|Donald MacDonald 1||20/03/2022 23:59:25|
|50 forum posts|
If we now take just the two connecting surfaces ("A." and "B." ) , and imagine that they are made out of a single thin sheet of paper, that has been creased to get around the corner...
PS By experiment it seems to be something like 19° off straight ( i.e. 161° in my diagram). Does that seem about correct?
Edited By Donald MacDonald 1 on 21/03/2022 00:19:36
|Michael Cooper 5||21/03/2022 02:43:56|
|16 forum posts|
I’m getting 109.5 deg, for your 161 .Definitely try it on paper before you take my word for it lol.Good luck Don
|not done it yet||21/03/2022 07:08:48|
|6812 forum posts|
You know the dimensions of the parts. A bit of trigonometry would provide you with the proper value.
|Gary Wooding||21/03/2022 07:13:16|
|983 forum posts|
I get 109.47°
22751 forum posts
yes 109.5 approx
Measure the 4 edges of the chamfered face off your CAD model and draw that "flat" then measure the angle, easier than trig
|686 forum posts|
Assuming that the chamfer is 45 degrees and the corner of the block is 90 degrees, you only need the chamfer distance to calculate this:
In either a side or end view of the part (does not matter because the chamfer is 45 and the corner is 90), you see the vertical height of the chamfer (top to bottom) as a true length (1). This is the chamfer distance.
In a plan view of the chamfer, you see the base length as a true length. It is the hypoteneuse of a 45 degree right triangle with side length = chamfer distance (2) .
Those two lengths allow you to calculate the true length of the intersection slope (the vertex of your unfolded pattern) (3).
The side or end view gives you the true length of the chamfer (the sloping bit) (4).
(3) and (4) allow you to calculate the half angle.
Using the same reasoning, you can write a general formula where the inputs are: chamfer angle, a characteristic chamfer distance (either vertical or horizontal) and corner angle.
A good place to start is an old technical drawing book, where you learn how to draw a view of something such that a particular feature is shown as its true length and its angle to a plane is a true angle.
|Michael Gilligan||21/03/2022 08:32:52|
20183 forum posts
Good explanation, DC31K
It’s also worth noting that Builders have been doing this stuff for millennia … so a visit to ‘Builder Bill’ is quite informative: **LINK**
6404 forum posts
Sheet-metalworkers handbooks have all that information too. They use it for making ducting etc. I suppose these days there would be sheetie websites and calculators that would do it for you like the builders site MG posted above.
Pipefitters handbooks/websites have all the same kind of info for circular forms (pipes) and cones etc.if you ever need it.
How's the invention going?
Edited By Hopper on 21/03/2022 10:50:32
|Donald MacDonald 1||21/03/2022 11:11:22|
|50 forum posts|
...Just in case anyone else might need all those decimal places!
Edited By Donald MacDonald 1 on 21/03/2022 11:15:19
|Paul Lousick||21/03/2022 12:47:24|
|2043 forum posts|
CAD software that has a sheet metal module can produce a flat pattern that is used for bending.
It is first modeled as a solid 3D part to the final shape. Then the software converts it into a part that is made from sheet metal. This part can then be flattened and dimensions added. Lines for bending are also shown.
1617 forum posts
I did it in CAD by using the Mirror tool.
|old mart||21/03/2022 17:44:00|
|3775 forum posts|
Paul Lousick has the answer with 19.47 degrees, (19-28-12".
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