James I have been trying to work with larger diameter conduit in other threads. From what I can tell the sizes vary a lot more than the smaller ones. I don’t think it will work well with the current tension system. Stainless is probably a better bet but I am also not convinced of that yet either as it has a lot of spring too it and that does not work well with the induced harmonics of a spinning bit. I am working on another way to allow for size variations but it cost more hardware…and in turn more weight. Never easy.
Definitely there are tradeoffs on size vs weight vs stiffness. Says me (not an engineer) stiffness goes up exponentially with the diameter of the tube, so a 1" EMT conduit should be much stiffer than a 3/4" , and 2" greater still. My guess is that the weight / stiffness tradeoff probably maximizes around 1" 1.5" EMT, but that is a WAG.
The issue of inconsistency is another problem altogether.
Still, I’d like to take a crack at making some larger tube fittings. Are the original CAD files available?
I’m giving up on asking for a bigger diameter, as it just seems to generate pushback and animosity. However, FWIW, when I read reviews that are critical of the MPCNC, they invariably say that it isn’t rigid enough. Now, I realize you guys take exception to that–“They’re using bad CAM!”–but if you offered an MPCNC that was a lot more rigid, I’m sure it would draw a lot more users. I mean, if you look at high quality CNC, it’s all super rigid, so it’s easy to see where the skepticism comes from.
You have not used one yet, so you are going on assumptions. After you use one we will all give your feedback more credit. You have asked for advice on every single piece and decision on the machine, and generally have not followed any of it. Most people will stop replying to that sort of thing.
The advice is very simple and used very often by everyone here. Build it small to learn. Small=extremely rigid. Trust me people are using this just fine for soft metals and on giant frames. The issue is always CAM. More rigid =more expensive. As I told you before we will not make it rigid enough for steel milling so why spend more money for no reason, it mills aluminum with enough accuracy for any of my projects, that is all I need. You are being very critical and spreading negativity by not taking our advice and continually posting that you want more…with no experience to base that off of. You are one of the people posting the critical reviews, and of the ones you have read are you sure they have used one? I was told by a CNC professional that what I did was impossible and was laughed off (aluminum milling with any 3D printed parts involved in the frame), until you try it your opinion is pretty empty.
Start with the pricetag, and the stereotyping you just did. What does super rigid mean. You are comparing a $350 cnc to a $350,000 machine. Dude you are killing me.
I am all for a more rigid machine. It is a system though all parts act together. At some point 3D printed parts are not the answer…I don’t think we are far off from that point. A decent sized build is (in my opinion) a very well balanced machine. 3D printed “spindle” mounts will need to be…not 3D printed. Rails will need to be way more accurate as right now the plastic has enough flex to take up the small deviations we have. A proper spindle will be needed as well as more perfect CAM.
Look at the ease of use of EstlCAM, and then look at what sort of settings are needed for the next step up in machines with Fusion 360 CAM…people get paid just to make Gcode.
Seriously a Tormach would be a good next step if you think the MPCNC doesn’t do what you want, they start at $5k. Orders of magnitude in price gain you different levels of machine. Not a few hundred dollars.
Not trying to be a punk here and I am open to ideas, but to come in asking for “improvements” when you have not tried the machine is a bummer for me. It is a few hundred dollars, if you need more you will have a CNC that can cut your new parts. I am not trying to knock Tormach out of the market, I am trying to get a CNC in every shop that wants one that can’t afford or doesn’t need a tormach or larger.
Dude, I feel you are being very defensive here – which I get, it’s your baby – but I’m not trying to attack you or the design. Often when you see this type of project on thingiverse, it’s OpenSource and parametric. Neither is the case here, that’s fine. I am thinking about building one – because I want to cut things hella precise, naturally – and noticed that 3/4" EMT is floppier than 1" EMT, which is pretty logical. It seems like a logical upgrade. And yeah, I haven’t used one (again, anyone in NC wants to show off?)
If there’s a 1" version in the works I don’t want to build a 3/4" version then realize I need to upgrade in the future. Yes, $500 is a reasonably substantial outlay for me, so I don’t want to do it twice.
My goal is to cut 2x4’ MDF, plywood, and maybe a bit of aluminum. If 3/4" EMT is rigid enough for that, then cool. If it could be a little more rigid, then what does it hurt to go to 1" or 1.5" EMT? I’m pretty handy with some fusion, so I’m happy to help. If you don’t want to open source, that’s absolutely your prerogative (bobby).
Anyway, I’m just trying to say where I’m coming from. No offense intended.
I honestly think most of the hobby machines are overbuilt. The genius of the MPCNC is that its not. It’s tough where it needs to be, and you can’t park your car on it.
The places where I’ve seen complaints about rigidity are in either in the context of “I have a 24inch high machine” or “It not as stiff as my 300lb of steel machine”. Would making it a little more rigid actually affect it’s performance? Prove it to me.
I can’t justify the lack of sharing autodesk files, but it’s not up to me. It’s not my work. The STLs and BOM are open. The software is open. A shitload of work goes into making something others can use. Ryan supports people who don’t buy from him. It’s a spectrum, and M$, this is not. Which is one of the reasons I volunteer my time to answer questions here. Other companies spend shitloads making changes so that it isnt reproducible.
Those were pretty much my goals as well. So I did my research and went with 1" stainless instead of the original 3/4" EMT version. It cost me $40 for 20’ of SS instead of $10 for 20’ of EMT. Would I have spent $18 for 20’ of 1" EMT if that had been an option, maybe, but probably not, most likely would have just gone ahead with the SS anyway. The bulk of what I have spent has been in the electronics and router, all of which are reusable should I decide on a different size or different version (i.e. lowrider). I think I have about $30 in filament to print the parts.
Re the router, I went with the Makita RT0701C and don’t regret that upgrade either. So far with that router on the MPCNC I have cut acrylic, mdf, pine and cedar. Also milled a PCB. And accidentally cut steel heads of hold down screws without a hiccup. I added a laser and have etched mdf, plywood and have cut 1/8" ply as well as cardboard. I have had zero problems with any of those, and all have been exceptionally accurate. And I expect to cut aluminum with no issues either once I decide to dive into that.
Bottom line, what my personal experience has been, is that the existing design is plenty strong enough given the surprising fact that it is significantly made up of 3D printed parts. Do your research on the 3/4" EMT vs 1" stainless option and give one a try. I think you will find that it works quite well without the need for a complete redesign to larger carrier tubes and higher moving mass.
Defending my choices, but 100% not offended, promise! Over the last week I have been challenged on everything so it is coming out condensed and to the point.
The beauty of the design, all the parts can easily be used for anything you want. I even do my best to keep upgrades from requiring anything to expensive. The last major update cost previous users 5 bolts. But you can use the “expensive” parts on a different cnc build or a printer. No specialty stuff. You would probably even be left with a new set of bearings for 10 skateboards.
100% LowRider territory, It would be an absolute monster at that size, and sheet material is why it was created. It is stronger at the low point, opposite of the MPCNC. See no larger conduit need, just a different geometry.
I have no experience with OpenSCAD. I do feel it would take a massive design hit if I tried to make something this complicated parametric. Someone else might but not me. Again, first thing that would happen is a 3" diameter build would happen and it would suck. Releasing anything better than STL also lets mass manufactures easily make molds, I would not be exited about that.
These all fall into the same category for me. The hardest part is the design, concept, proof. I have done all that. I have even done my best to show how complex parts can be made without support. The first few months people were doing all sorts of nasty things with my STL’s, combining them and making one giant weak part that “took less hardware”“better”“improved”. It was fine until I had to hear about how crappy it was and my design sucked because of those parts. My way of limiting that is keeping the easy, change a number, without fully understanding what it causes at a minimum. Like people strapping on giant routers calling it an upgrade, it is worse. Then the design and tool mounts started to get fragmented and people would only make a mount for there machine and not make the single dimension revision to make it fit the other two sizes. I would get flooded with emails asking me to fix it…nope.
With the concept proven and solid example proven the parts are super easy to reproduce. I am pretty sure there are 3 other fully redesigned MPCNC’s on thingiverse. It only took them a few days to do, and many revisions (recent college class pic, was 13 mini’s). At this point CAD is the easy part for edits. Knowing how the geometry is affected if the hard part.
I am passionate about supporting my creation to the best of my ability and providing everyone the best experience possible. Going open source will immediately trigger all the other people I have to keep DMCAing to start selling again, with there poor choice of components and crappy printed parts (1st gen parts freshly printed still show up in the forums from people selling/buying them trying to make a quick buck). This would take me away from helping anyone but my own supporters, that have proof of purchase. I already spend a vast majority of my time on support 7 days a week (started a coding project two weeks ago and haven’t been able to touch it). Anyone that needs help I do my best. I have never cared if they gave me any money. If I can not support myself on this I can not spend any time on it. I made a choice to make a machine that is not opensource but is easily sourced. So my open source machine does not take a specific board to run my custom firmware, or custom “open source” rails and bearings to use. Some of the others might be opensource but you still end up needing to give them money for some part or another. Not the case for me. Others have even started opensourced and since locked up there files (firmware, and hardware).
I am open to ideas about this as well. I just don’t see any other way at this time. Time spent, hosting fees, credit card processing fees (2.4%+$0.30), shipping packaging (ain’t free), returns, internet, power, R&D, all come out then taxes (state, fed, fees) take 38% of what is left. I probably do hold on to my creation a little too tight but from this perspective I give a lot of company’s more than half of my profits. Without this forum and people like Jeff helping (if you want to see what that looks like check the facebook group and the random “help” some people give) I would just go back to a regular engineering job, where everything I touch is patented for 20 years and I can;t even talk about some of them let alone help you build your own.
That’s helpful, thanks. Where did you get the SS rod from? McMaster?
I’m not going to tell you how to run your business, but this sounds a lot like an open-source project to me. Most are led by 2-3 key contributors until they get critical mass. They make money selling parts or support. The difference is that it’s not just you, it’s a community. You can still sell parts. Other people can sell parts. People will sell knock-offs (see Prusa i3. Josef Prusa still sells plenty of printers to keep him in business, though). I guess it depends on what model you want to support. It seems like you are trying to straddle the world of open source and proprietary commercial, giving away the design, selling the parts. Why not go all the way into either and make your living selling parts (Microsoft) or providing support (Red Hat). IDK, these are just the thoughts of someone in the software business. I’ve seen lots of businesses be successful with either model, but few that straddle the line. To put it another way, why give yourself the headache of doing all the design, support, sales, marketing, etc yourself? Other people want to help… at least Jeff does
Anyway, on the original subject, I’ll take a look at the lowrider again and some stainless rods for the MPCNC
I’m concerned that lowrider doesn’t give me the height that I want, about 8" .
I can see that you would be concerned about open source-ing your design … because some idiot like me will make a huge one that flops all over the place and try to park on top of it and say the design sucks, but if I’m the one who changed the design, I can’t really blame you, now can I?