Easy way or tool to cut centering rings

[mtarallo]

Hi All - new to the forum. I appreciate your thoughts and insights. I just got my son (9) into this, I used to do it as a kid and loved it. We made our first paper towel tube rocket and we used a B6-4 engine. (half of a plastic Easter egg as a nose cone and cardboard fins) The thing flew almost perfectly - see video - and survived. I am designing other homemade budget rockets and wanted to know what is the easiest way to cut centering rings? I don't have patience to use an x-acto knife and my scissor skills are less than perfect. I am having a rocket party with his friends and I want to see if we can do this easily - or at least have them pre-cut. For the first one, I used corrugated cardboard circles, which worked but was not ideal for what I wanted. I need a tool something that can punch about a 1 1/2 diameter with a 1/2 diameter center. I searched the internet and found a few promising things, but none of them worked as expected.

(I want to try some low power engines, so I hollowed out a B engine and an A engine fits perfectly in there - so I can use that as a motor mount. I just want to mount that in the tube. I appreciate your thoughts. Thanks guys.

Note - I bought the design kit too just for fun, but I want to save that stuff for my son and I.

[video=youtube;1WScHYcttJU]https://www.youtube.com/watch?v=1WScHYcttJU[/video]

 

[lcorinth]

I think Fiskar's has a circle cutting tool which makes circles up to 6 inches in diameter. I'm not sure how small a diameter it can cut, though, so I'm not sure about cutting centering rings. You can google it to see.

 

[lcorinth]

And if you want budget, you can get parts without the Estes Designer Special price at various vendors. My first go-to is JonRocket.com. You can get standard size tubes, centering rings, motor hooks, and nose cones. I've built rockets with their parts for probably 6 bucks tops.

 

[rharshberger]

Fiskars and Olfa both make a circle cutter for light duty materials (posterboard, card boards, and my favorite CR material for LPR....cereal boxes), of course if you don't mind spending 25 to 85 cents apiece Balsa Machining Service has the best service and most of the common LPR rings can be had in fiber (cardboard), lite ply or plywood for a great price and quick service. Not sure where you are at, but if its in the U.S., BMS is fast.https://www.balsamachining.com/#

 

[RocketFeller]

If you have a drill press, an adjustable circle cutter can produce some nice centering rings out of heavier materials.

 

[rharshberger]

If you have a drill press, an adjustable circle cutter can produce some nice centering rings out of heavier materials.

View attachment 273316
one of these, the one on the right works best (single cutter one, by General Tools), the two cutter one is from Harbor Freight, price difference is about $4. If you are just doing LPR then cardboard/fiber rings are fine, for MPR I like thin plywoods (up to .125") and for HPR .125" to .5" or thicker plywoods. These two tools can be very hazardous to fingers so use clamps/secure the pieces to the drill press table and keep hands away. For CRs under 2" I use a scroll saw with circle cutting jig for up to .125" or just order them from BMS its so much easier and costs me about 2 dollars at the most for my LPR rockets. Anything over 2" I cut myself using the scrollsaw and disc sander (on these jigs). Inside diameters are drilled with a 3/4", 1", or 1-1/8" bits for 18mm/24mm/29mm motors respectively, a Dremel can be used to adjust tight fitting rings to get the proper fit.





For paper, posterboard and cereal box CRs:

https://www.amazon.com/Olfa-1057028-Rotary-Circle-Cutter/dp/B001CEAMCY

and

https://www.amazon.com/Fiskars-93807097-Circle-Cutter-Replacement/dp/B0006HUJ0S

 

[kjohnson]

For low power stuff, a low/no cost solution for cutting rings can be found here:
https://georgesrockets.com/grp/Articles/CentRings/Rings.htm

kj

 

[mtarallo]

Thank you all - wonderful group of people. I will investigate these, I appreciate all your help.

 

[KenRico]

I use the supplied paper rings as templates -- and cut some hobby lite-ply to match.

Because the lite-ply is softer ..does not take alot of whitling to make the cuts and enlarge center hole to slide over tube.

Can do hand tools like xacto saw , a power drill & a $8 Harbor Freight rotary tool to get it sized and true .

Kenny

 

[gna]

For low power stuff, a low/no cost solution for cutting rings can be found here:
https://georgesrockets.com/grp/Articles/CentRings/Rings.htm

kj

I used a similar method--I have a cheap compass. I scribed with that, then used the groove to guide my xacto knife.

 

[GlenP]

In addition to centering rings, you can make your own ejection baffles, half discs for smaller tubes and discs with holes for larger diameter tubes. You can use a tube coupler or make your own from cereal box cardboard.

 

[taiwanluthiers]

I like to use a router or a dremel tool (using small end mills) and a circle cutting attachment.... You can make ones that allow very small diameter circles to be cut, and you don't have the danger that a drill press circle cutter may present.

Google Wells-Karol jig (used for guitarmaking) that can be used with lamiate trimmer, or alternatively a dremel with a small end mill can be used with circle jigs that Stewmac sells. (www.stewmac.com)

Motor mount holes smaller than 1" in diameter can be drilled out with an appropriate Forstner bit or spade bits.

By using a circle cutter/router (with carbide end mill) you will be able to make fiberglass centering rings as well.