Looking for websites that help members with sheet metal questions

[theastronaut]

Respectfully John, I gotta disagree with nearly all of that. John how do you lay out a blank with a FSP? You can't very accurately because the shape is already in the FSP. Profile gauges and a paper pattern will give the exact info needed to make any panel, especially a complex one. Including your VW lid. Profile gauges for the bubble and other areas like the depressed areas and overall gauge. I have watched enough of Wrays vids to see him screw up over and over because his FSP tells him to put too much shape in a spot. Then he has to chase his tail trying to fix that and it turns into a cluster****. It's flexible, it moves around and you can't accurately use it to gauge your profiles. If you can peel it off the lid how in the heck are you going to get it back to the correct shape and how do you know it's the correct shape if you think you have? That's what Wrays issue is with every vid he's done showing an FSP. To all the guys interested in learning shaping it looks easy and that's what makes it attractive. You can make something that resembles the FSP but it won't duplicate the actual part for 99% of the folks trying to use it.

Another thing with tape like that if it's 60 degrees when you start shaping then continue one day and it's 85 the tape is going to be a different shape. Subtle but it will change some.

I'm guessing you have never shaped anything complex like that lid using an FSP cause if you have you would not be such a fan. And if you have done that lid using the FSP and it fit well my hat's off to you because that would be an amazing accomplishment. (not being sarcastic). Doing it the traditional way would be far far quicker and more accurate. Might take more time to make profile gauges but they won't lie to you either.

I think I see where you might be missing a point of how a FSP is used? The shape of the FSP doesn't matter, so if it doesn't stay in the exact same shape thats totally ok. It doesn't show shape, it shows surface area, and works great to show the ***difference*** in surface area between a blank/in-progress panel and what the surface area of the panel you're making should be. They were never meant to show shape, only surface area.

The shortest distance between two points is a straight line, right? To add crown to a panel you have to change the amount of surface area there is relative to the fixed edges of the panel. For a door skin you'd lightly wheel the skin, usually more passes in the middle increasing surface area in the center, lengthening the panel between the fixed edges that the jamb opening determines. The straight line (blank panel) is no longer straight, you added length/surface area via stretching. You could achieve the shame shape crown by shrinking the edges instead, but either way the surface area relative to the flat blank you started with is the same at the end. The fixed length fiberglass strands in the tape of the FSP captures the exact surface area of the panel you make the FSP from. That fixed length is now a guide that shows the difference in surface area of the original panel vs the blank you're working on.

Metalshaping is just adding or subtracting surface area (stretching and shrinking) to a blank sheet (along with bending) in all the right spots until it's the same shape as the panel you're copying. Because the FSP is made from stranded fiberglass tape it won't change it's surface area as it is peeled off, and temperature doesn't affect the surface area because of the fixed length of the fiberglass strands, although heat will make the plastic in the tape more pliable so it changes shape easier, but again the shape of the FSP doesn't matter.

Profile templates show the target/finished/overall shape, not FSPs. Profile templates don't show surface area, at least not down to the square inch level like a FSP does. **Both** are helpful to make a panel that matches the panel the templates and patterns were made from. I wasn't clear about that in my other post.

Like I said, a FSP is some information but it's not complete information, just like a paper template isn't complete information. But a FSP does have more information than a paper template because of the accurate length of the fiberglass strands that hold the exact amount of surface area that the original panel has. Unless I'm just completely making paper templates wrong, they're basically one dimensional and don't capture the surface area of the panel being copied. They do show where to shrink or stretch, and they're great for initial layout so minimal material is wasted, but they don't show how much to shrink or stretch. They still have to be used in combination with profile templates, no different than FSPs. Even if you don't believe that a FSP is 100% accurate in how it copies the original panel's surface area, isn't it still 100 times closer to copying the surface area of the original panel compared to a one-dimensional paper template?

It's already been established that Wray isn't the greatest hands-on/teacher/follow-through guy that does metalshaping. Does that make the tool bad if he uses it the wrong way? I believe the idea behind FSPs is sound; how effectively you carry out that idea is up to the end user and even Wray himself proves that when he doesn't get it right. Not everyone will always get it right 100% of the time with a paper template either.

I forgot the pic in my last post, but we did make profile templates of the lid, each profile template matched to a grid line on the FSP. There are verticle and horizontal profile templates; it's pretty much an unassembled inside out buck. With a grid on the FSP you only need two initial matching grid lines on the new panel so the FSP can be matched to the exact same spot every time so you can accurately add or subtract surface area in specific areas until the surface area of the panel fills out the FSP with no loose or tight areas- a paper template doesn't offer that information to the user. I have not actually built the lid yet, the guy who was able to borrow the lid for us to make patterns/templates had a chance to buy a reproduction lid for his replica build, so we haven't had a need to make a lid yet.

I do appreciate the differing view and respectful conversation, it lets us all see the deeper details and reasons for/against both methods of patterning that aren't always described very well when each method is only briefly mentioned in a topic.

 

[MJM]

I wouldn't say that a FSP will lie, because the FSP's surface area can't change unless you damage it. There can be error in how the information the FSP gives is interpreted, the same way looking at an original panel and trying to determine a game plan for replicating that shape could be misread. The surface area of a FSP can't change, just like the surface area of a steel panel or sheet can't change unless you shrink or stretch it. The FSP is a pre-stretched/shrunk map of what and where a flat panel needs shrinking or stretching to arrive at the same amount of surface area in the same places the FSP has more or less surface area than a blank piece of steel. With that said, a FSP alone is inadequate to shape a new panel to match the old one- you'd need profile templates as well. Paper templates are also inadequate in that way, and neither pattern will tell you the best order of operations to use to arrive at a finished panel.

I would say that it takes some skill to look at a FSP laying on a flat sheet of metal to see where area needs to be added or subtracted from the blank panel to arrive at the correct form, where paper templates are more basic with only puckers or cuts. A limitation of paper patterns is that you can mostly only pucker the edges to shrink the edges, or cut the edges to stretch/expand the edges. If you were to tape the puckers/cuts so that the paper templates holds the exact distance/area across the puckers/cuts then you're partway to having a FSP... a FSP is just a more complex paper pattern with more exact information. As that thread points out, a drawback to FSPs is that they don't accurately work to trace out a blank so you'd need to add extra around the edges which wastes material. Labor is a lot more expensive than material though, so if a pattern helps speed up labor then the wasted material isn't that significant overall, and with practice you'll learn how much extra to leave without being as wasteful.

What if you're patterning a hood with a very distinct raised blister in the center, like an early Thunderbird? A paper pattern won't work, the blister raises the paper off the rest of the hood, where a FSP would perfectly conform to the blister and exactly replicate the amount and location of extra surface area that a flat panel needs to be stretched to achieve the same amount of form/area to develop the blister in the new panel. As you're stretching/forming the blister you can use the FSP as a guide; if you're not there yet with your stretching the FSP will be loose in the areas that need more stretching. If you've overstretched the blister then the FSP will be lifted away from the surface around the blister. You'd need to cut out the center of a paper pattern to let the blister protrude through the pattern to get a more accurate pattern of the rest of the hood, then you'd have no pattern of the blister... unless you made a separate paper template for the blister itself.

In my mind a paper template is better for mapping out an exact blank and locating tuck shrink locations around the edges but has a harder time mapping out accurate area/form the center of a panel. A FSP shows all of the differences in surface area across the whole panel/pattern. As a metalshaper, your job is to stretch, shrink, and bend until the new panel matches the old panel, and a FSP gives more info overall than a paper template.

Sweeps or profile templates will be the most accurate way of matching the shape of low crown panels. I don't think a FSP or paper template would be much help there other than setting the blank size and edge details, cutouts, etc.

That thread has master metalshapers who learned from master metalshapers... I imagine they never experienced nearly as much of the trial and error us normal people deal with because of their training. From my perspective as more of a beginner/hobbyist they're throwing off FSP as not needed because they don't need them with the experience they have; they mentioned being able to make accurate panels without either style of patterns or bucks. We're not all at that level, and tools like paper patterns and FSP can help us map out what to do when staring at a blank panel, I just see a FSP as having more info to offer than a paper template. Tour de France winners don't waste their time discussing the pros and cons of different styles or brands of training wheels, but a lot of four year olds appreciate a set that work correctly.

Another point of view- people have different learning styles and different ways of applying the info they've learned. Our brains all work a bit differently. I think part of the paper vs FSP vs buck/etc argument boils down to what works best for each individual- how they're able to understand and apply each method.

I made a FSP and a set of profile templates of a Hebmuller decklid last year for a local guy. We only had one evening's worth of access to the original lid, just enough to pattern it. A paper template or even a buck would never have this much detailed information about the panel. 3D scanning would have been an option if we weren't both cavemen when it comes to tech.

Outstanding FSP by the way, I'm still in awe looking at the amount of work involved making that.

I quoted this portion of your reply because it was spot on with regards to my wheeled project.
"Sweeps or profile templates will be the most accurate way of matching the shape of low crown panels. I don't think a FSP or paper template would be much help there other than setting the blank size and edge details, cutouts, etc."

If I'm understanding one of the uses, of an FSP and paper template, That use would only provide me with surface area information with regards to my wheeled patch. I would first need to layout the area of material to be cut out, then using a FSP or paper template, I would need to make them to the exact size of the laid out area. Then transfer to my sheetmetal to be cut out.

I was lucky enough that my radius gauge was my profile. Without that, I would have needed to make a profile template. An FSP or paper template was useless with my application, imho.

 

[MJM]

Today I made another patch panel to see if I could duplicate what I wheeled yesterday. To give myself a fighting chance not knowing what I'm doing, when wheeling yesterday, I kept count of the number of times I rolled the wheel back and fourth in a straight line. The magic number to achieve with the set pressure of the upper and lower wheel was, 8 times.

So that's what I did. The panel wheeled today came out almost exactly like yesterday's with the exception of a few areas I went back over for minor adjustments. Once that was done I had two panels I would call the same. There probably is minor differences, I just can't see them.

Top view

Side view

So not knowing what I'm doing, this is what I'm doing when wheeling. After making my 8th back and fourth wheeling, I would slightly position the sheetmetal at a slight angle, about 3/16" and wheel down. Then square the sheetmetal to my border line. This was moving the sheetmetal sideways between the upper and lower wheels. I can't see the pro's doing this because they are so fluent with their motion when wheeling but, it's happening.....I think?

Here is how much I'm shifting the sheetmetal over before making another series of passes.

Straightened out to start the next series of wheeling.

Here's a short video of my wheeling in action. When you see me stop, I'm positioning the sheetmetal for a new series of passes.

 

[Chris_Hamilton]

@MJM In this thread or another (can't remember) you asked about pics of a "shrinking" stump. I found one of the threads I was thinking of. It's on Peter's site. Some good pics of what the shape should be. Here is the link.

Shrinking stump - Forums

Looking at getting myself a shrinking stump. I have a good source of hardwood tree stumps at work to pick from. Can someone help with some advise on shaping a cutout in the top for shrinking on. Maybe some pictures and dimensions would be great. Thanks Michael

ce8df029be3e-004671.vbulletin.net

 

[OJ86]

This guys videos seem to time up perfect with this thread.