George's 8x4 router-me-bob

[JAZZCNC]

Hi George,

There's no reduction it's 1:1. The main reason for the belt is to reduce resonance and also allow easier positioning, the gearing is just a bonus if needed.
The previous drawing shows the motor up high but I also make them with the motor reversed, it just depends on the gantry design really. If possible I use the other position as it keeps the centre of gravity lower(no big deal) and it looks neater. I'll let actual real picks explain they show it better, ignore the bracket that looks like num 1 thats machine specific.

Tip regards material be very carefull when selecting or buying the Ali plate that it's perfectly flat. . . It's often not.!! Often it's cupped across it's width or even twisted in it's length.
If you look close at the pics you'll see I machine all the bearing mounting surfaces. I do this for 2 reasons.
#1 It gives me a register for the master bearings and rail to butt against which makes setting rails parallel easier and allows for easy replacement/setup if stripdown/cleaning required.

#2 Very important.!!. . If you try to bolt rails or bearings to material thats not flat then you get binding in the bearings increasing friction and causing premature wear, if bad it will lock them up soild when tightening.
Linear profiled rails are by far the best for performance and longevity but like all high performance things are tempromental and in tolerent of shoddy inferior material or poor workmanship so therefore require higher accurecy.
If you don't have the capabilty to machine surfaces flat then I strongly urge you to buy ground flat plate like the ECO CAST from Alu warehouse it's more costly but will save you a world of pain and give much less friction and smoother action. This is what I do now as the little extra it cost's is worth the expense as it saves me many hours machining and I just machine insert pins for master registers and machine the edge.

Making one with linear profiled rails, 16mm ballscrew and 20mm ground flat plate along with pulleys etc will cost you around £310 and will handle anything you throw at it for millions of years at DIY level.
Skimping on a Z axis is just plane dumb IMO if you want a accurate machine as it handles all the cutting forces.!!