Router build

[JAZZCNC]

i want to cut fast ... i cant sit around all day watching the machine scrape about ....

so what would you recommend to cut 2400x1200 MDF minimum ... my initial design was 76x76 tube which was too small ... so 150x100 is too big ...

Ok well if your wanting to cut fast then your concerns are not just strength.? Your main concern will be spindle power and tooling.
You Can build the machine like a tank but ultimately the spindle power and tooling will dictate the speed you can cut at. Any machine using 100x100 steel section for the gantry will more than match most spindles that would be attached to a DIY machine.

Building a successful machine is about balance. No point wasting money on expensive servo's, ballscrews and massive steel structure etc if your going to attach a 1.5Kw spindle at the sharp end.! . . . . . Equally no point attaching 10Kw ATC spindle if the machine is flexing like a jelly fish. The results while differant in practise will still be the same.? . . . Disappointing.!

Balance is required so you need to define what your going to cut with the machine and be realistic regards the feeds/speeds/DOC. Everything needs to match and suit to get a balanced machine and this is where it gets hard and expensive to achieve with a Jack of all trades machine. Esp if your chasing speed.!!

Edit:

so what would you recommend to cut 2400x1200 MDF minimum ... my initial design was 76x76 tube which was too small ... so 150x100 is too big ...

I never said 76x76 would be too small and 80 x80 would make a decent gantry if design was good so I wouldn't be too concerned using that size section provided it had decent wall size. . . BUT . . Your box on box with no bracing and open ends isn't a good design IMO so I'd be looking to change things in this department.

[Blackrat]

wahoo

my rails and servo kit has arrived

but now to finalize the design to get building

[Blackrat]

oops ..

the problem now is how do i do the Z axis

mount the rails so that they move ? or mount the bearings so that they move ?

i realize that mounting the rails so that 'they' move is better as the forces on the rails are consistent and that the bearings are fixed ( as per the drawing) and .. that the bearings are maximized as they are directly bolted ontop of each other

but ... the biggest problem is that the travel is now limited ....

if i google z axis pictures, the majority is showing the rails fixed, and the bearings moving ... is it really worth the effort to do the visa versa ?

[Blackrat]

i think this render explains it a little better

the gantry bearings are directly onto the Z bearings which is great ... but i can only lift the Z rails until they are level with the bearings, which stops Z clearance .... sheesh i feel like im speaking Chinese now

[Clive S]

i think this render explains it a little better

the gantry bearings are directly onto the Z bearings which is great ... but i can only lift the Z rails until they are level with the bearings, which stops Z clearance .... sheesh i feel like im speaking Chinese now

Why would you want to go higher than that you have shown, you can't go higher than the gantry so lower the bed. The Z rails (in my opinion) are better fixed on the plate that the spindle is fixed to as it helps to stiffen the plate etc. ..Clive

[Blackrat]

to clear the work piece ... the bit will foul if it doesnt retract far enough

dont really wanna lower the bed (or raise the gantry) as this will induce more flex , vibration , resonance and the list goes on

[Clive S]

to clear the work piece ... the bit will foul if it doesnt retract far enough

dont really wanna lower the bed (or raise the gantry) as this will induce more flex , vibration , resonance and the list goes on

Well how about moving the z bearing blocks higher up the plate. ..Clive