Hole saw for centering rings

lakeroadster

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I will refer to those by several names. One name resembles a Christmas decoration but cannot be used on the forum. The fly cutter earned it when it flew off and almost hit me in the groin. The other is the flying wheel of death.

If you use one for this purpose, ensure the grub screw is tight.

The key is to using a fly cutter is a very slow spindle speed. I was taught this by my shop teacher, Mr. Less Izmoore
 

BigMacDaddy

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You may have convinced me... the link you sent + the expansion? Will I need bits? Or ???? BTW: That looks like the Centaurus from ... oh what was the name of the company...??? I have it and the Swarm still in the boxes.

Yes you would need end mills - downcut for relatively thin stock. You can get 5 or 10 packs of 2mm bits for $10 or $15 (or much more for higher-end ones). There are lots of forums about selecting bits so I don't profess to know much in this space. 2mm is a good size for me since it lets me slot fins to fit other pieces of 2mm plywood inside them.

Those rockets are all ones I scratch designed / built that I also sell as kits -- Neptune R-360, Thunderbird 3, A-10 inspired rocket-plane, and Bomarc.... (I CNC'd 50 sets of fins this week since I am trying to attend a club launch to sell kits this weekend).
 

cls

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The key is to using a fly cutter is a very slow spindle speed. I was taught this by my shop teacher, Mr. Less Izmoore

My wood shop teacher had our complete and undying respect regarding everything he said about safety, because he was missing 3 fingers on his right hand.
 

PhilC

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You mentioned you do woodworking -- Why not add a CNC to your tools?
I've been using one for a while now. It's precise, repeatable and useful for all manner of other jobs.
If you want to waste 10 minutes of your life you can watch this video os a CR being made on my basic CNC.
 

beeblebrox

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It will definitely do the job. I leave tabs to hold the pieces together but you can also use blue tape and crazy glue or other methods. For me cutting tabs is not difficult. It was critical to upgrade to 3040 for me to be able to cut 200x300mm sheets of plywood which are pretty cheap per sheet (like $1.25-$1.50 per sheet). If someone has a business doing woodworking or similar I would recommend a higher-end CNC -- for $2000 or so you can get a much better unit with a bigger bed.

A laser cutter will also do the job and can be faster / reduce the need for clamps / hold-downs and larger tabs. However, diode lasers (the style you attach to the gantry directly) are pretty underpowered for cutting. A K40 laser will apparently cut thinply like butter (I am working to get mine setup now) but relies on a big laser tube so moves mirrors around on the gantry to redirect the laser beam. K40 lasers are not that expensive either (I have no experience with this one but came across it recently): https://www.amazon.com/OMTech-Engraver-Desktop-Engraving-Detachable/dp/B099KK2HGH/ (although you will need to purchase water pump, air pump, vent tube, etc...).

The CNC is loud and makes lots of dust (I have not fit a dust shoe yet) but the laser needs to be vented to outside and can cause fires so needs to be monitored all the time (i.e., you need to be next to it and paying attention). If I am cutting a couple of sheets of 2mm with dozens of small fins it might take 30 or even 40 minutes for the CNC but I can just walk away and do something else. Simpler fin setups take 10-15 minutes or even less. The CNC can also do other materials -- like carbon fiber or fiberglass (although enclosure, mask, and ventilation may become necessary with other materials) and can be used to make airfoils or otherwise bevel thicker material. A laser can make cleaner cuts as well -- CNC leaves some fuzzies that are easily sanded away unless your bit is brand new.

For me cutting fins was pretty annoying and stressful (particularly since I moved over to plywood long before I got my CNC) and curved shapes were a nightmare. Having a CNC has really changed how I design rockets. I like the reproducibility -- I like to design something and be able to reproduce that design repeatedly (or modify and make again without starting from scratch).

Here are some pics of my CNC and the fins I make with it.
View attachment 544411 View attachment 544412 View attachment 544413 View attachment 544414
Have to say it... I Love the Thunderbird 3. I have been wanting to do Thunderbird 1... and what is the red one from?
 

BigMacDaddy

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My wood shop teacher had our complete and undying respect regarding everything he said about safety, because he was missing 3 fingers on his right hand.
My dad was a contractor and was always proud to have made it to old age with all his fingers.

In my limited renovation and other work I have already nicked my fingers in ways that could have gone much worse. Knock wood.
 

cwbullet

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My dad was a contractor and was always proud to have made it to old age with all his fingers.

In my limited renovation and other work I have already nicked my fingers in ways that could have gone much worse. Knock wood.
The same can be said for many professional in the military but usually losses involve the whole limb.
 
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