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Another Radius Block Jig?


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http://www.rockler.com/tech/RTD10000352AA.pdf

I was browsing around the Rockler website and stumbled upon this jig contraption. Immediately, the first thing my mind jumped to was "RADIUS BLOCK!"

I'm not a big pro at trigonometry/geometry/math in general, but I didn't know if someone would find the method, at least, adaptable to use as a radius block maker. I dunno if it'll work, but I figured I'd pass it along to some other minds out there. Enjoy :D

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Neat idea in general, but I'm not sure you could use it to practically make a radius block. A table-saw disc is usually 8 or 10 inches in diameter itself, meaning that if you approached it completely perpendicularly, you'd get a 4 or 5 inch radius block. Approaching at an angle like the Rockler sheet will produce an even tighter curve that will not have a consistent circular radius.

Still, neat that people come up with this stuff... thinking outside the box rules.

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That was the main snag that was running around in my head, that the blade wouldn't be big enough. Eh, I like the idea, though. Maybe a violin fretboard, or some smaller guitar-type :D

People should start investing in 32" saw blades, so I can make some radius blocks.

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Looks like you still might have a fair bit of sanding to do after though. I had a go at the Safe-T-Planer method last weekend, I couldn't believe how rediculously simple it is and it works flawlessly, I turned a stick of scrap pine into an accurate 20" long radius block in minutes!

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I like to keep things simple. My hot water tank is 10" radius, stick some sandpaper to it and attack it with a block of wood. Slide it up and down until one side fully comforms to the curve and repeat with finer grits. Maybe one afternoon I'll visit a place that supplies various sized water pipes, barrels or whatever, with a bunch of wood and make a variety of radius blocks. They'd probably think I'm nuts. :D

Edited by Southpa
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:D

@ OZ - Genius!

@ Southpa - Crazy!

The only improvement to the tutorial would be to find the mathematics to calculate the angle for any radius, but otherwise, awesome job! For build #3 I'm thinking of buying a safe-t, and I'll definitely try this out. Thanks a bunch for the link!

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Am I the only one wondering why not just, y'know, buy a block or two? They're hardly that expensive. I find I use them less and less frequently, though, since I level with a flat beam, and radius with a router jig (faster, cleaner, faster, better, and did I mention faster?)

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Am I the only one wondering why not just, y'know, buy a block or two? They're hardly that expensive. I find I use them less and less frequently, though, since I level with a flat beam, and radius with a router jig (faster, cleaner, faster, better, and did I mention faster?)

Around £10 in some places for a 4" or 8" long block does seem a bit pricey when you can knock out a 24" one on the Safe-T-Planer in about a minute with wood that costs a few quid at the most. I've never actually seen any radius sanding blocks for sale by any major or small companies that are longer than 8", and when you get one that's around 20" long, sanding literally takes about a minute or two and is far more easy to get it accurate.

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  • 3 weeks later...
Am I the only one wondering why not just, y'know, buy a block or two? They're hardly that expensive. I find I use them less and less frequently, though, since I level with a flat beam, and radius with a router jig (faster, cleaner, faster, better, and did I mention faster?)

Around £10 in some places for a 4" or 8" long block does seem a bit pricey when you can knock out a 24" one on the Safe-T-Planer in about a minute with wood that costs a few quid at the most. I've never actually seen any radius sanding blocks for sale by any major or small companies that are longer than 8", and when you get one that's around 20" long, sanding literally takes about a minute or two and is far more easy to get it accurate.

Since wood movement is probably the issue in make longer blocks. I am sure they are made using long lenghts of hard wood and are cut to a size that will stay stable. Probably the reason SM went to aluminum for a longer beam.

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Neat idea in general, but I'm not sure you could use it to practically make a radius block. A table-saw disc is usually 8 or 10 inches in diameter itself, meaning that if you approached it completely perpendicularly, you'd get a 4 or 5 inch radius block. Approaching at an angle like the Rockler sheet will produce an even tighter curve that will not have a consistent circular radius.

Still, neat that people come up with this stuff... thinking outside the box rules.

Making cove cuts with a table saw has been around for many years. someone just made a jig to sell and make some dollars. vs the old wooden fence at an angle and set the blade.

mk

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Why make the cut at an angle with the table saw?

If the saw blade is tilted then couldn't the block be cut more accurately in the same manner as that of the safe-t-planer...

I had trouble visualising this so I tried tilting a cd and then a dinner plate inside a barrel and it does indeed look like it would work well.

Now to find a barrel of the correct diameter - the maths are beyond this rusty brain.

S.

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FWIW, I found Stu's method too quick and easy to even consider looking at other jigs for a radius block.

Mattia, where we are at least, it cost me less to make a 20" long sanding block than shipping would have been for an 8" long bought one.

Cheers,

Brian.

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Why make the cut at an angle with the table saw?

If the saw blade is tilted then couldn't the block be cut more accurately in the same manner as that of the safe-t-planer...

I had trouble visualising this so I tried tilting a cd and then a dinner plate inside a barrel and it does indeed look like it would work well.

Now to find a barrel of the correct diameter - the maths are beyond this rusty brain.

S.

Sounds feasible even with a 10" blade to make a larger than a 10" radius (90 deg to the blade = a 10" radius) using the tilt on the blade. I have tried the safety planer method and it works easily but does not leave a great surface. You would need to do some trial and error or find a math professor to help with the angles. A table saw would have the same issues with surface smoothness and from my experiences take a little longer than the safety planer. If i was doing them to sell I would buy a moulder planer or a large shaper and have the knifes cut for each size block. Probably the same way the big companies work since the finish would be smooth right out of the machine.

For a few blocks and cheap money the Wagner method is the safest. Also works well for cauls and other surfaces which can be covered with cork or something you have on hand. The safety planer is cheaper than most 10" saw blades.

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Why make the cut at an angle with the table saw?

If the saw blade is tilted then couldn't the block be cut more accurately in the same manner as that of the safe-t-planer...

I had trouble visualising this so I tried tilting a cd and then a dinner plate inside a barrel and it does indeed look like it would work well.

Now to find a barrel of the correct diameter - the maths are beyond this rusty brain.

S.

Cutting at an angle to the blade is what gives you a radius larger than the blade radius. If you fed the stock at a right angle to the blade (very dangerous BTW), you would get the radius of the blade. As you move the angle of feed closer toward parallel to the blade, the radius increases. The blade is kept at a right angle to the table always. That method has been used for a long time to make mouldings. It can be done pretty fast, but you will still have to clean up the surface.

To do it like the safety-planer method by tilting the blade, you would have to be feeding the stock at a right angle to the blade, which is a good recepie for a nasty accident. It would also take longer and cut rougher than feeding at an angle to the blade. But if you really want to use this method, the safety-planer would be a safer and cleaner way to do it (other than a purpose-made moulder as Spoke mentioned).

Though, I have to agree with Mattia about just buying them. The value of my time making blocks with any of these methods is WAY more than the $10 it takes to buy one already done. And I can buy a whole set of blocks for the cost of a safety-planer (since I don't already have one).

It's a good method to have in your bag of tricks though.

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