Da, e doar pt mine si am nevoie de 3 ...trebuie sa gasesc o alternativa... tre sa dau o tura prin magazine de profil sa holbez bine ochii poate pot incropi ceva...by realthor - Piața din centru
Yeah, that was stupid of me indeed to fail to see that. Wouldn't it be a better way to have 2 endstops for Z (in case of a corexy for example)? A parallel circuit (using both Z min and Z max for preventing a head crash and get rid of the flimsy spring-based shock absorbers? I have a design that would prevent sideways movement but funny enough I haven't yet designed a way to clamp the bed, just fby realthor - General
Quotethe_digital_dentist I did something dumb about a year ago and made the nozzle crash into a print that was stuck to the bed. It bent the heat break which I was able to straighten and continue using, but I ordered a spare for just-in-case. So far I haven't had to use it. Shouldn't motors skip steps before that happens? What monsters motors do you use? Quotethe_digital_dentistIf you wantedby realthor - General
@d_d: what about the shock_absorbing function of the spring part? Are you betting on the hotend never loosing position and never crushing into the bed? I wonder if I make one spring-thumbscrew a fixed one, if the head ever crashes in that area, there will be nothing there to cushion it and one might damage the nozzle...by realthor - General
@d_d: Yeah, I assumed as much. Coming back to the alignment of the rods I've got one idea: have one of the YRods inserted in metal, just as the upper ends of all 3 ZRods. This way I can really align X with Y and with Z with a square angle. Here's what I am talking about: So, with YZ I can do a square ruler alignment between Y and the Red tube/extrusion and then another measurement between theby realthor - CoreXY Machines
Hi guys, I am sure somebody else already thought about it and implemented it so I am asking those guys to post their solutions in this thread I am starting. My reasoning is that if one of the 3-points is fixed at a certain pre-determined height the other two points can be thumbscrews that adjust the plane relative to that pre-determined height. This way the complexity of the bed assembly decreasby realthor - General
OK, that pillowblock looks ok and it actually looks about the way I am clamping the linear bearings on the XCarriage for Horizontal rods that I am designing (discussion in another thread): But I will use this with common LM8UU bearings ...so there might be a difference. Also you seem to have the clamping bolt at the center of the bearing while I use the bolt to slightly catch the bearing recesby realthor - CoreXY Machines
I have previously designed for a vertical X carriage a tensioner that needed a screwdriver be rotated in between belts and it felt unnatural so this time, for the horizontal x carriage I am designing, I will adopt front accessible bolts with dome_nuts to push the belt in a recess in the carriage: But then again I have room to do this as the belt-catchers are not interfering with the printableby realthor - CoreXY Machines
SC8UU is too bulky for this. The bearing has some wiggle/play in it no matter what casing it has. The plastic casing will be a downside when the forces it's subjected to are greater than the carriage can handle. So for me I will limit the speed because if I want to go high-end there is no stopping for the better and better components you can go with. I am also thinking that stronger and strongerby realthor - General
Ultimately one solution is to not push it so hard that it overcomes all these failsafes ... You can push the limits very far and you'll need better and better parts ... but at some point you have to ask yourself what is it that you are after... So I try to listen and understand but unless linear guides don't come down in price abruptly I will stay with rods... Frankly I am tempted to go the otheby realthor - CoreXY Machines
I understand the wiggle in the bearings, I am sorry to prove such a thick skull sometimes but I fail to understand the lever thing. So far I thought you were talking about the bed itself but now I get it you are only talking about the relation between each Z carriage and the bed. So, if this is right, then on a cantilevered bed one would get the situation you describe, where 100g on the edge ofby realthor - CoreXY Machines
This is where I got with the design. It starts looking usable, still some things to straighten out but overall I am pretty happy with this Horizontal Rods version of an XCarriage but I there are quite a few supplementary hurdles that are introduced when 2 Horizontal Rods are imposed on the design and there are many good things about the Vertical Rods that I want and like. Moreover, in my opinion,by realthor - General
Quotethe_digital_dentist QuoteJamesK QuoteDD GT2 belt is 1.38 mm thick. When you interdigitate the teeth by folding the belt, the thickness becomes 2.2 mm. The clamp has 2.2 mm slots that don't allow the belt teeth any room to slide over each other. Hi Mark, I used your approach, complete with measurements, to make cable clamps for my new Y axis carrier. Works a treat - many thanks! Like that gby realthor - CoreXY Machines
In pagina principala pe forums.reprap.org e o sectiune care se numeste: "RepRap Marketplace and Job Shop", cu multe subsectiuni, dintre care si cea de vanzare de kituri, etc... Atata vreme cat scopul reprap este ca mentalitatea si imprimantele cu sursa deschisa sa ajunga la cat mai multi, eu zic ca o lista de felul celei care mi-ai trimis pe PM este binevenita.by realthor - Piața din centru
Quoterealthor Quotelkcl Quoterealthor Why do you say that "the distance between the left and right rods is too great"? leverage. the 300mm of the left edge is a massive lever which will rotate a tiny 30mm-long bearing on the right. that's a 10:1 force multipler. so a weight of 100 grams on the left end of the printbed now results in 1kg of force on the bearing. 1kg results in 10kg of rotatby realthor - CoreXY Machines
Quotethe_digital_dentist Quoterealthor realthor and i argued this back and forth in an entertaining way for what... a week? eventually we concluded that yes, amazingly, the triple join does actually create rigidity. it's the fact that each of the joints allow rotation only about one axis and restrict the freedom of movement of the other two axes that does it. so the total number of restrictioby realthor - CoreXY Machines
Quotelkcl Quoterealthor Why do you say that "the distance between the left and right rods is too great"? leverage. the 300mm of the left edge is a massive lever which will rotate a tiny 30mm-long bearing on the right. that's a 10:1 force multipler. so a weight of 100 grams on the left end of the printbed now results in 1kg of force on the bearing. 1kg results in 10kg of rotational force -by realthor - CoreXY Machines
Quoteggherbaz A bolt isn't the best way to retain a bearing in a loose environment, too much pressure from the bolt and you will deform the bearing or at least tighten it against the rod creating drag issues, it is also one point retention which means that with little time the bearing will slide back and forth in the housing and you will loose printing quality. If the bolt presses against a printby realthor - General
I have 8mm rods for X and 10mm rods for Y and Z. It's the weight that worries me if I go with larger rods. I have 340mm rods in X and 350mm on Y and for a bowden I have calculated flex and it's on the safe side. With motors on it it's a different story... If I was to go heavier I would serously consider linear guides or go straight to delrin wheels on extrusion a la Quadrap.by realthor - General
Quoteggherbaz You don't want to use that method to hold the bearings in place, you are better off making a new part in plastic or getting something that support the whole bearing in place. I have a feeling that pressing the bearing from the side isn't the industry standard but for this application is it really that bad? I don't expect to put a lot of pressure on the bearing to have it stay in plby realthor - General
This is how it would look with 25x25x2mm tubes and M4 Bolts+Locknuts: Edit: I wasn't happy with the extra width the carriage would gain by switching to larger alu tube so I have scratched my head for a while and tested one idea in CAD. Funny enough it works. Here it is: The M3 nut doesn't fit on the sides of the 20x20x2mm ALU Tube so that I do the above solution with this smaller tube but tby realthor - General
Quotelkcl 1) 2 bearings per rod, with distance maximised, stops y-axis rotation2) adjustment mechanism (slots in plate) allows taking up of machine-tolerance slack to stop both Z and Y upwards and sideways travel in each bearing.3) adjustment mechanism *also* has the side-effect of stopping both z-axis rotation (not completely) and x-axis rotation because the rods are pushed against the inner sidby realthor - General
Ok, I know what you mean about the ever so slight rotation about the Z axis. That can easily be done. 2) I was referring to the rotation of the YCarriage on the X axis as the belts are offset from the YRods center and tend to pull on the carriage from above, trying to take it down (like pulling a tree to take it down)... That is what is being resolved by having the nozzle right at that exact cenby realthor - General
@lkcl: 1) For the life of me I can't reverse-engineer what I meant there... but it was basically related to my belts being above the Y rods and also above the X rods, thus, because of this height, is pulling to rotate the YCarriages during functioning; 2) I don't understand the matrix thing but then again is past midnight here and I am quite tired. 3) ggherbaz's suggestion is of course the usualby realthor - General
Quoteggherbaz Use this instead: Yes of course I know about that. This was an exercise to re-use some of the left-out tube from the construction of the frame and bed supportby realthor - General
I am wondering if LME8UU (16mm diam LM8UU linear bearing) inserted in 20x20x2mm ALU square tube would be capable of performing under the loads of typical 3d printing. I am thinking of the following: but the bearing touches the ALU in 4 lines along the tube and It might pretty quickly wear out the aluminum walls and get play in there. So my question is: is plastic better for holding the bearingby realthor - General
Quoteggherbaz Unless you are planning on using thick rods and metal Y carriages, your movement in the X axis will swing your Y carriages Yes I am aware that in the sketch above the XRods insertion on the YCarriages should be VERY sturdy to prevent skewing of the XY assembly and that it asks for some metal in the YCarriage. Quoteggherbaz Best desig is X and Y axis at the plane. My 3) statementby realthor - General
Sorry for not waiting for answers from the community but I am trying to define how an ideal/efficient moving XY setup for horizontal rods would look like. So far I have defined that: 1) nozzle must be at the same height with YRods centers (to prevent positional errors due to slack/rotation of the YCarriages bearings) 2) the center of gravity of the XCarriage must be right in between the XRods (tby realthor - General
I was wrong in my reasoning above: the center of rotation is entirely dependent on the YCarriage and has nothing to do with where the XRods are situated, because rotation in YCarriage bearings will influence the rotation of the XCarriage thus the movement of the nozzle from its designated position. SO it's actually a little bit easier to position the nozzle at the same height with the YRods axisby realthor - General
The Closed bearings don't help with getting the nozzle as close to the rods, diameter as you have to add the difference but the open style bearings (LM8UUOP ex) can help a lot with bringing the nozzle upwards as much as possible. But I am not sure about the tolerances difference between the closed and opened bearings. How much worse are the open bearings with the forces involved with 3d printingby realthor - General