I finally got some 7x3.5 tri props, a Q-Brain ESC and some SK3 1275 motors from Hobbyking (3weeks shipping).
I measured it out on the grid to see what size I need to make the frame, it came out to be 280 prop centers,
Next up was to make the frame, I decided to use 10mm U shaped extruded aluminum as its easy to get and easy to work with. I cut to length then measured the center so I could cut down 50% with the hack saw and then file out two slots on each frame so that I could then slot them together and have a flat x.
First cuts made next was to use a small file to make them as wide as the side walls of the U shaped aluminum.
After the cutting and filing the boom slotted nicely together. I drill a hole in the center and used a small 3mm bolt to hole then tightly in a perfect 90degree x, then used CA to help make sure there was no movement.
I started to use this plastic container as a base and zip tied the booms to it and got it to flying stage before I changed direction and used the spare plates I had with the spare part Rctime 450 frame.
The motors were all lock-tighted to the prop adapters and motor mounts. I then used zip ties to hold them to the RCTimer boom motor mounts. This part of the frame (Booms and motor mounts didn't change when I we to the plates)
STOP THE PRESS .....I stuffed up ..... grrrr
I somehow while using the excellent eCalc I got the props , motor, weight combo wrong. So when the above quad was finished it took about 70-75% throttle to take off ..... guttered.
i went back and checked my inputs and found that with all the permutations I was inputting I had used APC Slowfly for the prop details, once I used GWS which is what the props I got were ... it showed 66% for the estimated weight. So with is a little heavier 70-75% was what I ended up with. So back to the drawing board.
Luckily when I ordered the SK3 1275kv motors I made sure that they could also spin 8x4.5 as I plan to also make a hex using these.... lots of plans :)
So I ended up using the spare plates form the spare parts of the second RCtimer frame I purchased ... hey it was on sale and it was the cheapest what to get replacement arms, which I have already busted one of.
I zip tied my x frame with motor mounts on to the spare plate. I then used double sided tape to mount the Q-Brain to the underside. All was looking great. However with the size of the Q-Brain and the need to put on the heli landing gear and battery I then decided to also add the other plate. I just used nylon stand offs. See I knew all that extra "stuff" I used to maximise shipping would come in handy.
Using the 8x4.5 props was a tight fit, I had to slide the motor mounts out 5mm, but the fitted and it took off about about 45% throttle. I was much happier.
So I now have a smaller "indoor" quad. But I soon found out smaller means twitcher ... But its all good pratice.