What's the best / Safest way to do this?

[Alan Lightstone]

I have a few cutting boards, approximately 15" x 15" that I need to cut down to circular shape, 12" in diameter. They are thick - approximately 2 inches thick.

I want to have smooth profiles on the outside curved part. Would ideally like to round off the top edge too. I've done one on a circle jig on my bandsaw, then finishing with a downcut spiral bit on my router on a circle jig.

The hairs are raising on my neck trying to rout 2" off the edge of that board. Doesn't strike me as terribly safe.

Is there another way of doing this? I've thought of making a pattern and running it upside down on my router table, but I'm not sure if that is even less safe. I'm also building a quick jig for my oscillating spindle sander, so that I can rotate the board at a fixed distance to the sanding head.

I'd also love to do this without making a hole in the bottom of the board, as I never get that patched to my liking.

What do people do in this scenario?

[Kirk Poore]

Make the pattern, with a hole in the middle, and hot glue it to the board. Cut on the bandsaw. Make an aux table for your 6x48 sander (doesn't every one have one?:)) to support the disk, and sand the edges with that.

Or put a faceplate on them and put them on your lathe to turn & sand.

Or put a 2" high stack of straight cutters on you shaper, add a rub collar to rub on the pattern, and smooth them that way. Note that you'll have to pay attention to grain so you don't get tear out, and you'll have to flip the work to keep it cutting properly.. Sort of like your router table idea, but more likely to catch the wood. Probably not the best choice without some innovative guarding.

Kirk
who realizes you may not have a 6x48 sander, 12"+ lathe, or shaper...

[Bill Huber]

I would think the band saw would do just fine and then sand the edges.
If need be get a band saw blade with more teeth and there would be less sanding.

You could also make a template and double tape it to the bottom of the board. Then cut about 1/16" away from it on the band saw, then use a patten bit on the router table to finish it.

Now switch to a round over bit and do the top edge.

[pat warner]

Just as I waste (http://patwarner.com/images/tswebb4759.jpg) 3/4" thick aluminum in very modest steps, your 2" thick billets can be stage routed without adversity. A well centered collar guide in a plunger, with a sharp, stout straight bit, will render that edge (360) tearout free. Sanding will take forever and it's arbitrary. Full thickness one step routing will wipe out the cutter, sicken the router, and mess up your work, especially the end grain.
Modest stage (templet) plunge cutting can also be climbed, lessening the insult.
My recommendation.

[Jim Rimmer]

You could also make a template and double tape it to the bottom of the board. Then cut about 1/16" away from it on the band saw, then use a patten bit on the router table to finish it.

Now switch to a round over bit and do the top edge.

That's how I would do it.

[Cary Falk]

How about rough it out on the bandsaw and then use a top bearing pattern bit. Place the pattern on top with double stick tape.. If you need to move the bit down for several passes, you can make as shallow as you need. After the first pass the cutting board becomes the pattern.

[Carl Beckett]

I saw a sanding spindle with a guide bearing on it once. That would seem pretty safe.

[Sam Murdoch]

You could also make a template and double tape it to the bottom of the board. Then cut about 1/16" away from it on the band saw, then use a patten bit on the router table to finish it.




Me too, getting close before routing is the key to safety and minimal tear out - or send it out to a CNC shop :rolleyes:.

[Lee Schierer]

How about rough it out on the bandsaw and then use a top bearing pattern bit. Place the pattern on top with double stick tape.. If you need to move the bit down for several passes, you can make as shallow as you need. After the first pass the cutting board becomes the pattern.

Just be sure to watch your grain as it is going to tend to tear out where the grain reverses. Try an over size pattern first to see if you get tear out in certain areas. Mark those areas and then make your cut every where except those areas as you normally would with your final pattern and then either climb cut those problems areas or sand them down.

[Alan Lightstone]

Great advice, guys.

If using the router pattern bit approach, how do you keep the cutting board from moving on the table when routing it? I tried double-sided tape (the sticky, Woodcraft turners tape) but the board still moved within a few seconds. I'm trying to avoid putting holes in the wood, the 12" board is small enough that I kept having to move clamps every few seconds of routing.

[Jay Jolliffe]

I've used the turners tape from Rockler & I've had to pry the template off the piece. Sometimes I'll use a clamp to set the tape under the template to the piece.

[Cary Falk]

Bench cookies would do the trick. Lowe's was closing the Bench dog ones for <$4.

[Bill Huber]

Great advice, guys.

If using the router pattern bit approach, how do you keep the cutting board from moving on the table when routing it? I tried double-sided tape (the sticky, Woodcraft turners tape) but the board still moved within a few seconds. I'm trying to avoid putting holes in the wood, the 12" board is small enough that I kept having to move clamps every few seconds of routing.

Maybe I am missing something or just not understanding how you are doing this.

Step 1, make the template out of say MDF, it is easy to sand and you can get a really smooth surface. On the band saw with the circle jig make the 12" template and smooth the edges by sanding if needed.

Step 2, with say 3 strips of double sided tape on the the template stick it to the 15"x15" block.

Step 3, take it to the band saw and cut the block very close to the template (like 1/16"), I use a guide on my band saw when doing things like this, it just makes it easier (see image below, works with outside or inside templates).

Step 4, take the block to the router table and set the bearing to the correct height so it rides on the template. I like and use a double bearing bit, this way I can turn the work over if needed because of the grain direction.

Step 5, remove the template from one block and attach it to the next and go to step 2 again. When all blocks are done change the bit to a round over and do the edges. Note on round over bits, if you are doing a large round over and there is a chance of tear out, put a little larger bearing on the bit and do the round over in 2 passes.

You are done.

This is the bit I use the most for template cutting, it has a bearing on the top and the bottom, I can flip the work part over if the grain is not running the way I need it to. Just adjust the height of the bit for the template on top or raise it up and flip the work part over for the template on the bottom.

http://www.amanatool.com/routerbits/down-shear-trimmer-47094.html

[Alan Lightstone]

Thanks, Bill. I like that approach. Definitely going to try it.

For kicks I made a jig for my oscillating spindle sander to try sanding the edge. Just for a different approach. Only took a few minutes to throw together a jig.

I have a similar Amana bit, but smaller diameter. I like the one you showed better.

How is that guide attached to your bandsaw? I've never seen that before.

[Chris Parks]

http://www.youtube.com/watch?v=Wxbzrf4z_cg

[Jeff Duncan]

You've got a lot of good tips already. My preferred way is to do it on the disc sander as it takes care of the final shaping and sanding in one shot. You could always glue a sub base on as the others have mentioned.....but if this is a cutting board why are you worried about the bottom anyway? Not like anybody is going to be flipping it over to look at the bottom. However if it does bother you, one option would be to just make a plug out of contrasting wood to highlight the hole, as opposed to trying to hide it;>)

good luck,
JeffD

[David Peebles 1]

If you have a shaper, there's another way to do this. Follow the above ideas with a pattern, and cutter(s) with a matching bearing. Do only the parts where you're cutting with the grain. Flip the cutter(s) over, and use the reversing switch so you can go the other direction, again staying with the grain. It's one of the things that a shaper has over a router table.

[Kevin Groenke]

Lots of good advice, all I've got to add is: if you end up doing it with a template/router set up, you might want to consider a vacuum pump/template if you're looking at production quantities since it will increase throughput, reduce cost (vhb tape gets expensive) and eliminate the tape removal process.

[Alan Lightstone]

Doh!!!!

Never thought of using my vacuum clamps with a template.

Great idea.

[Kevin Guarnotta]

I'd probably do it very similar manner to Bill, although I don't have one of those bandsaw things. I think I would do the roundover with a small handheld router and bearing bit. I might do the larger cut with a larger handheld router, with the piece on those rockler cookie things...

[Chris Fournier]

David Peebles has posted the only reply that attempts to address the fact that for 180 degrees of pattern routing you will be cutting up into the grain. Trust me a 2" cut up hill into the grain is gonna be very exciting and you will ruin plenty of work and the [otential for personal injury is HUGE.

As David points out a shaper which can be run in reverse is best for this work.

Another possibility is the good ol' lathe! I use my lathe to turn out Shaker candle stick stand tops. I use a gouge to get the top round and then a shop made scraper to put on the edge profile.

Breaking out solidy body guitars presents the same challenges that you are facing with these circles. I have used a router table and a pin router to do this and I'll explain my method.

The first thing I have to say is that I am not strong enough to fight my machines and hold the wood securely - I won't even attempt this. Second, I am assuming that you want a fairly precise piece so I am going to rule out sanding as a method of bulk material removal.

On my pin router I have machined up many guide pins that are sequential from on size to say 3/32" over size. These pins are graduated in 0.10" increments (turned on my metal lathe). I have a range of pins for 1/4", 5/16", 3/8" and 1/2" cutters. Use the largest diameter cutter you have for the best results.

I saw the blank to within 1/16" of the template - pencil layout line. Then I put the 3/32" over sized pin in my pin router and carefully machine the blank - this is the most dangerous phase because I am at the mercy of my bandsaw break out and I could really bite off more than I can chew if I have done a poor job - so I don't do a poor job!.

If you want to you can run a witness mark around the blank to help you see where you have machined wood and where you have not.

Now simply place the next 0.10" smaller pin in the router and repeat until you are on size. You have effectively controlled the depth of cut that your bit can take and in doing so have been safe and avoided tearout. On some species I will even climb cut the 180 degrees of "up hill " grain but this requires an experienced "feel" for the operation.

Now if you don't have a pin router I have one more method for you. I use 1/4" wide vinyl tape, the thinner the better. You can find this at autobody finishing supply stores. Packaging suppliers also sell a red vinyl tape that is used to seal bags. I wrap my guide bearing with this tape and build it up to 3/32" over size. Then I simply machine, remove a portion of the tape from the guide bearing and machine again until I am on size. Once again this method ensures that you are only taking a wisp of a cut off your blank with each pass.

It sounds like a lot of work and it is but the outcome is size on, tear out free work and 10 fingers no lacertaions.

I strongly suggest putting good handles on your template to ensure that you have control and are nowhere near the cutter.

Good luck.

[Bill Huber]

I use a 1/2" top and bottom bearing trim bit on the router table when I am doing templates that have grain problems. Us the top bearing for one grain direction and then flip the work over and use the bottom bearing to finish.