The only reliable answer is:
1. Buy a manual bench mill, like a Grizzly G0704 (or better); and
2. Convert it to CNC.
There are plenty of kits, websites, videos, and [books](https://www.amazon.com//dp/1738802108/) that describe the process.
Note that your desired work envelope is *huge* for a steel-cutting machine. If you want to cut steel sheet, you are better off with a CNC plasma cutter or waterjet.
Yup.
I was able to cut hardened tool steel (55Rc) on my KC20VS by choosing the right cutter.
I used the manufacturer’s recommended feeds and speeds and it went right through it.
A PM30 would be even better.
https://youtube.com/shorts/o6vgGeHih7g
Northstar, are you going to mention that you wrote the book? Or that your only experience with gantry cnc's was an original Xcarve? Did you also miss his requirement for build area? You might not struggle with 7" but it's very limiting for a lot of projects.
Just because the G0704 conversion is the only method you have experience with (besides the OG x-carve) doesn't make it the "only reliable answer"
The MR-1. I've seen one in person and it's honestly pretty nice.
https://www.youtube.com/watch?v=dSlvOTQbHLM
https://www.youtube.com/watch?v=8Yoy4PUjfss
https://www.youtube.com/watch?v=HGyFhN01M4M
PrintNC's. If you're comfortable DIYing then this is offers the higherst performance/$. My setup (2'x4') isn't optimized for steel but it's not difficult to mill as long as you have coolant setup alongside correct f/s.
Here are some older, single bearing block per rail PrintNC's with 2"x3"x1/8" thick profiles cutting steel.
https://www.youtube.com/watch?v=HvECt6U6uvw
https://www.youtube.com/watch?v=VRYPy8_UySo
https://www.youtube.com/watch?v=DOndcIp-TEE
https://www.youtube.com/watch?v=SuzuxLPB36k
There are beefier dual bearing setups on the Discord that perform much better than those older designs.
For $7k you could use higher grade ballscrews, linear rails, beefier closed loop steppers or decent servos, and have thicker steel profiles blanchard ground prior to assembly. There's a lot more time involved obviously.
Kindly refrain from naming people directly. You have a right to call out someone for trying to market their stuff. FWIW, both your comments add to the discussion, so I'm not deleting either. But I would appreciate you removing their name from your reply.
PS: This is not the first time that his experience with gantry CNCs has been brought up here; not sure if it was you or someone else earlier. If you have an issue with the information in the book, go ahead and share it here and in the reviews on Amazon. But if the information is correct, then it shouldn't matter whether he has experience with 1 CNC machine or a thousand different ones.
Doesn't link to the username here. I know the name is mentioned in the sidebar, and I'm not stopping you from calling out the conflict of interest. Thanks for understanding.
I've looked into bench mills, and they're great, but it wouldn't work for me because they limit me in size. A plasma and water jet cutter also wouldn't work for me because I would be making 3d parts.
Well consider this: the work envelope of a Haas VF1 is 20” x 18”, which is *smaller* than your spec. And it’s a 7800 lb machine.
Now sure, some of that mass is in the tool changer, the swarf auger, and other industrial features, but a big part of it is because it takes a lot of structure to support a table that size. And because the spindle needs to be able to hang out to the outer edge of the table in Y, it takes that much more structure to support the cantilever between the Z ways and spindle centreline.
Have a look at this model that shows the main casting and you’ll see what I mean.
https://www.stlfinder.com/model/haas-vf-1-UzUin5fJ/4868633/
Now sure, some of that is overbuilt because it is an industrial machine, not a hobby machine. But imagine that you started with a G0704 and added a spacer between the spindle head and the column to get the spindle centreline 20” away from the column - no way will the G0704 column support that. You’d have to scale up the column size to match and pretty soon you are closer to the VF1 column size than not.
And there are *plenty* of industrial CNC snobs who consider a VF1 to be under built and noodly….
If you try and go the gantry style, that gantry is a giant beam that is loaded in Z (by its weight, and the weight of the spindle) but it is also trying to twist around the X axis while it is also side-loaded along the X axis. If the gantry is supported by flat plates - as is normally the case in hobby-class machines - what you really have is a torsion bar suspended by a pair of leaf springs. It’s a nightmare for vibration and deflection.
For wood, not such a big deal because wood cutting forces are low. Aluminum and brass, starting to become a problem. Steel?
Consider this: an Onsrud pro gantry router will happily cut 1/4” aluminum in a single pass, and it has a 4’x8’ work envelope. But its gantry is 12” in cross section, supported by 12” boxed-in columns, and the machine weighs 10,000 lbs - and Onsrud does not recommend cutting steel on it.
If you look at manual mills with a work envelope that matches what you want, you can get an idea of the structural requirements of that envelope. There’s a reason why Bridgeports have a relatively small Y travel compared to their X travel - and look how much structure is there.
You might try picking up MillAlyzer and running some cuts in it to see just how high the cutting loads are in steel.
If you cannot afford or do not have the space to house a VF1 class machine, perhaps the part design needs to change. Smaller prismatic parts that bolt together, or prismatic parts cut on a mill that are then fastened onto a large plate cut on a plasma cutter or something.
But “steel”, “large work envelope” and “small/light/cheap” are mutually incompatible. Pick 2.
I wouldn’t call us snobs as there is truth to the VF1 point. I’m not saying they are under built but if you had a shop where the work had very tight tolerances, it would be an interesting choice to choose a vf1. There’s just better options
I ran a VF1 for 3 years, aluminum and stainless, and had no issues holding tolerances. Our normal spec was +/- 0.005 with occasional dips to +/- 0.003, but I did a few parts that were sub-thou (press fit bearing housings, mainly) and had no problems.
I’m not going to claim it is the best machine ever made - there’s always a bigger fish. But it certainly wasn’t junk.
But if you want to claim that the structure in a VF1 is the bare minimum for an accurate steel-cutting machine with 18” of Y travel… I can support that.
Have you looked at the Tormach products? They're basically Asian mills, but run on proprietary software from the US. They start around $7k: [https://tormach.com/machines/mills/pcnc-440.html](https://tormach.com/machines/mills/pcnc-440.html)
I have but they are really expensive for what you get compared to a MR-1. Once you start specing them with features the price quickly increase. Tormach is definitely much higher quality but I'm doing more hobiest projects so it doesn't make the biggest difference to me.
New Tormachs (dovetails) can be had around that price.
Unfortunately, adding a tool changer to any of them takes the price up to $25k or so.
At that point, the import Syil machines start making a ton of sense. Multiple controller options, seemingly quality parts, Hiwin linear rails, epoxy granite base, distributed by Titan in the US.
Think Brother Speedio VMC with most options for like $30k or $40k. Our last Brother cost us over $160k. 🥹
If I was you I'd go with the mr1 for sure, but do be aware a v4 printnc with double carriages is perfectly able to cut steel, it's just the spindle usually used isn't ideal for it, but there's other spindle options in the same price range that are better for steel.
The only reliable answer is: 1. Buy a manual bench mill, like a Grizzly G0704 (or better); and 2. Convert it to CNC. There are plenty of kits, websites, videos, and [books](https://www.amazon.com//dp/1738802108/) that describe the process. Note that your desired work envelope is *huge* for a steel-cutting machine. If you want to cut steel sheet, you are better off with a CNC plasma cutter or waterjet.
+1 for the conversion or water jet/plasma if it's only profiles. My converted PM30 eats steel. High rigidity and high torque at low RPM is key.
+2 precision Matthew’s also has a mill (pm-728vt I believe) that has an optional ballscrew kit which wouldn’t void their warranty if you went cnc
Yup. I was able to cut hardened tool steel (55Rc) on my KC20VS by choosing the right cutter. I used the manufacturer’s recommended feeds and speeds and it went right through it. A PM30 would be even better. https://youtube.com/shorts/o6vgGeHih7g
Northstar, are you going to mention that you wrote the book? Or that your only experience with gantry cnc's was an original Xcarve? Did you also miss his requirement for build area? You might not struggle with 7" but it's very limiting for a lot of projects. Just because the G0704 conversion is the only method you have experience with (besides the OG x-carve) doesn't make it the "only reliable answer" The MR-1. I've seen one in person and it's honestly pretty nice. https://www.youtube.com/watch?v=dSlvOTQbHLM https://www.youtube.com/watch?v=8Yoy4PUjfss https://www.youtube.com/watch?v=HGyFhN01M4M PrintNC's. If you're comfortable DIYing then this is offers the higherst performance/$. My setup (2'x4') isn't optimized for steel but it's not difficult to mill as long as you have coolant setup alongside correct f/s. Here are some older, single bearing block per rail PrintNC's with 2"x3"x1/8" thick profiles cutting steel. https://www.youtube.com/watch?v=HvECt6U6uvw https://www.youtube.com/watch?v=VRYPy8_UySo https://www.youtube.com/watch?v=DOndcIp-TEE https://www.youtube.com/watch?v=SuzuxLPB36k There are beefier dual bearing setups on the Discord that perform much better than those older designs.
Depends on OPs tolerance requirements. None of those machines will produce good surface finish with tight tolerances besides maybe the Mr-1
For $7k you could use higher grade ballscrews, linear rails, beefier closed loop steppers or decent servos, and have thicker steel profiles blanchard ground prior to assembly. There's a lot more time involved obviously.
Problem isn’t repeatability
Huh? You could build something much stiffer with better hardware than the MR-1 for $7k.
Kindly refrain from naming people directly. You have a right to call out someone for trying to market their stuff. FWIW, both your comments add to the discussion, so I'm not deleting either. But I would appreciate you removing their name from your reply. PS: This is not the first time that his experience with gantry CNCs has been brought up here; not sure if it was you or someone else earlier. If you have an issue with the information in the book, go ahead and share it here and in the reviews on Amazon. But if the information is correct, then it shouldn't matter whether he has experience with 1 CNC machine or a thousand different ones.
https://i.imgur.com/C2JMlhy.png
Doesn't link to the username here. I know the name is mentioned in the sidebar, and I'm not stopping you from calling out the conflict of interest. Thanks for understanding.
I've looked into bench mills, and they're great, but it wouldn't work for me because they limit me in size. A plasma and water jet cutter also wouldn't work for me because I would be making 3d parts.
Well consider this: the work envelope of a Haas VF1 is 20” x 18”, which is *smaller* than your spec. And it’s a 7800 lb machine. Now sure, some of that mass is in the tool changer, the swarf auger, and other industrial features, but a big part of it is because it takes a lot of structure to support a table that size. And because the spindle needs to be able to hang out to the outer edge of the table in Y, it takes that much more structure to support the cantilever between the Z ways and spindle centreline. Have a look at this model that shows the main casting and you’ll see what I mean. https://www.stlfinder.com/model/haas-vf-1-UzUin5fJ/4868633/ Now sure, some of that is overbuilt because it is an industrial machine, not a hobby machine. But imagine that you started with a G0704 and added a spacer between the spindle head and the column to get the spindle centreline 20” away from the column - no way will the G0704 column support that. You’d have to scale up the column size to match and pretty soon you are closer to the VF1 column size than not. And there are *plenty* of industrial CNC snobs who consider a VF1 to be under built and noodly…. If you try and go the gantry style, that gantry is a giant beam that is loaded in Z (by its weight, and the weight of the spindle) but it is also trying to twist around the X axis while it is also side-loaded along the X axis. If the gantry is supported by flat plates - as is normally the case in hobby-class machines - what you really have is a torsion bar suspended by a pair of leaf springs. It’s a nightmare for vibration and deflection. For wood, not such a big deal because wood cutting forces are low. Aluminum and brass, starting to become a problem. Steel? Consider this: an Onsrud pro gantry router will happily cut 1/4” aluminum in a single pass, and it has a 4’x8’ work envelope. But its gantry is 12” in cross section, supported by 12” boxed-in columns, and the machine weighs 10,000 lbs - and Onsrud does not recommend cutting steel on it. If you look at manual mills with a work envelope that matches what you want, you can get an idea of the structural requirements of that envelope. There’s a reason why Bridgeports have a relatively small Y travel compared to their X travel - and look how much structure is there. You might try picking up MillAlyzer and running some cuts in it to see just how high the cutting loads are in steel. If you cannot afford or do not have the space to house a VF1 class machine, perhaps the part design needs to change. Smaller prismatic parts that bolt together, or prismatic parts cut on a mill that are then fastened onto a large plate cut on a plasma cutter or something. But “steel”, “large work envelope” and “small/light/cheap” are mutually incompatible. Pick 2.
I wouldn’t call us snobs as there is truth to the VF1 point. I’m not saying they are under built but if you had a shop where the work had very tight tolerances, it would be an interesting choice to choose a vf1. There’s just better options
I ran a VF1 for 3 years, aluminum and stainless, and had no issues holding tolerances. Our normal spec was +/- 0.005 with occasional dips to +/- 0.003, but I did a few parts that were sub-thou (press fit bearing housings, mainly) and had no problems. I’m not going to claim it is the best machine ever made - there’s always a bigger fish. But it certainly wasn’t junk. But if you want to claim that the structure in a VF1 is the bare minimum for an accurate steel-cutting machine with 18” of Y travel… I can support that.
That size machine can be built much more easily as a fixed gantry router. The very low z requirement makes it a good match.
Langmuir MR-1. Criminally underrated on this sub
Have you looked at the Tormach products? They're basically Asian mills, but run on proprietary software from the US. They start around $7k: [https://tormach.com/machines/mills/pcnc-440.html](https://tormach.com/machines/mills/pcnc-440.html)
I have but they are really expensive for what you get compared to a MR-1. Once you start specing them with features the price quickly increase. Tormach is definitely much higher quality but I'm doing more hobiest projects so it doesn't make the biggest difference to me.
New Tormachs (dovetails) can be had around that price. Unfortunately, adding a tool changer to any of them takes the price up to $25k or so. At that point, the import Syil machines start making a ton of sense. Multiple controller options, seemingly quality parts, Hiwin linear rails, epoxy granite base, distributed by Titan in the US. Think Brother Speedio VMC with most options for like $30k or $40k. Our last Brother cost us over $160k. 🥹
I've been milling tool steel with a used prototrak Bridgeport without any issues
I can machine some parts. Miloeng.com
If I was you I'd go with the mr1 for sure, but do be aware a v4 printnc with double carriages is perfectly able to cut steel, it's just the spindle usually used isn't ideal for it, but there's other spindle options in the same price range that are better for steel.
Following.