# Compass advice



## Oldiebutgoodie (Jun 26, 2012)

I'm trying to round the sharp corners of a board, and someone told me a compass and a jigsaw might be the easiest way to go. I purchased a rather entry level compass from a national woodworking retailer. I paid about twice the cost of a grade school class trinket, but it looked nice.

The one I bought was a General, with one arm shut down by a knurled screw and the other held by spring tension. I found this absolutely useless as any kind of pressure overcomes the spring tension and gives me a wobbly line. I'd probably do better with classroom devices as both legs are held stationary by a wing nut. 

So, what's my next step? Am I using the compass incorrectly? I can't see any way that would not collapse the spring tension. Should I just pay a few more bucks and get something with higher quality? Any suggestions for something less than $30? Or, is there a way to round corners consistently without the compass?


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## Hammer1 (Aug 1, 2010)

The spring control is for fine tuning the setting, that leg can be replaced with a pencil. In normal use, you shouldn't be putting enough pressure on that leg to make it move but you may want to adjust it more towards the center of the adjustment. There are plenty of ways to mark round corners, any can, coin or round object can be held even with the edges and traced. There are drafting templates with many size holes and there are specially made corner markers, probably found at Rockler or similar suppliers.


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## Dave Paine (May 30, 2012)

I use a fixed radius template.

Woodcraft is selling 4 templates. Mine is the big yellow one.
http://www.woodcraft.com/product/2004218/703/quick-corner-four-pack.aspx


This is a single template, likely all you need.
http://eaglejigs.com/shopdisplayproducts.asp?id=38&cat=Radius+Template

I would NOT use a jigsaw to round the edge, the blade will flex and the corner will not be smooth.

Either use a belt sander, followed by Random Orbit Sander, or a rasp followed by ROS. A rasp can remove a lot of wood very fast.

These days I tend to use a 12 in disc sander with 80 grit discs, but not many people have one.

If I have to do a corner manually, I may use the band saw to rough out, then the rasp and finish up with the ROS.

I use the template for marking the radius.


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## Pirate (Jul 23, 2009)

For marking corners to round over, I just grab a can, or other object with a round bottom, the diameter that looks right.
Oh, dear, did you see that glass I like to drink out of......


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## Pirate (Jul 23, 2009)

For drawing arcs, I like this.


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## Oldiebutgoodie (Jun 26, 2012)

Thanks for all the help. I originally was going to use a can for an arc, but a local retail said that I would end up with many different non-identical corners. The templates look great.

If I use a rasp from there and then sand, any particular kind of rasp? I'm working on a 3/4IN hardwood. 

As far as the compass goes, the pointed pin is sturdy, but there is no solid adjustment on the compass leg with the pencil in it. So, when I set the pin end, and then open up the width to the correct radius, the pencil end will still exert pressure that acts together with the direction of the spring pressure making the smallest pressure against the pencil, just the grain of the wood even ride up and close the gap. That is that making the radius larger is prohibited by the set up but it will ride the legs closer together with the slightest touch. I don't see the as a micro adustment, but a gross adjustment that will not hold up.


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## BassBlaster (Nov 21, 2010)

I have 2 of the Alvin bow compass's from my college drafting classes. They still work great and are of good quality. You can get them at any art supply stores and probably amazon.


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## jigs-n-fixtures (Apr 28, 2012)

Go on eBay and buy a good set of drafting tools. They go pretty cheap, as there are a lot of them out there that are older professional level tools, that were replaced by computers.

Sent from my iPhone using Wood Forum


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## Pirate (Jul 23, 2009)

Oldiebutgoodie said:


> Thanks for all the help. I originally was going to use a can for an arc, but a local retail said that I would end up with many different non-identical corners. The templates look great.


So, if you use a can or glass, cup, coin, (basically a circle template), you think you will end up with different sized corners. ??????
I do it all the time. Mark corner. Cut close with band saw. Sand to line, on oss. Done. All the same.


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## timetestedtools (Aug 23, 2012)

I do the same as Pirate and I agree the corners come out fine. For bigger circles I just take a piece of scrap the right length, drive a nail in one end (as the pin) and drill a hole for a pencil in the other. Adjusting is just a matter of moving the nail. When I'm done I throw the scrap away. I've always been going to make one sliding adjustable, just never got to it.


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## cabinetman (Jul 5, 2007)

I use the technique of tipping the top of the compass into the direction of the radius. That way, there's no pressure on the marking point to compress the spring.










 







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## Longknife (Oct 25, 2010)

Pirate said:


> So, if you use a can or glass, cup, coin, (basically a circle template), you think you will end up with different sized corners. ??????
> I do it all the time. Mark corner. Cut close with band saw. Sand to line, on oss. Done. All the same.


+1. Why make science out of a simple task?


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## Alchymist (Jan 2, 2011)

Short answer: beam compass

Longer answer:
http://www.shopnotes.com/issues/097/videos/using-a-beam-compass/


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