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perfect angles


mike ryan
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This is nothing new or revolutionary but having cut approximately then sanded the pieces for my fuselage sides, I decided there must be a quicker method. I had been using my razor saw to cut the angles and wanted to do away with sanding. I had a small mitre guide for use with a junior hacksaw, so I araldited some 1/8th ply to the sides,and then cut new guide slots with my razor saw. I drilled and slotted 2 holes in the mitre block to allow me to attach it to the edge of my board. I could now place over the plan and Mark on either side of the wood the angle to be cut. After transferring the marks using a square around 3 sides I cut the angle with my razor saw using the block to keep it all square. This is now really quick and totally accurate, producing perfect mated joints every time. Like I said it's nothing new but once I started doing it this way I have found its such a good way of producing accurate angle cuts it almost feels like cheating! Some pictures are in my albums as I can't put them in here using my phone.
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Mike, I've copied the images from your album.
Maybe I'm also becoming an old dodderer but I'm not clear on how what you've done has improved how the mitre box is used without any mods.

Photo a)

Photo b)

Photo c)

Photo d)

Photo e)

Edited By PatMc on 18/03/2014 17:38:07

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The slot was just a little too large, being that it was for a hacksaw. I used it like that for a while but decided that it would be better if it was modified a little to be used with the razor saw. Also having slots to attach it to the edge of the board is one less hand you need. As I said it's not revolutionary but I know a lot of folk cut and sand joints and this way is a lot quicker.
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Got you now, Mike. thumbs up

Here's a couple of simple jigs I made from some scrap hardwood strip, in this case 1/4 sq to suit what i was building.
E.g. with longerons in place on the plan the exact size of spacers can be marked for right angle cuts or angled cuts then transfered to a mitre box & cut verticaly on the mark.
Hopefuly the photos make it clear.

guides.jpg

vert_2.jpg

vert_1.jpg

angle_2.jpg

angle_1.jpg

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I am going to suggest a completely different gadget to measure the angle and guide the saw. My saw guide uses the tiny but very strong magnets that are used as hatch catches ( I bought mine from Giant Shark)

magnetic1.jpg

 

magnetic2.jpg

magnetic3.jpg

The magnets are recessed into the wood and are flush with the wood, held in with epoxy.. The pivot is a countersunk bolt that is screwed into the ply ( it taps its own thread if the hole is tapping size -- 5mm for M6 ) which means it does not loosen with the wing nut. The saw guide part has a clearance hole for the thread - 6.1mm for M6. Actually I used a 1/4 Whitworth thread which is still common for wing nuts .. Note the wing nut 'wings' must be clear of the saw, so the hole is a little offset from centre.

The saw used must be deep enough to allow any 'back' to clear the guide, therefore I suggest a japanese type pullsaw which has no back. This is a most useful tool for cutting ply etc as well.

In use the magnets are just strong enough to allow the saw to slide along them but not to move sideways.  The balsa is held against the ply part with the thumb whilst cutting.   When measuring the angle off the plan a steel rule could be used in place of the saw blade  to extend down to the plan for accuracy.

Edited By kc on 19/03/2014 17:05:19

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I didnt mention although it should be obvious that my saw guide relies on the edge with magnets being exactly at 90 degrees to the underside to ensure accuracy of the cut.
Using a piece of timber with this edge already machined square may be easier for some people. It is also important to have the edges parallel so measuring from any edge is equally accurate. The same with the ply base.

I think you will be surprised how accurately the magnets guide the saw if you have never used this type of saw guide before.
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