Good level of precision for mitre angles?

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Brendan
Posts: 5
Joined: Mon Jan 14, 2008 5:28 am
Location: Bellows Falls, VT

Good level of precision for mitre angles?

Post by Brendan » Thu Jan 17, 2008 10:27 am

I am interested in building polyhedra out of a material like wood or plastic. I am wondering about the required precision of mitre angles. I noticed that Squeaky made a wooden one. What precision was used for cutting the wooden pieces?

I have a tool that looks like a combination square, but has a circular part with angle marks in degrees and other parts with straight edges that can be locked to an angle on the circular part. The angles marks are in increments of one degree. Is that enough precision for making mitre angles? Would the required precision vary with different polyhedra?

Squeaky
Posts: 47
Joined: Wed Jan 16, 2008 3:09 pm
Location: Derbyshire, England

Mitre Angles

Post by Squeaky » Thu Jan 17, 2008 6:39 pm

Hi Brendan,

Making models of polyhedron, from wood, is not really too difficult provided you are fairly precise with measurments of the component faces and set your bandsaw (cutting the mitres) as accurately as possible.

I use a digital angle gauge that I obtained via e-bay. The resolution of this instrument is 0.1 degrees. I try to get the angles as accurate as possible. In my humble opinion 1 degree accuracy, in measuring the angles, is not good enough

Start with a fairly simple shape .... say a dodecahedron ... don't go too small .... I would say make the component pentagons of a size to finish with a dodecahedron of about 12 inches diameter.

If you make a complicated model with lots of faces then any error in mitre angles is multiplied and when you come to assembly it may start off O.K. but it will not, what I term, 'close'.

If I can help you please ask.

Where do you source your wood from?

Squeaky

Brendan
Posts: 5
Joined: Mon Jan 14, 2008 5:28 am
Location: Bellows Falls, VT

Post by Brendan » Sat Jan 19, 2008 6:14 am

I haven't selected a source of wood yet and was just wondering about what precision level was good. What kinds of woods are good? Have you tried plastic?

Squeaky
Posts: 47
Joined: Wed Jan 16, 2008 3:09 pm
Location: Derbyshire, England

Woods

Post by Squeaky » Sat Jan 19, 2008 7:59 am

Hi Brendan,

I nearly always use hardwoods ... hardy ever used plastics except one time I covered a 'stellation' with mirror coated acrillic. When I sort out 'photobucket' I will send a picture of this particular model to the forum.

One very good source of hardwood is to buy a single pack of hardwood flooring ... the solid stuff not 'laminated' .. You can buy this material from big DIY shops in England ... it is well seasoned and a very convenient size.

If you are interested I could go through making a model step by step with you.

Squeaky

Squeaky
Posts: 47
Joined: Wed Jan 16, 2008 3:09 pm
Location: Derbyshire, England

Post by Squeaky » Sat Jan 19, 2008 10:31 am

Image

Brendan,

As promised ... I am posting a poor photograph of a model I made combining wood with mirror plastic

Brendan
Posts: 5
Joined: Mon Jan 14, 2008 5:28 am
Location: Bellows Falls, VT

Post by Brendan » Sat Jan 19, 2008 6:51 pm

That models looks like it'd look good in sunlight. :o When I have some wood and tools, I'll post about that here.

hamp856
Posts: 16
Joined: Thu Jul 21, 2011 12:22 pm

Post by hamp856 » Wed Nov 02, 2011 3:52 pm

I use a machinest protractor which can be easily set within 2' of arch. Works great.

Hamp

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