Hello good people of the internet.
im starting a thread where i will be posting cad models of the cnc i will be building in the next couple of months, it will be used for machining wood to hopefully pay it off at least partially. i plan on cutting wood with it and doing some light cutting of alu or maybe even steel if possible, i will be upgrading it in the future when i save enough as im only a broke student. its a budget cnc that will be under 2500e, i hope xd. made out of steel square pipes 100x100x4 or 80x80 as the base and 200x100 for the x gantry( smaller one). this is going to be my first cnc so be gently with critique lol, im still in the planning stage of it all as i have another 2 months of working to be able to buy all of the material needed. i will post the pic for you to critique and explain more about the design.



https://i.imgur.com/zLSNYwf.png
https://i.imgur.com/QTwbFgl.png
https://i.imgur.com/ZhOmEiv.png btw y gantry isnt connected to the base properly dont mind that just forgot to extend those when i was redesigning
Dont mind the model, obviously its not finished yet. you might see that i have 2 different z axis, just wanted to see how it looks and im liking the first 1 as it gives me same travel either way. unless i get bigger pipes to raise the y axis to get more clearance. only possible problem is that while it should give me more rigidity and clearence by having smaller distance between bottom carriage and bottom of the spindle it is still 107 mm from the bottom spindle holder to the bottom carriage. the x gantry will be connected to y carriages with 18mm thich alu or steel if i find some. im using 25mm rails on y axis and might do the same for x and z as i decided to not use the alu profile made by vallder made for cnc machine as i heard that steel for same weight is 7 times stronger so yea plus i save around 90$ on the gantry. distance between bed of the machine is 40mm, 15mm between bed and spindle for the smallest plate i would cut on it and 25mm for the smaller bit i found, total travel is around 210mm and clearence between bed and gantry is 207mm. already bought belt reduction for nema 23s for cutting alu and steel i will make a design where its possible to just move the steppers around to use direct drive for more speed when im cutting wood. the spindle im using is 2.2kw cheap chinese. ballscrews 25mm 10mm lead im hoping i can make the machine with 2000mmx1000mm but i now realise how hard it is. ballscrews and rails are actually kinda cheap compared to the rest of the stuff so thats why i wanted to make a bigger machine because there wasnt a big difference in price. the ballscrews are c7 so y axis will have a precision of 0.35mm over the whole 2m length which is fine with me. rails are either legit unprecise hiwin, which i doubt, or a cheap copy. it is very hard to get stuff in south eastern eu so yea. down the line i plan on selling it for a profit and building a metal cutting cnc around 1000x1000 with expensive ballscrews and beefy rails and a nice toolchanger but will see. i have been reading a lot on this forum and im hoping this is what an optimal gantry placment would look like, if not i will change with the advice i get from here. for the people saying that this is gonna turn out like **** because of welded stuff ik it probably will but i will get most surfaces machined by a friend of mine. the second half of the machine is what it would look like if i used a different z axis design btw. i tried calculating the critical speed for the y axis but i dont think i did it right i would be more then happy with 3-4m per minute which is 300 to 400 rpm on a 10mm lead, prob will use 5mm on x and z. critical speed is apparently, i calculated this with minimal info and knowledge btw, 700rpm which is more then enough so around 400 atleast working without prob i guess, 700rpm if both sides are fixed which i have to ask if that means that end machining is different or im just using different ball screw support units. i dont want to use rack and pinion because of poor precision. so yea. if theres anything else you would like to know feel free to ask thanks for your time, cya