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3d - Printworx

Printing 3d Forum

Carbon Fiber Square Tube 750x10.5mm (HobbyKing)

Started by teslahed, Tuesday,July 31, 2012, 10:30:32

Previous topic - Next topic

teslahed

I found some (fairly) cheap square carbon fibre booms that look like they could replace aluminium in many quadcopter designs because of the size;

http://www.hobbyking.com/hobbyking/store/__9012__Carbon_Fiber_Square_Tube_750x10_5mm.html

I ordered 4 which arrived today. Not sure when I'll get around to using them - probably on the next quadcopter i build after i crash one of my current ones.

I have read that cheap carbon fibre tends to split but one suggestion has been to use an 8mm balsa wood dowel with some expanding polyurethane glue to fill the centre to add strength without adding too much weight.

If you remember the issues i had with the redesign of the Sporan and the clamped arms (the design was changed from having the arms screwed into position to clamped into position without telling anyone which i wasn't too happy about) I may just be able to use them with parts from that frame. I seem to remember reading somewhere that it's best not to drill through carbon fibre if you want the possible best strength so it might work out quite well (or the arms might come flying off the first time i spin at speed).

One circlip short of a quadcopter.
 1 lobe short of an antenna.

Gaza07

That looks very use full a good alterntive to ali tube, its annoying when they stick the stickers on the end though as I always struggle to get it off the ali tube ive used from B&Q  :rolleyes:

teslahed

http://www.ebay.co.uk/itm/PURE-ACETONE-NAIL-VARNISH-REMOVER-500ml-1-2-litre-/350584524145?pt=UK_Health_Beauty_Nails_Manicure_Pedicure_CA&hash=item51a0774d71

You can buy pure acetone (active ingredient in the better nail varnish removers) on ebay. Ebay seems to be a good place to pick up basic chemicals for amateur chemistry and similar - It's where i get my hydrochloric acid from to dispose of the I mean clean the sink.
One circlip short of a quadcopter.
 1 lobe short of an antenna.

teslahed

Tuesday,July 31, 2012, 12:43:17 #3 Last Edit: Tuesday,July 31, 2012, 13:11:41 by teslahed
I've just cut some of the carbon fibre to size (outside because of the toxic dust then i ran the cut ends under a tap to get rid of any small bits).

The carbon fibre weights in at 12 grams and the aluminium booms at 19 grams for equal lengths. So there will definitely be some weight saving but not as much as i might have hoped.

I wonder if there are any other benefits to using carbon fibre over aluminium? Is it any better for vibration damping?

I've just assembled the frame of my new 'carbon sporan'; it now weighs in at 227 grams as shown below.

One circlip short of a quadcopter.
 1 lobe short of an antenna.

Gaza07

It looks nicer with black arms hopefully you will get some use out of it now  ~~

MadMax

Looks very good I doubt the uk dealers are to happy with HK setting up here  :rolleyes:

Gaza07

It might not affect them as much as you think as HK will have to pay import tax, when you order from HK in Europe the prices are higher than china because of the tax on them, still good news having a warehouse here though  ~~

MadMax

Good point I didnt think about import duties probably because I never do  :whistling:

Jumpy07

These looked ideal to replace the arms on my Spider Quad.. but out of stock :-(

BNUC-S Pilot with PfCo /PFAW.
UAQ / CAA PfCo Instructor / Flight Assessor

"All that is necessary for the triumph of evil is that good men do nothing"

XH558

 :cool2:

I';ve not seen that before and it seems so much better a prospect than aluminium box section so I';ve just ordered 6 lengths of it to start my next project a hexcopter. I have a mind to use ';sausagerolls'; design of 60 degree cuts on the tube ends and then clamp that top and bottom like you';ve done.

If I could just ask - is the centre section and the motor mounts own design - and made of what?? Looks like carbon fibre too :) Is it?

I like the idea of clamping to avoid too much drilling - so if you made them how did you go about it - looks like some precision cutting  :o

teslahed

Tuesday,October 23, 2012, 09:54:33 #10 Last Edit: Tuesday,October 23, 2012, 09:56:30 by teslahed
The cutting isn';t as clever as it could have been - the two pieces are not interwoven at the centre. Once piece goes all the way through the middle and one piece is cut in two so i have 3 lengths (and 2 different sizes) of carbon fibre making the quad.

With the amount of overlap it';s worked fine for me though.

I';m building a new quadcopter today - I';m using the flyduino centre piece and I';ve drilled out some of the carbon fibre tubing instead of using aluminium to try and save a bit of weight. The flyduino design used fewer bolts than the sporan but I';ve had to drill through the carbon fibre. This may weaken it but I';m hoping with a small 700 gram weight quadcopter it wont cause any problems.

The motor mounts are made of the same kind of fibre glass sheeting as the centre section. You can buy similar ones here;

http://quadframe.com/collections/sp/products/mm01

Although for the flyduino frame i am currently putting together i am going to try mounting the motors directly to the carbon fibre arms.

Last post in this thread;

http://www.multi-rotor.co.uk/index.php/topic,97.90.html

They seem to be about 1/3rd lighter than equivalently sized aluminium arms so you will save a bit of weight unless the motor mounts you use are too heavy in which case you may be better of sticking with aluminium.
One circlip short of a quadcopter.
 1 lobe short of an antenna.

teslahed

Thursday,November 29, 2012, 10:33:16 #11 Last Edit: Thursday,November 29, 2012, 10:44:11 by teslahed
I';ve had good success with the carbon fibre so far, but I';ve noticed it squashes quite easily once you';ve drilled a hole for a bolt to run through it and tightened that bolt up.

So I';ve been using some 8mm wooden dowl (pine, not balsa) which just fits inside the circular hole running through the carbon fibre. I';ve used gorilla glue (polyeurathene based expanding glue) with the wooden insert to produce pressure from the inside. I';ve redrilled the holes through the wooden inserts and now when i tighten the bolts up the carbon fibre isn';t squashed.

Gorilla glue is good stuff. It uses water as a catalyst so i ran the wooden dowl under the cold tap before i added the glue and inserted it into the carbon fibre quadcopter arms.

Before when i was flying there was a worrying rattling sound coming from the quadcopter. I';m hoping that after reinforcing it in this way I';ll get less vibrations as i';ll be able to tighten the bolts up more without the carbon fibre splitting.


One circlip short of a quadcopter.
 1 lobe short of an antenna.

Smeagol

Sounds like good stuff, I had planned to run the motor wires up the core, but might reconsider and use the dowel to strengthen them.

On my build the arms are not drilled, the securing bolts are either side of the arms and clamp in place.

Still waiting on UK stock

teslahed

You may be ok if you aren';t drilling holes through the carbon fibre. It may be worth testing a scrap piece to see how readily it squashes with the kinds of forces you';d be applying when you tighten up the bolts either side of the stuff.

I have only reinforced the end 6cms of each of my carbon fibre arms - where the holes are drilled. I haven';t run wood and glue all the way through, to save on weight. So hopefully it';s only the weak points that need reinforcing like this.

It definitely looks much neater if you run the wires through the arms - on my smaller stunt quadcopters i didn';t do this to keep the wiring more direct and keep the weight down - but if you aren';t going for maximum power to weight ratio you probably don';t care about that.

I';ll report back once it';s flown :-)
One circlip short of a quadcopter.
 1 lobe short of an antenna.

Smeagol

I was chatting with HK UK no sign of stock incoming so i';ll pop along to get some 10mm Aluminium.

It will give a little more room to house the motor cables also.

I prefer the look of the carbon fibre and the extra little bit of weight reduction.

Will be interesting to hear if you have lost your rattle.

XH558

I did consider adding some 8mm dowel - but then decided that the wires inside the arms was preferable - and not to drill the carbon arms but just glue them and bolt clamp on the motor mounts...

Then I did the disaster drill through 3 of the arms with a view to bolting through and realised the wires were already in there  :whistling:  - escaped that one - but moved on to another option - add another ply plate and bolt through either side of the arms as a kind of clamp to assist the cyano - so no more arm drilling needed  ;)

teslahed

Thursday,November 29, 2012, 12:37:27 #16 Last Edit: Thursday,November 29, 2012, 12:42:05 by teslahed
I expect you';ll be fine without.

In my case - tightening up the bolts really starts to squash the carbon fibre and it';s difficult to know what point is ';tight enough'; to keep things secure without also damaging the stuff. I didn';t really have much choice in my case - but i wouldn';t bother if i were you unless you really notice that it needs it.
One circlip short of a quadcopter.
 1 lobe short of an antenna.

Smeagol

Went off the idea for the CF, so i';ve cancelled the order from HK UK, getting some more LIPO';s instead, at least they are in stock.

So it';s aluminium for me, with wires up the core, hmmm must remember not to drill in to them  :evil
i';ll have to get some matt black camo paint for the arms now.

The idea of plugging the bore with dowel is good, starting to regain the weight though.



teslahed

Quote from: Smeagol on Thursday,November 29, 2012, 12:40:28 starting to regain the weight though.


That';s a good point - it';s not worth reinforcing carbon fibre if it makes it weigh the same as aluminium which doesn';t need it.

I weighed the 4 quadcopter arms on their own before and after adding the glue and dowel. Before they weighed in at 75 grams - afterwards 86. The extra 10 grams still makes them a fair bit lighter than the aluminium i replaced. Before adding the dowel i weighed the carbon vs the aluminium; I can';t remember the precise values but the carbon fibre was about 1/3rd lighter, and i had made those arms a couple of cms longer, so I';m still ahead on weight.
One circlip short of a quadcopter.
 1 lobe short of an antenna.

XH558

Quote from: Smeagol on Thursday,November 29, 2012, 12:40:28
So it';s aluminium for me, with wires up the core, hmmm must remember not to drill in to them  :evil


Tis OK - you';ve learned a lesson courtesy of me - the prat  - just drill BEFORE you thread the wires - then be careful putting the bolts through  :whistling:

Don';t bother with black paint - leave the arms as they are and use silver on everything else and go for the ';aluminium'; look  :azn

teslahed

Quote from: XH558 on Thursday,November 29, 2012, 12:56:22 Don';t bother with black paint - leave the arms as they are and use silver on everything else and go for the ';aluminium'; look  :azn


The main reason people like painting aluminium black is that it lessens the glare you can get when direct sunlight bounces off the stuff. If you fly in brilliant daylight you may find a matte black quadcopter easier to look at than a shiny mirror surfaced quadcopter.
One circlip short of a quadcopter.
 1 lobe short of an antenna.

Smeagol

Quote from: teslahed on Thursday,November 29, 2012, 13:06:46
The main reason people like painting aluminium black is that it lessens the glare you can get when direct sunlight bounces off the stuff. If you fly in brilliant daylight you may find a matte black quadcopter easier to look at than a shiny mirror surfaced quadcopter.

Good point - although finding brilliant daylight may be a problem unless I take the quad on holiday with me  :whistling:

I';m going for the "no drilling" arms, bought some of those lovely motor mounts that you have XH558, and clamped at the frame end

XH558

Quote from: teslahed on Thursday,November 29, 2012, 13:06:46
The main reason people like painting aluminium black is that it lessens the glare you can get when direct sunlight bounces off the stuff. If you fly in brilliant daylight you may find a matte black quadcopter easier to look at than a shiny mirror surfaced quadcopter.


MMmmmm - sceptical head on - may be true of an airship - or a 1/10th scale Mustang ..
But a quadcopter  :o  Surface area virtually zero  :rolleyes: and most aluminium isn';t shiny surfaced like a mirror - it';s pretty dull unless polished  :huh

Just my thoughts  ;)

teslahed

Quote from: XH558 on Thursday,November 29, 2012, 14:03:31 But a quadcopter  :o  Surface area virtually zero  :rolleyes: and most aluminium isn';t shiny surfaced like a mirror - it';s pretty dull unless polished  :huh


Honestly it';s just something I read when i was reading about the flyduino frame on rcgroups somewhere - the reason they sell the arms annodized black is said to be to reduce glare.

I';ve never flown a plain aluminium quadcopter myself so i have no direct experience one way or another - but quite possibly this is less of an issue in the UK than some countries...
One circlip short of a quadcopter.
 1 lobe short of an antenna.

XH558


rundtmeg

Quote from: teslahed on Thursday,November 29, 2012, 10:33:16

Before when i was flying there was a worrying rattling sound coming from the quadcopter. I';m hoping that after reinforcing it in this way I';ll get less vibrations as i';ll be able to tighten the bolts up more without the carbon fibre splitting.


What about the rattling sound after you filled the arms?

teslahed

I didn';t manage to fix my problems - but the theory is sound i think.
One circlip short of a quadcopter.
 1 lobe short of an antenna.

rundtmeg

Ok, but you don';t have this problem on your mini quads/teslaquad?

teslahed

No i don';t - i have mounted the motors a totally different way with those using clamps rather than drilling through the carbon fibre.
One circlip short of a quadcopter.
 1 lobe short of an antenna.