[av8or1]

Is there no way you could use a .040" cut-off wheel on an air die grinder from the top and put a stop disc on the cut-off disc to regulate your cut depth in the critical areas ?

You'd still need to cover all glass, etc, but it would seem to require much less edge finishing to get the dimension you need.

Well yeah, I did consider the small air-powered cutoff wheel option. The problem with that is that I was concerned about the vibration that any circular cutting device would introduce into the panel. Also, using any cutoff wheel poses a challenge when cutting the radiused corners. That said, I haven't 100% ruled this option out.

Thanks!

[av8or1]

Well I had a rather long conversation regarding this project with a fella who does this for a living. He told me that they cut the hole in the roof from above, which has been my preference all along. The difficulty I've encountered with that scenario is transferring the cut lines from the bottom (where they will be determined) to the top. This fella further told me that they use templates when cutting a new hole. I can determine the template size from deduction given the parts I have on-hand.
And with that, it occurred to me after today's discussion that if I have a template and create a fence from that size, then I could merely drill a small hole in the center of the opening from beneath. That would give me the ground-zero point from which I could lie the template/fence on the top of the vehicle to perform the actual cut. I found this idea more appealing.

And so I am a-gonna switch horses a bit on this one; gonna head down a different path and see where that leads. I'm considering building that storage rack that I've had on the back burner for a while now. Space is at an all-time premium in the workshop. Thus the only means of decluttering a bit apart from trashing a bunch of stuff that I don't want to trash is to go-vertical. If I build this rack (which is 12' long, 32" deep and 5' 2" high) I could first use it to hover above the car to make the cut. Then pull it into the workshop and put stuff on (and beneath) it. I'm giving that a serious think tonight...

Anyway thanks!

[kiwi2wheels]

Is there no way you could use a .040" cut-off wheel on an air die grinder from the top and put a stop disc on the cut-off disc to regulate your cut depth in the critical areas ?

You'd still need to cover all glass, etc, but it would seem to require much less edge finishing to get the dimension you need.

Well yeah, I did consider the small air-powered cutoff wheel option. The problem with that is that I was concerned about the vibration that any circular cutting device would introduce into the panel. Also, using any cutoff wheel poses a challenge when cutting the radiused corners. That said, I haven't 100% ruled this option out.

Thanks!

The best option is a Rotabroach.

[Poland308]

The time out to me sounds like a ground issue. My cheap china plazzz has a pilot arc that will cut for about 3 or 4 seconds. But if it doesn’t sense a good ground it will extinguish. Heavy paint in the cutting area even if I have a bare metal ground is enough to make it happen. Think it has to do with an inferior arc sensing circuit.

[av8or1]

The time out to me sounds like a ground issue. My cheap china plazzz has a pilot arc that will cut for about 3 or 4 seconds. But if it doesn’t sense a good ground it will extinguish. Heavy paint in the cutting area even if I have a bare metal ground is enough to make it happen. Think it has to do with an inferior arc sensing circuit.

Yeah, based on my experience I would have to concur with this assessment. I say that because I switched from cutting the hood to a simple piece of 1/4" flat plate. It cut through that, no issues (though higher PSI and amperage of course), which is to say that the arc definitely lasted more than 3-4 seconds. The cut appeared normal. After that, I returned to the hood and things were, as if I had waved a magic wand, working again. After a few cuts though, the phenomenon repeated. 3-4 seconds and poof, the arc extinguished. The tech for PrimeWeld (that George fella) did mention that grounding could be the issue at work here. However the majority of his commentary centered around the notion of grounding to clean, bare metal. And of course I had already done that. 'Point being that I think that it was simply the cutting through the paint on the hood as Poland308 describes that was ultimately causing the issue. 'Just as he experienced.

With that, I attempted to cut the piece of the hood that I had cut out entirely. Ergo, just that piece, which was now separated from the rest of the hood altogether. I ground both sides, hooked the work piece clamp to it and went full throttle. I attempted everything I could think of in order to replicate the failure. Neit. Running it low on air, nope, it still cut. Moving too slow or too fast only produced the expected results from moving off-speed. Zig-zag cutting, no problem. So in the end I'd have to agree with Poland308's feedback. Gotta watch the ground and also what you're cutting through.

Kinda disappointing because the PrimeWeld website states the following:

"...Continuous pilot arc enables you to cut expanded, rusted, or painted metals"

That should have an asterisk at the end, with a footnote that states "sometimes but interruptions in arc stability can occur due to poor ground connection" or some such language.

[av8or1]

After doing some testing last night (as mentioned in the previous post), I have decided that the 60A rated consumables that the CUT60 come with are decent-to-good quality. However in this context of cutting a roof, I think that a tip that yields a smaller footprint would be a better approach. And so I bought a PrimeWeld consumables kit from George last night. Also purchased a circle cutting kit, but that's another story. The point being that I am a-gonna delay this cut until after the new tips arrive and I practice with those a bit. The standoff and 60A tip are a bit cumbersome to use with a fence, though it can certainly be done. Really what I'd prefer to see is a smaller-in-width line cut through the panel. And with that, hopefully there would be less heat introduced into that panel as well. And so my formula will be (assuming the testing proves out) to utilize a 40A tip which should produce a cut that is 0.9mm/.032" in width, along with a drag shield and no standoff. This reduces the amount of distance that the center of the torch is located from the fence, which means that I will need to wait until I receive this consumables kit prior to building that fence.

The good news is that I did receive the dimensions of the moon roof hole that should be cut. That removes the guesswork out of that portion of the equation, which is to-the-good. So. Hopefully it'll be here by early next week. It was shipped this morning... TBD.

[av8or1]

With the storage rack on solid footing (hah!) I refocused on the plasma cutting adventure. The goal is to cut a hole in the roof of a 2006 Ford Crown Victoria. The quick backstory is that I bought this car to serve as a parts car for the 2006 Ford Crown Victoria that is her current daily. The cars are almost identical actually (fortuitous happenstance) with the exception of a couple of minor options. The primary difference is the color. Yup, the color. Her daily is plain-Jane white (its nickname is highly inventive = "whitey") while the supposed-to-be parts car is Dark Blue Pearl. That was an actual Ford factory color for a handful of years on these particular vehicles, thus not a re-spray. So. The wife-eee sees the blue variant - which I gotta admit looks fantastic in the sunlight - and says "I want this." Oh boy. [shudder] I thought to myself "I am in trouble. This was a PARTS car!" but managed to blurt out "ah ... well ... ok, I'll make it happen." Talk about famous last words. That thing had more issues than I care to remember and is requiring a full rebuild. And I MEAN that, a FULL rebuild. About the only thing I don't intend on doing is to separate the body from the frame. And the only reason I am not doing that is that we're in the South and I see no evidence of rust. Heck, I am practically there at present, but am trying to climb back out of this hole not dig it any deeper.

Anyway, anyway.

Fast forward to a few months ago. She sees a similar car, a Lincoln Town Car, in an online picture that I happened to be looking at, also to see if I could scavenge some parts off of (it was a similar vehicle underneath). This LTC had a moon roof in it. She asks me "can you do that?" Fellas, listen to your other halves. I didn't and am paying the price. Without a mere wave of the hand and only half to 1/4 listening to her, I muttered "oh sure", not even looking up from the laptop. She texts her girlfriends telling them about the pending moon roof installation. Then tells me about that. "Wha-? Moon roof? What moon roof?" I ask, immediately correcting myself with "oh yeah, THAT moon roof. Ok. Yeah." It was at that point that my goose was cooked.

Ok enough of the long backstory. I'll spare you the technical details regarding the moon roof selection I made, installation procedures, etc. In the end I need to cut a hole for it, right? And just how are you gonna do that? Reciprocating options are poor due to the vibrations that they cause. Circular options aren't far behind it. And so I considered plasma. And then started this thread. In the end that's the way I'll go, as I found that it didn't distort the sheet metal of the vehicle if you go about it in the right way. At least not on the hood that I tested with it didn't.

Gheez but this is becoming lengthy ...

[av8or1]

Alright moving forward here ... so I built the storage rack with the intention of using it to suspend myself in the air above the wife-eee's CV (Crown Victoria) while I cut the hole. As I mentioned at the outset of the previous post, with the storage rack ready to serve that purpose, I revisited the notion of making the actual cut.

There are dimensions that you need to adhere to and placement that you need to locate on the roof. During the past couple of nights after work I took another look at this. The primary driver for this aspect of the work is the headliner. I managed to source a headliner from a Mercury Grand Marquis (GMQ) that had a fully functioning moon roof installed in it, post-manufacture. Likely done by a dealership or someone that the dealership contracts with. Anyway I bought the full system from a guy in Houston, to include the headliner. This would be key in positioning the cut.

So I bought a few 3rd hand devices from HF:

sunroof 108.jpg (232.33 KiB) Viewed 2046 times

And used them to secure the headliner in the vehicle:

sunroof 109.jpg (215.37 KiB) Viewed 2046 times

[av8or1]

And took measurements of the headliner opening with it inside the CV and with it outside:

sunroof 111.jpg (61.27 KiB) Viewed 2045 times

I divided the longitudinal and lateral numbers in half and made marks on the underside of the roof with a soap-stone pencil:

sunroof 113.jpg (45.65 KiB) Viewed 2045 times

With one set of marks completed while the headliner was still installed and the other taken after its removal (I transcribed an outline prior to removing it). As fortune would so have it, those marks aligned rather well.

[av8or1]

So I applied the straight edge and made a cross-hair from those marks:

sunroof 114.jpg (36.86 KiB) Viewed 2044 times

Then sat back to verify that the result was indeed centered, at least as much as a DIYer could reasonably achieve anyway:

sunroof 116.jpg (233.4 KiB) Viewed 2044 times

Satisfied with what I saw, I drilled a hole:

sunroof 117.jpg (52.95 KiB) Viewed 2044 times

Which will serve as the center point of the opening as a whole. I can then outline the opening shape on the top side of the roof by referencing that hole. That is first on the agenda tomorrow.

Which leads me to the crux of the matter fellas: barring issues that might crop up during the process, it is my intention to make this cut sometime in the afternoon. Wish me luck that I don't screw it up (too badly). You have but one opportunity at this type of thing, so best to approach it in some type of logical, methodical fashion.

And in the absence thereof cross your fingers that you get lucky.

Anyway TBD. Thank you for reading.

[av8or1]

Alright so first thing's first...I wasn't able to fit the cutting of the moon roof hole in Ol' Blue today prior to darkness falling. 'Had a rough night last night, didn't sleep much and then slept in late. Upon discovering just how late, I immediately decided that I would defer the actual cut until tomorrow. No sense in rushing through anything like this. Instead, I elected to focus on refining the jig and cutting a few test pieces out of some 16ga sheet that I had left over from the plasma table build.

Originally I had planned on hacking up the spare trim support ring that I still have from the LTC:

sunroof 136.jpg (210.08 KiB) Viewed 2003 times

In order to create a jig. The idea would be that the plasma torch would "run around" inside the resulting jig to create the hole. However there were several problems with that plan. Not the least of which was size; with the torch placed to the inside and with the distance between the center of the cutting orifice and the edge of the torch, times 2 (one for each side), you would end up with a hole that would be much smaller than needed. So why not reverse that and cut around something? Say for example the spare glass from the LTC's chassis (which is the identical moon roof BTW). I had initially considered this, but in this scenario you would have the opposite problem. The torch would extend too far and you'd run the risk of creating a hole that was too large.

However I hadn't actually laid tape to it to verify that conclusion with the glass removed, so I set the LTC chassis on the plasma table and went to work:

sunroof 126.jpg (75.55 KiB) Viewed 2003 times

[av8or1]

I had the glass and inner cover removed in no time:

sunroof 131.jpg (224.58 KiB) Viewed 2002 times

Then set it on the sheet of 16ga from which I cut the plasma table collector for some measuring:

sunroof 137.jpg (63.94 KiB) Viewed 2002 times

[av8or1]

And a soap stone pencil trace indeed showed a hole that was just a tad large. So. What to do? I decided to make a few test cuts to see what would happen if I held the torch at a slight angle inward. After making the cut like that I measured the new hole. To my surprise, the hole was too small! Wha-? How the heck did that happen?

Long story short, I made 2 additional cuts with the torch at a 90-degree angle to the sun glass (with its rubber seal removed, as that contributed to the too-large size). Both of those were within reasonable margin of error:

sunroof 139.jpg (61.62 KiB) Viewed 2000 times

So I ended up with three cut-outs that had a moon roof visage to them:

sunroof 140.jpg (65.71 KiB) Viewed 2000 times

[av8or1]

I noticed that these cut-outs themselves could be used to cut the hole as well. I tried running the torch along side one of them and noticed that the drag shield standoffs were positioned well to run along the rather low height of the 16ga edge. Therefore this is indeed a possibility. I am considering both options as I compose this post, in fact.

In the end, I think that I could go either way. Using the sheet though would offer the advantage of being easier to align with the hole in the roof and easier to clamp into position such that it won't move during cutting. For those reasons I am leaning in that direction. TBD.

With that I had to close the workshop for the night and get inside to help the wife-eee with the lil' un. I did manage however to position the storage rack back above Ol' Blue:

sunroof 141.jpg (227.71 KiB) Viewed 1998 times

And prepare the hack-job of a portable air supply:

sunroof 142.jpg (244.25 KiB) Viewed 1998 times

For this is a-gonna go-down tomorrow if I have anything to say about it. And the moons align properly. And ...

Thank you for reading.

[RacerRon]

I have a friend who installs sun roofs. They use a nibbler to cut the sheet metal. No heat or distortion. They make them in both air and electric power.

Sent from my Pixel 4 XL using Tapatalk

[av8or1]

Well today was indeed the day. The short version is that I created the hole for the moon roof without too much incident. I need a little touch-up work with the flap disc but apart from that things are looking pretty well. The plasma worked out in fantastic fashion; cutting sections at a time and using 30 seconds of postflow kept the roof from even getting all that warm really. I checked it a couple of times and could easily touch it with a bare hand. And the storage rack did its job well too. All in all a good day! Some pictures follow if you're curious. I realize that an automotive application like this might not necessarily be of keen interest to folk who visit the forum to discuss welding and fabrication related topics. Therefore I'll keep it short. The last picture shows where I left it for the night, which was to cover the bare metal in self-etch primer.

Thank you for reading!

sunroof 152.jpg (85.18 KiB) Viewed 1966 times

sunroof 158.jpg (45.27 KiB) Viewed 1966 times

[RacerRon]

I have a friend with a shop who used to install lots of sunroofs. He used a nibbler and made clean holes with no heat or paint damage. The nibblers are available in both air and electric power.

Sent from my Pixel 4 XL using Tapatalk

[cj737]

Looks like a really clean cut from this distance. Is it as clean up close?

Fabrication is fabrication, whether it's structural or automotive or aesthetic. I think you did a helluva job on all of it.

[av8or1]

I have a friend with a shop who used to install lots of sunroofs. He used a nibbler and made clean holes with no heat or paint damage. The nibblers are available in both air and electric power.

Now ya tell me! Hahaha!

Well I was warned by the guy I spoke with who does this stuff for a living to avoid the cheap nibbler tools. So I did. The others ran several hundred dollars. For that reason, I decided to stick with the plasma. Granted, it's a pure DIY approach, sure. This was a DIY operation, so it kinda fit really. If someone were to get into the business of sunroof installation, I would not recommend the plasma approach. In that scenario the tooling investment makes sense. For a pretty-much-one-time-use-in-a-DIY-operation scenario ... well it doesn't. As it just so happens, I planned on touching up the paint anyway, so the paint peeling that came with the cut didn't bother me.

Thank you for the feedback though. If the quality nibbler tools would have been more affordable, I would have opted for that choice. But they weren't, so I didn't. 'Appreciate the recommendation just the same!

[av8or1]

Looks like a really clean cut from this distance. Is it as clean up close?

Fabrication is fabrication, whether it's structural or automotive or aesthetic. I think you did a helluva job on all of it.

Ah ok, well I wasn't sure if such projects would be all that welcome in a welding and fabrication forum, so I decided to err on the side of caution. Thank you for the correction.

The initial cut had trace amounts of slag all around it, so I'd have to say 'no' it wasn't as clean as I had hoped. The reason for that was ultimately my skill I think. I just had too slow of a travel speed. And the reason for that was simply that I was being too "careful" ... somehow or another when I cut the practice panels I could go faster, do whatever I wanted, I mean who cares, right? On the real McCoy though, well I found myself more diligent, more cautious and that lead to a travel speed that was too slow. That said, all of that slag cleaned off easily with a flap disc on a 4.5" grinder. So in that light, it worked out ok. Unfortunately the sun was setting and so I didn't have an opportunity to finish that cleanup yesterday. Hopefully I can get to it after work.

Thank you for the kind words though CJ, I appreciate it!

[BillE.Dee]

av8or,,,YOU did one helluva job. Congrats !! I had a situation similar when I installed dually fenders to my pickup several years ago. I didn't have a clue how to go about it. My 6 year old said, "c'mon dad, I'll show ya." the first cut was the worst, but we got R done.
Again, congrats and thanks for sharing.
gramps

[DavidR8]

Well done!
I find the anticipation of the job, so much thinking and preparation often outweighs the actual execution!


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