Cutting Centering Rings?

[fireone]

I am in the planning stages of a fairly big project 10 Dia. and was wondering from all the expiriance(never could spell) out there what the most efficent way of cutting 10" centering rings is. The largest hole saw I have is 6". I really don't want to have to pay someone to do it for me unless I absolutely have to. Any suggestions?

Thanks
John
TRA L2

 

[Missileman]

I cut my larger rings that I can't get with my circle cutter on a band saw then sand to fit.

 

[Rocketmaniac]

One way to do this is to rough cut the outside diameter. Drill a small hole in the center. Use a bolt, two washers and a nut to clamp it together (bolt then washer then centering ring then washer then nut) Then put the bolt end into a drill, turn on the drill and sand until it's the right size.

This is a good way to make several centering rings at the same time. Then when the outside is right, make your inside cuts.....

 

[Elapid]

...was mark all the rings out using a compass, then cut them out with a coping saw, doing the final trimming with a flex-shaft dremel and a sanding drum...

 

[Bill]

Originally posted by fireone
I am in the planning stages of a fairly big project 10 Dia. and was wondering from all the expiriance(never could spell) out there what the most efficent way of cutting 10" centering rings is. The largest hole saw I have is 6". I really don't want to have to pay someone to do it for me unless I absolutely have to. Any suggestions?

I do not know who came up with this technique, but Bob Wilson demonstrated it at a recent club meeting.

Drill a hole slightly larger than a router bit about 6" from one end of a piece of stiff plywood. Flooring stock will do nicely. Mount a router on one side of the wood so that the bit protrudes through the hole. Measure a distance from the edge of the router bit the outer radius of the ring you want to make and drill a hole in the wood the size of a bolt. Thread a 2" long bolt through that hole from the router side and secure with a nut on the bit side. This will be your cutting table. Support it horizontally on sawhorses with the router side down.

Drill a hole the size of the bolt in your ring stock at least an outer radius distance away from any edge. This hole needs to be just large enough for the bolt to fit through; too sloppy and your ring will not be a perfect circle. Turn on the router and place the stock over the bolt on the cutting table. Slowly rotate the stock about the bolt until the circle is cut through. If your stock is thick, you may have to turn it upside down and repeat the process to cut all the way through.

Remove the newly cut bulkhead from the bolt and remove the bolt from the table. Measure another point the distance of your desired inner radius from the far side of the router bit (you want the bit to be just within the radius from the new hole). Install the pivot bolt in this hole and repeat to cut the hole from the ring.

This method is much clearer seeing it in action than trying to describe it in a few words. You can make huge rings this way.

Suggestion: practice using scrap plywood or more flooring stock until you get the radii correct. It often takes more than one try to get an exact size.

Further suggestion: pay someone else to do it...


Bill

 

[fireone]

Thank You so much for the suggestions. Since I do not own a router I will try the drill suggestion in the morning. I will let you know how it goes.

 

[Bill]

Over dinner, I kept kicking myself for forgetting to tell you the best technique for cutting rings before I was mesmerized by the router table.

There are hole cutting bits to be used in a drill press. I am not talking about the hole saw, a cylinder with teeth, but with a bar perpendicular to the shank that fits into the chuck. Cutting bits can be attached to the bar at appropriate locations on the bar corresponding to the size of the hole to be cut.

The cutting bits have an angled point; that side of the bit is positioned inward to cut out a circular disc and outward to cut a hole in something.

Attach two cutting bits onto the bar, with the inner bit slightly lower. Clamp your plywood stock onto the drill press table beyond the swing of the outer cutting bit. As you slowly lower the cutting assembly, it first cuts the inner hole, then the outer edge of the ring. The two cuts are automagically centered and you do not have to clamp the piece down twice.


Bill

 

[rocketsonly]

Originally posted by Bill
Over dinner, I kept kicking myself for forgetting to tell you the best technique for cutting rings before I was mesmerized by the router table.

There are hole cutting bits to be used in a drill press. I am not talking about the hole saw, a cylinder with teeth, but with a bar perpendicular to the shank that fits into the chuck. Cutting bits can be attached to the bar at appropriate locations on the bar corresponding to the size of the hole to be cut.

The cutting bits have an angled point; that side of the bit is positioned inward to cut out a circular disc and outward to cut a hole in something.

Attach two cutting bits onto the bar, with the inner bit slightly lower. Clamp your plywood stock onto the drill press table beyond the swing of the outer cutting bit. As you slowly lower the cutting assembly, it first cuts the inner hole, then the outer edge of the ring. The two cuts are automagically centered and you do not have to clamp the piece down twice.


Bill

Do they make cutters large enough for a 10" diameter ring? I have one myself but it only goes up to 5 inches (diameter) I think. I havn't used it since my TARC team realized we were allowed to use the CNC router

 

[Stymye]

Jasper makes several sized circle cutting jigs ( for routers)

https://www.soundlabsgroup.com.au/jasperaudio/jasper_audio_model_300.htm

 

[moocrew]

if you have a somewhat good eye and steady had....and dremel...and router attachment...

you can make your circles on the material to be cut..then lay the dremel on it and cut away...
works perfect for me..

-matt