1250 x 1250 cnc router (from scratch)

[kingcreaky]

Greetings Dan.
Il answer what I can, however Im no pro...
*You want 2 ballscrews driving the X on a gantry that wide, to stop it crabbing
*in regards to one stepper or two, this is a bit of a sore subject on this forum. Both methods have their advantages comes down to personal choice. Im going for one stepper driving two screws.
*(controlelr/breakout board) This is talked about in lots of different threads by people far cleverer than I. So I wont comment.
*extrusion...get a design drawn up, its the design stage that will answer that question. Its all very well me saying yeah 80x40 but it depends on your design. Mine uses two peaces of 100x50 box 5mm thick in a L setup
*The HiWin type cartridge rails are the ones to get.. They are expensive but from what I read are about as good as it gets.
The supported round rails from china are what I went with, which I understand are good enough (so long as you pick the supported ones) but nowhere near as good as the HiWins

I would read ALL the build threads... If you had done this prior to the above post you would of been able to answer all those questions yourself, from the wealth of information you gather from reading them. Then get some designs uploaded and be prepared for them to be picked apart!!!

:-D wish you all the best with your build. make sure you keep this thread updated as there are some sad individuals (me) who regularly check for updates to build threads!!!

[Danielroyal25]

Thanks for the reply / info.
just working on the CAD model now so will hopefully have a few images up here soon for everyone to give their input.
I have decided to go with two rails on the x driven by 1x motor via toothed belt. I have read a few more posts and learnt tons more and have seen quite a few heated debated over that issue but think the belt will eliminate any room for error as its mechanically sound.
I will have a read up on the controllers, I can see the ads / dis ads of both but I guess i just have to make a decision and stick with it.
Will keep you posted on the progress.

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Got quite a bit done on the model today but still a few bits to do before the pics go online.
Just want to confirm a few things before i progress any more. My shopping list for rails and ball screws are as follows (all lengths TBC):

Ball screws (machined with ball nuts)
X = RM1605 (400mm)
Y = RM1610 (1500mm)
Z = RM1610 (1500mm)

Linear round supported rails (with SBR20/25UU bearings)
X = SBR25 (1500mm)
Y = SBR20 (1500mm)
Z = SBR20 (400mm)

Looking at getting these from the famous ebay guy, does he machine the ball screws to accept pulleys to or just couplers? can the length machined for couplers be used for pulleys? has anyone used pulleys from cnc4you or does everyone generally use HTD pulleys?

On the X and Y's is it best to have BK15 bearings on both ends of the ball screws for extra support and BF and Bk on the Z or will BF and BK's all round be ok?

I was looking at using dia 20mm ball screws originally but after reading posts on here, will probably go with 16's.
As feed rates and resolution are always discussed regarding ball screw size is it just down to what the machine is used for, as to what to go with. Are the 16's a good all rounder for both?