Hello Peter
it seems like you are on the right track. Make it Rock Solid? Just replace every plastic part with aluminum, refit anti backlash ball screws and end bearings on all axes, and you still will be dealing with a limited table top thickness. Due to the nature of the single motor drive setup on the y axis the shark needs a moving bar under the table. Some other machines drive the y with a separate motor on each side, and have no bar under the table, allowing a more rigid table top.
But all is not lost, you can improve your machine greatly for a modest amount of money.
IMHO, the aluminum router clamp is a must do, more to prevent catastrophic failures than to enhance precision. it will help hold the router more firmly and give better cuts as well..
Like the clamp, The aluminum backplate will strengthen up the gantry assembly and should add to the resale if you move on to a better machine in the future.
Precisebits collets for your router are a must have for minimizing runout.
For the table top, consider swapping your bed plates around to put the narrow ones on the outside. Then you can bridge the sections together with hardwood slats on the top.
The slats add to the strength of the tabletop by locking adjacent sections together and creating a stiffer top. The slats must be bolted to the rails in at least 3 places, center and ends, to strengthen the bending resistance of the top. I use 8 bolts per slat on a standard 24" shark. The slats are then machined down to be coplanar with the router travel. This allows you to keep the center slot in each wide rail open for clamping. I then use a very thin spoil board ( 1/8th inch or less) under the workpiece itself if you are doing a cut through type of operation. For carving etc it is not needed. These threads have more info.
http://www.cncsharktalk.com/viewtopic.p ... 6&start=10
and
http://www.cncsharktalk.com/viewtopic.p ... 59&p=22946
Now the bad news, depending on your need for precision, the above modifications help keep cuts straight by reducing deflection. You still have to deal with the backlash issues from the lead screw and nut, etc. If the machine has .002 backlash (on a good day), you will need to optimize your cutting techniques to work around the shortfalls of the machine. For instance, orient your neck so that the fret cuts are perpendicular to the y axis so that axis does not need to move while the fret is being cut with the x. etc.
Personally, I would wait with the spindle until you can have the machine working to your satisfaction. You may not be able to get the spindle cost back out if you resell, and I am not sure that the NWA package is shipping with the promised on-off control. Then you would also need now router camps as I believe the NWA supplies clamps are plastic.
Hope this helps a bit.
Bob
