How to accurately bevel fins

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Performance nut

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I have a project in the works that will have some nice thick birch fins. I'd like to put a nice bevel on them but I'm trying to figure out how to do it consistently as it has 4 fins that split. Is there a jig or tool out there that makes this something that is reproducible? I'm not a huge woodworking guy so I have a limited number of tools and skills. But I'm willing to learn and invest some money to do this as I see using it on several projects.

Again, I think I could figure out a rough bevel process, I'm hoping for something more refined and consistent. I appreciate the help, thank you!
 
people have built jigs / slides that fit their belt or table or oscillating sander. they clamp to or slide the fin thru the jig at the 5° or whatever angle they set to get the bevel.

Other's (like me) do it by hand. a plane, then sand paper, lots of elbow grease! :D
 
I bevel fins using a router and a simple jig. You want a router, right? Get one with a nice, flat table. The jig (blue) is out of scraps of wood. The fin (red) is attached to the jig with double-sided tape and extends a consistent distance past the edge of the jig (an inch or so). You pass the assembly over a router bit, doing both sides. With a bit of practice, you can do a set of fins in about 15 minutes and they come out perfect.

Jim

Jig.jpg
 
I bevel fins using a router and a simple jig. You want a router, right? Get one with a nice, flat table. The jig (blue) is out of scraps of wood. The fin (red) is attached to the jig with double-sided tape and extends a consistent distance past the edge of the jig (an inch or so). You pass the assembly over a router bit, doing both sides. With a bit of practice, you can do a set of fins in about 15 minutes and they come out perfect.

Jim

I have a Dremel that I believe they sell router bits for. I think they even sell a router "table" accessory that clamps to a bench and holds the Dremel in place. Have to look into that.

Totally love the drawing Jim, makes total sense. Thank you sir. I got some scrap wood that I'm going to see if I can piece together what you have here and give it a whirl. I appreciate the input!
 
people have built jigs / slides that fit their belt or table or oscillating sander. they clamp to or slide the fin thru the jig at the 5° or whatever angle they set to get the bevel.

Other's (like me) do it by hand. a plane, then sand paper, lots of elbow grease! :D

I don't mind the elbow grease, I just doubt I will be able to do this consistently (not that guy who can eyeball something that accurate). Maybe it is my OCD but I hate when my fins come out different in some fashion or another. Anything I can do to automate the process and improve odds of replicating a result, I'm all for. I appreciate your input!
 
just takes practice and technique.. holding the sanding block / plane level takes practice. Not rotating thru the stroke takes practice. Counting strokes takes practice.

Multi-layer ply fins help, because each layer gives you an indication of how much / what angle you've been sanding at over the total area being sanded. If the 'sanded width' of each layer is about the same, the overall beveled angle is about the same..

one day, I'll have a similar jig for my belt sander! :D
 
I bevel fins using a router and a simple jig. You want a router, right? Get one with a nice, flat table. The jig (blue) is out of scraps of wood. The fin (red) is attached to the jig with double-sided tape and extends a consistent distance past the edge of the jig (an inch or so). You pass the assembly over a router bit, doing both sides. With a bit of practice, you can do a set of fins in about 15 minutes and they come out perfect.

Jim

Jim, What kind of bit do you use? I'm imagining a wide angled bit that is usually used for cabinet making. I think those take a pretty powerful router to turn.

I was thinking about building a jig that would hold the fin 80 deg from the table surface and then using a straight router bit. Kind of like what John Coker does with a sander: https://www.jcrocket.com/finbevels.shtml
 
Jim, What kind of bit do you use? I'm imagining a wide angled bit that is usually used for cabinet making. I think those take a pretty powerful router to turn.

I was thinking about building a jig that would hold the fin 80 deg from the table surface and then using a straight router bit. Kind of like what John Coker does with a sander: https://www.jcrocket.com/finbevels.shtml

I just use the top of a straight bit for the cutting. I think it's a 1/2" bit, but a smaller bit would be fine - it would just take a little more time to make sure that the entire surface got touched. The main thing is that the bit and the table shouldn't be able to move relative to each other. Otherwise, you won't get a consistent bevel.

I've seen the method you linked and I think it puts fingers at risk. If you give the design of my jig just a little thought, you can arrange for the bit to project only a little above the surface of the table. And, a split fence on either side of the bit can prevent you from accidently routing into the jig itself. Once you have the right setup, it's safe and consistent.

Jim
 
I just use the top of a straight bit for the cutting. I think it's a 1/2" bit, but a smaller bit would be fine - it would just take a little more time to make sure that the entire surface got touched. The main thing is that the bit and the table shouldn't be able to move relative to each other. Otherwise, you won't get a consistent bevel.

I've seen the method you linked and I think it puts fingers at risk. If you give the design of my jig just a little thought, you can arrange for the bit to project only a little above the surface of the table. And, a split fence on either side of the bit can prevent you from accidently routing into the jig itself. Once you have the right setup, it's safe and consistent.

Jim

I like the jig you displayed because there is zero chance of over cutting. Even if the jig is as crooked as a politician with respect to the router bit, the bevel will be evenly cut so long as the fin is laid down on the jig properly and doesn't shift. KISS principle applied :)
 
I like the jig you displayed because there is zero chance of over cutting. Even if the jig is as crooked as a politician with respect to the router bit, the bevel will be evenly cut so long as the fin is laid down on the jig properly and doesn't shift. KISS principle applied :)

Double-sided take (aka golf grip tape) is an essential feature of this device. I used to call double-sided tape the most important tool that I use (and I use it almost every day for something). But, first place has been taken over by a digital caliper for stuff I've been doing over the past few months. But, rocketry would be a much more difficult endeavor without double-sided tape.

Jim
 
I have done mine on my table saw with good results. I clamp the fin vertically to a piece of 1x4, put the desired angle on the blade and run the 1x4 along the fence. All I have to do is flip the fin & repeat for the other side. When I do this, I use a fine tooth "plywood Blade"

Tried to make a pretty drawing like Jim, but after 2 tries with MS Paint, it was still too small to be useful.
 
I just use the top of a straight bit for the cutting. I think it's a 1/2" bit, but a smaller bit would be fine - it would just take a little more time to make sure that the entire surface got touched. The main thing is that the bit and the table shouldn't be able to move relative to each other. Otherwise, you won't get a consistent bevel.

I've seen the method you linked and I think it puts fingers at risk. If you give the design of my jig just a little thought, you can arrange for the bit to project only a little above the surface of the table. And, a split fence on either side of the bit can prevent you from accidently routing into the jig itself. Once you have the right setup, it's safe and consistent.

Jim

Is there a reason you take that approach, rather than mounting the fin vertically and having the cutting flutes of the bit do the bevel? I guess your method would allow a much shallower angle (5° or so)...
 
How would you put a precision bevel or a rounded edge on a fin that has a curved edge? Any special tools for that? I see how these jigs described above would work for fins with straight edges, but what would you do with a curve? I have a project with a fin that has a long concave curve, and I’d like a nice rounded edge on it. Thanks!
 
How would you put a precision bevel or a rounded edge on a fin that has a curved edge? Any special tools for that? I see how these jigs described above would work for fins with straight edges, but what would you do with a curve? I have a project with a fin that has a long concave curve, and I’d like a nice rounded edge on it. Thanks!

This is how I did it on my Terrodactyl fins. (Post # 16). https://www.rocketryforum.com/showthread.php?137744-Fin-Airfoil




Sent from my iPhone using Rocketry Forum
 
Is there a reason you take that approach, rather than mounting the fin vertically and having the cutting flutes of the bit do the bevel? I guess your method would allow a much shallower angle (5° or so)...

The router and table that I have aren't particularly good. It would be difficult for me to set up a jig that had to be moved past the bit. As it is, I mount a piece of plywood on the table surface just to get a nice flat surface, which you can see in the pic of Zebedee doing some fins a while back. I have a bit with top cutting surfaces, but I have done lots of fins with a plain straight bit.

Jim

DSCF0920.jpg

DSCF0922.jpg
 
As a long time professional woodworker, some thoughts..

I consider the router to be the scariest tool in my shop, no question. I have a 5HP bandsaw, a 5HP Unisaw, a big spindle sander, a big, oscillating belt sander, a 25" widebelt sander, a 3HP router table, and a good number of other things that bite. The router can go from all fine to disaster more suddenly than any of than all the others, IMO, and in a more catastrophic way. Fingers can be sewn back on, mangled fingers can be repaired, often, but the router, when it bites, it will sometimes take a tendon and wrap it up, and pull it out from the body so that there is nothing left to repair, short of tendon grafts, if you have some to spare. The router will turn fingers into bloody overspray, bones too, nothing left to sew back on, or repair. I have had some close calls with some of the tools over the years, and only one real accident, with a pneumatic drill. One of my first experiences with a real shop router was routing a 1" x 1" piece of nice clear Maple, and having the router break it while I was holding it, in between the bit and where I was holding it. It felt like a baseball bat hitting my finger tips, impressive power. I do a lot of pattern routing. I never enjoy using the router, though I enjoy what it does. Always have huge respect for it. Little tiny 1/8" roundover bits, sure, not too much danger there. When it gets up past 1/2" straight, or flush cutters, there is a real danger factor there, if you recognize it or not. The router is indespensible, and all my tools, including the router, are top notch. My router is in a table with a Jessum lift. The router terrifies me. Do not underestimate it's ability to get you a helicopter ride faster than you knew possible. Still, people use them everyday without accident. Thought I would share this for those who are new to routers.

Personally, I am building a jig for a 108" oscillating belt sander, for beveling fins. It cuts very fast, and with a well designed jig, the bevels will be quite accurate.

I like the design of Jim's jig. If I were going that route, I would make on that had a stable platform, maybe a quick release hold down clamp to back up the double sided tape, and I would design the 'sled' so that it left very few options for my hands to be in harms way, and minimal sharp edges or corners.
 
As a long time professional woodworker, some thoughts..

I consider the router to be the scariest tool in my shop, no question. I have a 5HP bandsaw, a 5HP Unisaw, a big spindle sander, a big, oscillating belt sander, a 25" widebelt sander, a 3HP router table, and a good number of other things that bite. The router can go from all fine to disaster more suddenly than any of than all the others, IMO, and in a more catastrophic way. Fingers can be sewn back on, mangled fingers can be repaired, often, but the router, when it bites, it will sometimes take a tendon and wrap it up, and pull it out from the body so that there is nothing left to repair, short of tendon grafts, if you have some to spare. The router will turn fingers into bloody overspray, bones too, nothing left to sew back on, or repair. I have had some close calls with some of the tools over the years, and only one real accident, with a pneumatic drill. One of my first experiences with a real shop router was routing a 1" x 1" piece of nice clear Maple, and having the router break it while I was holding it, in between the bit and where I was holding it. It felt like a baseball bat hitting my finger tips, impressive power. I do a lot of pattern routing. I never enjoy using the router, though I enjoy what it does. Always have huge respect for it. Little tiny 1/8" roundover bits, sure, not too much danger there. When it gets up past 1/2" straight, or flush cutters, there is a real danger factor there, if you recognize it or not. The router is indespensible, and all my tools, including the router, are top notch. My router is in a table with a Jessum lift. The router terrifies me. Do not underestimate it's ability to get you a helicopter ride faster than you knew possible. Still, people use them everyday without accident. Thought I would share this for those who are new to routers.

Personally, I am building a jig for a 108" oscillating belt sander, for beveling fins. It cuts very fast, and with a well designed jig, the bevels will be quite accurate.

I like the design of Jim's jig. If I were going that route, I would make on that had a stable platform, maybe a quick release hold down clamp to back up the double sided tape, and I would design the 'sled' so that it left very few options for my hands to be in harms way, and minimal sharp edges or corners.

Aaaand you just scarred me for life on a router. Remind me not to invite you over when I need a pep talk. J/K :D

Seriously though, I considered a sander but didn't trust myself not to go too far. I have a palm sander that I have used a few times. Any thoughts to using that? Not to discount Jim's idea, just taking in further input.
 
Thanks! That’s what I have in mind. Now I just need to find someone with a good router. Hopefully I don’t end up having any of my tendons yanked out!

The key is to use a round over bit with an edge guide like this: https://www.lowes.com/pd/IRWIN-3-16-in-Carbide-Tipped-Roundover-Bit/50226873.

Notice in my pictures that I had to stack and clamp the fins together to give a surface for the guide to roll on. I later did something like this for a scratch build, but I first cut a pattern the same shape as the fin to follow. Like Jim said, double-sided tape is your friend. It worked great to hold my fin to the pattern. Sorry, I don't have any pictures of that set-up.
 
The key is to use a round over bit with an edge guide like this: https://www.lowes.com/pd/IRWIN-3-16-in-Carbide-Tipped-Roundover-Bit/50226873.

Notice in my pictures that I had to stack and clamp the fins together to give a surface for the guide to roll on. I later did something like this for a scratch build, but I first cut a pattern the same shape as the fin to follow. Like Jim said, double-sided tape is your friend. It worked great to hold my fin to the pattern. Sorry, I don't have any pictures of that set-up.

Thanks for the info. Now that I know what I’m looking for, I think there must be someone I know locally who has this equipment and knows what they’re doing who can help me out.
 
Aaaand you just scarred me for life on a router. Remind me not to invite you over when I need a pep talk. J/K :D

Seriously though, I considered a sander but didn't trust myself not to go too far. I have a palm sander that I have used a few times. Any thoughts to using that? Not to discount Jim's idea, just taking in further input.

It would be difficult to get precise results with a palm sander. A guide could be made for a wood block with some 80 or 100 grit on it, though, and that would work, with patience.

A mill, like a Bridgeport is probably the most accurate way to bevel fins. Not really a tool for the hobbyest, though. The router is not a bad way to go, it is as accurate as the setup.
 
I did the Coker-style disk sander method here: https://www.rocketryforum.com/showthread.php?143469-Madcow-Adventurer-2-2-quot&p=1753385#post1753385

Yep, sanded my fingertip in the process.

At the end of the Coker article, he does suggest a router method/jig which looks easier and safer. Now, all I need is a router and table!

That method looks nowhere near as good as using a router table and fixture. Looks kinda sketchy, too. The Porter Cable 7518 in a lift is the gold standard for router tables.
 
Hey guys, would something like this work? It is cheap as heck (way cheaper than some of the router tables) and has an adjustable angle. Only thing is keeping the edge of the fin parallel with the blade and having repeatable results might be a challenge.

Thoughts?
 
I assume you would replace the diamond blade with an abrasive one? Maybe the diamond would work anyway. Worth a try on some scrap. Don't forget it will stir up a lot of carbon dust and that scares me. Good vac with HEPA is needed!

My main concern otherwise would be the material removal rate might be a bit unforgiving.
 
I use a cheap tile saw and a simple 10 deg jig I made from scraps to cut bevels on fiberglass fins. It makes super smooth cuts and, being a wet saw, there is no dust cloud. The downside is the water will warp your wood jig if you don't waterproof it.

Hey guys, would something like this work? It is cheap as heck (way cheaper than some of the router tables) and has an adjustable angle. Only thing is keeping the edge of the fin parallel with the blade and having repeatable results might be a challenge.

Thoughts?
 
I have a project in the works that will have some nice thick birch fins. I'd like to put a nice bevel on them but I'm trying to figure out how to do it consistently as it has 4 fins that split. Is there a jig or tool out there that makes this something that is reproducible? I'm not a huge woodworking guy so I have a limited number of tools and skills. But I'm willing to learn and invest some money to do this as I see using it on several projects.

Again, I think I could figure out a rough bevel process, I'm hoping for something more refined and consistent. I appreciate the help, thank you!

Here is my beveling jig.
https://www.rocketryforum.com/showthr...54#post1576854
 
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