Plywood/mdf placement on table?

[myxpykalix]

I have talked to a few botters who have expressed regret in where they placed their plywood/mdf on their table (I assume because of clearances or other factors). I have a 5'X8' (10 ft actual length) table with an indexer and am just getting it together now and wondered if there were recommeneded distances from edges or ends in general experiences that i might not be aware of? For example I thought, since my table was 10 ft long I would have the plywood start say 6" in from one end, then the 8' plywood and leave me a 12" space to mount some type of vertical holddown system if I wanted to cut dovetails on a board, plus my 6" clearance on opposite end. Is there something wrong with that thinking or am I not taking something into consideration here? thanks

[gerald_d]

Remember to take the offset of the router within the y-carriage into consideration. It may be about 4" off-center, towards the y-motor and towards the 0,0. This means your table surface is 8" nearer the one end of the table than the other, if your want your cutter to reach the two ends to the same extent. Quite a significant effect.

[dingenis]

placing table,
i have a prt96 2003
with my bot i noticed that i could not get the x rails straight all the way.
doing two sided cutting i cant use the first and last 4 inches of x-carriage travel.(router placed about 110mm off-center, towards the y-motor and towards the 0,0).
i have placed my plywood-table as close to the lower left corner as possible, to have some space left at the other end ( space for vertical holddown).
yes, i regret this.
I am planning to move my plywood table to the middle of the x rails.
fyi the accuracy i realise is < o.15mm overall in the midle of the table.(so in two sided cutting the accuracy is <0.3 mm)
on the ends of carriage travel it is about 0.3 mm
check straightness of rails!