The rods I'm using are tool steel rods. They are hardened, and I am using synthetic grease on them. As for deflection, it is true that they might deflect, however when put on a stretch the deflection is nearly non existent. Like I said my printer is rostock based, however it strays from the design, being that it is open source you can call it what you will. I am aware the 3dr uses a similar design, however 3dr does not stretch the rods, it merely places them in their perspective holders. While this reduces the quantity of deflection, it does not eliminate it. For steel to be used as a precise guide it must be exploited to its designed potential. When builders make such a design tension is desired in any structure where one hopes for torsional stability.
Steel has a few states which must be observed.
rest (holds its own shape however it is easily disturbed and does flex) - not desired
spring state (It is mildly stretched holding its shape to a higher degree as well as maintaining a higher accuracy when under load) - not desired
plastic state (overstretch and warping) - not desired
In this kind of build, especially on oversize printers where those extruded aluminum rails commonly used can get quite expensive in lengths of 36inches or more where torsional stability becomes an issue even for those extrusions. A design where one uses simple black pipe and solid steel rails or as in my case recycled aluminum tubes reinforced by all thread rod removes any torsional flexing in the chassis and further improves the stability and minimizes axial loading on the rails when stretching the guide rails probably less than .5mm....
I also believe there will not be much if any appreciable wear on the rods or bearings after packing them with proper grease and simply performing routine maintenance on the system to ensure proper lubrication, I personaly think the wear comes from the rods flexing and the bearings being forced to dig into them vs gliding on a thin film of lubricant. I also have an idea to automate the lubrication of the rails when the printer homes before a print, I may or may not implement this portion.
My goal is quite different from reprap mentality here. Frankly speaking; my goal is to build a solid 3d printer that once setup it will work as designed. My real goal is to remove all plastic parts from the interior of the printer, and keep those plastic parts out of it while adding fire safety and a heated build chamber allowing for large ABS prints with no warping. Time will tell.
Steel has a few states which must be observed.
rest (holds its own shape however it is easily disturbed and does flex) - not desired
spring state (It is mildly stretched holding its shape to a higher degree as well as maintaining a higher accuracy when under load) - not desired
plastic state (overstretch and warping) - not desired
In this kind of build, especially on oversize printers where those extruded aluminum rails commonly used can get quite expensive in lengths of 36inches or more where torsional stability becomes an issue even for those extrusions. A design where one uses simple black pipe and solid steel rails or as in my case recycled aluminum tubes reinforced by all thread rod removes any torsional flexing in the chassis and further improves the stability and minimizes axial loading on the rails when stretching the guide rails probably less than .5mm....
I also believe there will not be much if any appreciable wear on the rods or bearings after packing them with proper grease and simply performing routine maintenance on the system to ensure proper lubrication, I personaly think the wear comes from the rods flexing and the bearings being forced to dig into them vs gliding on a thin film of lubricant. I also have an idea to automate the lubrication of the rails when the printer homes before a print, I may or may not implement this portion.
My goal is quite different from reprap mentality here. Frankly speaking; my goal is to build a solid 3d printer that once setup it will work as designed. My real goal is to remove all plastic parts from the interior of the printer, and keep those plastic parts out of it while adding fire safety and a heated build chamber allowing for large ABS prints with no warping. Time will tell.
