RE: Epoxy Advice Needed
Need to clarify which tube is failing.. Are you making the main load carrying tube (wing joiner) or the carry tube that is in the wing which the load carrying tube is inserted into? I assume you are making the wing joiner (load carry) tube and this is failing in compression. Not sure the best solution is a change in epoxy - true there are differences but I don't think this is the reason for failure. The glass choice is not optimal for a load carrying tube. Uni directional material (preferably carbon) orientated along the tube would be my choice. Changing the orientation of your glass to 45/45 would prove beneficial. Glass can also be 'sheared' (45/45 glass pulled out of shape) so that the fiber orientation is more aligned with the tube length would increase the load carrying ability. vaselene on the mandrel with a wrap of plastic sheet is a common release sustem used when we make DLG booms - rolled in one go and released after full cure. Lots of info on making booms/tubes in the Handlaunch section of rcgroups. cheers jeff
Posted on: 6/22/2009 11:14 PM by Author "jirvin" in the forum "Composites Fabrication And Repair"
http://www.rcuniverse.com/forum/fb.asp?m=8872992

RE: Reintroduction of the Smasher
No longer racing myself but very much into composite construction. Spends lots of time trolling in this forum as it is probably the most active for home composite builds This link shows F5b techniques including:- hinging with kevlar use of joggle gaskets to avoid voids in the seam lines painting in the mold babelfish translation....... http://66.163.168.225/babelfish/translate_url_content?.intl=us&lp=de_en&trurl=http%3a%2f%2fwww.rc-network.de%2fforum%2fshowthread.php%3fs%3d192e4db2e67c0e48d8118f995556f213%26t%3d98558%26highlight%3deisvogel Thanks for sharing you work on youtube cheers jeff
Posted on: 2/22/2009 12:59 AM by Author "jirvin" in the forum "Q-500 Racing"
http://www.rcuniverse.com/forum/fb.asp?m=8503826

RE: Voids in the seam of a fiberglass fuse..
[quote]ORIGINAL: diggs_74 I've posted on this in the past I think but I couldn't find it.. I am having a heck of a time with a new fuse mold when joining the halves of the mold with everything still wet. Any suggestions for reducing the voids? I would really like to paint in the mold but it's not worth it if I have to fill and sand voids on the finished part.. Thanks. [/quote] Can you take us through you technique and maybe we can identify what is going wrong. I paint in the mold and do wet seam joins. I do this by leaving out the last layer of cloth until the outerlayers have greened and are trimmed. The inner layer is then added with the usual method of offset as described by Dan. I also use joggle gaskets for fuz's that need to be vacuumed. This creates a seam to use for joining after the mold has cured. Not sure if you spend time over in rcgroups however a big thread plus many posts in the slope forum on the wet seam techniques. cheers jeff
Posted on: 2/16/2009 8:45 AM by Author "jirvin" in the forum "Composites Fabrication And Repair"
http://www.rcuniverse.com/forum/fb.asp?m=8482155

RE: "Sparky" vintage R/C electric project
Wow - I know the Sparky[:D] My first rc plane I saw fly was my dads Sparky. I was 4 years old - now 52! I keep getting keen to build one - I have the water damaged original plans with the pin holes. Recently I obtained from the x list a fresh copy plus a mate gave me a copy of the original article. Dad had his Wright single channel gear he made from a kit - remnants of the are still in the rafters in mums shed. I remember him winding the rubber for the escapement. I think you model needs a scale cylinder head sticking out the top for the full affect[:)] Thanks for the memory cheers Jeff
Posted on: 10/18/2008 2:27 AM by Author "jirvin" in the forum "Golden Age, Vintage & Antique RC"
http://www.rcuniverse.com/forum/fb.asp?m=8059742

RE: Plug/Parting board
[size=4] I use bondo or epoxy and micro balloons. I over fill the slot and then remove the plug after it has hardened and then sand the bondo flat To ease removal of the plug the splitter boards are made in 2 halves - secured with screws onto a base. That way i can loosen of a splitter board to get the plug out. I stabilize the plug in the holding frame with the use of bondo also. A big blob of bondo either end with somethin plastic lunch film over it to protect the plug - plug nescelled in while bondo still wet. Somewhere in the composite forum on rcgroups is a discussion on use of bondo as a gap filler. To improve the bonding of the bondo I put a slight bevel on the parting board to give a wider flatter adhesion surface. Using bondo allows more freeplay in fitting the plug to the shadow board as the bondo is more stable and doesn't get messed up when waxing. cheersd Jeff[size=4][/size][/size] [size=4][/size]
Posted on: 10/15/2008 7:39 AM by Author "jirvin" in the forum "Composites Fabrication And Repair"
http://www.rcuniverse.com/forum/fb.asp?m=8050657

RE: Sand
Hi ed, I think there is a very long thread on sand as backfill in mold contruction in the beginning of this forum cheers Jeff ps quick search of this forum using "sand" and "mold" found this http://www.rcuniverse.com/forum/m_2421428/anchors_2421428/mpage_1/key_sand%252Cmold/anchor/tm.htm#2421428 there is also the fred Mclung (not sure of spelling) and making the molds for his fredaplane f3b 3m model
Posted on: 1/19/2008 7:49 AM by Author "jirvin" in the forum "Composites Fabrication And Repair"
http://www.rcuniverse.com/forum/fb.asp?m=6932409

RE: My vacuum bag layup has crinkles, any advice?
[quote]ORIGINAL: dreadnaut Lay it up then soak up excess. I like to take a paper towel cut into 2'' wide strips, and rolled like a cigarette. I use this to roll the fabric down, and to soak up excess resin. It is inevitable that there will be some wrinkling of the release film but is it is kept to a minimum you should be OK. [/quote] I have put hthe layers in like David (most sucessful method) plus another method -wet all the layers up as a group on the bench and put them into the mold as a wet mass (only on small molds). The all layers at once method has troubles with air entrapment! Yes I like to soakexcess resin before the final vacuum. With my little molds that fit in a bag with clips (easy to get at) I do an initial quick vacuum with tissue, remove the saturated tissue and then proceed with the normal vac techniques. Then I can use much thinner breather so that I can more easily massage out the wrinkles. Hint:- I often use a hair dryer to warm the laminate once it is under vacum -it makes the epoxy more runny. The vac bag I use is heat shrinkable and the hair dryers shrinks out the wrinkles in the bag and allows the bridges in the bag to stretch down into the mold. Stuffs up the bag for repeated use[X(] I am using food packaging tube as my vac bags - designed for heat shrink. cheers Jeff
Posted on: 12/7/2007 5:41 PM by Author "jirvin" in the forum "Composites Fabrication And Repair"
http://www.rcuniverse.com/forum/fb.asp?m=6727147

RE: My vacuum bag layup has crinkles, any advice?
One other trick. Massaging the layup- I squeegee the plastic vag bag film during and after the vacuum is pulled. In the larger areas I use a plastic squeegee (apply talc to the plastic to make it slippery) and in the small tight areas I use my fingers. What I am trying to do is smothe it all aut. History:- I attended a composite seminar at Oshkosh and one of the demonstrations was vac bagging a single piece of cloth over a foam pyramid. Using the squeegee (plus talc) the all the wrinkles and puckers in the glass were removed - impressive stuff. In the demonstration of the squeegee method no breather was over the composite itself (breather around the edge of the bag). The process relied on squeegeeing the excess air and resin out to the breather material. Result:- No wrinkles. cheers Jeff
Posted on: 12/7/2007 5:28 PM by Author "jirvin" in the forum "Composites Fabrication And Repair"
http://www.rcuniverse.com/forum/fb.asp?m=6727106

RE: My vacuum bag layup has crinkles, any advice?
I have had similar results - wrinkles and ridges with plastic release. Like David said comes with the teritoy. I recently tried home made plastic breather (wanted more flexible/stretchy plastic) made in a similar fashion to your description - this caused me problems with pockets of air being trapped and incomplete bleed of the epoxy. I used peel ply instead and had a great result. Still had to be real careful in the initial draw down to look for wrinkles and bridging. http://www.rcgroups.com/forums/showthread.php?p=8538068#post8538068 BTW - over in the composite section of rcgroups IIRC there is a long thread discussing wrinkles in vac bagging. http://www.rcgroups.com/forums/showthread.php?t=467397&highlight=wrinkles Like what you are doing[:D] cheers Jeff
Posted on: 12/7/2007 5:17 PM by Author "jirvin" in the forum "Composites Fabrication And Repair"
http://www.rcuniverse.com/forum/fb.asp?m=6727046

RE: Reproduction of Curare Fuse Project Thread
I would worry about spliting the fuz to put onto boards. The distortion may be difficult to manage. May be better to use splitter board? For a project like this I often make a very quick splash (thin) mold to lay up a heavy plug in - this gives a much more stable suface to get a good finish on. When doing this I simply fill cutouts with blocks of foam and cover with 2" wide sticky tape. The heavy plug then allows finer finishing of these details. Making the extra throwaway mold may sound like more work however the joy and time saved working on a more solid plug soon make up for this. I have often gone the 2 mold method when resurecting a favourite crashed balsa model - glue back together - sticky tape and plasticine over the divots - quick mold - heavy plug- mold number two - and turn it into a fiberglass job. cheers jeff
Posted on: 4/28/2007 1:16 AM by Author "jirvin" in the forum "Composites Fabrication And Repair"
http://www.rcuniverse.com/forum/fb.asp?m=5781401

RE: New CDI - opensource project JMJ and Bigboat
[quote]ORIGINAL: Bigboat [quote]100n = 0.1u c7 greencap/mylar sufficient - OK?[/quote] 0.1 uF is a littlebit low, use 470nF/400VAC / 600VDC atleast [/quote] Hi Rob I wonder is this [b]C7[/b] you are suggesting to be "470nF/400VAC / 600VDC" it looks more like [b]C1[/b]? I have used greecap/mylar type for C7 0.1u as per circuit diagram - is it correct to change this to 470nf (0.47u)? cheers Jeff
Posted on: 7/1/2006 9:17 PM by Author "jirvin" in the forum "Engine Conversions"
http://www.rcuniverse.com/forum/fb.asp?m=4453182

RE: New CDI - opensource project JMJ and Bigboat
Thankyou Rob >0.1 uF is a littlebit low, use 470nF/400VAC / 600VDC atleast 0.1 shown on circuit diagram will try larger value- off to the shops in the morning! >5 Volt is (to) high for a BT151, he will ignite on 0.8 Volt allready (don't forget a resistor into the gate!) I will include r3, c3 and r4 onto test board and use this to trigger. > don't forget to ground the metal of your coil to the sparkplug and powerboard, otherwise it isn't work !! Thankyou- I was carefull to do this - I get a solid spark but tapping faster than 1hz shows no spark. cheers Jeff
Posted on: 6/30/2006 12:40 PM by Author "jirvin" in the forum "Engine Conversions"
http://www.rcuniverse.com/forum/fb.asp?m=4448817

RE: New CDI - opensource project JMJ and Bigboat
[size=3][b]I have spark- ouch![/b][/size] [quote]ORIGINAL: jirvin Yes a lot of talk about electronics. It is an open source project where this talk helps develop the goal to a DIY CDI for engines. [b]I take it on faith that it works.[/b] [/quote] All very messy at the moment[8|] Operating at this stage without scr by earthing the capacitor C6 to earth to generate spark. Using 4 cell nicad (5.2v
Posted on: 6/30/2006 10:59 AM by Author "jirvin" in the forum "Engine Conversions"
http://www.rcuniverse.com/forum/fb.asp?m=4448517

RE: New CDI - opensource project JMJ and Bigboat
Yes a lot of talk about electronics. It is an open source project where this talk helps develop the goal to a DIY CDI for engines. I take it on faith that it works. The original thread (see page1) shows video of strong spark and success with the project Rod has his mounted on a gas engine - see page1 of this thread. Cost? This is DIY so far around $30AUS plus 3 days of research (priceless!) it is cheaper to buy completed project ie Desert Aircraft, CH, so on at $200 or more if you want it now. cheers Jeff
Posted on: 6/25/2006 10:02 PM by Author "jirvin" in the forum "Engine Conversions"
http://www.rcuniverse.com/forum/fb.asp?m=4430364

RE: New CDI - opensource project JMJ and Bigboat
Hello Rob On the schematic the capacitors c3,c7 are listed as 0.1u (100n) + (electro type?) These have been difficult to find - must be looking for the incorrect thing? Could these be replaced with greencap "mylar" type similar to the c8,c4,c5 100n cheers Jeff ps found the low drop out 5v regulator[:)]
Posted on: 6/25/2006 9:03 PM by Author "jirvin" in the forum "Engine Conversions"
http://www.rcuniverse.com/forum/fb.asp?m=4430166

RE: New CDI - opensource project JMJ and Bigboat
Thanks Rob Sleep soon- now 1.30am - home with a brocken arm plenty of time off[:o] (fell of my nice BMW bike) Last for today I find cheap JDM programmers on Ebay - will research later. I can see 16F628A pic not 16f628 - will reseach to see if compatible with your hex? cheers jeff
Posted on: 6/25/2006 11:25 AM by Author "jirvin" in the forum "Engine Conversions"
http://www.rcuniverse.com/forum/fb.asp?m=4428381

RE: New CDI - opensource project JMJ and Bigboat
Thanks again Rob Im getting closer[:D] Capacitor for storage C6 is what we call Greencap, Polyester or"Mylar" I have found 630v dc 470nf 26mm lead spacing ? L4 1uH is this a RF Choke type? IC3 LP2950CZ from specs is 100maH +5v I have found similar 78L05 100maH low power This leaves just the capacitors and resistors plus programminf pic (next week!) and pc Board cheers Jeff
Posted on: 6/25/2006 10:45 AM by Author "jirvin" in the forum "Engine Conversions"
http://www.rcuniverse.com/forum/fb.asp?m=4428288

RE: New CDI - opensource project JMJ and Bigboat
Thankyou Rob I have spent day going around in circles looking at available online Australian electronic shops I find to my embarrasment that the final hall was originally listed on the original site:- http://home.online.no/~jon-mj/cdi_ignition.htm Now to find most of other components_ have found Bt151 locally Your circuit lists "Flashlight" is this a led or incandescent? Any thing special about opto TIL111 "standard led photodiode"? here i find 4N28/4N25 it appears similar except the pin 2 is anode and pin 3 is cathode wheras til111 has pin1 anode and pin2 cathode from research? cheers Jeff
Posted on: 6/25/2006 9:46 AM by Author "jirvin" in the forum "Engine Conversions"
http://www.rcuniverse.com/forum/fb.asp?m=4428137

RE: New CDI - opensource project JMJ and Bigboat
Hello Rob I feel more informed in my searching for the hall unipolar type Also available locally is this IC, sensor, Hall Effect, unipolar, SS443A Details from data sheet Am I close to the correct type cheers Jeff
Posted on: 6/25/2006 8:25 AM by Author "jirvin" in the forum "Engine Conversions"
http://www.rcuniverse.com/forum/fb.asp?m=4427987

RE: New CDI - opensource project JMJ and Bigboat
re suitable hall switch Am I looking for the correct type of hall switch? I think I may be closer with this UGN3177UA http://www.ortodoxism.ro/datasheets/allegromicrosystems/3175.pdf These Hall-effect latches are temperature-stable and stress-resistant sensors especially suited for electronic commutation in brushless dc motors using multipole ring magnets. Each device includes a voltage regulator, quadratic Hall voltage generator, temperature compensation circuit, signal amplifier, Schmitt trigger, and an open-collector output on a single silicon chip. The on-board regulator permits operation with supply voltages of 4.5 volts to 18 volts. The switch output can sink 10 mA. With suitable output pull up, they can be used directly with bipolar or MOS logic circuits. These are available for resonable price in Australia ~AUS$5 cheers Jeff
Posted on: 6/25/2006 12:02 AM by Author "jirvin" in the forum "Engine Conversions"
http://www.rcuniverse.com/forum/fb.asp?m=4427350

RE: New CDI - opensource project JMJ and Bigboat
Thankyou Rob for the reply on the E-Core - I will buy the fluro p/s and use the rewound transformer. I am now researching locally (Australia) available hall switch. From my reading to directly use hall effect with pic it has to be switch (high low) and not sensor. Sensor could be used if pulse is conditioned as in 5Bears tim4 circuit or use of IC's? cheers Jeff
Posted on: 6/24/2006 10:19 PM by Author "jirvin" in the forum "Engine Conversions"
http://www.rcuniverse.com/forum/fb.asp?m=4427112

RE: New CDI - opensource project JMJ and Bigboat
Re Suitable hall effect sensor New to electronics - understand the basics! I have seen mention of this Hall Sensor in the thread:- "Also I want to use the H501 Hall switch (Unipolar type) from www.Conrad.de with the ordering code 185120-62" Is this essential? I have found this hall sensor- http://www.jaycar.com.au/productView.asp?ID=ZD1902 ___________________________________________________________________ UGN3503U Hall Effect Sensor A miniature sensor to accurately track extremely small changes in magnetic flux density - changes generally too small to operate hall effect switches. Specifications: - Operating voltage: 4.5 - 6V DC - Supply current: Typ. 9mA - Output voltage: Typ. 2.5V DC - Output resistance: 50 - Size: 4.5(W) x 4.5(H) x 1.5(D)mm Applications include notch sensor, current monitor, gear tooth sensor, etc. ____________________________________________________________ Or should I go for the switch type? http://www.jaycar.com.au/productView.asp?ID=zd1900 ____________________________________________________ This device consists of a Hall Effect semiconductor sensor separated across a small gap by a magnet. In its normal state the Hall sensor (with inbuilt output transistor) is conducting. It will sink up to 40mA between the impressive temperature range of -40 to +150 degrees C. When an iron vane is introduced into the gap between the Hall element and the magnet, the output transistor switches off. The sensor is hermetically sealed, resistant to petroleum products and incorporates metal bushed mounting hols to facilitate fitting to a carrier plate, bracket etc. It is ideal as the commutator for an electronic ignition; however it has many other usage areas. Lead connections: Red V+, Black earth, Green signal (on/off). ___________________________________________________________________ My concern is that from reading about hall there are analogue and logic level hall devices. What paremeters should I be looking for? Cheers Jeff
Posted on: 6/24/2006 7:48 PM by Author "jirvin" in the forum "Engine Conversions"
http://www.rcuniverse.com/forum/fb.asp?m=4426755

RE: New CDI - opensource project JMJ and Bigboat
re Using a fluro power supply transformer for the coil. On the CDI page http://www.modelbouw.gompy.net/newcdi/newcdi.htm mention is made of using transformer from here:- http://www.electroniccity.com/shopping/pricelist.asp?prid=565&brandinc=58 In Australia I have found what looks similar or the same (good price):- http://www.jaycar.com.au/productView.asp?http://www.jaycar.com.au/productView.asp?ID=SL2868 On the CDI web rewinding is mentioned- " Unfortunately the transformer cannot be used without rewinding the coils " Is this coil totally stripped of wire and rewound as per the torroidal? So is the fluro supply merely supplying a E-Core? cheers Jeff
Posted on: 6/24/2006 7:24 PM by Author "jirvin" in the forum "Engine Conversions"
http://www.rcuniverse.com/forum/fb.asp?m=4426677

RE: Opensource CDI ignition
[size=3][b]E-Coil wind?[/b][/size][quote]ORIGINAL: Ben_C My high voltage coil is wound on an E-core. I would rather spend $200 on a professional CDI than wind another toroid coil! The E-core coil only took about 20 minutes to wind. Ben [/quote] Hi intersted in having a go at building this CDI for a Ryobi whipper Snipper I too find the idea of winding a toroidal intimidating! I have been looking for a tutorial on how to wind a E-Core? Closest so far is this- http://www.repairfaq.org/sam/jshidbal.htm Anybody have links or pictures on how to do an E-Coil wind? cheers jeff A walk through on programming a pic would be good also (my wsishlist)
Posted on: 6/24/2006 2:07 AM by Author "jirvin" in the forum "Engine Conversions"
http://www.rcuniverse.com/forum/fb.asp?m=4424783

RE: Trying to estimate strength vs weight.
I'm trying sandwiches to find the strongest, lightest and lowest cost material for my uses. Fuses being one. I'm trying to find a 1/16in flexible foam to make a thin, light, skin material. For an example of strength, just take 2 layers of laminated 4oz fabric and compare that to the same thing with a piece of shirt cardboard or just about any other thin separator laminated in the middle. Its just that the only kind of cheap, readily available 1/16 in foam ---------------------------------------------------------------------------- Hi, On a 1/4 scale texan harvard I stiffened the large round shaped fuzelarge with 1/16 hot wired 1lb white foam backed up with 3/4 oz glass. A friend repeated this process on a 60 size pattern fuz and this made the fuz back stong enough to hold the completed model by! We didn't use vacuum! the foam and 3/4 glass was placed in as we layed up the fuz and then held in place with a large tubular plastic bag filled with sand. (poor mans vacuum- didnt mess up the cloth on the flanges for easy trimming. regards Jeff
Posted on: 5/4/2005 11:43 AM by Author "jirvin" in the forum "Composites Fabrication And Repair"
http://www.rcuniverse.com/forum/fb.asp?m=2941985

RE: Big mold making advice!
Would these 2 videos help? http://www.fibreglast.com/showproducts-category-Videos-118.html Advanced Moldmaking and Plug Construction By Fibre Glast Developments, 45 minutes The first of this two part series shows the students from the University of Akron beginning the process of building the first all composite, frameless Supermileage Racer. In this video you will see them develop the plug design, construct the plug from scratch and build the large polyester mold all in an environment similar to a home garage! Vacuum Bagging and Sandwich Core Construction By Fibre Glast Developments, 45 minutes The second of this two part series begins with the completed molds. The student team will lay-up and vacuum bag the Supermileage Racer shell as well as release and finish it! You will see the complete process of scheduling, laying up the graphite layers, a carbon/ honeycomb sandwich and the vacuum bagging process! These techniques have never been captured on tape before! I havent seen either of them but they sure look interesting. regards Jeff
Posted on: 4/14/2005 1:46 AM by Author "jirvin" in the forum "Composites Fabrication And Repair"
http://www.rcuniverse.com/forum/fb.asp?m=2875003