1250 x 1250 cnc router (from scratch)

[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?

[Jonathan]

6mm cutters tend to be convenient if the thickness of the material is roughly 10mm or greater, so I tend to space parts out by 7mm. You can get away with a little less, but the finishing pass tends to work better if there's a reasonable amount of clearance.

[JAZZCNC]

6mm cutters tend to be convenient if the thickness of the material is roughly 10mm or greater, so I tend to space parts out by 7mm. You can get away with a little less, but the finishing pass tends to work better if there's a reasonable amount of clearance.

On top of this make sure there's room or spacing for a Lead-in and lead-out or ramping etc otherwise it means plunging into material and person doing cutting wont thank you for that.!

Really your better letting the person doing the cutting setup the layout to suit there clampings methods and machine.? If you try to cut it too fine on material it's easy to get into trouble so better having a little extra for safety sake.

[Danielroyal25]

cool ok, Just laying it out roughly to get an idea of the overall sizes of the plates that i will need to order. I will go for 10mm gaps and then whoever cuts the parts should have enough room to reposition.

[Danielroyal25]

Still yet to post the build images... But Was cutting some oak today and all was going well until the grub screw holidng the pulley to the stepper motor on the z axis come loose almost scrapping the material!
what do most people use 1 grub screw or more, any locking compond, keyways?
i checked the others before starting the machine again and they were all loose. They are stainless steel m4 screws but being so small the Allen key just rounds off if they are done up too tight.