Great job Tom. You'll probably want to use a dial indicator to tram the linear rails to each other. Also fill any none moving parts with sand to reduce vibration and chatter.
No you should use a dial indicator from 1 of the rails to you bed so that you get that one rail aligned to the bed, then you mount the Z axis and the second rail that will be aligned automatically to each other. Start by tightening the screws in one end of the second rail and tighten them as you move the Z axis along the way.
I'm working on a similar project, and what I've found is that our muscles are unreliable at assessing stiffness of structures meant for CNC machines. A frame that "feels" rigid can still flex by amounts many times greater than the tolerances we wish to hold. I've run many FEA analysis on my machine and keep having to add stiffness to reach my goals. One of the beauties of T-slot extrusion is it's easy to add rigidity by strategically adding members. A downside is it's not generally the most cost effective path to adding rigidity.
Indeed, though the chunky stuff like this is big enough to have a central core you can fill in epoxy granite type mixes for some small gain, but any gains are good. Though the slots themselves are not the best either... Still not how I'd build a CNC given a choice - as I might not be good at it but I can weld well enough to get by and big boxy thickwall tubes are going to be much better than these extrusions...Though I am somewhat tempted by an extrusion based thing coming as a cheap kit - something to get me working subtractive CNC quickly and should be good enough to bootstrap itself into a better machine if required.
These extrusions are generally quite light compared to i.e steel tubes the same size and even those don't have enough mass to dampen vibration. I mean it also depends on how hard you gonna push it and what material. One of my biggest doubts about these designs is using the thread holes in the ends of the extrusions. As the aluminium is quite soft the threads often wear out with a lot of vibration and forces. So the extrusions themselves might be rigid, but the joints maybe don't last long and for a CNC they need to be precise. Maybe using gusset plates if possible would be a good option and use the slots to connect. They might loosen too, but you can tighten those joints back up.
For all intents and purposes once you start getting into the micron turf you notice that everything is made out of rubber. Even a Deckel FP4 is rubber if you pull at it with your hand and look at it with precise enough measuring tools.
Folks on a budget should consider V1E LowRider 3, the entire gantry goes up/down, so you get relatively rigid cuts for thin stock. Personally built a 4 foot x 8 foot CNC and Sled for $900...
If you're only worried about Y-axis wobble, some diagonal supports from the gantry mount to the edges of the bed could do wonders. Pretty cheap, can either be under compression or under tension and it'll work. People often do that with 3D printers with this design, obviously with much cheaper/smaller supports than would be needed here, but the theory does scale up
Make sure your rails are perfectly parallel and level when you do the final assembly. Your end unit should glide more freely than that. I had the same issue when I built mine.
Agree. You can use the z axis plate to set the height end to end. Fully tighten one tail, loosely tighten the other. Then tighten screws a bit at a time using the z axis plate the pitch.
Yeah I'm kind of concerned he hasn't made any mention of that so far and he doesn't seem to be accounting for how much variance there is in the flatness / thickness of AL plate stock since he isn't milling the faces of those parts... Machines like the Avid CNC go through a lot of extra engineering to make a useable machine with T-slot extrusion...
I love that we're in the era of CNC machines that we used to be in with 3D printers. I remember the old days of plywood and other makeshift designs that users themselves would build, coming up with machines from scratch with little or no help from plans/etc online. Just a community of makers truly making. Nowadays we are seeing a similar renaissance-of-sorts but with CNC machines instead of FDM printers. A great journey to follow along with!
Well, really, we've come back to that in the 3D printing scene. Behind the glitz and glamour of the latest Bambu, and after the generic I3 ubiquity, there is a diehard custom built community that is going hard pushing limits of speed, acceleration and flow. A re-renaissance if you will!
@@darkmann12 And I'm all for it to see what will happen to the consumer/prosumer-market once the big names (like Bambu) adapt what the diehard custom scene comes up with. Like, the X1C just wouldn't even exist without the likes of Voron and co.
I am skeptical of that ball screw placement. Ideally you'd want to position it in a location that wouldn't create torque on the gantry, which in a non-loaded situation would be in-between the two linear rails. You could also position it on the underside of the carriage in a spot that would oppose the torquing force produced during cutting.
Between the rails is best. Chinese ball screws have excellent low backlash for the price, but are not quite concentric. The pushing and pulling on the floating end of that aluminum plate will likely cause a slight tilting of the spindle in the Y direction on each revolution.
I have this exact problem on my diy machine. That torque created on the gantry translates into the end mill falling a little behind the movement. This gets worse with time and it wears the linear bearings a lot faster.
One technique for mounting linear rails is to tighten just the top rail (preferably against a straight edge) and loosen the bolts on the bearings and other rail. Then tighten the bolts on the bearing blocks that attach to that fixed rail. Next, tighten the bolts on one of the lower bearing blocks; that will set the distance between the two rails. While moving the carriage side to side to hold the two rails at the set distance apart, tighten the bolts on the second rail. And finally, tighten the second lower bearing block.
I'm building one myself currently so here's a few tips: I had the luck to find some really heavy steel tubes at the scarpyard to build the machine base. They need to be scraped/sanded by hand to provide flat surfaces to mount the linear rails. So do aluminum extrusions, the can easily have a 0.05 to 0.1mm bow over a 1m length. You also need to make sure the surfaces you mount the rails to are not skewed on top of being individually straight, you can do this with a machinist's level (it's not that hard to improvise one). As someone else already mentioned you need to tram your rails: you can do this by tightening only one of them and using the sliding assembly to set the second one at the correct distance. A lot of stuff on a cnc machine is overconstained: unless you have a bigger machine already, it's really hard to have everything fitting together perfecly, then when you tighten the screws everything warps... Sometimes you can get around this by epoxying stuff together: just let it sit however it wants to sit when it's drying, you can add fasteners later on. It's also a good idea to epoxy everything you don't plan to disassemble for added stiffness, especially when you have a lot of contact surface area between parts Remember to fill will sand all tubes
@@lyrag6376 just look at the hiwin assembly instructions instead. the formulas for calculating the tolerances of the mounting/reference surfaces are all in there
As I'm sure you've figured out by now, the trick with those linear rails is to pass the bolts through each hole, and start the Tee-nut onto the bolt, then slide the whole assembly onto the 8020 bar.
Pro Tip: you actually don't have to slide the nuts in from the side 😊. Their shape and the ball detent on the back allow them to be added anywhere on the track just by pushing them in sideways and then rotating them INSIDE the slot by 90°. This works perfect for the original item system - I assume it will be the same for other extrusion brands. The more you know. Love your content!
I need this sort of inspiration like a hole in the head which just goes to show what an awesome project this is. For anyone looking to build something like this I cannot recommend your local fasterners supplier strongly enough. You'll get bulk quality bolts and nuts (and piles of other handy consumables and what not) for a decent price and know what you're getting each and every time. Cheaper then you'd expect too!
Degrease and regrease the linear rails to make them a LOT smoother. Often the stuff that comes in them aren’t great and also if there are any missing balls you can add some more. It makes a big difference to how smooth they move.
Great video Tim! Looks like you're already getting bombarded with suggestions in the comment section. Everyone becomes an expert in this topic 😅. It's a great learning experience building a CNC and someone such as yourself will get lots of use out of it.
I think a good idea would be loosening one of the two rails, tighten down the plate to both rails, and then tightening down the second rail while moving across the whole length to ensure that they are absolutely parallel
4 месяца назад
I use aluminium extrusions in a somewhat off-label way, as the frame structure for arcade stick-style game controllers (laser-cut panels go on the top and the bottom to complete the enclosure). This video was super validating in showing how tricky it often is to think through the order of operations for assembly.
I am not sure if this has already been suggested, but filling the extrusion with epoxy granite or a mix of sand and epoxy would add a considerable amount of mass. This would help with resonance and keep things from shaking around as much. The vibrations from milling metal can be significant. I have an MR-1 CNC machine which is of a similar design. It weighs about 1000lb and still shakes around when milling.
Hi Tom, Great project, look forward to seeing the next update. With the rails, they might be over constrained as they are hence the slightly stiff movement. If you slacken the screws on one rail slightly, only enough so that the rail can move if pushed but not by itself (i.e. it's not loose) then slide the carriage back and forth a few times and then tighten the screws back up. You might have to repeat with the other rail. Sometimes it's just enough to allow the rail to move to where it needs to be. I have used this technique on 3D printers a couple of times and it seems to work
Woo! Nice! You'll want to definitely gusset, locktite and tram EVERYTHING. Explore adding pebble or some other aggregate epoxy mix to the structure to add rigidity and dampen vibration. And nothing is overkill in a project like this!
Hi 👋, that looks very impressive, and a few months time I’m hoping to build myself a router flattening table, keep up the great work. Look forward to seeing it all up and running.,
This is beautiful construction. I have currently made a basic design with al extrusions from an old project that I want to make into a router sled for wood flattening. Definitely got good tips from this
Another awesome series, looking forward to the conclusion. I'm thinking of a mill, at around £1500. That would buy s lot of extrusion, methinks... 🤣 Get better, mate.👍
Nice $turdy machine! Having a CNC + 3D Printer makes so many projects possible. Built a mostly 3D printed CNC, awesome value, v1e lowrider 3. Look forward to seeing projects Tom makes with this thing.
Hey Tom, awesome build! I think your frame will out live all of humanity :) I work as an engineer for an automation company and we produce off the shelf axes that are also used for CNC applications. These enclosed axes offer a lot of rigidity by themselves and have internal guiding so they save you the hassle of having to align your guides. Added bonus is that these axes also enclose the spindle and thereby provide protection from chips and coolant (both tend to cause issues over time when they come in contact with the spindle). We also have servo's and what not to power everything. Feel free to contact me if you want to chat about your project!
Easy way to get the linear rails to move smoothly is to loosen all the bolts just slightly and move your plate to one end and tighten that end's bolts. Then slide it to the other end and tighten those bolts. Hopefully this will remove any non parallelism and it will move smoothly and you can then tighten all the other bolts. Make sure it's as square as possible everywhere you can. Parallelograms are the bane of these machines.
I should add that rigidity can easily be tested with a calibrated load like a fish scale or hoist scale, and a dial indicator, either to avoid FEA, or to validate it. Simply apply a test load at a relevant location and measure its influence at another equally relevant location to high accuracy. If you are unhappy with the result, bolt on more extrusions.
The linear rails should glide much more easily than that. You will need to make sure the two rails are dead parallel, to get the bearings to work properly.
A 45° metal triangle instead the backplate at 5:52 would safe you lot of money and would give you way more stability. There is no need for a double backplate, just a minimum 45°.angle to give it stability so that it can lead the forces to the ground. /|\ just so 🙂
Another great video. I would be tempted to try and link as many of the central bores of the extrusion together and fill them with either concrete or ideally epoxy granite. Should bind it all together and do some vibration damping. Could also throw some rebar in to add even more rigidity.
For the linear rails you can put the bolts and the T Slot nuts in advance, don't tighten them, slide all of them together on the extrusion, once you have 3-4 in the rest just slide in with ease and then tighten them in place. Saves a lot of fiddling trying to get the nuts in place once the rail is on.
You’ll want to tighten the top rail first. With all the bearings in nice and tight. Then move the Z-plate side to side tightening the second rail as you go. Then the rails should line up and be nice and smooth. Looks like you will end up with a solid little machine.
For the rails (and really all of the other moving parts), Castrol Hyspin e4, or another good spindle oil will keep the friction to a incredible minimum while maintaining a super thin film layer. Its not a cure all, but its something that always helps out a little.
Projects are always fun and hope it works out :) I have considered building one but i know the work it takes as my engineer friend has built and used multiple over the years also a company here in NZ "Zealandia Systems" with public support has decided they are going to do a more hobby based one which for the price and support is will be well worth buying.
0:50 good stuff this is one of the strongest way of joining those aluminium profiles, and also requires the least amount of fixings, there you used two screws, next worse thing would be using those angle brackets, two of them, each has two screws and two t nuts, that adds to 10 parts!
Instead of tightening through a hole, I would insted consider having the screw's head on the other side of the extrusion, which would leave space for a proper tightening tool, like at least an L shape clicking screwdriver, or a dynamometric wrench. Also adding beams in diagonal stiffens a lot the structure, it's not only visual, as a twisting deflection for a beam, is a compressing one for an other. I made a project were two boards (10cm wide each) needed to be linked perfectly parallel to one another, just 3d printing and cross bars using wooden food picks used fo skewers did the trick (though, I needed to glue them with epoxy at their ends). I didn't stand on it to prove the point, but it could easily withstand at least 40N with minor deflection, with just 16 bars made of wooden skewers
I'm pretty sure those rails require lubrication. Check for a threaded hole on either side of the sliding module. And there should be a lubrication channel visible on both upper and lower parts of those rails.
The good thing about using linear rails compared to rods or wheels, is that if you have any kind of imperfection, that imperfection will be the same every single time. That's great for reliability, because you can modify designs compared to the physical end result.
Looks interesting! I used similar size rails and carriages to build a sliding door for my bathroom so the gap between the door and the wall is minimal. I don't see anything overengineered in this video. Looks good to me.
I work with aluminum extrusion at work a lot, and I have to say that method of mounting them together is not ideal. We used to do it that way with button head screws, but what we found is overtime the part slowly moves down the slot. Then when you try and disassemble, your hole to access the screw doesn’t line up and it causes a whole world of problems. I would recommend sending a screw all the way through the clearance hole instead
Your x axis should be more free. The most likely culprit is the extrusion not being perfectly flat. I built a much larger one and I had to take the gantry to a machine shop and have a skim cut done on the face used for the linear rails. Also, have the lower side of the extrusion skim cut to be perpendicular to the rail face. This will remove any subtle twist in your gantry.
Those carriages have some amount of preload, they are not supposed to move freely. That is a good thing, because if they could move freely there would be backlash. On a 3d printer where the forces on the carriages are minimal, little to no preload is fine, but here its a bad thing. Also, the X carriages are not coupled together at this point, because he hasn't actually gotten fasteners that are short enough to be tightened all the way.
I'm pretty sure the X-rails aren't moving smoothly because they're not perfectly parallel. After attaching the plate, you should try loosening one of the rails, move the plate to one side, tighten one side of the rail, then move the plate to the other side and do the same
Nice looking build. One thing I think may be a bit more rigid is putting a plate on the outside of the gantry uprights and the side rails to tie them together, possibly a bit more rigid.
The x axis will probably travel better if you true up the linear rails to each other. I imagine you can find methods online, but I would lightly tighten the rails to the gantry and tap them with a lighter mallet until the movement is smoother. You could measure the ends to see which way the taper is and be more precise, but with precise bearings like that bringing them in can make a huge difference. I'm surprised they moved at all to be honest.
You're not going to get a stiff machine with bolted extrusions. Yes, you can site on it, but that means nothing. I can sit on a bean bag but I'm not going to use it to machine something. Here is a simple thing to try: put an indicator on the middle of the gantry touching the middle of one of the two support beams and push the gentry & pull the front beam and see how much deflection you get. That's going to be the maximum accuracy of your machine. I'm going to bet it will be in the realm of 0.5mm at best. That will break small endmills. Get a 10mm steel T plate cut to mount to the outside of each side and that will improve matters substantially, better than just doubling the vertical extrusion. Even better, make the vertical arm substantially wider and join across them with more steel plate behind the gantry, bolted (or better welded) to the vertical arms of those plates with as much crosswise bracing as you can. Best of all, join the side plates across the bottom with a couple of steel plates. The extrusion is fine for bolting rails to, but that's about all. As the aluminium and steel will move differentially with temperature you'll need to think through the mounting of the extrusion carefully.
Check out minitec extrusion system. They have this funky fastener that you put into the end of the beam, but tighten from the front rather than the back. So you can loosen it and slide it over when you need to, without having to have new holes thru which to tighten the fastener.
Make sure you lubricate you rails and ball screw properly ! Otherwise you'll will fry them quite fast... Rails (and carrier blocks) are tipicaly sold with a protective oil that need to be cleaned and replaced with proper lubrication oil or grease. You can find documentation on lubricant type and quantity for your rails dimension if you search for brand-name rails. Also, as other said, the gantry should move with as little friction and binding as possible, and the rail must be properly aligned. Any friction will translate in faster wear.
I think you need to find a better way to mount the lead screw. I'm really not trusting t-nuts taking the side load without shifting the whole thing sideways
