Front Panel Intake Duct Mod (built from scratch using fibreglass) – GAM's HTPC

GAM · 5th February 2007, 2:19 AM

Hi all, this is my initiation attempt into fibre glassing, which I am using to create an irregular formed air duct.
Objective - Form an air duct from the two front panel intake grills to the case mounted 120mm fan behind:

After measuring the openings to be mated and their relative locations to each other I drew it up in illustrator and created some blends.
The illustration on the left gives you the idea of what was to be. The illustration on the right is the template I used on each layer.

I had the idea to create a mould form using several templates, 5-6mm thick, stacked together to guide the subsequent shaping process.
I spent a couple of half days checking with various businesses in my local light-industrial area (Brookvale, NSW) to obtain the materials I (thought I) needed to do create this duct. No luck on the 'architectural foam' I had in mind for each template form. I did manage to obtain an off cut tail from a surfboard 'blank', though, thanks to one of the surfboard makers in the area.
Long story short, this is what resulted—unsatisfactory. As the initial piece I started with was not square nor of equal thickness, my roughly shaped form was irregular and wouldn't mate with the two surfaces correctly.

Plan B – Home manufactured foam sheets from 2-part polyurethane foam.
I was very impatient as I had to get this mod done by the 31st of Jan for the OCAU 'friendly modding challenge'. Patience is not one of my virtues

.
At least this way each template would be square and of the same thickness. 6mm was cutting it too fine for this simple mould exercise, so I settled on four 8mm sheets (32mm overall). Front to back of the duct needed to be about 30mm.
I made a simple mould to form each foam sheet by nailing three strips of timber onto a piece of scrap melamine sheet, forming three edges of the foam sheet.
Polyurethane mixed and poured onto the mould with waxed paper on the bottom and the top for subsequent separation and removal.

Before the foam started to rise, I clamped another piece of scrap sheet on top to form the top surface of the foam sheet. Once the foam had expanded out of the mould and had hardened, I could remove it. The hardening process only takes minutes when the proportions of the 2 part polyurethane are correct. I made some mistakes and waited over an hour before I realised that something was wrong.

Once hardened, I removed the top sheet, the waxed paper and then the foam sheet.

Four home manufactured foam sheets.

GAM · 5th February 2007, 2:20 AM

I adhered a copy of the template to each sheet using photographic spray adhesive. Not ideal, but it did do the job. I've since purchased a stronger spray adhesive for subsequent attempts.

Now the cutting process begins.

Foam template cut and stacked together.

Originally I had planned on shaping the final edges of each template (using files and sandpaper) to form the mould but I soon realised that I hadn't given enough thought to the final dimensions. I decided to err o the side of caution and filled the steps with modelling clay (Plastercine). I'm starting to feel very pleased with myself at this stage. The issues I had obtaining materials and then the day spent manufacturing these sheets demoralised me quite a bit.

Now to the fibre glassing…
I did some Google researching before this, and but went head on into it, trial and error style, anyway. Naturally, the 'error' of trial and error emerged. The proportions of catalyst must be precise! I had trouble ensuring 0.5ml of catalyst to 50g of resin. I realised the gravity of this when my first resin soaked fibreglass didn't harden. I ripped it all off the mould and started the FRG process again. This time, impatience weighing heavy, I didn't bother brushing the resin on first, instead I placed the fibreglass strips over the mould as best I could and then brushed the resin into it. All these things get very sticky and hard to work with. If I had help or another pair of hands, things would have been better.

GAM · 5th February 2007, 2:20 AM

The second time around, I realised it was important to elevate the workpiece above the bench, thus…

One hardened, single layered, moulded fibreglass duct!

In my travels, someone told me that the resin (containing Styrene) would dissolve the polyurethane foam and counselled me to cover the entire mould with Plastercine. I did, but in the end I deemed it unnecessary.
Now to remove the foam template from the mould. I started by cutting away large chunks off the corners, layer by layer.

Surprisingly, this process was quicker than expected. Nevertheless, it probably still took close to an hour before I was left with this.

The Plastercine was a real nuisance now, although it did allow me to remove the foam more easily. The fibreglass would have stuck to the mould which would have meant leaving much of the foam in place… still not a bad alternative though as I needn't have applied so much body filler later.
To remove the centre core of foam and Plastercine, I slid my little metal ruler inside and around the edges, breaking the bond between the plastercine and the fibreglass. Once this was done, I manage to push the core out from the other side.

Core removed.

One FRG mould! At this point I SHOULD have applied additional layers of fibreglass matting. I thought this would have been longer and more difficult and opted for the 'bondo' job instead. Bad idea…

The mould needed reinforcement as it was quite flimsy with the single FRG layer. So I applied body filler to the rear surfaces to provide more stiffness and subsequent 'shape-ability'.

After a little edge trimming and much filing and sanding.

GAM · 5th February 2007, 2:21 AM

Lots of things were giving me the shits at this stage, so morale was low. Initially I did most of the shaping by hand as every time I tried to use the sanding drum on the Dremel it would tear apart. I think I realised later that I had the RPM too high and the centrifugal forces were splitting the sandpaper drum apart. Once I got the hang of shaping with the Dremel, life seemed brighter.

I decided not to bore you with the 50 thousand 'in-progress' pics of the shaping process. Note, there were several applications of body filler and subsequent shaping before I got to the following stage.
Obviously this is less than perfect, but given the time restraints and the fact that this will not actually be visible, I didn't bother filling and sanding any further. If it was external or visible, I wouldn't have tried to make it perfect.

After measuring and marking up the required cut out for the little front panel LCD and cables, I cut it out with the Dremel.

Quick check. Fits roughly.

More reinforcing and shaping work was required.

Some famous 'Spray Putty'. I've never used this stuff before either.

By the way, I have a 'Multi-tool' (disc sander/linisher) attachment on my bench grinder which I used to sand down the edges to give the correct external dimensions.
Another trial fit and I start to see where I need to make modifications to the front panel.

GAM · 5th February 2007, 2:21 AM

One of the reasons I used hot melt glue to adhere the MeshX previously was that I knew it can be removed fairly easily. Lucky, as I had to remove quit a bit that was obstructing the duct and preventing it from sitting flush to the surface.

Now the next problem… overall height! This pic show much the duct is sitting proud of the back of the front panel. The black plastic in the foreground, bottom right, sits flush against the front of the case where the 120mm fan is mounted.

I removed some more glue bits and worked out that about 5mm had to be removed. Holding my pencil flat on the bench, I rotated the workpiece in contact with the pencil to give me a cutting guide.

In the vice and cut with the Dremel.

Close to the right height now. I sanded this further to clean up the cut and take off a little more material.

More filing required to clear the PCB of the LCD.

Another test fit. Looking good! Surfaces are now flush.

Coat of primer. Single, heavy coat of black satin spray paint (can). Recall, this is not visible and I was running out of time, so I settled for the rough finishing job.

Getting closer to the business end. Another test fit and I can see where I need to modify the front panel to allow everything to fit. One screw location (bottom, left) for the side-mounted USB ports was removed entirely. Some material on the right was removed previously. More marked for removal. It is not clear in this shot, but the marked plastic bits come into contact with the duct and deform the shape of the front panel.

GAM · 5th February 2007, 2:21 AM

Now I am really pissed about this little oversight. Hastily filing another little clearance spot I didn't realise that I had also filed the edge of the front panel. Doh! Stupid stupid little mistakes. I was in a hurry at this point and this is what happens when you're in a hurry. It should be fixed when I get around to spraying the front panel, on the agenda for another time.

Extra bits removed and fits nicely. Note the four clips near each corner of the duct. These are the original clips that hold that piece of the front panel in place, still doing their job and now holding (squeezing) the duct in place too. Bonus!

After the screw-ups and additional shaping, it is not quite a perfect mating between grill and duct, but it is fine for this first attempt/experiment.

Wires, switches etc., need to go back in their places and the USB ports remounted. I was prepared to sacrifice the USB ports but I still managed to fit the PCB in its original location, albeit on a slight angle, and keep it mounted with only one of two mounting screws.

Neato!

Unfortunately you'd never know it was there. All done!!!

This mod is really quite superfluous, but recall, this is my experiment in creating ducts (practical) and other moulded forms using fibreglass.

5th February 2007, 2:19 AM	#1
GAM OCAU Sponsor Join Date: Sep 2006 Location: Newcastle, Australia Posts: 828	Front Panel Intake Duct Mod (built from scratch using fibreglass) – GAM's HTPC Hi all, this is my initiation attempt into fibre glassing, which I am using to create an irregular formed air duct. Objective - Form an air duct from the two front panel intake grills to the case mounted 120mm fan behind: After measuring the openings to be mated and their relative locations to each other I drew it up in illustrator and created some blends. The illustration on the left gives you the idea of what was to be. The illustration on the right is the template I used on each layer. I had the idea to create a mould form using several templates, 5-6mm thick, stacked together to guide the subsequent shaping process. I spent a couple of half days checking with various businesses in my local light-industrial area (Brookvale, NSW) to obtain the materials I (thought I) needed to do create this duct. No luck on the 'architectural foam' I had in mind for each template form. I did manage to obtain an off cut tail from a surfboard 'blank', though, thanks to one of the surfboard makers in the area. Long story short, this is what resulted—unsatisfactory. As the initial piece I started with was not square nor of equal thickness, my roughly shaped form was irregular and wouldn't mate with the two surfaces correctly. Plan B – Home manufactured foam sheets from 2-part polyurethane foam. I was very impatient as I had to get this mod done by the 31st of Jan for the OCAU 'friendly modding challenge'. Patience is not one of my virtues . At least this way each template would be square and of the same thickness. 6mm was cutting it too fine for this simple mould exercise, so I settled on four 8mm sheets (32mm overall). Front to back of the duct needed to be about 30mm. I made a simple mould to form each foam sheet by nailing three strips of timber onto a piece of scrap melamine sheet, forming three edges of the foam sheet. Polyurethane mixed and poured onto the mould with waxed paper on the bottom and the top for subsequent separation and removal. Before the foam started to rise, I clamped another piece of scrap sheet on top to form the top surface of the foam sheet. Once the foam had expanded out of the mould and had hardened, I could remove it. The hardening process only takes minutes when the proportions of the 2 part polyurethane are correct. I made some mistakes and waited over an hour before I realised that something was wrong. Once hardened, I removed the top sheet, the waxed paper and then the foam sheet. Four home manufactured foam sheets. __________________ GAM Mods - PC Water Cooling and Modding Supplies \| Project 'IOU' \| Project '5.25 PC' Last edited by GAM; 11th February 2007 at 8:36 PM.

5th February 2007, 2:20 AM	#2
GAM OCAU Sponsor Join Date: Sep 2006 Location: Newcastle, Australia Posts: 828	2 I adhered a copy of the template to each sheet using photographic spray adhesive. Not ideal, but it did do the job. I've since purchased a stronger spray adhesive for subsequent attempts. Now the cutting process begins. Foam template cut and stacked together. Originally I had planned on shaping the final edges of each template (using files and sandpaper) to form the mould but I soon realised that I hadn't given enough thought to the final dimensions. I decided to err o the side of caution and filled the steps with modelling clay (Plastercine). I'm starting to feel very pleased with myself at this stage. The issues I had obtaining materials and then the day spent manufacturing these sheets demoralised me quite a bit. Now to the fibre glassing… I did some Google researching before this, and but went head on into it, trial and error style, anyway. Naturally, the 'error' of trial and error emerged. The proportions of catalyst must be precise! I had trouble ensuring 0.5ml of catalyst to 50g of resin. I realised the gravity of this when my first resin soaked fibreglass didn't harden. I ripped it all off the mould and started the FRG process again. This time, impatience weighing heavy, I didn't bother brushing the resin on first, instead I placed the fibreglass strips over the mould as best I could and then brushed the resin into it. All these things get very sticky and hard to work with. If I had help or another pair of hands, things would have been better. __________________ GAM Mods - PC Water Cooling and Modding Supplies \| Project 'IOU' \| Project '5.25 PC'

5th February 2007, 2:20 AM	#3
GAM OCAU Sponsor Join Date: Sep 2006 Location: Newcastle, Australia Posts: 828	3 The second time around, I realised it was important to elevate the workpiece above the bench, thus… One hardened, single layered, moulded fibreglass duct! In my travels, someone told me that the resin (containing Styrene) would dissolve the polyurethane foam and counselled me to cover the entire mould with Plastercine. I did, but in the end I deemed it unnecessary. Now to remove the foam template from the mould. I started by cutting away large chunks off the corners, layer by layer. Surprisingly, this process was quicker than expected. Nevertheless, it probably still took close to an hour before I was left with this. The Plastercine was a real nuisance now, although it did allow me to remove the foam more easily. The fibreglass would have stuck to the mould which would have meant leaving much of the foam in place… still not a bad alternative though as I needn't have applied so much body filler later. To remove the centre core of foam and Plastercine, I slid my little metal ruler inside and around the edges, breaking the bond between the plastercine and the fibreglass. Once this was done, I manage to push the core out from the other side. Core removed. One FRG mould! At this point I SHOULD have applied additional layers of fibreglass matting. I thought this would have been longer and more difficult and opted for the 'bondo' job instead. Bad idea… The mould needed reinforcement as it was quite flimsy with the single FRG layer. So I applied body filler to the rear surfaces to provide more stiffness and subsequent 'shape-ability'. After a little edge trimming and much filing and sanding. __________________ GAM Mods - PC Water Cooling and Modding Supplies \| Project 'IOU' \| Project '5.25 PC' Last edited by GAM; 5th February 2007 at 2:26 AM.

5th February 2007, 2:21 AM	#4
GAM OCAU Sponsor Join Date: Sep 2006 Location: Newcastle, Australia Posts: 828	4 Lots of things were giving me the shits at this stage, so morale was low. Initially I did most of the shaping by hand as every time I tried to use the sanding drum on the Dremel it would tear apart. I think I realised later that I had the RPM too high and the centrifugal forces were splitting the sandpaper drum apart. Once I got the hang of shaping with the Dremel, life seemed brighter. I decided not to bore you with the 50 thousand 'in-progress' pics of the shaping process. Note, there were several applications of body filler and subsequent shaping before I got to the following stage. Obviously this is less than perfect, but given the time restraints and the fact that this will not actually be visible, I didn't bother filling and sanding any further. If it was external or visible, I wouldn't have tried to make it perfect. After measuring and marking up the required cut out for the little front panel LCD and cables, I cut it out with the Dremel. Quick check. Fits roughly. More reinforcing and shaping work was required. Some famous 'Spray Putty'. I've never used this stuff before either. By the way, I have a 'Multi-tool' (disc sander/linisher) attachment on my bench grinder which I used to sand down the edges to give the correct external dimensions. Another trial fit and I start to see where I need to make modifications to the front panel. __________________ GAM Mods - PC Water Cooling and Modding Supplies \| Project 'IOU' \| Project '5.25 PC' Last edited by GAM; 5th February 2007 at 2:31 AM.

5th February 2007, 2:21 AM	#5
GAM OCAU Sponsor Join Date: Sep 2006 Location: Newcastle, Australia Posts: 828	5 One of the reasons I used hot melt glue to adhere the MeshX previously was that I knew it can be removed fairly easily. Lucky, as I had to remove quit a bit that was obstructing the duct and preventing it from sitting flush to the surface. Now the next problem… overall height! This pic show much the duct is sitting proud of the back of the front panel. The black plastic in the foreground, bottom right, sits flush against the front of the case where the 120mm fan is mounted. I removed some more glue bits and worked out that about 5mm had to be removed. Holding my pencil flat on the bench, I rotated the workpiece in contact with the pencil to give me a cutting guide. In the vice and cut with the Dremel. Close to the right height now. I sanded this further to clean up the cut and take off a little more material. More filing required to clear the PCB of the LCD. Another test fit. Looking good! Surfaces are now flush. Coat of primer. Single, heavy coat of black satin spray paint (can). Recall, this is not visible and I was running out of time, so I settled for the rough finishing job. Getting closer to the business end. Another test fit and I can see where I need to modify the front panel to allow everything to fit. One screw location (bottom, left) for the side-mounted USB ports was removed entirely. Some material on the right was removed previously. More marked for removal. It is not clear in this shot, but the marked plastic bits come into contact with the duct and deform the shape of the front panel. __________________ GAM Mods - PC Water Cooling and Modding Supplies \| Project 'IOU' \| Project '5.25 PC'

5th February 2007, 2:21 AM	#6
GAM OCAU Sponsor Join Date: Sep 2006 Location: Newcastle, Australia Posts: 828	6 Now I am really pissed about this little oversight. Hastily filing another little clearance spot I didn't realise that I had also filed the edge of the front panel. Doh! Stupid stupid little mistakes. I was in a hurry at this point and this is what happens when you're in a hurry. It should be fixed when I get around to spraying the front panel, on the agenda for another time. Extra bits removed and fits nicely. Note the four clips near each corner of the duct. These are the original clips that hold that piece of the front panel in place, still doing their job and now holding (squeezing) the duct in place too. Bonus! After the screw-ups and additional shaping, it is not quite a perfect mating between grill and duct, but it is fine for this first attempt/experiment. Wires, switches etc., need to go back in their places and the USB ports remounted. I was prepared to sacrifice the USB ports but I still managed to fit the PCB in its original location, albeit on a slight angle, and keep it mounted with only one of two mounting screws. Neato! Unfortunately you'd never know it was there. All done!!! This mod is really quite superfluous, but recall, this is my experiment in creating ducts (practical) and other moulded forms using fibreglass. __________________ GAM Mods - PC Water Cooling and Modding Supplies \| Project 'IOU' \| Project '5.25 PC'