For BP motors you shouldn't need any "assist" with BP powder. And you shouldn't need to "scrape" the motor unless you see clay coloring on the BP grain in the motor. There are some other threads around discussing clustering and staging that talk about how you can gently get that clay off. I've not had to do that myself.
Originally Posted by Rocketeer Gator
For clustering Estes igniters you'll want a beefy 12V power system. That usually means having a battery near the pad and a relay to control the power.
Also coil the launch leads near the pad so that there is some slack that the rocket can take up with it while the last motors ignite. But you probably only need that for a wimpy ignition system. Some people will suspend the leads to get the same affect. You can see the same technique used for boost gliders.
You might want to try an experiment and connect three of the igniters of your choice to the launch system of your choice using exactly the same wiring system you'll use on launch day. Try firing that and if you see the igniters firing sequentially instead of all at once you need to revise your plans.
I've had very good luck with the Quest Q2G2 igniters and BP clusters.
Will Marchant, KC6ROL
NAR 13356, Tripoli 10125 L3, AMA 800142, FBIS