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Centering Rings

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edwardw

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Hey everyone,

I am at the point that I need to make the centering rings for my L1/L2 rocket. I used to make them with hole saws, but at 3" they get pretty darn expensive. Does anyone have any good techniques for making larger centering rings. I will be using 1/4 and 1/2 material for centering rings and bulkheads. I am thinking right now a scroll saw would be the tool of choice...but I'm not sure. I have heard it can be done on a table router, but I don't have one of those so no luck there.

Thanks,

Edward

www.stlrocketry.com
 

powderburner

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I am certainly no expert at this (I bought my plywood rings for the one and only 4 inch rocket I have built) but I think lots of people use an adjustable 'fly cutter' attachment on their drill press.
I know there are lots of old threads here on TRF that addressed this. Maybe you could try a search on 'centering rings' or something like that.
You can also look through the old threads on the Forums section of Rocketry Online.
 
A

Austin

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Edward,

Making your own rings is both rewarding and financially pleasing. You can make rings for $.25 - $3 compared to buying them for $3 - $10 each. Your cutting tool will run around $8 and I have found them at both Lowes and Home Depot...the tool pays for itself in the first two or three rings which is a good thing.

For this reason, I have several of the tools, each adjust for either inside or outside cut at various diameters up to 4" body tube size. Above that and you need to use a table saw, router or Rotozip with a circle cutter. Using the tool and good quality ply are all you need; I prefer more plys to the wood, such as aircraft ply found at the craft stores like Michaels or Hobby Lobby.

As far as making rings, this should help quite a bit:

http://www.rocketryforum.com/ctulanko/album/index.php?display=tres/Tres 009.jpg

Good luck and we wanna see pics of your goods when done! :)

Carl
 

sandman

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I use a band saw. I made a jig like Norm Abrams uses on "The New Yankee Workshop".

Real simple jig.

You can also make a circle cutting jig using a router.

If your interested I'll post some plans.

sandman
 

edwardw

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Is the tool just called a circle cutter? And are you using it in a drill press?


Edward
 

wwattles

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I've heard comments on other pages that the Jasper 300 circle jig is an outstanding tool for using your router to make centering rings. I, personally, haven't purchased one yet (my rockets are still small enough I can use my fly cutter). The makers advertise that you can get precise cuts without any trial cutting first.

If anybody has any experience with those I'd be interested to hear about it. I've tried to find one locally, but the only place I can find it is online.

WW
 

sandman

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Is the tool just called a circle cutter?
It's called a flycutter.

And YES you have to use a drill press...you just cannot hold that tool in a hand drill without hurting yourself!

sandman
 

wwattles

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Edward,

I got one of those for Christmas - Craftsman brand from Sears. Cost my father-in-law 20 bucks. I'm sure you can probably get them at other fine hardware stores nationwide. Using a steady pressure, it cut through 1/4" aircraft ply in nothing flat. If you get that brand, though, I'd recommend replacing the set screws with something longer (you can buy those at home warehouse stores in the bulk screws section). The ones I had stripped after only 4 adjustments and I had to replace the whole cutter (thank God for warranties).

The tool itself MUST be used in a drill press - when it cuts it puts a LOT of torque on the drill, and the speed must be held steady. Mine recommended a top speed of something like 500 rpm, because that small blade is on a weighted arm, so spinning it up faster than that would be dangerous.

WW
 

jetra2

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The tool that Rotozip makes as an attachment for their tools is called a circle cutter. There are two versions of it, and they look VERY easy to use, if you already have a Rotozip-style tool but don't want to invest the money for a drill press. You can find the first one here. It does circles from 3.5" to 12", so it's probably not the best choice for a L1-L2 project. The one that I want, here, looks to be the best for a MPR-L3 style project. It will cut circle from 1" to 12", and as you probably guessed, that gives you just about every circle you could possibly want. It seems pretty simple to use. I think you just put one side of the attachment at the center of a circle you want, adjust the size, insert Rotozip into other side, and go!

If you're looking for a cheap drill press, go here. You'll also need a set of these. Then from your local Rocket Depot, you should be able to find a circle cutter or fly cutter (I'm not sure what they're called) for it, and you'll be in business!

Jason
 

LarryH

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Harbor Freight has bench drill presses in thier flyers starting at $39.99, aint no reason to not own a drill press unless you're just REALLY cramped for space, probably the most usefull tool you'll ever own(with the possible exception of a dremel)!;)
 

astrowolf67

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Originally posted by sandman
It's called a flycutter.

And YES you have to use a drill press...you just cannot hold that tool in a hand drill without hurting yourself!

sandman
Oh great, now ya'll tell me!! I've been using one for years in hand drills with good results. The key is to go slow on the cutting. The accuracy is not as good as with a drill press, so I cut just a tad oversize. Then place the ring on a bolt the same size as the pilot bit and clamp it in place with a nut and washer, chuck it into the drill, turn in on, and bring it down to size with a sanding block. Then I cut the motor mount hole out with normal hole saws, reaching final size with a sanding drum on my dremel. I've done up to 4 inch rings with this method. If this is the same tool I'm using. I got it for a few bucks at a local tool sale (HDC I think).
 

Micromeister

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Astrowolf:
I always stack cut centering rings, as many as 10 to 20 depending on the size and thickness for materals or mix of materials being stacked. If I'm only cutting 1/8" ply I usually limit myself to 12 pieces. On smaller sets, BT-80 and below I throw in pairs of thicker and thinner material, cardstock, 14ply sho-card, and various thickness light plywoods to fill up a stack at least 1-1/2" thick. After cutting the inside hole with the very FlyCutter tool you have in your previous post pic. I then cut the outside diameter on a band saw then sand the stack until it fits perfectly into the bodytube with a vertical belt sander. Finish sand the inside tube diameter with drill press mounted drum sanders. 10 to 20 rings in about 30 minutes! they are very cheap to make. I think it takes longer to set up the stack with the Double faced masking tape than it takes to actually finish off the entire operation.
 

Stymye

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welcome bfraley,
nice technique but,
I'm even more impressed with your fin alignment technique.
talk about accuracy !
 

Karl

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Originally posted by CTulanko
Edward,
As far as making rings, this should help quite a bit:

http://www.rocketryforum.com/ctulanko/album/index.php?display=tres/Tres 009.jpg

Good luck and we wanna see pics of your goods when done! :)

Carl
Thats the excact same tool as I use , just make sure your out of the way when its spining.That tool makes EXCELLENT Centering-Rings! And it means you can make CR's for those odd dia tubes you have lying round ;) So I'd say its definitely worth investing in one!
Yep good luck , and post plenty of pics ;)

-Karl
 

eugenefl

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Originally posted by jetra2
The tool that Rotozip makes as an attachment for their tools is called a circle cutter.

If you're looking for a cheap drill press, go here. You'll also need a set of these. Then from your local Rocket Depot, you should be able to find a circle cutter or fly cutter (I'm not sure what they're called) for it, and you'll be in business!

Jason
The Rotozip circle cutter is worthless plastic junk. Might as well take a drill and drill tiny holes until you chew out a circle.

I'd say go the cheapo drill press route. They can be had for $40. Add a cheapo circle/fly cutter for $7 from eBay and you're golden.
 

wwattles

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I got my cheap drill press at Harbor Freight (got a 1/2 price special!), along with my cheapo flycutter and cheapo digital calipers. The calipers REALLY help get the thing adjusted right, and can be had at a fairly low cost also.

WW
 

Ryan S.

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flycutters are nice, it just takes a while to clame everything down, and you do want to clamp it down because it will chuck things across the room. You also need to be very careful not to go to fast so the tool wont bind up and so you dont make to much heat.

A scroll saw is also nice though, takes longer, but it comes in handy to do other things. I would also have a belt sander handy to clean up the edges after you use the saw to cut them
 
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