1250 x 1250 cnc router (from scratch)

[Danielroyal25]

Hi, here are a few more screen shots of the model. Done a lot of work on it, but still a few more hours to go... Please let me know your thoughts as i would much rather make the changes now than down the line. I have still got to add diagonals / gussets onto the frame to strengthen it up. What are peoples thoughts on the X pulley set up (i have left the cross bar unsupported so material can be slid through), ways to mount X ball screws and set up of motor / pulleys on Y axis?

[kingcreaky]

nice work. i can see some time has been put in to these drawings.

Pretty confident the guys will tell you to mount the Z rails the other way round.. so the Y plate holds the bearings and the moving Z has the actual rails if you understand? see my machine

I suspect the pro's will suggest more strength under that bed.

To be honest, I took all the useful pointers from the guys on here regarding strength and rigidity and resonance with a pinch of salt..I use 6mm steel box section and 50x100x6 ali for the gantry.... every one of my mates told me its over-engineered.

Now, I sh*t you not. It is only now my machine is working I understand what they were talking about. Its literally got to be SOLID AS A ROCK otherwise you watch the thing flex when cutting hard wood let alone Ali. Your only down the road... Come and watch mine do it before you spend any money

[JAZZCNC]

Pretty confident the guys will tell you to mount the Z rails the other way round.. so the Y plate holds the bearings and the moving Z has the actual rails if you understand? see my machine

If you look again Matt you'll see he's got it correct way round.!. . . BUT . . You have put the Ballscrew upside down with Fixed end at bottom. You want fixed end bearing near motor.

To be honest, I took all the useful pointers from the guys on here regarding strength and rigidity and resonance with a pinch of salt..I use 6mm steel box section and 50x100x6 ali for the gantry.... every one of my mates told me its over-engineered.

Now, I sh*t you not. It is only now my machine is working I understand what they were talking about. Its literally got to be SOLID AS A ROCK otherwise you watch the thing flex when cutting hard wood let alone Ali. Your only down the road... Come and watch mine do it before you spend any money

He really does shit you not.!! . . . Don't under estimate the forces they are high and if you want high Precision and accuracy then the average, and even well tooled up DIY-er can't over engineer.
Build it strong and don't be afraid of weight when it comes to gantry.? Better to have rigidity and sacrifice speed thru using larger motors than end up with flexy resonating gantry which gives crap finish.

[Danielroyal25]

Yeah I am the same really, thinking that the framework can be fairly rigid (nothing too over the top) but not seeing many cnc routers in the flesh it's hard to judge how much force is actually created from them. The idea was to try and create some storage for sheets etc under the bed (as workshop space is limited already) but this can be sacrificed by adding some more support struts etc to beef up the frame.
i was worried about keeping the weight down too for some reason? But as its going to be in the same position in the workshop and weight is a key factor for reduction of resonance and improving quality of finish those worries are out of the window.
still unsure whether to go with alu or steel tho...
matt - my gantry design is based on 2x lengths of 50 x 100mm 6mm wall aluminium in a L shape config. And 60 x 60 x 4mm wall alu box for the frame. Based on your machine would you change the material of the gantry?

[WandrinAndy]

The idea was to try and create some storage for sheets etc under the bed (as workshop space is limited already) but this can be sacrificed by adding some more support struts etc to beef up the frame.

To reduce the workshop space needed, it may be worthwhile considering going vertical..... JAZZCNC has a great design if you search the threads.

[Danielroyal25]

Yeah I'd considered jazz's vertical design but going to go with the standard horizontal set up as it will better for setting up the jobs that I will be cutting.

I should have the "finalised" model up pretty soon so all comments will be welcomed as I will start ordering materials and components soon after.

Just a quick question on fixings, is there any reason why hex cap head bolts (with counterbores) are commonly used over hex head countersunk bolts? Is there much difference in strength or is it just personal preference?

[Danielroyal25]

Hi guys. The design is now complete and into ordering parts!! Just arranging the machine parts so that they can be machined from one large plate. What is the minimum gap I can have between each part. I have made it 4mm so far will this be ok?