Hey y'all. Yeah it's me! Standing in front of the camera and not hiding behind a software screen! Welcome to what I'm reluctantly calling Part 8 of my series... ...on Vectric software titles for the absolute beginner. I say reluctantly because while it is applicable to all of the Vectric software titles... ...it's also applicable to just about every piece of CAD/CAM software out there. Now before I get started, let me go ahead and give you my standard disclaimer. And that is I am in no way sponsored nor endorsed by Vectric Ltd., or any other company. I'm doing this series to help the person who has never done anything like this before... ...get into the CAD/CAM software and successfully design and finish a project within that software. So today, I'm going to kind of tread into controversial waters... ...by discussing climb cutting versus conventional cutting... ...the difference between the two and when you would use one over the other. I say controversial because most of us who have been around CNC for a while... ...have either read somewhere or seen it explained, that you always get a better finish with a climb cut... ...and, strictly speaking, that's just not 100% true. Let me also say that when I'm talking about materials in this video... I'm referring to solid wood. I'm not talking about sheet goods... ...like MDF, HDF, PVC, extruded polystyrene, or high-density urethane. I'm talking about solid wood. Also, to the more experienced woodworkers, a lot of what I'm going to talk about, you probably already know. Hopefully you'll pick up a nugget here and there, but we'll see what happens. Also to you more experienced CNCers... ...please keep in mind that we don't all
have the same equipment. You may have or have access to a machine that's perfectly capable... ...of cutting through one-inch thick hard maple in one pass at 200 inches per minute. Most of us don't. We're talking about folks who have the X-Carve, the Shapeoko, the Stepcraft... ...all of these various home hobby level CNC routers... ...just simply are not rigid enough to handle those kinds of feeds and speeds. I've had enough questions from people who are either fairly new to woodworking... ...or are new to CNC that I felt this kind of a discussion was warranted. So for now let's go ahead and get a little bit closer here. I can show you some material to better illustrate what I'm talking about. I brought out a couple of pieces of material to give you a little bit better illustration of what I'm talking about here. But let's take a step back from CNC for a minute and go back into standard woodworking. When you're using a handheld router in its normal operating position like this... ...looking down at the top of the router, the bit spins clockwise. Now if you remember back to wood shop class... I was taught that the way to remember which direction to move the router... ...was to approach the edge you're going to cut... ...make a pistol with your right hand... ...point your thumb at the edge you're going to cut... ...your index finger tells you which way to move the router. That's with a hand-held router. So we're going to take the hand-held router, put it down... ...introduce the bit into the wood, and we're going to move the router in this direction. That is, technically, cutting against the direction of rotation of the bit. That's what we want to do. This is a conventional cut. Cutting against the direction of rotation gives you that... ...firm, easy, consistent resistance when you move the router that's easy to control. You control where the router goes. Moving the router backwards, with the direction of rotation... ...is a Climb Cut. It's called a climb cut because when you're moving with the direction of rotation of the bit... ...the bit will actually attempt to climb out of the cut. Now with a handheld router, this is generally considered to be a very unsafe move. There are exceptions to that rule but those exceptions are few and far between. Now translated over to the CNC... ...because the router is oriented the
same way, with the bit pointing downward... ...the same rules generally apply. We should always try to introduce that bit and feed that bit with the direction of the grain. And this is where getting some experience in reading grain direction becomes necessary. I brought out this example, it's a piece of yellow pine... ...and it has very pronounced grain direction down on this portion here. You can see the grain runs downhill toward the edge of the board... ...and if I tip it up on to the edge grain... ...you can see the grain runs upward, but again running longitudinally this direction. That is a very distinct grain direction. This is a candidate for a conventional cut. We are milling or machining with the direction of the grain. The bit would come up here and do the end grain... ...then up here it gets a little bit convoluted. You would be running with the grain here, until you get to this spot... ...where we have a couple of knots that poke through the back. Here's where we're going to have the grain changing direction... ...and suddenly we would be doing a climb cut here. As a whole, this piece would still be a better candidate for a conventional cut... ...because it's easier to do a little bit of cleanup work up here on this corner... ...than it would be to do cleanup work around the rest of the entire piece of material. So sometimes you just have to find that balance. Now if you can just flip over the piece of material, fine. But we can't always choose which side of the material we're going to machine... ...for aesthetic reasons or other reasons. So all in all, learning to read the grain to see which direction it's running... ...and attempt to use a conventional cut whenever and wherever possible. Now, sometimes that's just not possible. You have cases like in this piece of sapele here, that includes a little bit of a sap wood... ...you can really see the curve in the grain. You have a piece of material with grain going in both directions over its full length. This area down here would cut great with a conventional cut... ...but this area out here, with a conventional cut, would chip out like crazy. This is a good candidate for a Climb Cut. The thing to remember with a climb cut, however, is to take shallow passes. I usually stay out of the feed rate and router rpm discussion... ...because every machine and every tool is different. But in a situation like this... ...or even more so on this piece of sapele where that arch is even more pronounced... ...and over a longer stretch of the piece of material... ...a climb cut, taking shallow passes, would be the strategy to use for this material. And when I say shallow passes, we may be talking about 1/32 of an inch, maybe less. You'll just have to experiment with it. If you have some scrap, cut it. Experiment with it. See how your machine cuts. In cases like this piece of walnut, where you have a very dramatic grain change because of this knot... ...it's even more apparent that this is a candidate for a climb cut... ...with very shallow passes when cutting a profile or pocketing. There are some who will say that you're safe with plywood because plywood doesn't have a grain. Well, that's true and false at the same time. Plywood itself doesn't have a grain orientation... ...but the veneer on the surface of the plywood certainly has a grain orientation. And when you're cutting this type of material, it's the grain orientation... ...as well as the type of bit you use... ...that's going to decide whether you have a lot of cleanup to do or you have to scrap a piece... ...and mount a new piece of material and try again. And this is where we get into the discussion of Upcut vs Downcut spiral bits. This bit is a downcut spiral... ...and this bit is an upcut spiral. How can I tell the difference? When you turn them over into their cutting position... ...the cutting edge is at the top of the spiral on an upcut bit. It spins, cuts, and ejects the chips and splinters upward. The cutting edge is on the top of the spiral. Conversely, on a Downcut spiral, the cutting edge is on the bottom of the spiral. And you can see that cutting edge on both. So a downcut bit ejects the chips downward, and shears the top surface of the material downward... ...avoiding splintering and a lot of chip
out. Again, on the downcut, the cutting edge is on the bottom of the spiral... ...on an upcut, the cutting edge is on the top edge of the spiral. That's how you can visually tell the difference between the two. So it's a combination of being able to read the grain direction... ...and using the proper bit for the operation you're doing... ...that will give you a better surface a cleaner surface... ...that will require less sanding and preparation for finish. I hear some of you saying, "Great, Mark - that's all well and good... But I've got this nice chunk of maple burl. Now what do I do?" In situations where you have grain running in different directions like this piece of maple burl... ...a climb cut is the proper strategy to take. But again - use shallow passes. Most of us don't have a bunch of burl around that we can practice on. I'd love to be in that situation. In this case I would take a conservative approach... ...and use a climb cut, with shallow passes, and a moderate feed rate. Something along the lines of 40 inches per minute, until I see how the material is cutting... ...then I can speed up or slow down that feed rate on the fly... ...if I start getting bit chatter. Because it also depends on the diameter of the bit. If you've got a 1/2 inch bit it's gonna chatter less and be able to move faster than a 1/8 inch bit will. By the way, any numbers I give you are kind of "ballpark figures." You should learn your machine, learn your material... ...maple is going to be harder than, say,
pine, fir, or cedar... But generally speaking, taking a conservative approach to start out... ...then speeding up, on the fly... ....if the situation allows, is the better way to go. Taking everything we discussed outside... ...and applying it to the software when we're creating vectors and calculating toolpaths... ...we have a few more things to consider. Number one being the geometry were getting ready to cut. On straight, linear lines like these rectangles or even this triangle... ...we can basically use the direction of the grain... ...to decide whether we're going to climb cut or cut conventional. Both this triangle and these rectangles can be cut with a conventional cut... ...and I'll show you that here. I'll select these two, hold down shift, and select this one. We'll go over to our toolpath tab. and I'll select a profile toolpath. I've got all of this set up - my cutting
depth is all the way through the material. I'm using a 1/4 inch end mill. And it's going to make that cut in six passes. Now if I'm using that pine with the straight, even grain... ...this is just fine. For this, cutting outside the vectors, I would use a conventional cutting strategy. Go ahead and enter all the rest of my information here, then calculate the toolpath. If I were going to be cutting into that sapele... ...or that maple burl... ...instead, I would probably want to increase the number of passes... ...that it's going to take to cut that toolpath. Let me spend a little bit of time up in here. I've got my 1/4 inch end mill selected... ...and I'm going to take a look at the criteria of that bit by clicking EDIT. If I come over here and I look at the cutting
parameters I have set for that bit... ...the pass depth is 1/8 of an inch. That is one half of the bit's cutting diameter. My feed rate, I have set at a conservative 40 inches per minute... ...and a plunge rate set at a conservative
20 inches per minute. That's one half of the feed rate. For this size of bit, that works out just fine. Now, when I say 40 inches per minute is conservative; it's not too slow, but it's not real fast either. I know on my machine setup outside, I can increase this feed rate on the fly. So I'll start with a conservative feed rate... ...see how the material is reacting to the bit; how it's cutting... ...then I can bump that feed rate up or down as the material warrants. I may end up cutting this at 100 inches per minute... I may end up cutting it at 20. It's just going to depend on the material and how it's reacting to the cut. I'll cancel this, because I'm not going to make any changes there. So in that pine, six passes would be just fine. But if I were going to cut this in that sapele with that big, dramatic arc... ...or even in that maple burl that has
grain going in all directions at once... ...I would want to use a climb cut. So I would select a climb cut... ...but then I'd also want to cut shallower. I wouldn't want to cut that at 1/8 of an inch per pass. The way I would change this is come over here to this button... ...and click Edit Passes. This opens up the form where you can specify your pass depth. I'm going for a total depth of cut 0.755
inches... ...and this diagram here is showing me each pass. It's going to plunge down to a little more than 1/8 of an inch here... ...and then plunge down to a little more than 1/4 of an inch on the second pass, and so on, and so forth... I can increase the number of passes down here, where it says Number of Passes. For that maple burl, I want to go for a fairly shallow pass... ...so I'll bump this up to 10 passes and see how that diagram reacts. I'll click Set Passes... ...and I can see here that I'll be cutting a little bit more than 1/16 of an inch. That's still a bit aggressive for my tastes... ...so I'll use my up arrow, here, and bump it up to 12... ...and that brings me to just under 1/16 of an inch per pass. I think that'll work out much better in that hard maple burl... ...so I'll click OK... ...and now my number of passes reflects that change. I'm going to use a Climb Cut. I would fill in all the rest of my information here, then calculate the toolpath Something to keep in mind... ...is that it's very seldom that we will cut straight, linear geometry like this. More often than not, we'll be cutting a lot of curves... ...like in this circle here, or these ovals. These require a little bit more thought, and a little bit more care. Because in the case of this circle... ...it's going to cut with the grain and against
the grain within the same vector. And it'll do so in quadrants. This quadrant here, you'll be cutting with that nice, even grain on that pine. This quadrant here, you'll be cutting against that grain. This quadrant, you'll be cutting with... ...and this quadrant you'll be cutting against. There's very little you can do about this... ...so on this circle or these ovals... ...I would use a climb cut rather than a conventional cut. So we'll go back over here to the profile toolpath... ...and whether I'm cutting the pine, or I'm cutting the sapele... ...or the maple burl, I want to use a climb cut. In the pine, I would still want to edit my passes... ...but I don't need to make 12 passes. It's a softer wood, it's a little bit more resilient. I can probably bump that up to 8 passes and be okay. If I were cutting the sapele or that maple burl... ...I would definitely want to bring that up to 12... ...set my passes... ...and depending upon how this goes I may even want to go to 14 or 16... ...especially in the case of that hard maple burl. So reading the grain, using the proper bit... ...and reading the vectors will help you decide the number of passes, and how deep you want to cut. I'll go ahead and click OK. For the sapele or the maple I would go ahead fill in the rest of my information here... ...then calculate the toolpath. The same holds true for a pocketing toolpath... ...but mainly when you're talking about using a large area clearance tool. If I want my pocket to be 1/4 of an inch deep... ...cutting in that pine with a 1/4 inch end mill... ...1/8 of an inch deep per pass is going to be alright. So I would still use the same feed rates and then bump them up on the fly. Click OK... It says it's going to cut it in 2 passes - we'll see how it goes. If I'm using a large area clearance tool, I would apply it here. I don't need to use it. I think that'll be alright... ...but I again I would use a conventional toolpath. If I were cutting the maple or the sapele, again I would change to a climb cut... ...and I would edit the number of passes. Where you run into a little bit of difficulty... ...is in v-carving. In v-carving to a flat depth... ...you select your v-bit... ...let's say I'm going to cut this to a flat depth of 0.25... ...and I'm going to use a 90-degree v-bit... ...that may be a little bit deep... ...and a little bit too aggressive of a pass depth for that maple or that sapele. I'm going to use a feed rate of 40... ...and a plunge rate of 20... ...click OK... ...but I want to go back and edit this bit. Because there's no way of controlling how aggressively that v-bit is going to cut. For my flat area clearance tool I can go in, select a... ...whoops wrong button... I can go in and select my 1/4 inch end mill, because it's a fairly large circle... ...but again I have no way of adjusting my depth of cut per pass. I'll have to do that here in the Edit function. 1/4 inch for that maple and that sapele is a pretty aggressive cut. Here is where I would change that for this cut. I would come in and change that to .0625... ...which means my pass depth... ...would be 1/16 of an inch. Click OK. I would do the same here... ...set the pass depth to .0625... Click OK, and for these toolpaths only... ...the v-bit and that 1/4 inch end mill will cut these at 1/16 of an inch per pass. I don't have any control of that over here. I have to go in and edit the bit. As I said, it's very rare that we're gonna cut any geometry that are straight, linear lines. Most of our toolpaths are going to be loaded with curves. The thing to take away from this is... ...read the grain of your material... ...attempt to adjust your toolpathing strategy to cut with the grain of that material... ...as much as possible. Conventional cut when you can. If you can't, and you have to use a climb cut, shallow passes and conservative feed rates... ..will get you a better result. So hopefully this gives you a little bit of insight into... ...some of the decisions you have to make when deciding between a climb cut or a conventional cut. It's learning to read the grain of the wood that you're going to be using... ...learning the vectors, the bits, and the depth per pass... ...of those bits when you go to calculate the toolpath. This video was never meant to be the definitive guide... ...on what feed rates or speeds or depth per pass that you should use. It's meant to be food for thought. These are the things that you should consider. Your machine may be able to cut a lot deeper, a lot faster than mine. Your machine may not be able to cut as deep or as fast as mine. And every material is different. One piece of sapele, one piece of maple burl is completely different from the next. So starting conservative and being able to bump up or down the feed rates on the fly... ...is usually the better way to go. Hopefully you got something out of this video. If you did, please give me a thumbs up down below. I would appreciate it. If you'd like to continue following this series... ...or if you'd like to follow along with some of my other CNC adventures... I hope you'll consider subscribing to my channel. Now I know that you've noticed this bright green... ...Holly Denny Wood Art t-shirt. If you'd like to get one of your own... ...and let's face it who wouldn't? I'll put a link in the description below where you can get hold of Holly herself... ...and get you one of these highly prized t-shirts. Believe me, I get a lot of comments wearing this. I mean, come on - you can hear this color! As usual if you have any questions or comments... ...feel free to leave them in the comment section down below. If you'd rather not leave a public comment or you just need to get a hold of me... ...head over to my website marklindsayCNC.com... ...and hit that Contact Us link. I read every message that I get through marklindsayCNC.com... ...and I do my best to reply to every single one of them. marklindsayCNC.com is sponsored by Harneal Media. They are the website and web hosting service... ...that is geared specifically toward makers and the maker community. We're both also proud members of the Makers Media Network. Again I hope you got something out of this video. I'd like to thank you very much for watching. Y'all take care.
