As people have contacted me about my nosecones, it is clear that my explanation of their construction is not very clear. I decided to post a more detailed description of my setup and of the construction process.
I came up with the basic need for a slow lathe and an active bit many years ago. In researching it, I have found several others who have built similar setups. ( search for Vaatsas brothers and I think it was aeromoe? on TRF ).
I have incorporated some ideas from theirs into mine. If you see something that I could do better, please let me know, and if you want to copy any of this for your use, be my guest.
The rail is 1 x 2 inch 80/20 for adjustable length and the uprights are also adjustable though I usually don't change the height.
The drive is a 3/8 drill chuck on a threaded shaft, driven by a small gear motor from ebay. The motor speed control is a 555 timer with MOSFET circuit – there are many variations online and the components are not critical and very cheap. With the timing belt reduction, I get 0 to about 25 RPM. While I'm cutting the foam, I usually run top speed, when cutting the wood nose and base about ½ speed. I have found with some of the larger cones I am running out of torque and I am planning to upgrade the motor drive.
One picture is just a hold down clamp for the pattern for the nose cone.
The router is a ¼ in. trim router from Harbor Freight - only $30 – but it works for this. The router base is screwed to the aluminum angles for stability and the router just slides in from the back. There is a small hole on the side to reach the tightening screw for the router base.
Under the router is the most important part of the whole setup – the vacuum. You can't believe how much foam dust is created cutting a big cone. The tube is 2in airframe- fits standard vac hose adapter. At the bottom is a follower, which is changeable. It must be the same size and shape of the router bit being used, and centered accurately, to be sure the bit doesn't gouge too deeply.
I usually use a ¾ straight bit for the rough cuts, till I'm about ¼ inch from the pattern. The final cut is done with a ½ inch downward angled straight bit for less grabbing on the foam.
The last pics are of an extra vacuum tank – a large cone will almost fill that twice.
The screen is aluminum window screen stapled to a ply ring in a smaller section of concrete tube The fittings are 2 inch PVC plumbing parts.
I keep the fan on the other side of the piece when cutting and especially when sanding the fiberglass to keep airflow and dust going away from me. It also catches most paint over spray if I have to paint in the house.