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Author Topic: VP Hubs - for the techies among us  (Read 12770 times)
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jakepF1D
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« Reply #175 on: January 10, 2017, 11:55:18 AM »

Does 8 turns of the same thickness of wire make for a stronger spring?

More turns will give a softer spring.  My understanding is that the softer the spring, the faster the prop will change pitch.  With my hub I haven't timed the changeover on a full motor, but on my 37.5% motors it took a little over 2 minutes to fully change pitch.  This would equate to around 6 minutes on a full motor.  I can't say if that's ideal, but test flights indicate my model should be capable of more than 25 minutes at West Baden, and more than 27 minutes at Kibbie.
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jakepF1D
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« Reply #176 on: January 10, 2017, 12:11:19 PM »

Intriguing that you are using a tube! Treger's are solid rod with a slot in them, but I like what you are doing.

The idea for using an aluminum tube originally came from Kevin Lamers.  He got the Albion tubing at a local store and found that he could make screws with it.  Luckily I can get it in the US at the link I posted previously.

It takes some practice to get the process down, but once you get going it isn't all that difficult to make your own screws.
« Last Edit: January 10, 2017, 01:28:43 PM by jakepHLS » Logged
brabazon
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« Reply #177 on: January 10, 2017, 02:51:50 PM »

Hi Jake,
Thanks. I've tracked the tubing here. With the name Albion that perhaps wasn't too surprising!
I'm using a jewellers frame saw and I'm curious what fret saw blades you are using for your carbon. I've been using Pebeco/Niqua blades, which are apparently great for wood marquetry. To my thinking the 1.7mm spacing between the teeth on mine is too wide and there's too much 'catching'.
Hans
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jakepF1D
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« Reply #178 on: January 10, 2017, 03:29:53 PM »

I'm using a jewellers frame saw and I'm curious what fret saw blades you are using for your carbon. I've been using Pebeco/Niqua blades, which are apparently great for wood marquetry. To my thinking the 1.7mm spacing between the teeth on mine is too wide and there's too much 'catching'.
Hans

I don't use a jeweler's saw for anything.  All of the carbon is cut with a diamond blade in my rotary tool, and the slot is cut in the driver with my Proxxon setup using a .013" diameter carbide end mill.  I mount a piece of scrap plywood to my X-Y table, and I use a 1mm diameter spiral bit to cut a 1mm wide by 0.4mm deep groove in the plywood.  I make the groove about 25mm long.  I cut the driver blanks to a rough length of about 20mm, and they're a press fit into the groove in the plywood.  I also use a little tape at each end to make sure the carbon doesn't lift or move.  Then I swap bits to the .013" end mill and use the X-Y table to precisely locate the holes and mill the slot.  I use the depth stop on the drill press stand to ensure that the bit is just deep enough to go all the way through the carbon.  When cutting the slot I plunge the bit into the carbon and lock the head in place using the set screw.  Then I move the table the proper distance and unlock the head to retract the bit out of the material.  The result is perfectly spaced holes, and a perfect slot.

Here's a link to the end mill I use.  I would recommend using the Proxxon collets rather than the 3 jaw chuck for this process.  The chuck is very good, but the collets run truer with less runout.

http://www.ebay.com/itm/1-KEO-013-X-039-x-1-8-Micro-2-FLUTE-CARBIDE-Square-END-MILL-83709-USA-NEW-/360490322278?hash=item53eee5c966
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brabazon
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« Reply #179 on: January 10, 2017, 04:05:29 PM »

 I mount a piece of scrap plywood to my X-Y table, and I use a 1mm diameter spiral bit to cut a 1mm wide by 0.4mm deep groove in the plywood.  I make the groove about 25mm long.  I cut the driver blanks to a rough length of about 20mm, and they're a press fit into the groove in the plywood.  I also use a little tape at each end to make sure the carbon doesn't lift or move.  Then I swap bits to the .013" end mill and use the X-Y table to precisely locate the holes and mill the slot.  I use the depth stop on the drill press stand to ensure that the bit is just deep enough to go all the way through the carbon.  When cutting the slot I plunge the bit into the carbon and lock the head in place using the set screw.  Then I move the table the proper distance and unlock the head to retract the bit out of the material.  The result is perfectly spaced holes, and a perfect slot.

Given what you have that makes sense Jake.
To recap when you refer to X-Y table you are referring to this http://www.proxxon.com/en/micromot/27100.php or perhaps even this set up http://www.proxxon.com/en/micromot/27112.php#27114
At present I have this http://www.proxxon.com/en/micromot/28606.php
I'm not sure whether I could mount a compound table on to that. I think your set up is for the milling machine.
Hans
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jakepF1D
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« Reply #180 on: January 10, 2017, 04:31:01 PM »

Correct, I have the compound table mounted to the MB 200 drill press stand (http://www.proxxon.com/en/micromot/28600.php).  It will also mount to your drill press stand and includes the necessary hardware.
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mkirda
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« Reply #181 on: January 10, 2017, 05:24:06 PM »

Correct, I have the compound table mounted to the MB 200 drill press stand (http://www.proxxon.com/en/micromot/28600.php).  It will also mount to your drill press stand and includes the necessary hardware.

There was a very nice article on the Dumore sensitive drill press in INAV recently. You can do much of the same work it and a microscope slide holder more cheaply than the Proxxon route.

Regards.
Mike Kirda
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brabazon
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« Reply #182 on: January 10, 2017, 05:51:27 PM »

Correct, I have the compound table mounted to the MB 200 drill press stand (http://www.proxxon.com/en/micromot/28600.php).  It will also mount to your drill press stand and includes the necessary hardware.

One thing I learned is that it's foolhardy to try to make a groove with my very nice drill bits I bought https://www.amazon.co.uk/dp/B01ILXNJDW/ref=pe_385721_51767431_TE_dp_1
they break almost instantly with sideways pressure. Presumably you must also be careful with the milling bits!

Thanks for the Dumore tip Mike! It looked at the INAV piece. It looks like a solid piece of kit, although the 110v is disadvantageous for me.
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jakepF1D
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« Reply #183 on: January 10, 2017, 05:56:59 PM »

I saw that article and actually looked for a used Dumore.  Perhaps I have bad luck, but I've never seen one for under $200, and the ones available at that price are typically in pretty bad condition.  The Proxxon setup is probably slightly less precise, but the runout with a collet is less than I can measure and it's capable of 20,000 RPM.  I've also found the Proxxon to be more versatile because I can use it handheld as rotary tool, or rotate the drill stand 90 degrees and use a diamond cutoff blade to slice parts to precise length.  

Ultimately I think it depends on what you need, and what you can find.  The Proxxon setup I have is probably about $350, but I had a $100 gift card which is part of why I chose it.
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jakepF1D
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« Reply #184 on: January 10, 2017, 06:04:05 PM »

One thing I learned is that it's foolhardy to try to make a groove with my very nice drill bits I bought https://www.amazon.co.uk/dp/B01ILXNJDW/ref=pe_385721_51767431_TE_dp_1
they break almost instantly with sideways pressure. Presumably you must also be careful with the milling bits!

Drill bits are designed only to bore holes.  Any side load and they'll break as the carbide is quite brittle.  End mills on the other hand are specifically designed for milling slots.  You can still break an end mill if you feed the material too fast, but I'm still on my first one after cutting about a dozen drivers arms.
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dslusarc
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« Reply #185 on: January 10, 2017, 07:07:23 PM »

Jake,

Thanks for posting all this info. I have been buying as links get posted. My carbon arrived form CST. Ordered the tubing and end mills today.

So to make a mill setup this is what I would need to buy correct?

Precision Rotary Tool FBS 115/E or Professional Rotary Tool IBS/E
Drill Stand MB 200
MICRO Compound Table KT 70

Or do I go for the whole mill: MICRO Mill MF 70

Any other suggested accessories or holder I might need?

Don
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mkirda
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« Reply #186 on: January 10, 2017, 07:30:29 PM »

I saw that article and actually looked for a used Dumore.  Perhaps I have bad luck, but I've never seen one for under $200, and the ones available at that price are typically in pretty bad condition.  The Proxxon setup is probably slightly less precise, but the runout with a collet is less than I can measure and it's capable of 20,000 RPM.  I've also found the Proxxon to be more versatile because I can use it handheld as rotary tool, or rotate the drill stand 90 degrees and use a diamond cutoff blade to slice parts to precise length.  

Ultimately I think it depends on what you need, and what you can find.  The Proxxon setup I have is probably about $350, but I had a $100 gift card which is part of why I chose it.

Hi Jake.

It is sort of hit or miss unless you decide to take your time. $200-$250 is the range typically for one in decent shape. You can still get bearings for them too, so no worries there.
(I have a contact if you need it.)

The Proxxon looks like a very nice unit as well. Me, if the Dumore can't do what I want, I just head to the local Maker space and use their Bridgeport.  Smiley

Regards.
Mike Kirda

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jakepF1D
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« Reply #187 on: January 10, 2017, 08:37:46 PM »

Jake,

Thanks for posting all this info. I have been buying as links get posted. My carbon arrived form CST. Ordered the tubing and end mills today.

So to make a mill setup this is what I would need to buy correct?

Precision Rotary Tool FBS 115/E or Professional Rotary Tool IBS/E
Drill Stand MB 200
MICRO Compound Table KT 70

Or do I go for the whole mill: MICRO Mill MF 70

Any other suggested accessories or holder I might need?

Don

Don,

It really depends on your needs and goals.  I bought the Proxxon 50 EF rotary tool and the NG 2/S transformer from a local woodworking store because I had a gift card.  After that I went down a rabbit hole and bought a bunch of accessories.  Ultimately the setup I have works, but it is a compromise.  The MF 70 is likely nicer and easier to use for most of the parts necessary to make a VP similar to mine, but I've never used it. 
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dslusarc
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« Reply #188 on: January 10, 2017, 10:17:01 PM »

Well I decided to buy the mill and the precision vise for it. Guess I will have no more reasons to not make one of these carbon VP hubs eh  Grin

Don
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jakepF1D
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« Reply #189 on: January 10, 2017, 11:47:29 PM »

Well I decided to buy the mill and the precision vise for it. Guess I will have no more reasons to not make one of these carbon VP hubs eh  Grin

Don

I'll be curious to hear what you think of it.  Some day I'd like to get one myself.  I also found a whole bunch of CNC conversion kits that exist for it including a couple that you can 3D print.  You can get the electronics and hardware for under $100, and it would open up some interesting possibilities.

http://www.thingiverse.com/thing:21890
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jakepF1D
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« Reply #190 on: January 12, 2017, 11:34:42 AM »

I added more photos to the photo album I linked in reply 170.  It includes photos of the finished prop which ended up at 300mg.
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« Reply #191 on: January 13, 2017, 11:39:18 AM »

impressive work, Jake. Now you're making me wonder about a carbon outline! Is it possible to make those with single strands of Mike Woodhouse's Russian carbon cloth and the Zpoxy finishing resin? I imagine if you have a fibreglass template made from a prop block you can cut a groove in the end of that and layup the fibres. I'm having a go as we speak on the aluminium screws on the 1mm tube. It's very easy to break the tips off! I'm going to try with a bit of lube.
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mkirda
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« Reply #192 on: January 13, 2017, 11:48:03 AM »

impressive work, Jake. Now you're making me wonder about a carbon outline! Is it possible to make those with single strands of Mike Woodhouse's Russian carbon cloth and the Zpoxy finishing resin? I imagine if you have a fibreglass template made from a prop block you can cut a groove in the end of that and layup the fibres. I'm having a go as we speak on the aluminium screws on the 1mm tube. It's very easy to break the tips off! I'm going to try with a bit of lube.

Double that tow to the first rib at least, otherwise you will get significant flex on the inner portion.

I've built one but not flown it yet. I will rebuild it as above though for that reason.

Mike
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« Reply #193 on: January 13, 2017, 11:56:56 AM »

Mike: what did your outline weigh, and what do you estimate for version 2?
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mkirda
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« Reply #194 on: January 13, 2017, 11:58:39 AM »

Mike: what did your outline weigh, and what do you estimate for version 2?

I don't recall offhand. Maybe I'll make one this weekend and get back to you.

Mike
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jakepF1D
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« Reply #195 on: January 13, 2017, 12:11:00 PM »

Is it possible to make those with single strands of Mike Woodhouse's Russian carbon cloth and the Zpoxy finishing resin?

I think this is a risk because we have no idea what carbon is in that Russian cloth.  Not all carbon fiber is equal, and you need something with high modulus so it doesn't flex too much.  If you want more information on molding blades, you need to read Brett Sanborn's article on INAV.  It's incredibly thorough, and he even gives a detailed explanation of why most types of carbon fiber won't work for blade outlines.

https://indoornewsandviews.com/2013/04/05/carbon-prop-outlines-brett-sanborn/
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jakepF1D
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« Reply #196 on: January 13, 2017, 12:22:36 PM »

Brett also wrote a follow up linked below.  I'm using the EZ-Lam 60 he mentions in this article.  It's very inexpensive when compared with most of other composite resin.  I've been curing for 24 hours at 90F and it seems to work well.

https://indoornewsandviews.com/2013/06/25/carbon-prop-outline-follow-up/
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mkirda
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« Reply #197 on: January 13, 2017, 12:24:02 PM »

Is it possible to make those with single strands of Mike Woodhouse's Russian carbon cloth and the Zpoxy finishing resin?

I think this is a risk because we have no idea what carbon is in that Russian cloth.  Not all carbon fiber is equal, and you need something with high modulus so it doesn't flex too much.  If you want more information on molding blades, you need to read Brett Sanborn's article on INAV.  It's incredibly thorough, and he even gives a detailed explanation of why most types of carbon fiber won't work for blade outlines.

https://indoornewsandviews.com/2013/04/05/carbon-prop-outlines-brett-sanborn/

Depends upon what you are looking for, Jake. If you use a balsa spar/ribs, but ditch the 0.025" square balsa outline for the carbon one, the carbon one is less likely to break.

Regards.
Mike Kirda
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jakepF1D
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« Reply #198 on: January 13, 2017, 12:37:47 PM »

Depends upon what you are looking for, Jake. If you use a balsa spar/ribs, but ditch the 0.025" square balsa outline for the carbon one, the carbon one is less likely to break.

Regards.
Mike Kirda

If you're saying build a traditional prop with a full length spar, but replace the balsa outline with carbon then I'm not sure I understand the point.  The carbon outline will be significantly heavier than balsa, but you don't get the advantage of reduced drag by removing most of the spar.  I've never had an issue with breaking balsa prop outlines.
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« Reply #199 on: January 13, 2017, 05:55:46 PM »

going back to the subject of vp: my third version has a carbon rod on which hang my fibreglass prop blade tubes. The rod in turn runs through a carbon tube. It seems very smooth in terms of action. But what I've been reading from your experience and Kang's, it would appear friction is an issue, I guess under load. You talk about teflon dust... is a bit of lube out of the question?
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