all in the first place.

Ok. Now get ready for more opinions and methods folks prefer! Try them all, and decide which you like best yourself.

[TReischl]

I am running a large 3d carving. I am using a .5 inch up cut for my ruffing pass. it is splintering the maple? Should I use a down cut?? Also when I run my finishing pass should I go with the grain?? Thanks

Is the splintering during the roughing pass causing an issue with the carving? I ask that because quite often when I am roughing I get splinters too, but they do not ruin the carving. I am thinking splinters are pretty much inevitable when using a raster pass with the grain. Every other cut is a conventional cut with the bit trying to lift wood as it cuts. I am not so sure an downcut will help very much when the cut is conventional. The cutting edge of the tool is still trying to pull the wood apart as it goes.

I cut a lot of pine which will definitely splinter. I am getting ready to carve a large model in a day or so out of 1.75 thick pine. Just for the heck of it I am going to program this one to rough perpendicular to the grain. That will definitely take care of long splinters.

I have quit using a lot of carbide bits. Especially for endmills. I seem to get much better results with HSS bits. I know, that is heresy. But the way I see it a HSS bit is inexpensive. Mine seem to last a pretty decent time. I can easily cut 10 or 12 large carvings (20 X 20 X 1.5 dp) with one before needing to replace. So doing a little math those HSS bits add about 40 cents to the cost of a carving. Edit: Yes, carbide bits last longer but they also cost more. To my current way of thinking the cost difference is pretty much a wash in the end. And one other thing, I do a bit of aluminum and a new HSS bit does a much better job than any carbide I have tried.

You might also try raster cutting with the angle set to 45 degrees. I have done that in the past and it seems to work pretty good with less splintering.

Like Mr. Tyler says, you are going to get a lot of opinions. I wish there were "the right way to do it" but I sure as heck have not found it yet.

[Jim_in_PA]

I've found that what Mr Tyler states has worked pretty consistently for my own efforts to-date.

[Will Williamson]

Rough in with a down spiral then, 25 degree, raster angle makes a superior finish cut.
Large splinters, indicative of, high moisture content.
I've cut maple, like you describe, one of my, most difficult, projects.
High speed steel tools are sharper, than carbide. and a good way to go, for cutting solid wood.
I tried every tool I had, ended up with 3/4" down spiral end mill, for roughing, then 3/4" ball up spiral for finish.

[martin54]

Not an expert like some of these guys, I actually asked aout cutting with the grain or across the grain some time ago & got a lot of differnt answers as Michael suggested you might

Most types of wood do seem to have cut better with the grain for me but there are some that seem to cut better across the grain, Yew is one wood that comes to mind but Yew is a strange wood anyway

Every now & again I come across a piece that doesn't want to cut very well using my normal strategy, I normally stop the machine when I notice & recalculate he toolpath to cut the other way or at a 45 degree angle if this happens which has so far worked OK for me
Elm in particular seems to give me these sorts of problems, wish there was a way to tell before I started machining but the pirces that cause problems don't look any different from those that machine with ease

[Will Williamson]

The moisture content of the wood, is the major variable, in cutting solid wood.
If, the moisture content is high, when the grain starts to lift, it tears out far ahead of the cutter.
Proper kiln dried stock with 6 to 8 percent moisture content. Will produce chips and break up in small chunks
My preference is 7 percent
Tooling lasts at least 3 times longer with kiln dried stock.
Checking moisture contend, is fairly easy, once you acquire a technique.
I started my lumber and mill work business, 35 years ago, by building a 4,000 ft dry kiln.

[martin54]

The moisture content of the wood, is the major variable, in cutting solid wood.
If, the moisture content is high, when the grain starts to lift, it tears out far ahead of the cutter.
Proper kiln dried stock with 6 to 8 percent moisture content. Will produce chips and break up in small chunks
My preference is 7 percent
Tooling lasts at least 3 times longer with kiln dried stock.
Checking moisture contend, is fairly easy, once you acquire a technique.
I started my lumber and mill work business, 35 years ago, by building a 4,000 ft dry kiln.

Most of the wood that I use is kiln dried Will, I buy kiln dried slices from a sawmill, I know that the wood will have started to absorb moisture so it won't be as dry as it was when it first came out the kiln but to be honest I have no idea at what sort of rate the moisture content increases.
I do have a moisture metre but not sure I am using it correctly

[TReischl]

I have not seen any studies on whether moisture content makes splitting wood easier or not. But my anecdotal evidence comes from when I used to split firewood. There were two situations. If the wood had sat around a long time it was difficult to split with a maul. If it had been fresh cut and frozen it split easily. I have no doubt moisture plays some part, just not sure how much when it comes to kiln dried lumber.

What I do know is that some wood is way more prone to splitting than others. Red oak and white oak are two examples. Red oak is very prone to splintering. White oak isn't, but it tends to be stringy. IIRC, white oak grain is cross linked whereas the composition of red oak is more like a bundle of straws.

Maybe the all time champ for splintering and splitting is cedar, I can just look at it and make a splinter fall off.

It could have a lot to do with how fast the tree grew and where it grew.

[Uncle Bob]

HSS bits usually give a much better cut. HSS takes a sharper edge than carbide. Always a trade-off: sharper edge or longer lasting???