All good suggestions. I think the stepper motor changes are definitely a low hanging fruit for me i.e. changing the micro-stepping to full-stepping for all the drivers and adding a second X motor. The others will require some bit of investment 
which I will probably take up next. For example my Ramps 1.4 board will not be happy with the 24V option. Just to keep my eye on the prize, can you pls share some numbers (feed rate, doc, material) that you are able to accomplish (I assume you have tried all these changes)?
You can run a ramps at 24v but you need to modify it a bit. There are videos on youtube explaining how (this one for example : Converting a Ramps to 24volts - YouTube ). The bottleneck on some board are the capacitors voltage.
I canāt say for sure what your exact build will be able to do but I can offer a few suggestions.
First, try a single flute up cut for wood. Dual flute is not large enough to get wood chips out of the way in time for the next revolution.
Second, a bit more amperage on your power supply is a good idea unless you have a very high quality 3A, they are typically overrated so you need 40W+ to be safe if you are really going to push it hard.
Third, are your drivers set right? I ship the boards at least 20% under powered and that seems to be plentyā¦but you used larger steppers, so they will need more power.
BleepBleepBloop, has great suggestions but lets leave those out for a minute for this reason.
That means the machine is balanced. The router is slightly more powerful than the steppers that are recommended (and you have larger ones, 24v is nice but at your speeds will never produce a noticeable difference. The machine stiffness drives all other parameters. If it is possible to outperform the frame upgrading other stuff is a waste of money.
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Hi Ryan. Thank you for pitching in with your endmill and power supply suggestions. My 6A supply just came in today. I will order the single flute endmill next.
However, one part which is slightly bothering me is that there seems to be no documented baseline performance for the stock lowrider. This makes it difficult for someone who is building a CNC machine for the first time to evaluate how good the performance (and therefore the quality) of their build is. I know this a DIY effort with a lot of variables at play and the word āstockā in the DIY context is meaningless but let us substitute that word with āRyanās own buildā.
Some benchmarks w.r.t materials, DOC and feed rates from your own build will help a lot with debugging. A case in point being the problem I was having earlier wrt performance which eventually turned out to be a belt slipping issue. Kind of a rookie mistake but may be I am making more such mistakes and I am not even aware of them. If there was a way to calibrate oneās results against a set of known results, you would at least know that there is āsomeā problem. Debugging becomes easier if one knows that there is a problem to begin with.
The milling basics settings are the base line. Beyond that it is highly build dependent. For example my MPCNC can cut the stock 16 minute cut down to 39 seconds, my LR (2x4ā) can also go much faster but a full sheet build should be able to do at least the milling basics settings.
You will see the settings can vary even from board to board, standards do not really exist.
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It is probably highly dependent on the board & firmware. I was using the SKR Octopus and if I recall correctly it supports 24v out of the box and there was nothing I had to change in the firmware since the TMC2209ās automatically adjust for current.
Yeah basically mirror the parts on the current X1 motor to the other side for an X2 motor. I believe they are called XZ end caps so you use the ones with the zip tie attachments then print another X idler assembly. Iād recommend a drag chain too. Itās really the best way to manage cables. I think itās interesting that the LR2 mounts the X motors on the X carriage rather than putting them on the Y and having them be stationary. It would simplify a lot of the cable management if they were stationary.
Another thing I forgot to mention is the X axis can handle a lot more force than the Y. The LR2 can wobble a bit when loaded in the Y direction due to slippage in the Z axis rails. One rail goes slightly up and the other goes slightly down. The X axis may also have shorter belts depending on your setup. It can be useful to make sure you do most of your cutting in the +/- X direction.
For sure. Itās very easy to swap motors out too. I found some 92 oz/inch motors on Amazon for $14 each. To do a full LR2 and add on a second X motor thatās ab out 85 bucks and itās money well spent.
Personally I really like the SKR boards and thatās one reason why. You can also mount a touchscreen that makes it super easy to use the machine as it doesnāt require a computer/usb at that point.
Iāve been using it a lot but the most impressive thing Iāve personally done is flatten some maple with a 1" surfacing bit at 1/2" depth of cut and 25mm/s feedrate. Basically it is removing 1/2 a cubic inch of material per second. I only run it that fast with a brand new bit and change the cutting blades every time I use it as there is a noticeable drop in the routerās tone near the end of the process.
When I built my first LR2 from PETG to cut a 4x8ā area the frame was definitely heavily underpowered compared to the router. After some carbon fiber PETG printed at 100% infill & salt packed & remelted in the oven the frame was no longer the weak link but rather the belts and router (mission accomplished).
Well right out of the gate you get the advantage of running smaller wires which is a huge win in my book. I have my movement commands running at 5 ips or 127 mm/s which is roughly 238 rpm if my math is correct. I was sure to look up the tables for my motors online and the torque curve fell by about 20% at the 200 rpm mark. For what I was doing it was absolutely critical to have fast movement commands as slow movement commands were a huge bottleneck when cutting such a large area.
Itās a really bad idea to get close to the frameās limits so you want to stay far away from that or you start talking about breaking the machine and possibly catastrophic failure. A better goal is aiming to max out the limits of the belts. If you start to see the belts droop you can back off on your feedrate.
Iām just going to interject a few things about 24V powerā¦
So long as the boardās regulator can take it (Most of whatās available can now) it requires zero changes to firmware. The polulo drivers on the RAMPS style boards are current regulated via the trimpots on board. Others like the SKR Pro (Or Octopus) have a firmware setting that tells the board how much current to give the motors, and it sticks to that.
It would be a nice advantageā¦ but 24V makes zero difference to the required wire size. Wire size is dictated by current, which we set the same regardless of motor voltage, so itās going to be the same amount of current and dissipated power, regardless. If you set your driver for 1200mA, you get 1200mA from 12V or 24V (or 48v for that matter.)
You may also have seen this:
I=v/R
Ohmās law. Current is equal to voltage divided by resistance. As stated above, the current is set either by the driver pot, or a digipot controlled by firmware. If you specify 1200mA, you get a max of 1200mA. Resistance is a function of the motor. The coils on the motor are going to provide the same resistance when ordered to move. This is a combination of the inherent resistance of the circuit, the inductance of the coil, and the amount of mechanical power generated. All of these variables are the same for a given commanded speed/acceleration of the motor.
So in that equation above, if I (current) is a constant as dictated by the driver, and R is a constant dictated by the driverā¦v must also be constant as seen by the circuit.
The driver manages this by modulating the motor voltage switching it off when the threshhold current is reached. In effect, the voltage seen by the motor remains the same for a given situation. (This is important, or weād overheat the coils and burn out the motor.)
Soā¦ What good is the extra voltage? Well, consider that any electric motor also functions as an electric generator. Youāll have seen this with printers that have LED lighting. The printer is powered off, and you move something, and the LEDs light up. This happens because the motor is generating some electric power from you moving it. As soon as it hits the Vforward of the LED, the LED lights. This happens regardless of the source of what moves the motor.
So when you command that the motor spin at some given RPM, that takes a certain amount of voltage to generate the set current. The motor responds by generating voltage in the opposite direction. Say it takes 3.5V to generate the required current. The motor may generate 1.5V in the opposite direction. The driver will compensate when the current drops by switching on the 12V source for longer, generating 5V at the source. The motor sees the net difference of 3.5V, passes the requested 1200mA, (I guess weāre assuming 2.92 ohms effective resistance.) Now, letās turn up the speed. The motor starts generating higher voltage. When it passes 9.5V, the driver is no longer able to give the necessary 3.5V difference, since it only has 12V to give. The effective voltage drops, which means the amount of current drops, which drops the amount of power (aka torque). If you have 24V, the speed at which this happens increases, which is good for high speed printers.
So, higher motor voltage does result in higher top speeds, but at speeds where the 12V supply is sufficient, it makes zero difference to what is supplied to the motors. This is pretty much any cutting operation that youāre likely to be doing on the LowRider. (Fast travel moves could potentially be different.) This i what Ryan meant when he said that you wouldnāt likely see speed increases. Iām pretty sure that heās talking about cutting speeds, and not ramped up travel speeds. Iām nowhere close to the 5ips rate for cuts, Iām at maybe 1/3 of that as commanded by my CAM.
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Yo, i followed that! Iām making progress!
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There is a small tweak that can be made in config advanced to change timings.
Which is exactly what limits my speeds on my stock build, at moderate speeds. That is why the rest of your changes seem a bit overkill for me. On a 4x8ā build the rails are 100% the limiting factor. Not sure how you are swinging it around at 120mm/s+ mine would not like that even just for travel speeds.
While we are on the subject, even my 2x4ā build rails can be overpowered by my stock recommendations, and I have not found the printed parts to be a factor whatsoever. Maybe because I have a normal-sized MPCNC sitting next to it. I know exactly how hard I can push it, the LR frame is way lacking compared to the MPCNC frame (itās a size thing). I think I could do the same cut at least 5xās faster on my MPCNC, but my lowrider cuts bigger stuff, I use both.
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By the frame I assume you are referring to the steel tubing and wood panel parts since you refer to the 3D printed parts separately. The frame on mine hasnāt been an issue so there must be some asymmetry there between your scenario and mine. I used 1" 304 stainless steel tubing with 0.065" wall. The Y plates are stock with 0.5" MDF but the X plate is modified with 0.5" MDF and I widened it a bit for attaching some larger tools. Even with the bigger motors I canāt get the frame to budge even if I crash the tool head into something. The most Iāve noticed is some wobble that tilts the dwp_611 plate +/- Z direction when cutting on the +/-Y direction due to slop in the Z rails which are aligned parallel in in the Y direction.
Iāve run it much faster than that too but backed off because this was as fast as I was comfortable running it. At this speed it doesnāt give you much reaction time to identify a problem and cut the power.
I think Iāve seen a few people on the forums whoāve had parts break (usually layer separation) which was my experience as well. Stronger 3D printed parts also allows for higher clamping forces. You can tighten the XZ main and endcaps a lot tighter with stronger parts.
I am not sure what you are referring to specifically since Iāve mentioned quite a few. The motor changes were necessary to avoid the X axis from getting stuck with debris build up, the 24v power supply allows you to run the machine super fast and reduces the size of the wiring needed, the carbon fiber parts drastically increase the rigidity of a machine that when printed with plain PETG was quite flimsy and had several part breakages.
If we are talking a difference in usage of the machine then I can see how you might think these things are overkill however for the things Iāve been doing these changes have made big improvements. If you think itās overkill thatās fine I am just sharing my own experience.
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Everyoneās machine is their own. Making the changes youāve made are fine for you. Where it gets a little abrasive is when trying to encourage others to do the same.
This is a thread where the question was asked. You answered with your opinions and experience, and some of that was disagreed with. Mostly for the sake of less experienced users.
It is a healthy discussion.
Iām glad youāre happy with your changes. It sounds like your machine is crushing it. More power to you.
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It is perfectly fine to change it to suit your needs, please just be careful making people feel these are needed changes. I would love to see some video to convince myself to test any of these things again, I am wrong all the time.
On my 2ā wide machine I can easily overpower my 1"x.083" rails. that is basically twice as rigid as a 4ā wide build. I think we use our machines differently. Instead of moving faster I cut deeper (same load, one is just more suited for this machine). Deeper cuts also tend to extend the life of the endmill. Have you seen the drag race stuff we did a while back? I would love to do that again with the LR, that would be a great way to convince me to revisit my design choices if you are interested.
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I am not even going to try threading the needle between āsharing my experienceā and ābeing careful making people feel these are needed changes.ā Thatās an impossible standard to meet. I am getting the feeling you were offended by some of my improvement suggestions. The LR2 is a cool machine and you did really well with it. That being said it is far from a perfect machine and, in my opinion, requires a lot of modifications to make viable. Have a nice day.
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Viewing this from the side, I donāt get that feeling at all.
I really DO want to see your machine zipping along at 5ips though. That would be awesome.
Iām running my LR2 pretty much stock standard, working area 45" by 60". Itās definitely slower than my Primo, but since I intended to use it for the larger work area, Iām fine with that speed. if I need 5ips or better, Iāll go spend the money on a machine designed around those capabilities. (I came really close to building a Joes Hybrid at one time, which would be more than up to that task. ā I used to talk to Joe on a different forum when he developed his first 2006 machine.) Actually, speaking of that, Joeās 2006 is pretty capable DIY CNC too, though by the plans, a little bigger than my Primo. It will cost more though. Youāll spend more on motors, drivers, and control boards.
I guess it depends on how you define āviableā
The LR2 works. It does what itās designed to do and does it more than reasonably well. As a budget hobbyist CNC itās price point is unbeatable. I donāt think youāll find any other full sheet capable CNC that you can build for less money.
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Absolutely not, that is why I kept asking to see them. I have a ton of 24v power supplies on hand and they cost pennies more, I can get any steppers, etc. If your improvements do what you say and the X rails are not the limiting factor I can increase the speed of the LR for pennies. I am genuinely excited to see your results, like I said I would like to run some drag tests, speed and material removal rate are completely separate. If you can beat me I am very interested in making some changes.
I donāt think so. Say things like here is a link to my build thread and videos of what my machine is capable of. In that thread is what I changed and how much it cost.
Saying things like,
Is the part I most disagree with. I did not find this to be true, but would love to be proven wrong, especially since this would cost the least to change.
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Iām with Dan. I donāt know how far away you are from being a beginner, but Iām close enough that I remember it well.
It can be hard to figure out whatās wrong when youāre getting started, and even though you (and many ither folks) modify your machines for good reasons and with good results, the best way for MOST people to have a good experience is to get a machine working correctly under known parameters.
There has been a ton of discussion around this in the past, whether certain mods might be recommended under certain conditions or something to shorten the path for people who want more. You fit right in with all the rest of the power users, and we all love seeing high performance machines, especially mpcncs.
I think a lot of the old hands are most interested in helping people get to a reliable starting point that we all understand first, and the OP just hasnāt gotten there yet.
Iāve found everyone here to be really supportive of mods and new ideas, and genuinely helpful, inquisitive problem solvers.
Hope my perspective helps to fill in some of the intent blanks that always seem to be missing in internet forums.
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If you want to know my thoughts on the LR2 as well as recommended improvements you can contact me at bleepbleepbloop1234@gmail.com.
The topic of the thread was āperformance boostā not āintro advice.ā Itās clear there is some hostility here by the bias that is being portrayed & disproportionate reactions given to mere upgrade advice. I apologize if I made you upset with my criticisms of the LR2. Have a nice day.
I thought this point was worth addressing.
Setting aside the clear advantage of being able to run smaller wires and faster movement speeds, the stepper motor torque curve usually reaches a peak at 50-75 rpm or something to that effect (it depends on the motor). Before this point it declines, after this point it declines. Doing slower cuts does mean you are operating in a sub-optimal part of the torque curve. Moving at higher RPMS does produce higher torque at least before the peak, and at those higher RPMs the higher voltages do improve torque. You can see that clearly in examples such as this and this. Now the question is if it is reasonable to cut at the speeds where this higher torque band occurs. I will attempt to estimate this but it really depends on your particular setup.
A GT2 timing belt has 2mm per tooth which combined with a 16 tooth pulley produces 32 mm/rot. 50 RPM is 1600 mm/m which is roughly 27 mm/s. In other words, based on this estimate it is feasible, depending on the type of motor and cutting speeds, that you can reach a more optimal part of the torque curve at a reasonable feedrate for the LR2 and, at that RPM, 24v would probably improve torque. Someone running a 1/8" bit through MDF could, in my opinion, easily reach 27 mm/s. I believe the benefit would be far greater for motors with 400 steps/rev.
If you are running your motors at sub optimal values then, yes, the input voltage doesnāt matter. A racecar and a minivan both perform the same at 25mph. But, as I said before, I would be more comfortable continuing this conversation via email.
I donāt think we are far off in our technical opinions. And I thought we were all being pretty nice about the differences. If you donāt want to deal with a little criticism, then fine. I am disappointed youāre leaving. You seem like you want to help and share, which are both qualities we look for here.
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I think you got me confused with someone else, because I canāt understand where you got the impression i was upset or that I even had any opinion on the upgrades. I was just trying to show you that this crowd is motivated to help people, not tear them down. Many of the folks in here are also incredibly technical, and many of them professionals, where theyāve gotten used to debating merits and drawbacks with folks who arenāt emotionally attached to their arguments.
And dude, I GET where youāre coming from, but look at it this way (to borrow your auto analogy). Suppose a guy showed up in a car forum and said this :
āHey guys, i just 350-swapped my miata, and i ran the quarter mile in 18 seconds. I think it should be faster, so if i were to throw money at this, what would be worth doing?ā
I really do hope youād have better ideas than telling him he should go look for an LS or strap a supercharger on his 350 or get better tires.
Yeah, theyāre all performance boosts, but something looks REALLY wrong first.
As for other folks, I think everyoneā¦ EVERYONE in the thread who had questions about your setup said they wanted to see it. They have understandings of how things work based on other things they know. If those things arenāt right, their understandings may not be right. IIRC, Ryan even said he might have to update his recommendations if 24v really is that much better than 12. (maybe that was another thread?)
The people here change their minds and learn from each other, and they do it by experimenting, discussing, and back to back testing.
Donāt believe me? Search for āconcrete filled tubesā. Lots of skepticism, then big claims about epoxy filed tubes, skepticism about that, then some testing, and now we all know that we can expect a little bit of improvement if done a particular way, and how much that improvement is. Or the double decker mpcnc. That one was fun.
Now, Iāve done my absolute best to help you understand what I think is going on here because you seem like a good dude and I think you belong here. Your comments in general (not just in this thread) have been positive and helpful, and I really appreciate your input.
@sparkm, Iām sorry this is your thread now.
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Spark asked what could money be best thrown at. You provided an awesome answer. I should have just stayed out of it. 100%.
I can assure you no one here is offended, and I have said that before. I would offer the advice that over the last 7 years no one really gets wound up around her. If you read all the replies like we are very excited kids I think it might read more true. This is not like most other forums in that way. At the same time trust me when I tell you some people around here really really understand some of this stuff to a very very high level, it sounds like you are one of those guys. If we donāt understand something you do, try and help us understand like we are very excited kids.
Again, I am sorry for even poking my head in this one. I just got excited about what you have achieved with your build, I did not mean to sound so skeptical, I was just excited and wording things poorly.
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