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bkahler · 10-29-2015, 12:27 PM

Martin, you're right. I guess this is one of those times where I thought I made a mistake but ended up being right the first time

No matter which way I look at this it's going to be tough. It's such a big piece of flexible plastic that in order to make a good mold it's going to have to made rigid. By the time this project is done the original valance will likely be destroyed in the process. That's ok with me as long as we get good parts from the new mold!

Brad

martin300662 · 10-29-2015, 05:01 PM

Quote:

Originally Posted by bkahler

No matter which way I look at this it's going to be tough. It's such a big piece of flexible plastic that in order to make a good mold it's going to have to made rigid. By the time this project is done the original valance will likely be destroyed in the process.

snip

This really worries me Brad. Not only are you fixing yours, you are then destroying it for the cause.

How about we get one of the commercial companies take a look and at least quote before we end up with two Argosy without front valances?

bkahler · 10-29-2015, 05:33 PM

Martin, I've been thinking about what to do since this subject came up a while back. My valance definitely needs some repair so I have to do something no matter what. Assuming I just fixed mine and re-installed it I would still be sitting with a valance that is made of ABS plastic that has seen better days and is very brittle.

Or I could sacrifice it (if need be) to allow some decent molds to be made. This approach would get myself and however many other Argosy owners decent valances as well. I certainly don't have a problem with this approach.

I will freely admit I'm not a mold maker nor have I ever attempted to make one. I'm pretty handy at some things but if commercial company can make valances that are affordable that's all right with me as well.

No matter which approach is taken I will have to get my original valance in somewhat reasonable shape so I can put it back in place so a jig can be made to hold it in the right shape so a mold could be made. I'm not kidding when I say it flops around like a wet noodle!

bkahler · 10-31-2015, 06:40 PM

Well, I must be doing something wrong. I bought these ABS pellets and half filled a small class jar with them and then poured in enough MEK to cover the pellets. I let them sit for 24 hours and I still have solid pellets and liquid MEK in the jar.

The MEK doesn't seem to be melting the pellets. I'm pretty sure its the real MEK and not the substitute thats on the market.

Any suggestions?

martin300662 · 10-31-2015, 07:18 PM

The issue maybe that they are polycarbonate/ABS mix Brad. PC isn't soluble in most common solvents.

bkahler · 10-31-2015, 08:05 PM

Interesting. I didn't see polycarbonate mentioned in the auction but having polycarbonate in the mix would explain why it's not melting.

Tomorrow evening I can try some of the scrap ABS saved from the 345 to see if it melts. If it melts I'll know what the problem is.

Thanks!

Brad

tevake · 10-31-2015, 09:38 PM

I'm wondering if taking a first mold of the piece while it is in place is something to consider. It will be held into the desired shape while mounted.

Repair and clean the outer surface through ly then coat with mold release. And start building up the layup with fiberglass. Once it is substantial then glass on some stiffeners on the outer surfaces to maintain the shape once it is pulled off the original piece.

Then the new valence is layed up in the mold. And comes out of the mold with a finished outer surface. Could even start with a tinted gel coat to get the desired color on the new piece.

Just brain storming here. Have done lots of Fiberglass work, but mostly building the pieces and then finishing the surfaces.

If the mold is well done this fairing and finish would not be nessary.

Brad do take care while using the MEK as both the fumes and what can be absorbed thru the skin are to be avoided.

Cheers Richard

bkahler · 11-01-2015, 06:00 AM

Richard,

There are enough tears and holes in the valance that definitely need to be repaired before any mold is made. I'm not sure trying to make a mold while it is mounted to the chassis would be all that easy. There are enough angles and cavities that I feel would make the in situ attempt very painful and messy.

I don't I don't think it will be that difficult to make a stand or jig to hold the valance. I've got enough lumber and building materials laying around to do the job, I just need time to do it. Things should be winding down on my friends house rebuild in a few weeks at which time I hope to be able to spend a lot more time on this project.

When working with MEK (and other chemicals) I always use a respirator

Thanks!

Brad

Isuzusweet · 11-01-2015, 09:21 PM

Please don't in anyway think in this response that I know what I'm doing, but merely offering a suggestion.

Have the valence mounted on the coach. Construct a box with expansion holes that encompasses the valence but be an inch or so away from the face of the valence. Cover valence with Saran Wrap and Pam (release agent), mount box and then using expansion spray foam for windows and doors, spray through the expansion holes, just enough that the foam touches the valence part and expands through the expansion holes in the box. Let harden and then remove carefully, giving you a reverse hole that exactly mimics the valence in place.

Remove valence from truck and insert into foam shape, then you could foam the inside of the valence and let harden to maintain the valence's shape or by some other means build a structure on the inside that will maintain that shape, allowing you to pull the valence out and then create a mold on the outside of the valence that's an exact copy of the valence when installed on your coach.

The structure behind the valence could allow you to make repairs with Bondo or some other material, just so you could get an accurate mold. The repairs wouldn't have to be structural as the valence hopefully wouldn't be needed again.

Again please don't take this post as gospell.

Making popcorn
Cheers
Tony

bkahler · 11-02-2015, 12:59 PM

Tony,

I'm open to anything that might work although at some point I'll have to pick one and move on with the project. There's a saying I've heard at several different projects I've worked on that goes something like this "There comes a time in every project when you must shoot the engineers and begin production."

I've not heard of that process before. Do you have any links for viewing?

Isuzusweet · 11-03-2015, 08:50 PM

Sorry Brad I was away from the computer buying a Honda Pilot for the DW to get her off my back for the winter.

This video shows one type of expanding foam. The foam I would use comes in the cans so you could shoot it through the expansion holes in the box but you may find this foam cheaper or easier to use.

https://www.youtube.com/watch?v=RQbfGSttIFU

What I'm talking about is this.....Imagine wanting to make a impression of the piece he took out of the mold. So you would wrap the piece in Saran/Cling wrap, construct a box with expansion holes to allow the foam out. Place box over the piece and start foaming. After foam hardens, you remove the box and you have an impression of the piece that was molded.

So wrap your valence while still on your coach in Saran/Cling wrap. Construct a box to surround the valence and then add foam. Pull off box with hardened foam off valence. Now you have an impression of your valence while installed on your coach. Remove valence from coach and insert into impression. Now add structure behind the valence (foam and wood) so to hold the shape of the valence. Once structure has been added so the valence will retain that shape, you can remove from impression giving you a valence that has retained the exact shape that was on your coach but not installed. Now you can repair and prepare the valence to make a fibreglass mold of it.

Clear as mud?
Cheers
Tony

Smartstream · 11-03-2015, 11:59 PM

A bit of experience use the two part foam. The stuff in the spray cans must be exposed to air to cure. If you spray it in to fill the gap to your support box and have to add more to fill taps, the first part will return to liquid. If you spray some let it fully cure, maybe overnight and then add more the next day and it might work. I've tried more than once to build some up and it has always failed. The two part stuff works great but is not as handy and is much more expensive.

Gregsch · 11-04-2015, 04:09 AM

Brad If you need me to I can you the info on the pellets I used but, I bet yours are the same. I put the pellets in a glass mason jar ( about half full) then fill the jar 3/4 full with MEK. It will take several days, open the jar , stir it up , then let it set for another day. repeat as required. . Use lots of Mek. If it is too runny simply pour out the amount you need for the current project and let the air get to it. stir occasionally to keep it consistent. It will get thicker pretty quickly. the MEK wil evaporate very quickly.
For the repairs to the existing valance try simply painting MEK on the back of the two pieces ,several coats until you have a nice thick slurry on the surface, then clamp them together for a few hours.
Look at the pics in my thread to see how I lapped a new piece over the old piece to reinforce it.

bkahler · 11-04-2015, 10:50 AM

Tony,

Now I see what you're talking about. I think it would be pretty difficult to build a box around the front of the valance while attached to the motorhome. The valance is fastened to the outer front corners of the shell and has the front bumper support bars sticking through it.

I'm pretty sure before I can make any mold I need to repair the tears and holes in the valance first. I think I've figure out a way to make a support jig for the valance. Once I have that made I can make any repairs needed to the valance. Once mounted to the support jig I can evaluate whether molding foam would be a viable alternative.

However after watching the video of the 2-part foam process I've got some ideas for using it in other projects!

Brad

bkahler · 11-04-2015, 10:52 AM

Quote:

Originally Posted by Smartstream

...The two part stuff works great but is not as handy and is much more expensive.

I tried searching for someone that sells the 2-part stuff and couldn't find any sources.

bkahler · 11-04-2015, 11:02 AM

Quote:

Originally Posted by Gregsch

Brad If you need me to I can you the info on the pellets I used but, I bet yours are the same. I put the pellets in a glass mason jar ( about half full) then fill the jar 3/4 full with MEK. It will take several days, open the jar , stir it up , then let it set for another day. repeat as required. . Use lots of Mek. If it is too runny simply pour out the amount you need for the current project and let the air get to it. stir occasionally to keep it consistent. It will get thicker pretty quickly. the MEK wil evaporate very quickly.
For the repairs to the existing valance try simply painting MEK on the back of the two pieces ,several coats until you have a nice thick slurry on the surface, then clamp them together for a few hours.
Look at the pics in my thread to see how I lapped a new piece over the old piece to reinforce it.

Greg,

These are the pellets that I purchased. ABS Virgin pellets

I've had a jar of the pellets covered in MEK for about 5 days now. I haven't checked them for the last couple of days but will do so tonight. Assuming they haven't melted yet I've got some scrap ABS that I'll try this evening. I haven't been able to get time to work in the shop since last Friday. Way to much other stuff going on right now

I'll try painting some MEK on the backside of some of the cracks this evening to see if that does anything.

Thanks!

Brad

martin300662 · 11-04-2015, 11:04 AM

I think this is the stuff Brad,

Liquid Urethane Foam Kit, 2 Lb Density, Includes 1 Gallon Part A & 1 Gallon Part B: Other Products: Amazon.com: Industrial & Scientific

I have never used it but seen it used for molding race car seats etc

martin300662 · 11-04-2015, 11:08 AM

Quote:

Originally Posted by bkahler

Greg,

These are the pellets that I purchased. ABS Virgin pellets

I've had a jar of the pellets covered in MEK for about 5 days now. I haven't checked them for the last couple of days but will do so tonight. Assuming they haven't melted yet I've got some scrap ABS that I'll try this evening. I haven't been able to get time to work in the shop since last Friday. Way to much other stuff going on right now

I'll try painting some MEK on the backside of some of the cracks this evening to see if that does anything.

Thanks!

Brad

Although it really isn't clear from the listing the PC part of the name means polycarbonate.

If you search for Polymer Resources PC /ABS-FR1 (the long name shwon lower in the listing) it gives the details.

bkahler · 11-04-2015, 11:57 AM

Quote:

Originally Posted by martin300662

Although it really isn't clear from the listing the PC part of the name means polycarbonate.

If you search for Polymer Resources PC /ABS-FR1 (the long name shwon lower in the listing) it gives the details.

Wouldn't you know I would just happen to order pellets with PC in the label

Not that I knew what that meant until just recently

I think I'll try these pellets next.

bkahler · 11-04-2015, 12:08 PM

Quote:

Originally Posted by martin300662

I think this is the stuff Brad,

Liquid Urethane Foam Kit, 2 Lb Density, Includes 1 Gallon Part A & 1 Gallon Part B: Other Products: Amazon.com: Industrial & Scientific

I have never used it but seen it used for molding race car seats etc

Interesting stuff. The molding foam in the video is listed as 3 lb density, the above is 2 lb. I wonder how much difference that makes. I've sent a note off to the Industrial Polymers asking about price. It will be interesting to see what they have to say.

Brad