Jump to content
Dzimm

How to Reproduce?

Recommended Posts

It finally happened! Thanks to JPEX05, I was finally able to get a street Comanche air dam! :banana:

IMG_20190708_222233.jpg.5079722829c02150f9b4d99949944b60.jpg

 

It has minimal damage, none of which would really be seen when installed.  

IMG_20190708_222248.jpg.13362fb485eb1b9a371e98dffb1e9dc0.jpg

IMG_20190708_222257.jpg.82e731ab38d3a2e8641ba4c5344e60aa.jpg

 

Now my big master plan was to make a couple copies of it so I didn't have to worry about tearing up the real one but now I'm not exactly sure how to proceed.  

 

I had thought the street MJ ground effects were made of fiberglass but turns out it's very flexible and made of like a polypropylene or a PVC of some kind.  Probably the same material used on the fender flares.  

 

Anyone have any ideas on exactly what it is made of or how else I may reproduce it?  I could still make fiberglass ones I suppose but I actually like the flexibility in it.    

Share this post


Link to post
Share on other sites

You would start by building a wooden buck to hold the piece, to straighten out the piece.....attach to the buck.

Then you make a mold of the piece. 

From the mold you make a casting.

From the casting you make a new mold. 

Remove all imperfections of the new casting.

From casting you make a final mold.

From the final mold you lay up fiberglass.

Or you can do vacuum carbon fiber. 

 

It goes something like that.

 

 

Time, tools, materials, knowledge, talent = S-loads of money. 

I've tried to encourage you guys to watch all forms of car related vids, instructional vids. Even vids/instruction that does not necessarily relate to Jeep.

Some things do or can transfer over to 4X trucks.

When you watch custom, one-off, car/truck builds......metal forming, glass work, paint and body...........this is where the money is spent, well into the hundreds of thousands of dollars.  

 

 

Share this post


Link to post
Share on other sites

The fiberglass and carbon fiber process are definitely very involved and I'm okay with that.  I've never done it before and it's something I certainly am willing and wanting to learn and do.  I've already seen about every video available on it so I already know what in getting myself into.  

 

After receiving the part and realizing it's not a rigid part, I started to think about heat forming or vacuum forming plastic maybe, basically looking for an option to create a flexible part.  I'm just not familiar with any processes other than fiberglass or carbon so I don't know what other options are out there and am hoping someone knows of something else.  

Share this post


Link to post
Share on other sites

maybe talk to the guy that does Lund visor re-pops.  they are fiberglass, but honestly I wouldn't be opposed to them being fiberglass on my truck.  :L: 

 

I worked for dupont's plastics division many, many moons ago and dabbled in vacuum forming.  But we were only doing small 12" long parts, not 5 ft long front ends.

Share this post


Link to post
Share on other sites
19 minutes ago, Pete M said:

maybe talk to the guy that does Lund visor re-pops.  they are fiberglass, but honestly I wouldn't be opposed to them being fiberglass on my truck.  :L: 

 

I worked for dupont's plastics division many, many moons ago and dabbled in vacuum forming.  But we were only doing small 12" long parts, not 5 ft long front ends.

I'm not really opposed to fiberglass either, there are many many vehicles with fiberglass body parts hanging low.  This is currently still my top choice.  

Share this post


Link to post
Share on other sites

I think fiberglas would be a serious mistake. It's far too fragile. I don't know what the original part was made of but I imagine its something like what the Old Town canoe company calls "Royalex." I think that's similar to (if not the same as) the material the drop-in bed liners are made of. It's much more damage resistant than fiberglas.

Share this post


Link to post
Share on other sites
1 hour ago, Eagle said:

I think fiberglas would be a serious mistake. It's far too fragile. I don't know what the original part was made of but I imagine its something like what the Old Town canoe company calls "Royalex." I think that's similar to (if not the same as) the material the drop-in bed liners are made of. It's much more damage resistant than fiberglas.

It's definitely not the same as a drop in bed liner, this is far too soft.  It feels and flexes just like the factory fender flares.  

Share this post


Link to post
Share on other sites

This looks like it would create a close copy but would require a very accurate mold of both the inside and outside of the air dam.  For an inner mold, it would have to be collapsible due to the overhang that wraps around the flare so this may not be a very easy or cost effective route but may be an option.

 

Model-Pro Polyurethane Casting Resin 4 Making Models 2 Gallon Kit https://www.amazon.com/dp/B001VMWLBC/ref=cm_sw_r_cp_apa_i_mOvjDb6YR7SC5

Share this post


Link to post
Share on other sites

Comparing the condition of yours to Stroker's..........yours may be too distorted to even make a good mold from.

 

IMG_0780.JPG

Share this post


Link to post
Share on other sites
4 minutes ago, Jeep Driver said:

Comparing the condition of yours to Stroker's..........yours may be too distorted to even make a good mold from.

 

IMG_0780.JPG

Mine does still have some droop in the middle opening but it's not nearly as bad as in my original pictures.  It had been sitting in the box outside all day so it was very hot and droopy in that picture, after cooling off it straightened out quite a bit. 

 

Either way it needs some work before a mold is pulled from it as it's got some chipped paint and the slight damage on the ends.

Share this post


Link to post
Share on other sites

Here's the deal.............

 

I don't care about air dams.......not one bit, but I'm interested in the concept of someone actually pulling off some custom work. 

 

I did some brief reading on mold injection........what I already knew, mold will cost $50-100K with 10,000 units produced. Now that that's off the table......let's get past our delusions. 

 

 

Fiberglass, that is the material that is available to you.

 

Could I reproduce that in fiberglass, I know for a fact I can. I see that as about a 300 hour winter project, maybe a few hundred dollars in materials. 

I may have a lot of finish work involved but I know I can pull it off, assuming I have a good one to work with. I'm pretty good at doing something one time and having no desire to ever do it again. 

 

 

You put that much effort into an air dam you better have one hell of a truck to install it on.

 

You say, others say- not fiberglass. It's done all the time. If you are worried about running up on the curb at McDonalds? Guys who spend that much time and money and effort don't pull up to McDonalds. let alone curbs. 

 

 I'm not putting more than 400 hours into my bodywork to drive into the woods and drag a tree down the side of it. 

 

Metal forming or fiberglass.........that's what you got. 

 

 

BTW, there is no reason you cannot reinforce the backside with metal. 

Share this post


Link to post
Share on other sites
11 hours ago, Dzimm said:

It's definitely not the same as a drop in bed liner, this is far too soft.  It feels and flexes just like the factory fender flares.  

 

Well, I have two drop-in bed liners here, and I've had two others. IMHO they are the same material and flex about as much as the factory flares.

Share this post


Link to post
Share on other sites
3 minutes ago, Eagle said:

 

Well, I have two drop-in bed liners here, and I've had two others. IMHO they are the same material and flex about as much as the factory flares.

That's interesting.  The bedliners I've seen have all been thin and very hard plastic.  Granted none were for an MJ.  

Share this post


Link to post
Share on other sites

Pretty neat undertaking, none the less. Who originally produced these air dams? How many were actually made? 

Share this post


Link to post
Share on other sites
10 minutes ago, Jeep Driver said:

Here's the deal.............

 

I don't care about air dams.......not one bit, but I'm interested in the concept of someone actually pulling off some custom work. 

 

I did some brief reading on mold injection........what I already knew, mold will cost $50-100K with 10,000 units produced. Now that that's off the table......let's get past our delusions. 

 

 

Fiberglass, that is the material that is available to you.

 

Could I reproduce that in fiberglass, I know for a fact I can. I see that as about a 300 hour winter project, maybe a few hundred dollars in materials. 

I may have a lot of finish work involved but I know I can pull it off, assuming I have a good one to work with. I'm pretty good at doing something one time and having no desire to ever do it again. 

 

 

You put that much effort into an air dam you better have one hell of a truck to install it on.

 

You say, others say- not fiberglass. It's done all the time. If you are worried about running up on the curb at McDonalds? Guys who spend that much time and money and effort don't pull up to McDonalds. let alone curbs. 

 

 I'm not putting more than 400 hours into my bodywork to drive into the woods and drag a tree down the side of it. 

 

Metal forming or fiberglass.........that's what you got. 

Yeah definitely not going to do any sort of injection molding (that's my day job) and wouldn't work very well for a part like this anyhow.  

 

I'm not really worried about fiberglass, and honestly would probably more consider carbon fiber myself, I was just curious if anyone knew of a different method feasible for diy that would have some flexibility to it.  The urethane method is one I came across that could work but is likely going to be way more work than it's worth.  

Share this post


Link to post
Share on other sites
7 minutes ago, 13 Legion said:

Pretty neat undertaking, none the less. Who originally produced these air dams? How many were actually made? 

They were a dealer promotion out of somewhere in California in 1987.  I've read the ground effects were produced or designed by the Archer Brothers and as of 2009, they supposedly had some stock left in their warehouse but never got back with the info.  I want to say it was HOrnbrod who had contact with them but I could be wrong. 

 

We know 100 street Comanches were produced, plus some extra probably so maybe a total of 125 full kits built, and that's probably generous.  Actual numbers are unknown and never will be known.  As for the molds that produced these parts, they are probably long gone.  

 

I have also read that the Archer Brothers have no interest in the past and won't respond to anything about it anymore.  It's possible they may still have a pile of parts collecting dust somewhere but I don't think we will ever know.  

Share this post


Link to post
Share on other sites

I recently watched a Youtoob video about a guy who used sand casting to make a bronze cannon. There were actually a series of videos, because he had a lot of failures before he finally got one that was mostly okay. One of the alternatives he experimented with was a plaster mold. I wonder if you could make a plaster mold off the original and then cast fiberglas or carbon fiber into the plaster mold.

Share this post


Link to post
Share on other sites

It was me that was in contact with the Archers a few years ago and it’s true that they still had a few incomplete sets of skirts on the shelves at that time. I bought as close to a full set that I could, a fiberglass hood, a full race suspension, and their last original front valance. After a couple years of keeping in contact with them and hearing the same “haven’t found it yet” I gave up and sold my skirts to someone doing a restoration on their Street Comanche. 

 

The Archer valances were all made from fiberglass. Bobby Archer was the one in the shop that made them from their mold. It was damaged long ago, however. Mine is pretty thin but theirs weren’t meant to last more than one race. 

Share this post


Link to post
Share on other sites

My suggestion is stop asking the azzes of the masses. If you want it, go for it like anything in life. If what half these guys say we're true, less than 200,000 total mjs made, every injection mold type piece would have been operating in the millions at a loss. You drink milk from a cow you don't buy it from the guy who knows where the farm is around the corner. Nothing would get down and progression would never take place in life if everybody listened to everybody.

Share this post


Link to post
Share on other sites

indeed.  :L:  best I can offer is I can likely tell you how they were made IF I had one of the parts in my hands.  There are always little telltale indicators on plastic parts. 

 

BUT, I'd wager that knowing how the originals were made doesn't actually bring new parts closer to fruition.  you have to work with what you have available, and that is likely going to be 'glass.  :L: 

Share this post


Link to post
Share on other sites
14 minutes ago, Pete M said:

indeed.  :L:  best I can offer is I can likely tell you how they were made IF I had one of the parts in my hands.  There are always little telltale indicators on plastic parts. 

 

You will in a few days lol 

Share this post


Link to post
Share on other sites

welp, that's how exhausted my brain is.  literally couldn't put 2 and 2 together.  :roflmao:

Share this post


Link to post
Share on other sites

I am a retired mechanical engineer who worked with LOTS of plastic molded parts in my career, so here are my two cents:

 

Owing to their size, the original parts were probably created by some short of sheet forming compound.   This is a plastic sheet resin that is heated, and placed into a mold where it is pressed into shape and then allowed to cool.  Sometimes the material has glass or mineral strands added to increase stiffness of the finished product.

 

Making a duplicate of this part would, of course, involve first making a die (mold) that is essentially an inverse image of the part, both inside and out.   Of course, the mold has to be "tweaked" so that the softened plastic does not pull too sharply in corners and whatnot, and thus tear, so an exact inverse image is not usually the shape of the final die.  Believe it or not, in low volume production, this could actually be made from hardwood, like maple.  

 

Once a die is made, then a suitable material must be found.   Sheet forming compounds in large sizes and thicknesses can become pretty expensive in low volumes.   It might cost a couple of hundred dollars just for a sheet that is 6 feet long and "x" wide.   Of course, the compound you choose also needs to be formable in the die you create, as the "stretchiness" of various resins are different.  This might mean some trial and errror experimentation might be needed, and you might end up creating several unusable versions before the die is optimized.

 

All of this, of course, would required a facility with a large oven to heat the resin sheet, and a the ability to fixture the mold halves and compress them together once the heated sheet is placed into the mold.

 

Owing to all of this (cost of raw sheet material, cost of die development and fabrication), making a duplicate of the OEM part in low volumes  would result in some pretty high piece part costs.   This makes creating parts from fiberglass or carbon fiber MUCH more cost-effective.

 

Making the part in fiberglass or carbon fiber would be done similarly to the way boat hulls are fabricated.  A wooden mold is still needed, but it's only the inverse of the outside of the part is required, so the mold cost is lower.   The actual part is them "laid up" by hand, with sheets of glass or carbon mat soaked in resin, and then applied to the mold (which has been coated in a mold release compound.)

 

This method is tedious from a labor perspective, but does not involve a fancy facility with an oven and mold presses.  It also is more fragile, as noted previously.

 

All things considered, unless you are indepenently wealthy, the idea of "tooling up" to make a OEM equivalent to the original "spoiler" is pretty much problematic.

 

Sorry to rain on the parade here.

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


×
×
  • Create New...