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| Airframe's Mid BEC LMP http://www.locostusa.com/forums/viewtopic.php?f=36&t=2142 |
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| Author: | BHRmotorsport [ April 1, 2017, 11:40 am ] |
| Post subject: | Re: Airframe's Mid BEC LMP |
Did you folks ever wonder why airframe fixer seems obsessed with fasteners and their correct use? The answer is at the end of this video. https://www.youtube.com/watch?v=pOcm6E1 ... e=youtu.be |
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| Author: | airframefixer [ September 7, 2017, 4:03 pm ] |
| Post subject: | Re: Airframe's Mid BEC LMP |
... posting from the flightdeck while I wait for fuel... been having an insane year since last post... all good. |
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| Author: | a.moore [ September 8, 2017, 2:56 am ] |
| Post subject: | Re: Airframe's Mid BEC LMP |
Those look good - great work! |
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| Author: | sevenesqueron [ September 8, 2017, 1:55 pm ] |
| Post subject: | Re: Airframe's Mid BEC LMP |
Nicely done Andrew. Any problems that required re-doing or did you get it right the first time? What's the material and thickness? Ron |
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| Author: | JackMcCornack [ September 9, 2017, 11:59 am ] |
| Post subject: | Re: Airframe's Mid BEC LMP |
+1 for Ron's comment (and question). And while you're telling us about material and thickness, show us the pattern you used for those headlight covers...and what vacuum forming equipment? |
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| Author: | ckouba [ September 9, 2017, 10:51 pm ] |
| Post subject: | Re: Airframe's Mid BEC LMP |
JackMcCornack wrote: +1 for Ron's comment (and question). And while you're telling us about material and thickness, show us the pattern you used for those headlight covers...and what vacuum forming equipment? Forget all that... What'd you promise the missus to be permitted to do it in the kitchen!??!?!?? Looks like the pattern and vacuum box are visible in the first pic? |
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| Author: | airframefixer [ October 5, 2017, 6:55 am ] |
| Post subject: | Re: Airframe's Mid BEC LMP |
ckouba wrote: JackMcCornack wrote: +1 for Ron's comment (and question). And while you're telling us about material and thickness, show us the pattern you used for those headlight covers...and what vacuum forming equipment? Forget all that... What'd you promise the missus to be permitted to do it in the kitchen!??!?!?? Looks like the pattern and vacuum box are visible in the first pic? A 2017 Honda CRV LX AWD. kidding.. as long as it doesn't stink up the house, its fair game. I feel like this is the first few days since the winter months I've been able to post. Plastic forming... the material is .080 PETG, or Polyethylene terephthalate glycol, trade name spectar. Same plastic in pop bottles, good clarity, pretty resilient, but lacks rigidity. Going into this sub project was filled with unknowns. Unlike Paint, or composite, or metal fab, processes are well known and established and repeatable. This differs as the variables are far greater, namely material type, thickness, heat, time, vaccum flow, and vacuum pressure. Like Ron mentioned, it all comes together in about 3-5 mins. so, nope, I have a big pile of plastic scrap to show for those parts. you should be able to see the form in the pictures, I used two vaccums connected to the box for flow. I have since tried acrylic in .125 to test the mold and vacuum, additional ports needed to be added and higher temps required to get a complete draw. Acrylic, being much more brittle is not ideal. poly carbonate, or lexan need to be heated for several hours to remove moisture. So before going to polycarbonate, Ill try .125 PETG next. A small back up frame will be required to help with rigidity. Have a feeling that will be the sweet spot. .... |
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| Author: | airframefixer [ October 5, 2017, 7:23 am ] |
| Post subject: | Re: Airframe's Mid BEC LMP |
Life update.. and next car project progress Ok, so since my posting in late April about the exhaust heat shield, while making those brackets I managed to lodge a sliver of steel into my eye right on the edge of my iris. Yes I was wearing safety glasses, the cooling fans airflow from my grinder blew it under my glasses. I didnt notice it for a few days. off the to hospital to get that carved out with a needle. I bought a full face shield shortly after... yikes could have been a major life interruption. Be mindful out there, safety gear has it limits. No damage. On to work. I moved up to Captain in may, which was about 7 weeks of training in Toronto. I used to be number 1 bidding First officer, now 4th from the bottom Captain, which means I no longer pick my schedule, but am on call 18 days a months. On average I've been called out 12-14 days. So I have been flying lots, which I don't mind. Being back in the left seat is far more rewarding for me. My company was also staffed thin due to a global demand for pilots, many at my company, have gone overseas for larger paychecks...not this guy. My business continues to grow to the point all I'm doing is lawn care, (fertility, pesticide applications, turf renovation). I should have it wrapped up by late October which leaves the winter to work on the car and home repairs upgrades.... speaking of, my dishwasher leaked in July, so the decision was made to reno the basement while I was ripping out drywall. |
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| Author: | GonzoRacer [ October 5, 2017, 7:29 am ] |
| Post subject: | Re: Airframe's Mid BEC LMP |
Yo Airframe! Thanks for the updates. Your work is a magical as ever, very cool stuff that forming hot plastic... Left seat in front of the yoke looks like a great office to me. (Wanna-Be GA Pilot, Flight School Dropout here.) Enjoy! And take care of those eyeballs! Good advice, Sir.  JDK |
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| Author: | airframefixer [ October 5, 2017, 7:42 am ] |
| Post subject: | Re: Airframe's Mid BEC LMP |
Whats next. Ive been working on a new support spar for holding up the sidepods, the old one was just a strip of 6061-t6 which bent a its weakest point, perhaps from me stepping on the side pods. The new one is cut from extrusion, and will be fastened to an angle.. 3.5 lbs before fasteners. Ive mentioned solid rivets are nt ideal for 6061 t6 as it isn't as hard as the alloy its meant for. I have a few titanium hi loks and collars. unfortunately the pin doesn't meet pin protrusion limits, so have to use MS21042 nuts. the pin number is an HL11, with a reduce shear head for were csink fasteners are required. Hi loks are interference fasteners and must be driven in. If done right you wont need the hex key. So how does one countersink a hole for an interference fit fasteners and know the dept is correct. you can do many test samples, or in my case, drill to Number 21, countersink to AN426-5(which is the same head diameter as NAS1097-6), then ream to .185 (undersize) and drive your pin. It will work out. The other ones are NAS1466 lockbolts, My C6L's are the correct grip, but dont like the lack of grove swaging on the collar. Of course, everything gets primed and sealed before final assembly. So the other benefit of not working on the car, is I spend more time thinking things through, which ultimately makes for better lighter parts, and I get right to business in the shop, like I did before. I also never stop procurement, always looking for material, parts and tools. Trying to get back to my old ways of getting it done. hers some pics.. |
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| Author: | Warren Nethercote [ October 5, 2017, 10:16 am ] |
| Post subject: | Re: Airframe's Mid BEC LMP |
Andrew, if you think a vacuum pump would be better for pulling down the headlight shields I have a fairly agricultural one that you could borrow. I suspect that two vacuums may be better from a flow-rate perspective though .... Never change two variables at once during an experiment! |
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| Author: | JackMcCornack [ October 5, 2017, 12:26 pm ] |
| Post subject: | Re: Airframe's Mid BEC LMP |
Thanks for the plastic forming advice, airframefixer. I'll try PETG for my next attempt at making headlight covers. If you wouldn't mind spending a few more paragraphs of text (and photos, if you have them) could we have more details on the mold? I see it's a female mold, why choose that over a male pattern? What did you make the mold of? What's the surface? How did you treat the surface to make it easy for the vacuum to get in? Any sticking problems, and if so, how did you solve them? PS--Yes, I know vacuum doesn't go anywhere, and vacuum is what remains after the air is gone; I was just being witty and cute. |
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| Author: | ckouba [ October 5, 2017, 2:31 pm ] |
| Post subject: | Re: Airframe's Mid BEC LMP |
JackMcCornack wrote: I see it's a female mold, why choose that over a male pattern? I'm going to guess because it's easier to position the hot and floppy piece of PETG over the female mold and then pull vac than to try to manually stretch the hot sheet over a male mold and properly position it onto the vacuum box. Just a guess. Chris |
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| Author: | airframefixer [ October 5, 2017, 7:47 pm ] |
| Post subject: | Re: Airframe's Mid BEC LMP |
Thanks Guys. Warren, I think we're due for a visit. I have the vaccum dialed in now on .125 acrylic, it was mostly the size of holes and number that was limiting. What it could use for deeper draws is a surge tank. Chris, there was no reason to make a female other than the plug/form was a male piece, the mold was female. I only though about making a male tool after the first round of draws. Jack. No worries, Ill do a video of some forming when the .125 PETG shows up. the basic forms were MDF placed back to back. I then filled and primed them with high build polyester surfacing primer. The mold is gelcoat and fiberglass the same way I made the body work molds. If you look close youll see some spider cracks in the mold... this is from some selective tapping with a dead blow hammer to release the plug from the mold. Unfortunately, the local supply didn't have tooling gel in stock. Ill also take some credit for the need to hammer it off due to some poor draft angles that have been sanded out. The process involves, heating the precut sheet in the oven at 300 for approx 5 mins, I ended up using a sag reference for timing. The sheet is supported on an aluminum frame that screws together. once the ideal sag has reached, the tray/frame is pulled from the oven, and imediately placed on the form with the vaccums running, a shop vac, and a canister vaccum. The mold was greased with vaseline. Heres a few more pics, again. Ill do a video and post.. Ill be doing more videos as well for various fabrication stuff. The first pic shows flame edge sealed acrylic, sanded edge acrylic, .080 PETG, and another .125 acrylic after cutting with a fiber disk. |
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| Author: | airframefixer [ October 5, 2017, 7:51 pm ] |
| Post subject: | Re: Airframe's Mid BEC LMP |
No call from work today, managed to get the support spar done. |
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