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  #31  
Old 04-26-2017, 01:00 PM
Mike Rouse Mike Rouse is offline
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Sweeps are regular curves meaning that they have a single radius unlike a parabola which is an irregular curve which has a constantly changing radius.
That being said, it is possible to combine two different radius curves (sweeps)
And have what I call a combination curve. I have an example picture of one in my album showing how it is constructed. I have found as Kerry pointed out that panels are rairly a single radius.
I combine two or more of my sweep patterns for instance in capturing the vertical profile so a door panel of a 1933 Chevy. It is most important to keep in mind the relationship of the individual radius lines and center points.
Refer to my combination curve drawing.
Discovering where the panel changes radius is important.

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  #32  
Old 04-26-2017, 02:17 PM
cliffrod cliffrod is offline
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Quote:
Originally Posted by Kerry Pinkerton View Post
I guess if you were making something that had a consistent radius top to bottom and you were concerned about the surface being with a few thousands, that might make sense. But, imo, that is very, very rarely the case. Most the cars I've worked on have changing radii top to bottom.

I have a set of 50 sweeps that I don't use much simply because the radius is never EXACTLY right for what I'm doing. Usually, I find the one that fits the best and try to maintain a consistent relationship side to side.

I agree, especially for anything that is going to be handmade. If you are developing patterns, model or buck headed for male & female tooling manufacture of mass produced & standardized interchangeable parts, they would make more sense. For the work done by most people here, I think $$$ purchased sweeps may be useful but are more luxury than necessity.

The publication pics specifically note about their utility re: clay work. Another post mentions sourcing from Chavant Clay. Not many here regularly do a full 1:1 model for a job in clay to duplicate (as I have been doing in studio for the past 2-3 wks.) Repurposing tools is great, but it's my understanding sweeps are most useful for 3D model development in plastic media.

Whether 2D or 3D, straight lines, perfect circles and square edges & corners are always tough. Even a total novice can see they are right or wrong. Curves are easy to fake.... jmho.
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  #33  
Old 04-26-2017, 02:46 PM
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Kerry Pinkerton Kerry Pinkerton is offline
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Originally Posted by toreadorxlt View Post
His are milled... he will tell you that yours need to be milled for accuracy, then give you a long rant. Especially if you tell him you want to get a set laser cut for cheaper.
There is no doubt that Fay is a master craftsman. That said, when someone tells me that their way is the ONLY way to do something, I tend to get REALLY skeptical of most everything they say.

Regarding sweeps, I find the shorter sweeps more useful. Mine are 36" and I wish they were 24 or less. I have a couple long adjustable curves like the ones Per (MetalMan Sweden) and others sell (including Harbor Freight). I find them to be much more useful.
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  #34  
Old 04-26-2017, 03:36 PM
bobadame bobadame is offline
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It seems to me that shorter sweeps, maybe 20-24" long would be most useful. Slide the sweep along the surface to see where the surface either lifts of drops away which would show the exact point at which the curvature changes. This would allow you to measure exact arc lengths. In fact this method could be used to "digitize" a surface. For example, mark a grid on a door at 6" intervals, in X and Y. Find a sweep that fits the curvature along a line. Slide it up and down to find the tangent points of that arc, and so on vertically and horizontally.
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Last edited by bobadame; 04-26-2017 at 04:56 PM.
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  #35  
Old 04-26-2017, 04:33 PM
Gareth Davies Gareth Davies is offline
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Originally Posted by toreadorxlt View Post
His are milled... he will tell you that yours need to be milled for accuracy, then give you a long rant. Especially if you tell him you want to get a set laser cut for cheaper.
Another reason not to contact him! Laser cut will be more than good enough for what I want.
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  #36  
Old 04-26-2017, 04:51 PM
longyard longyard is offline
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Quote:
Originally Posted by Kerry Pinkerton View Post
That said, when someone tells me that their way is the ONLY way to do something, I tend to get REALLY skeptical of most everything they say.

There are various metal religions... power hammer vs English wheel, oxy vs TIG, form/shape vs area/arrangement...

I completely agree with Kerry. Doubt the zealots and take what's best from each that works for you.
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  #37  
Old 04-27-2017, 07:35 AM
Essexmetal Essexmetal is offline
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Before everyone gets too caught up in accuracy of the edge or strength of the material just remember sweeps are a device for checking curves and transferring that shape. In the case of most of us it is either side to side on a vehicle or between the buck and your work.

The only time you will need an exact numbered sweep with an edge you can shave with is if you are building off a print and need to transfer the "#32" radius to a buck or panel. Point is make them out of whatever you want, thin with a crisp edge is best but for 99% use these are just reference tools. To support those above..... short is best. Also make them the same radius on both the convex and concave portion of the sweep. The originals had the next size up on the opposite edge.
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  #38  
Old 04-27-2017, 07:48 AM
billfunk29 billfunk29 is offline
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Default French curve sweeps

Has anyone used French curve sweeps? For drawing cars, a french curve is much more useful than a circle template.

GrabCAD has a step file for a french curve.
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  #39  
Old 04-27-2017, 08:27 AM
Dyce Dyce is offline
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Quote:
Originally Posted by billfunk29 View Post
Has anyone used French curve sweeps? For drawing cars, a french curve is much more useful than a circle template.

GrabCAD has a step file for a french curve.
I use them a lot. Using an overhead projector I enlarge curves if needed. This is has been a very good discussion and thank you everyone for your input.
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