Something like what you'll find at this link,but offset the center points so that the edge you are routing sits horizontal.
http://translate.google.ca/translat...ev=_t&hl=en&ie=UTF-8&layout=1&eotf=1&u=http://www.archiwood.com.ua/&sl=ru&tl=en

Or use some temporary method of attaching square blocks to the ends of your cylinder and do it on the router table. Adjust position of square blocks to orientate the grooves where you want to route them.

 

Brian, the easiest way I have seen is to make a box and mount the tapered cylinder level in it with screws into each end. The ends of the box will be at angles so the cylinder is level. Once you make your cut loosen the screws and rotate the cylinder to the position for the next cut. The smaller end of the tapered cylinder will be offset to one side of the end of the box for clearance.

 

I would do it in a similar way to Mike but I would just lay the taper flat on the router table. The screw on the tapered end would be 3/4" off the router table and the screw on the large end would be 1 1/2" high. The front screw would also be 3/4" farther away from the router fence than the rear one so that the cylinder would be parallel to the router fence. You could use a protractor on one of the box end plates to mark your angles, centering it on either screwhole.

If you don't have a router table, you could build a trough on top of the box for a router to slide on and level to the top instead of the bottom. If you go this way, I would put a second screw into the large end about 3/4-1" away from the center screw to keep your cylinder from rotating while you are working on it.

By the way, Derek Willis posted a jig about 2 or 3 months ago for grooving a straight cylinder. What I described would be a minor adaptation of it. Do a search for him and then check his most recent downloads.

 

Thanks guys
You have definitely put me on the right track.
Much appreciated.
Brian

 

Being now inspired by all your suggestions I went to the shed to begin. Mentally calculating angles of ends to set tapered cylinder level etc. I suddenly had a revelation.
I could use my B&D portable bench/vice to dispense with the sides and also set the angles of the ends all in one go.
Cut two pieces for the ends and screwed them to the cylinder ends. Put 3rd screw in to prevent rotation. Mounted in B&D at correct angle. Set router fence to edge of bench. Voila. Perfect job first time and repeatable.
Thanks again for starting me thinking.
Brian
PS Pics attached.

 

Good, practical solution, Brian.

 

The best solutions are the simple ones. I'm glad it worked out for you. Now you have to take photos of the rest of the project and post them.

 

Hi Mike
It's not really a project, it is an automatic rope making top. If you check out my video on youtube, search for "longropeadsl" and you will see an earlier one in action at our local Historical Village in Hervey Bay.
Apparently I have not posted enough to put in the full URL yet.

I liked the various comments, especially the upside down thinking. Sometimes that can work well, it's similar to thinking "outside the square".
Brian

 

It takes an Aussie mind to solve a problem like that Brian!

 

Aussie mind? What? Do you mean thinking upside down, Harry? :wacko:

 

Nice and straight and smooth. Good job.

 

Brian, Forum members have a wide array of interests and would enjoy seeing photos of the application. I will post the link for you if you send it to: mike.m@routerforums.com

 

Brian, Your description was very clear and your execution was very wise. I enjoyed your photos, also. A more accurate name for the shape you worked on is "conical frustum". Frustum shapes can be from cones (as is yours) or from pyramids - these are also known as prismoids. Frustums do not come to a point, but rather have tops and bottoms that are parallel to each other. Great Work! OPG3

 

Hi Mike
Did you get my reply re. the rope making?
Brian

 

Yes Brian. My cable company has been having issues and I could not get online. They know it's in the main cable on the poles from a test a tech ran the other night but unless 5 people call in about it they wont fix it.(Thank you Comcast!)

Here are some links to Brian's project application:
Brian shows the ropes of making rope - ABC Wide Bay Qld - Australian Broadcasting Corporation
LongRopeADSL - YouTube