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post #61 of 233 Old 03-15-2011, 05:51 PM - Thread Starter
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Matt: I missed your questions before. A bearing in the front of the assembly? The problem is that the linkage attached to the blades is rotating and also going up and down. The voice coil is just going up and down, but has to transfer that to the linkage while allowing the linkage to spin....and hopefully with minimal slop. A linear bearing or bushing around the drive shaft and attached to the linkage or voice coil would keep the voice coil from tilting around.

The plug will likely be some baltic birch plywood cut into 3" diameter disks with a 1.5"(?) hole in the center for an aluminum cylinder to be glued inside it. I will stack the disks inside the voice coil while still allowing the voice coil clearance to move into the driver motor.

Noah: The drive shaft will be turning, so it may not cause stiction, but definitely some friction. I want to avoid that if possible. That is why I will not go with a linear bearing/bushing right from the start. I could use a slightly oversize bushing and have very little friction, but prevent the voice coil from moving more than .01".

Could you explain the X shaped flexure a little more? I don't quite understand.

The two spiders are only separated by about an inch.

I think the way the linkage has 5 radially spaced threaded rods attached to arms with a pivot in a single plane will prevent the linkage from moving laterally. I want to get the parts to see for myself.

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post #62 of 233 Old 03-15-2011, 05:55 PM - Thread Starter
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Quote:
Originally Posted by LBDiver View Post

How about machining a small aluminum collar to press the bearing into and then epoxy that inside the former

Are you talking about the voice coil former? If so, that is similar to what I am doing....except I will be using wood which I think will be lighter than aluminum....unless you are using a very large bearing...which would then also be heavier.

I will think about it though.

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post #63 of 233 Old 03-15-2011, 06:23 PM
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Yes, the former, if it is quite large say ~3.5" and you want to use a smaller bearing, you can always machine away the excess leaving spokes. I would be worried with using wood as a bearing retainer in regards to precision and long-term stability.
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post #64 of 233 Old 03-16-2011, 11:29 AM - Thread Starter
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The former is 3". I think using 3 layers of 1/2" thick ply 3" in diameter inside the voice coil along with a 1.5" aluminum tube glued inside the ply to attach to the angular bearing would be plenty strong and stable. What do you envision being the problem? There is a lot of contact area of the wood on the voice coil and the aluminum tube to avoid any enlargement. Mind you, that everything will need to be aligned, so even a CNC'ed aluminum piece would then be glued in by hand to the VC and then the driver will also need to be mounted aligned to the linkage plate and then the linkage plate will need to be aligned to the fan blades.

I wouldn't be opposed to machining the aluminum, but it seems like a lot of work for a heavier part that would be much stronger than the rest of the voice coil.

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post #65 of 233 Old 03-16-2011, 11:29 AM - Thread Starter
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I also ordered a bunch of stuff today...bearings, mounts, drive shafts, etc.

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post #66 of 233 Old 03-16-2011, 01:00 PM
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cool, where did you order from?

I have been looking at emachineshop.com for some custom aluminium pieces for a project I am working on..

I am in the land of machine shops here that serve the oil industry so I may just search them out but emachine shop seems just so much easier.


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post #67 of 233 Old 03-16-2011, 01:41 PM - Thread Starter
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Mcmaster and vxb.com

Yeah, emachineshop looks pretty awesome. I was going to use them to machine parts for my RC business a few years back, but never did. You can get parts made at a reasonable price if you make at least a few of them. I was thinking of that for this project, but I didn't want to pay 400 for 3 flywheels if no one wanted them....otherwise it would have been something like 280 for 1!

I have a friend with a CNC mill that I may ask to help with a part or two. I have a CNC router that I could use for aluminum parts in a pinch. I'm thinking I won't have to do much fancy machining, but we'll see. I need to get some steel to weld up for a frame at some point too.

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post #68 of 233 Old 03-16-2011, 03:06 PM
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Quote:
Originally Posted by AndreasMergner View Post

The former is 3". I think using 3 layers of 1/2" thick ply 3" in diameter inside the voice coil along with a 1.5" aluminum tube glued inside the ply to attach to the angular bearing would be plenty strong and stable. What do you envision being the problem? There is a lot of contact area of the wood on the voice coil and the aluminum tube to avoid any enlargement. Mind you, that everything will need to be aligned, so even a CNC'ed aluminum piece would then be glued in by hand to the VC and then the driver will also need to be mounted aligned to the linkage plate and then the linkage plate will need to be aligned to the fan blades.

I wouldn't be opposed to machining the aluminum, but it seems like a lot of work for a heavier part that would be much stronger than the rest of the voice coil.

I see what you are doing now, I thought you were going to press/glue the bearing into the wood. I was thinking just a small ~.800" width aluminum ring that you could friction fit or glue into the VC that would accept a 2" inch bearing with a 1" extended inner race. Using an extended inner race you could press a oil-filled bronze linear bearing within it, and attach the splayed linkage plate to the outside of the same inner race, so its doing double/triple duty and will help keep the overall length added to a minimum since the TC2000 motor assembly is pretty deep with the double spiders. That 3-2" aluminum reduction ring would be ~5oz, the 3 BB 3"-1.5" reduction rings are ~3.5 oz before adding the inner aluminum tube.

I was also thinking about the heat cycling of the VC when in use, that it may be better to use like materials that would expand and contract together. However I think in the low frequency range it operates (with little regular content) and the fact it is in open air, I doubt it ever heats up much.
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post #69 of 233 Old 03-16-2011, 03:21 PM
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Quote:
Originally Posted by AndreasMergner View Post

Mcmaster and vxb.com

Yeah, emachineshop looks pretty awesome. I was going to use them to machine parts for my RC business a few years back, but never did. You can get parts made at a reasonable price if you make at least a few of them. I was thinking of that for this project, but I didn't want to pay 400 for 3 flywheels if no one wanted them....otherwise it would have been something like 280 for 1!

I have a friend with a CNC mill that I may ask to help with a part or two. I have a CNC router that I could use for aluminum parts in a pinch. I'm thinking I won't have to do much fancy machining, but we'll see. I need to get some steel to weld up for a frame at some point too.

You can definitely use you CNC router for the small parts. There is nothing wrong with dry machining aluminum and using a router as long as you have your IPM's right, which with CNC you can easily ensure.
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post #70 of 233 Old 03-16-2011, 03:45 PM
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Andreas ,
Have you decided what materials you will use for the fan blades ? ..and what thickness
If i remember right , the RSW original has flat blades.. pretty thin , not sure what materials it uses though.
You would be able to make them of carbon fiber sheets - in your router ?

Your project has reached a state of "no return" now... I'll look forward to see your progress
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post #71 of 233 Old 03-16-2011, 05:44 PM - Thread Starter
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LBDriver: The aluminum ring weighs only 5 ozs because it only has .8" contacting the VC as opposed to the ply contacting 1.5". This weight is very important to reduce since most of the other mass is being rotated with a lever. I'd calculate the apparent mass, but I don't have weights for all of the bearings and such. I think your way has merit.... Still, let me think about it some more. I'll be doing everything else first and have not even ordered the bearings and such for the VC.

Also, I have machined aluminum on my CNC router, but it is not something I prefer to do.

Frank, my plan is to use 1/4" thick balsa reinforced with fiberglass for my blades. They should be lighter and stronger than carbon plate....and more efficient. You can cut carbon plate with a fine toothed jigsaw no problem. Actually, that is how I cut the aluminum frame off the TC2000 in less than 20 minutes!

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post #72 of 233 Old 03-16-2011, 06:06 PM
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Quote:
Originally Posted by AndreasMergner View Post
The problem is that the linkage attached to the blades is rotating and also going up and down. The voice coil is just going up and down, but has to transfer that to the linkage while allowing the linkage to spin....and hopefully with minimal slop.
Not sure if someone mentioned this before or if it just occurred to me now (my memory is that bad), but how addressing that issue about mounting the the driver asy to the rotor so it rotates with the blade?

There's your flywheel mass, but you need some slip rings to get the power in.

Noah
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post #73 of 233 Old 03-16-2011, 06:14 PM - Thread Starter
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So, I guess I never said how I was going to do things. My plan right now is:

1. Fan and driver supported on drive shaft supported on both ends with bearings. Motor is coupled to drive shaft and removable. Motor does not support fan as in Thigpen design. This is better for rigidity/vibration and also allows use of any motor (even a drill) or easily replacing a motor.

2. Fan size 24"-36" in diameter depending on blades fitted. I can fine tune the rotary for RPM/noise and output to work with my enclosure/dead vent.

3. Open design where pillow block mounted bearings support fan blades on a steel flywheel. There is almost no machining this way. (Another reason I want to use plywood for the voice coil. )

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post #74 of 233 Old 03-16-2011, 06:20 PM - Thread Starter
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Quote:
Originally Posted by noah katz View Post
Not sure if someone mentioned this before or if it just occurred to me now (my memory is that bad), but how addressing that issue about mounting the the driver asy to the rotor so it rotates with the blade?

There's your flywheel mass, but you need some slip rings to get the power in.
You are the first to mention it. I did think of that idea earlier, but thought it might be better to just have a decent mechanical linkage. I thought there might be some noise with the connection or other complications I didn't want to deal with. Plus you'd have to replace brushes and such...but probably not any more often than the motor itself!

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post #75 of 233 Old 03-17-2011, 02:23 PM
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I'd much rather replacing brushes than worn mechanical linkages.

Quote:
Originally Posted by AndreasMergner View Post

You are the first to mention it. I did think of that idea earlier, but thought it might be better to just have a decent mechanical linkage. I thought there might be some noise with the connection or other complications I didn't want to deal with. Plus you'd have to replace brushes and such...but probably not any more often than the motor itself!


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post #76 of 233 Old 03-17-2011, 04:24 PM - Thread Starter
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Well, I can still change that part of the design. I still think the big disadvantage of the slip rings is electrical noise, but maybe that is not a problem here since it is moderate current and voltage compared with a true signal level circuit? The advantage is that I can remove a pair of angular bearings from the mechanics and the mounting of those bearings.

Anyone with expertise have any thoughts?

Current HT: HTPC-->Epson 5010 projector-->135" screen, BFM TLAHs x7 & THT
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post #77 of 233 Old 03-17-2011, 05:01 PM - Thread Starter
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I also received a bunch of supplies today...drive shaft, couplers and bearings, clevis, threaded rod. I went by the metal supply store and they have a bunch of offcuts I can get for a decent price. I just have to figure out what I need....and nail down what my final design will be.

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post #78 of 233 Old 03-17-2011, 05:19 PM
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Man this thread is WAY over my head, but WAY fun to follow.


"If you build it, they will come!"


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post #79 of 233 Old 03-17-2011, 05:39 PM - Thread Starter
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dbl: I bet you would catch on better if I posted pics, but with a demanding 8 week old at home I barely have enough time to shower and eat, so I feel lucky to be making any progress on this at all....nevermind pics/diagrams/drawings/CAD etc.

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post #80 of 233 Old 03-17-2011, 05:45 PM
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AM - please don't get me wrong! You're rockin this! Absolutely no disrespect intended. In fact just the opposite. I totally understand the kids deal too. I've got two rag-a-muffins of my own

Keep it up!

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post #81 of 233 Old 03-17-2011, 05:49 PM - Thread Starter
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Dbl: no offense taken. Just saying I feel bad I can't post more/any pics to clarify what I'm planning.

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post #82 of 233 Old 03-18-2011, 02:30 AM
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Same boat as DBLdare but it is interesting to follow.
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post #83 of 233 Old 03-18-2011, 06:23 AM
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Quote:
Originally Posted by AndreasMergner View Post

Well, I can still change that part of the design. I still think the big disadvantage of the slip rings is electrical noise, but maybe that is not a problem here since it is moderate current and voltage compared with a true signal level circuit? The advantage is that I can remove a pair of angular bearings from the mechanics and the mounting of those bearings.

Anyone with expertise have any thoughts?

Hi..
i was thinking of such design too.. but an issue with that design (depending on how other parts will be designed though..) is how to handle the torsion effekt towards the voicecoil - when it is moving the arm to the pivot of the blades..

It could be that i don't see it correctly of course
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post #84 of 233 Old 03-18-2011, 06:32 AM
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Quote:
Originally Posted by AndreasMergner View Post

dbl: I bet you would catch on better if I posted pics, but with a demanding 8 week old at home I barely have enough time to shower and eat, so I feel lucky to be making any progress on this at all....nevermind pics/diagrams/drawings/CAD etc.

Yes, pics, diagrams, CAD stuff would be awesome

Take your time!! 8 week old is crazy. My girls are 4 and 2....that is a hand full alone and just when I think I can spend 30 minutes in the garage its "DADDY Kayla Bit me!!!!!!"

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post #85 of 233 Old 03-18-2011, 06:35 AM - Thread Starter
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Frank, yes you are correct! Good point. For some reason I was keenly aware of that for the original design (moving the arms will rotate the actuating plate), but with the driver mounted to the hub the voice coil will be torqued with any movement of the blade arms.

I requested a quote for a fancy noiseless way to get power to a rotating driver. I was going to make a decision based on price (!)....but this detail will save me a bit of grief. It would be nice to get the weight of the angular bearings out of the system though.

Current HT: HTPC-->Epson 5010 projector-->135" screen, BFM TLAHs x7 & THT
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post #86 of 233 Old 03-18-2011, 06:44 AM - Thread Starter
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Don't worry, I will take my time. It is fun though. I like making weird stuff. We have a difficult 8 week old. She is tough, but cute. I guess they are designed that way so you don't throw them across the room....?

You want some CAD?? I got your CAD right here!




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post #87 of 233 Old 03-18-2011, 06:52 AM - Thread Starter
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The part is a 230 @ $60 shipped from mercotac.com

It is within the budget, but unless I come up with a way to take care of the arms rotating with respect to the VC (without using bearings-- otherwise, what's the point?), I don't think I will go that route.

Current HT: HTPC-->Epson 5010 projector-->135" screen, BFM TLAHs x7 & THT
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post #88 of 233 Old 03-18-2011, 07:37 AM
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Quote:
Originally Posted by AndreasMergner View Post

The part is a 230 @ $60 shipped from mercotac.com

It is within the budget, but unless I come up with a way to take care of the arms rotating with respect to the VC (without using bearings-- otherwise, what's the point?), I don't think I will go that route.

very very very cool!

wouldn't the whole unit rotate at the same rpm so why would you have to worry about the arms rotating at a different rate? or am I waaaaaaaaay out to lunch (just trying to imagine this in my head)

btw, love the cad rendering! lol

Matt

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post #89 of 233 Old 03-18-2011, 07:41 AM
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[quote=AndreasMergner;20168551]You want some CAD?? I got your CAD right here!
QUOTE]

I like your CAD .. i use this system a lot myself..
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post #90 of 233 Old 03-18-2011, 08:17 AM - Thread Starter
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Glad people are liking my CAD because you might see more of it.

Matt, yes the arms and driver/VC will be rotating at the same RPM since they will be bolted together. The problem occurs when the VC goes up and down causing the arms to rotate. There is an up and down motion along with a side to side motion. Since there are 5 blades/arms, the side to side motion causes a rotation along the axis of the VC. Make sense?

Don't make me whip out my MAD CAD SKILLZ YO.

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