Hi, I’m Bob Warfield, Founder of CNCCookbook and author of G-Wizard Calculator. If you’ve got questions about Feeds and Speeds or G-Wizard Calculator, now is your chance to Ask Me Anything. This is something that’s been popular elsewhere on the Internet, but is totally new for us here at CNCCookbook.
We’ll use the comment section of this blog post as our venue for Q&A. Just post a comment with your question, and I will respond (at least to those that are on-topic) in the comments. I’m totally here to help and will answer to the best of my knowledge, even if I have to do a little research to enhance that knowledge. The main thing I’ll ask is to keep it fun.
We’ll keep Ask Me Anything open for 1 week starting now. So, what would you like to ask? Just post your question below as a comment.
Postscript: I’m going to close this after 1 week. Thanks for all your good questions. I’ve answered them all below. If you have more questions, feel free to use QuestionX. It’s perfect for that kind of thing.
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Bob is responsible for the development and implementation of the popular G-Wizard CNC Software. Bob is also the founder of CNCCookbook, the largest CNC-related blog on the Internet.
Our conversational programming tool asks for peck depth. Gwizard has “cut depth”. How are the two different, and how can I use the GWizard tool to program peck depth? Thanks in advance
brose185, I’ve seen “peck depth” mean a variety of things–usually either how deep you can drill before you must start to peck, how much deeper you go between each peck, or how far to retract on each peck.
There’s no consideration in G-Wizard Calculator for Peck Depth, though it will suggest one.
How do you prefer to generate feed/speed of cuts with a strong Z component? The example in my head is the spiral down entry routine for digging a pocket.
Rich, it depends on whether I am lazy or in a hurry, LOL. If I’m lazy, I will use the Plunge Feed Rate. It is super conservative and always works. But it is slow. This won’t matter if we don’t have to do it too many times.
If the helix is not too steep, I will just use the regular feedrate. This is somewhat aggressive and gets more aggressive the higher the helix angle.
If I am worried about it because of a high helix angle, tough material, or other factor, I will use the Interpolation Mini-Calculator to fine tune the feedrate.
Hei – I am from Germany and I’m an absolute Newbie in CNC. My english is very poor, but I try to describe my problems with my new Shapeoko 3.
The assembly of the machine is finished and I want to try my first tests. At first I started with your G-Wizard Editor Trial – a fine instrument, indeed – and now I want to get the correct values with your Calculator.
The trouble I have is, that with my machine (Shapeoko3 with a Dewalt Router 611), it is impossible to get a good value for the speed. This router has only a range betwen 16.000 and 27.000 rpm, which is to high for drilling or milling for example in MDF. I want to drill holes with a diameter of 10mm – is there any possibility to get it without milling endless with an 3mm end mill? BTW because of my bad english and to few knowledges in CNC , some of the items of the menue are currently a bit nebulous.
Can you give me a hint?
Wolfgang, this is a common problem for CNC Routers depending on what material you’re cutting. The two big limitations are inability to slow down the spindle below a certain rate and (potentially) the inability to feed fast enough to avoid rubbing. These are compounded by the fact we also typically use fairly small diameter cutters. The material you’re cutting can also compound things.
I wrote a blog post that’s intended to provide a grab bag of techniques to help you work around these issues. You can find it here:
My question its related to High Speed Machining. Many have seen videos of new machining strategies (volumill, vortex, etc) where you use the whole flute of your cutter to do roughing at very high feed rates. How can I do proper adjustments if I have no access to a high end or a new machine like in the demos? I have an old CNC VMC which has a 7.5 HP spindle, 4,000 RPM and a maximun feedrate 195 ipm, also just ER tooling. Can this new strategies be applied on my cnc?
Alex, as many articles attest, the name “High Speed Machining” can be a bit of a misnomer as you don’t need high spindle rpms to benefit from it at all. What HSM is really all about is using chip thinning to your advantage or using constant engagement toolpaths to your advantage. There’s more to it than that, but both work regardless of rpm. So if your CAM supports HSM toolpaths, go right ahead and use it and G-Wizard will calculate your HSM Feeds and Speeds for it and stay within the limits of what your machine can do.
When I use the calculator most of the time it recommends conventional cutting. What happens when I am cutting (wood) with the grain the bit grabs the wood and rips off large strips before it can cut it. Is there any reason I couldn ‘t use climb most of the time to eliminate this?
The reason for the Conventional recommendation probably sheds some light on why this can happen. Basically, beyond a certain Cut Width, Climb Milling will result in negative rake geometry even on a positive rake tool. That negative rake will tend to push down on the workpiece, require more cutting force, generate more heat, and generally be less efficient at cleanly slicing off a chip. But that same pushing down is helping to reduce the pullout you’re getting on the wood, so go for it and try the Conventional milling there.
Any plans to add manufacturer recommended specs into the calculator? For instance, Lakeshore Carbide provides recommended material removal rates. Huge amount of data to maintain so understandable if the answer is no.
Tom, absolutely. We have a plan to do this via crowdsourcing. Before we get there, we’ll also be introducing some new features around our new all-in-one Tool Selector (currently the UI mockup is there for review and feedback) to make it dramatically easier to enter your own Manufacturer information.
I don’t want to get too far ahead of myself and jinx it though–more to come.
Bob, I want CNC to be my hobby and I want to be really good at it. I’m just getting started In the past year I have learned 2-1/2 axis milling in my school’s student machine shop, using free software, and have become fairly acquainted with its options. I hope some day to own a 5-axis machine.
How tough is it to make the jump from 3 axis to 5 axis CNC software? What are the best resources out there for learning to do it right?
William, I think the problem you’re going to encounter doing 5 axis in a Hobby context is the software. Decent 5-axis software is very complex and hence very expensive. We all have high hopes that products like Fusion 360 will bring some of that cost down, but the proof will be in the pudding.
You might ask yourself why you want 5 axis in a Hobby context? BTW, I am a firm believer that for Hobbyists anything is possible, and anything is justified just because it’s Cool. After all–do what floats your boat in a Hobby.
But if you’re looking for some particular benefit, maybe you can get there without 5 axis. There’s a lot to learn in the journey from reasonable but not expert 2 1/2D proficiency to true 5-axis work.
Hey Bob I was wondering how you calculate the final depth speeds and feeds say I’ve got a quarter inch end mill and I’m going to cut .003, 3/4″ deep on final pass on aluminum what kind of speeds and feeds. Thanks
Ed, I’m assuming you’re asking about finish pass feeds and speeds?
Pretty much the same as roughing. Enter your parameters left to right, top to bottom. The difference is you want to move the Tortoise-Hare slider left to reflect a finish pass. There are two settings–finish and fine finish. Most of the time you’ll want finish. Fine finish is set to choose the lowest feed rate that won’t rub–it’s as slow as you can go and in theory will leave the best finish as a result.
Mike, if you bring up the Materials menu, select Plastics: Hard, and click the “More” button, you will see there is an entry for High Temp Epoxy Modeling Board. Pretty similar stuff.
You can go from there to determine your feeds and speeds.
If I am using (for example) a 6mm carbide ball end cutter in a shrink fit holder, does the “stick out” include the shrink fit extension from the collet or just the tool from the end of the shrink fit?
Mike, in general, if there is an extension or a necked-down shank, you will have to make a value judgement. The two things to consider are whether the diameter of the extension and the length below the toolholder are such that they’re much more rigid than the tool itself (or fluted portion).
How to do that?
For micro-mills, they often have a 1/8″ shank that necks down to the tiny flutes. It’s almost always a good idea to measure stickout from the end of the 1/8″ portion to the tool tip.
For extensions, it’s a little tougher. Are they carbide or HSS? You can use your tool for comparison coupled with G-Wizard’s Rigidity Calculator to get an idea. Set the top portion to reflect the portion of the tool that sticks out of the extension. Set the bottom to reflect the portion of the extension that sticks out of the toolholder. Let’s take your case (or one similar) and assume we have a 6mm tool that is 10mm out of the extension and a 20mm diameter extension that is steel and 60mm long.
In that case, the Target Tool is 1.5x more rigid than the portion sticking out. That makes me a little concerned about the rigidity. I’d like it to be more like 4x before I’d ignore it. So, playing with the rigidity calculator, I can get 4x as rigid by setting the length of the 6mm tool to be 14mm.
Even though that isn’t the real stickout, I think I’d enter 14mm and use that for all the deflection calculations for that setup.
Bob – I’m looking at cutting (turning, drilling, reaming, and milling) a in a Swiss type machine, a material that I can’t seem to find speeds and feeds for. The material happens to be E9310 alloy steel. I can however find the rating, in this case is 50% of the standard AISI 1212 steel. How can I figure what is a comparable material to choose from, from your material selection?
Also, is there recommended tooling information for a certain material, say tool material, geometry and coatings as opposed to already knowing what tooling to choose.
Hi Rich. It’s a Low Carbon Alloy, so use that category. Using the “More” button set the Brinell Hardness to 241 for annealed. That should get you going. I will add it to the list in the next release.
Our conversational programming tool asks for peck depth. Gwizard has “cut depth”. How are the two different, and how can I use the GWizard tool to program peck depth? Thanks in advance
brose185, I’ve seen “peck depth” mean a variety of things–usually either how deep you can drill before you must start to peck, how much deeper you go between each peck, or how far to retract on each peck.
There’s no consideration in G-Wizard Calculator for Peck Depth, though it will suggest one.
Cut Depth is the max depth of the hole.
How do you prefer to generate feed/speed of cuts with a strong Z component? The example in my head is the spiral down entry routine for digging a pocket.
Rich, it depends on whether I am lazy or in a hurry, LOL. If I’m lazy, I will use the Plunge Feed Rate. It is super conservative and always works. But it is slow. This won’t matter if we don’t have to do it too many times.
If the helix is not too steep, I will just use the regular feedrate. This is somewhat aggressive and gets more aggressive the higher the helix angle.
If I am worried about it because of a high helix angle, tough material, or other factor, I will use the Interpolation Mini-Calculator to fine tune the feedrate.
Hei – I am from Germany and I’m an absolute Newbie in CNC. My english is very poor, but I try to describe my problems with my new Shapeoko 3.
The assembly of the machine is finished and I want to try my first tests. At first I started with your G-Wizard Editor Trial – a fine instrument, indeed – and now I want to get the correct values with your Calculator.
The trouble I have is, that with my machine (Shapeoko3 with a Dewalt Router 611), it is impossible to get a good value for the speed. This router has only a range betwen 16.000 and 27.000 rpm, which is to high for drilling or milling for example in MDF. I want to drill holes with a diameter of 10mm – is there any possibility to get it without milling endless with an 3mm end mill? BTW because of my bad english and to few knowledges in CNC , some of the items of the menue are currently a bit nebulous.
Can you give me a hint?
Many thanks,
Wolfgang
Wolfgang, this is a common problem for CNC Routers depending on what material you’re cutting. The two big limitations are inability to slow down the spindle below a certain rate and (potentially) the inability to feed fast enough to avoid rubbing. These are compounded by the fact we also typically use fairly small diameter cutters. The material you’re cutting can also compound things.
I wrote a blog post that’s intended to provide a grab bag of techniques to help you work around these issues. You can find it here:
http://blog.cnccookbook.com/2013/03/15/what-now-my-cnc-wont-go-slow-enough-or-fast-enough/
Using those methods, you can dodge around most, but not all problems of this sort.
My question its related to High Speed Machining. Many have seen videos of new machining strategies (volumill, vortex, etc) where you use the whole flute of your cutter to do roughing at very high feed rates. How can I do proper adjustments if I have no access to a high end or a new machine like in the demos? I have an old CNC VMC which has a 7.5 HP spindle, 4,000 RPM and a maximun feedrate 195 ipm, also just ER tooling. Can this new strategies be applied on my cnc?
Alex, as many articles attest, the name “High Speed Machining” can be a bit of a misnomer as you don’t need high spindle rpms to benefit from it at all. What HSM is really all about is using chip thinning to your advantage or using constant engagement toolpaths to your advantage. There’s more to it than that, but both work regardless of rpm. So if your CAM supports HSM toolpaths, go right ahead and use it and G-Wizard will calculate your HSM Feeds and Speeds for it and stay within the limits of what your machine can do.
When I use the calculator most of the time it recommends conventional cutting. What happens when I am cutting (wood) with the grain the bit grabs the wood and rips off large strips before it can cut it. Is there any reason I couldn ‘t use climb most of the time to eliminate this?
Thanks
Gary
Gary, no reason you couldn’t use Climb.
The reason for the Conventional recommendation probably sheds some light on why this can happen. Basically, beyond a certain Cut Width, Climb Milling will result in negative rake geometry even on a positive rake tool. That negative rake will tend to push down on the workpiece, require more cutting force, generate more heat, and generally be less efficient at cleanly slicing off a chip. But that same pushing down is helping to reduce the pullout you’re getting on the wood, so go for it and try the Conventional milling there.
Any plans to add manufacturer recommended specs into the calculator? For instance, Lakeshore Carbide provides recommended material removal rates. Huge amount of data to maintain so understandable if the answer is no.
Thank you!
Tom
Tom, absolutely. We have a plan to do this via crowdsourcing. Before we get there, we’ll also be introducing some new features around our new all-in-one Tool Selector (currently the UI mockup is there for review and feedback) to make it dramatically easier to enter your own Manufacturer information.
I don’t want to get too far ahead of myself and jinx it though–more to come.
Bob, I want CNC to be my hobby and I want to be really good at it. I’m just getting started In the past year I have learned 2-1/2 axis milling in my school’s student machine shop, using free software, and have become fairly acquainted with its options. I hope some day to own a 5-axis machine.
How tough is it to make the jump from 3 axis to 5 axis CNC software? What are the best resources out there for learning to do it right?
William, I think the problem you’re going to encounter doing 5 axis in a Hobby context is the software. Decent 5-axis software is very complex and hence very expensive. We all have high hopes that products like Fusion 360 will bring some of that cost down, but the proof will be in the pudding.
You might ask yourself why you want 5 axis in a Hobby context? BTW, I am a firm believer that for Hobbyists anything is possible, and anything is justified just because it’s Cool. After all–do what floats your boat in a Hobby.
But if you’re looking for some particular benefit, maybe you can get there without 5 axis. There’s a lot to learn in the journey from reasonable but not expert 2 1/2D proficiency to true 5-axis work.
Hey Bob I was wondering how you calculate the final depth speeds and feeds say I’ve got a quarter inch end mill and I’m going to cut .003, 3/4″ deep on final pass on aluminum what kind of speeds and feeds. Thanks
Ed, I’m assuming you’re asking about finish pass feeds and speeds?
Pretty much the same as roughing. Enter your parameters left to right, top to bottom. The difference is you want to move the Tortoise-Hare slider left to reflect a finish pass. There are two settings–finish and fine finish. Most of the time you’ll want finish. Fine finish is set to choose the lowest feed rate that won’t rub–it’s as slow as you can go and in theory will leave the best finish as a result.
Hi Bob,
What sort of feed/speed would you suggest for roughing high temp epoxy tooling board with a density of 0.68 KG/M3 (the blue stuff).
The tool I want to use is a 5 flute indexed tip cutter, 25mm in diameter with a 20mm shank… stickout is about 180mm.
Max cut depth on the inserts is about 7mm.
Max RPM for the tool is about 11000.
Can GW calculate for this material?
Mike
Mike, if you bring up the Materials menu, select Plastics: Hard, and click the “More” button, you will see there is an entry for High Temp Epoxy Modeling Board. Pretty similar stuff.
You can go from there to determine your feeds and speeds.
If I am using (for example) a 6mm carbide ball end cutter in a shrink fit holder, does the “stick out” include the shrink fit extension from the collet or just the tool from the end of the shrink fit?
Mike, in general, if there is an extension or a necked-down shank, you will have to make a value judgement. The two things to consider are whether the diameter of the extension and the length below the toolholder are such that they’re much more rigid than the tool itself (or fluted portion).
How to do that?
For micro-mills, they often have a 1/8″ shank that necks down to the tiny flutes. It’s almost always a good idea to measure stickout from the end of the 1/8″ portion to the tool tip.
For extensions, it’s a little tougher. Are they carbide or HSS? You can use your tool for comparison coupled with G-Wizard’s Rigidity Calculator to get an idea. Set the top portion to reflect the portion of the tool that sticks out of the extension. Set the bottom to reflect the portion of the extension that sticks out of the toolholder. Let’s take your case (or one similar) and assume we have a 6mm tool that is 10mm out of the extension and a 20mm diameter extension that is steel and 60mm long.
In that case, the Target Tool is 1.5x more rigid than the portion sticking out. That makes me a little concerned about the rigidity. I’d like it to be more like 4x before I’d ignore it. So, playing with the rigidity calculator, I can get 4x as rigid by setting the length of the 6mm tool to be 14mm.
Even though that isn’t the real stickout, I think I’d enter 14mm and use that for all the deflection calculations for that setup.
Bob – I’m looking at cutting (turning, drilling, reaming, and milling) a in a Swiss type machine, a material that I can’t seem to find speeds and feeds for. The material happens to be E9310 alloy steel. I can however find the rating, in this case is 50% of the standard AISI 1212 steel. How can I figure what is a comparable material to choose from, from your material selection?
Also, is there recommended tooling information for a certain material, say tool material, geometry and coatings as opposed to already knowing what tooling to choose.
Thanks
Hi Rich. It’s a Low Carbon Alloy, so use that category. Using the “More” button set the Brinell Hardness to 241 for annealed. That should get you going. I will add it to the list in the next release.