Author Topic: New direct drive on a solid shaft (Read 25759 times)

jarrod9155 · « **Reply #2 on:** May 01, 2011, 08:23:15 PM »

Its been about three weeks sence my last home brew style turbine spit the bearings out for last time . So with some advise and help from Chris O I came up with this design . It uses a 1/1/2 solid keyed shaft with two bearings mounted 2 feet a part .the offset is 6 and 1/2 inches , I also matched the tail hinge offset to match for clearance and balance . I used a spring setup for furling , still have the tail to build and bolt on. I was able to reuse my magnet plates and hub for the blades just made some adapter and welded the old stuff to the new keyed hubs .

Jarrod
Maine,

jarrod9155 · « **Reply #3 on:** May 01, 2011, 08:36:07 PM »

Some more photos showing the hubs . All these parts can be purchased through fasental and tractor supply so really makes its easy for getting parts .

jlt · « **Reply #4 on:** May 02, 2011, 07:12:03 AM »

Looks to have plenty of forward offset . Helps with furling. How do you keep the fore and aft movement Out of the shaft?
Yours could benefit with some holes drilled in the rotors to allow for better cooling.Keep up the good work and keep us informed when you get it running.

jarrod9155 · « **Reply #5 on:** May 02, 2011, 08:39:45 AM »

The bearings have two set screws and both hubs on the blade also have 2 set screws so a total of 6 set screws and the last hub for the blades will have a bolt that threads in to the end of the shaft and connects to hub locking the blades to the shaft .

Royalwdg · « **Reply #6 on:** May 02, 2011, 12:30:42 PM »

Jarrod, side load is surely an issue with those bearings. If you rig up a simple, very ridged pocket with a 3/4 ball and a little grease you could take care of all your end thrust problems. Just set screw are to keep your shaft from moving around under normal motor/pulley kind of conditions. Your 20 foot machine can see up near 1500 pounds of face pressure in its normal conditions. Nice fab work. Dave Moller

jarrod9155 · « **Reply #7 on:** May 02, 2011, 03:17:23 PM »

I don't have pictures now but the blade hub is two pieces and the last part will have a bolt that will lock the hubs to the shaft so the set screw aren't taken the total force . But yes if the bearing fails the stator will get the magnets chewing threw it . I brought this problem to Chris attention since he has had more experience with these bearings . He thought radial thrust was the problem . It does worry me but I guess at this point trial error !!

jarrod9155 · « **Reply #8 on:** May 02, 2011, 03:33:23 PM »

I had little knowledge about these bearings and thought they were pressed in to the blocks at first so thrust was worry but did ask Chris about thrust and this was his answer .

Those bearings should not be pressed in. They are pillow block and should be self-aligning ball bearings. The outer race of the bearing is convex and fits into the bore of the block by twisting it into place. There's two notches in the pillow block to allow changing the bearing in the block, but it has to be twisted 90Â° to the bore of the block, inline with the notches, to get it out.

fabricator · « **Reply #9 on:** May 02, 2011, 06:54:01 PM »

Nice lookin machine, personally I'd be just a little concerned about horizontal support for the main shaft tube, you have a gusset on the main shaft tube to the yaw tube in the horizontal plane, but not much to keep the main shaft tube from twisting horizontally in relation to the yaw tube, but I aint no engineer so it's prolly worth less than $0.02

jarrod9155 · « **Reply #10 on:** May 02, 2011, 07:12:34 PM »

At first my engineering buy seat felt the same way . I ended up fully boxing in the main tube with quarter inch plate and the added gusset is a 30 deg tilt to horizontal but your right it could become a weak point or not . I know at work on the frame machine fixing truck frames that if that was a point that I needed to move or straighten it would take quite a bit of hydraulic pressure to move . Point taken I will keep a close I On the design over time . I won't lie looks influence my design sometimes more than it should or I would have just added a gusset and call it good !!
The whole thrust thing worries me more , I think tonight I will design a bump stop so should the bearings fail it will be metal on metal and not stator on magnets !!!

Jarrod
Maine

fabricator · « **Reply #11 on:** May 02, 2011, 07:23:03 PM »

Hey we're all workin by the seat of our pants, another spot that could use a little gusset is the inside corner on your tail bracket, that 90 degree bend or what ever it is is gonna take a lot of abuse and if that is bent tubing it's already a weak spot.

zvizdic · « **Reply #12 on:** May 02, 2011, 08:22:11 PM »

Jarrod

Nice work!

What is a prop size?
I assume it is 12' or 16' ,those bearings are like Chris is saying impossible to push out unless turned to 90 deg.
Tail hinge locks fine, my 10' locks thinest then any on a board.

ChrisOlson · « **Reply #13 on:** May 02, 2011, 08:28:29 PM »

Quote from: jarrod9155 on May 02, 2011, 07:12:34 PM

The whole thrust thing worries me more , I think tonight I will design a bump stop so should the bearings fail it will be metal on metal and not stator on magnets !!!

Jarrod,

Self-aligning deep groove ball bearings have a load rating based on their block series and the maximum radial load they will handle and survive one million revolutions. The load ratings are given at different speeds - the higher the speed the less load the bearing can handle and survive the industry standard one million revolutions.

For instance, a 208 block 1.25" bore deep groove self-aligning ball bearing is rated at 4,414 lbs radial load and 2,207 lbs axial load @ 250 rpm. This is just one bearing. IIRC, you got two 1.5's on the mainshaft. The two together will probably handle somewhere in the vicinity of a couple tons of axial loading before the bearing even warms up.

Your blade hub should be shimmed or rest up against the front main bearing inner race or lock ring and be secured to the shaft. The thrust load from the hub is transferred to the front main bearing directly, and to the rear main bearing thru the shaft.

The set screws are merely to retain the bearing lock ring or inner race to the shaft to prevent the shaft from "hammering out" and eventually becoming loose in the bearing inner race. They are not designed to handle the axial loading. I took a couple pictures of a 12G turbine that I got in the shop here to show you how I retain the rotor hub to the input shaft.

This first photo shows the machined spacer that goes between the front main bearing lock ring and the rear of the hub. That spacer is machined to the right thickness so the front of the hub extends past the end of the transmission input shaft by .005":

The front of the hub is retained by a bolt threaded into the input shaft with a thick washer. The bolt is lock tighted in place and is torqued to 45 lb-ft. The thrust loads are transferred directly to the front main bearing, and to the rear main bearing thru the shaft, and the set screws in the bearing cam lock rings and hub are not used to handle any axial loading.

--
Chris

jarrod9155 · « **Reply #14 on:** May 02, 2011, 09:11:20 PM »

It's a 20 footer Zvizdic ,

Chris thanks you , you made me feel better about the bearing design and I am attaching the blade hub similar to how you have it done In the photos .
The whole reason I post here is for opinions and ideas so thanks again to all that contribute .

zvizdic · « **Reply #15 on:** May 02, 2011, 10:43:34 PM »

20' and it lucks like you are going with Goe222 airfoil.

I am thinking slow prop and thin stator cant be a good thing.
If everything works out you should see 7-8KW and to achieve that stator I am guessing cant be thicker then 1/2 ".
Stator mount needs a reinforcement . I always look at it as a 10 horses tugging at it.

Hope you get good results!

windy · « **Reply #16 on:** May 02, 2011, 10:50:24 PM »

jarrod9155,
Not sure but 6.5 inches doesn't sound like a lot of offset for a 20 foot diameter blade. Thinking it should be more like 10 inches. Never tried a spring setup for furling so the offset may be fine. Any comments?

windy

jarrod9155 · « **Reply #17 on:** May 02, 2011, 11:56:09 PM »

I ran the 20 foot blades for a month in febuary on my old setup that had only 4 mounts on the stator and never saw a issue with stator fatigue . And now I have double the mounts plus the length of the half inch studs are only 4 inches of stud from the frame I never cared for the Hugh pigot stlye of just 4 mounts but it did work with out any problems on a machine way bigger than he designed .
As for the offset I would think all it takes is to be off center enough to start the process the spring load will determine at what speed the machine will furl at . I started with a real light spring pressure so I can step it up into higher output .I hope in a couple weeks I can test a lot of these theories .

Janne · « **Reply #18 on:** May 03, 2011, 05:49:12 AM »

Hi,

For my standards, the shaft looks a bit under sized. I've used the traditional 1% rule for deciding the shaft size, meaning that the main shaft diameter should be 1% of the rotor diameter. For 20' it would be around 60mm. 1% is propably a bit overkill, and 1Â½" might be ok, but feels still a bit too small for comfort.

The rotor offset is under a bit of a debate. Too small, and you might risk getting into the rotor seeking problems, which have been occuring on some machines with too little offset - like happened with my small axial turbine, when it refused to furl in a storm, even with a quite light tail. However, many commercial machines get away with small offsets, so with a bit of luck the 6.5" offset should work fine.

Anyways, the basic idea behing your construction is much more sound than using the wheel hub for the bearing. With that kind of distance between the block bearings I think at least the bearing problems will be a pain left behind. (not a pain in the backside

)

jlt · « **Reply #19 on:** May 03, 2011, 12:22:48 PM »

The 6 1/2 offset should work . But the pipe in pipe bearing may have too much drag. most of my furling problems Have been the shafts binding and not turning out of the wind. The rear mounted alt should help to keep the weight balance .

zvizdic · « **Reply #20 on:** May 03, 2011, 05:57:17 PM »

Quote from: jlt on May 03, 2011, 12:22:48 PM

The 6 1/2 offset should work . But the pipe in pipe bearing may have too much drag. most of my furling problems Have been the shafts binding and not turning out of the wind. The rear mounted alt should help to keep the weight balance .

Agreed 100 %.
Do not like pipe on a pipe for a yaw bearing.
On my 5' I experience that binding even do I covered the top to prevent grease washing out.
So 10' have a real bearings in a yaw.

fabricator · « **Reply #21 on:** May 03, 2011, 06:06:40 PM »

Quote from: Janne on May 03, 2011, 05:49:12 AM

Hi,

For my standards, the shaft looks a bit under sized. I've used the traditional 1% rule for deciding the shaft size, meaning that the main shaft diameter should be 1% of the rotor diameter. For 20' it would be around 60mm. 1% is propably a bit overkill, and 1Â½" might be ok, but feels still a bit too small for comfort.

The rotor offset is under a bit of a debate. Too small, and you might risk getting into the rotor seeking problems, which have been occuring on some machines with too little offset - like happened with my small axial turbine, when it refused to furl in a storm, even with a quite light tail. However, many commercial machines get away with small offsets, so with a bit of luck the 6.5" offset should work fine.

Anyways, the basic idea behing your construction is much more sound than using the wheel hub for the bearing. With that kind of distance between the block bearings I think at least the bearing problems will be a pain left behind. (not a pain in the backside )

Where did you get the your "traditional 1%" number? That would make the main shaft for a 20' machine 2.375 inches, overkill? I agree.

zvizdic · « **Reply #22 on:** May 03, 2011, 07:55:51 PM »

Quote from: fabricator on May 03, 2011, 06:06:40 PM

Quote from: Janne on May 03, 2011, 05:49:12 AM
Hi,

For my standards, the shaft looks a bit under sized. I've used the traditional 1% rule for deciding the shaft size, meaning that the main shaft diameter should be 1% of the rotor diameter. For 20' it would be around 60mm. 1% is propably a bit overkill, and 1Â½" might be ok, but feels still a bit too small for comfort.

The rotor offset is under a bit of a debate. Too small, and you might risk getting into the rotor seeking problems, which have been occuring on some machines with too little offset - like happened with my small axial turbine, when it refused to furl in a storm, even with a quite light tail. However, many commercial machines get away with small offsets, so with a bit of luck the 6.5" offset should work fine.

Anyways, the basic idea behing your construction is much more sound than using the wheel hub for the bearing. With that kind of distance between the block bearings I think at least the bearing problems will be a pain left behind. (not a pain in the backside )

Where did you get the your "traditional 1%" number? That would make the main shaft for a 20' machine 2.375 inches, overkill? I agree.

Janne is wary close with a 1% rule.

Formula is as follows

Diameter = Square Root of 60xHP/max RPM

So 60x15HP/300RPM=3 Square root =1.75" for a keyed shaft .

Motor safety factor is to double HP rating.

60x30/300=6 sr.=2.5

jarrod9155 · « **Reply #23 on:** May 03, 2011, 08:22:02 PM »

I was really surprise to think some one would think the shaft size maybe just slightly undersized . Compared to some machines with trailerhubs , I figured I oversized it !!
As for balance on this machine it well more balanced on the yaw bearing than my past machine .And the last machine would steer into the wind as low as 4 to 5 mph and start rotating .

fabricator · « **Reply #24 on:** May 03, 2011, 08:51:44 PM »

Quote from: jarrod9155 on May 03, 2011, 08:22:02 PM

I was really surprise to think some one would think the shaft size maybe just slightly undersized . Compared to some machines with trailerhubs , I figured I oversized it !!
As for balance on this machine it well more balanced on the yaw bearing than my past machine .And the last machine would steer into the wind as low as 4 to 5 mph and start rotating .

You are not undersize on the shaft, you will be just fine.

zvizdic · « **Reply #25 on:** May 03, 2011, 09:35:03 PM »

He is going to be fine for a simple reason that he is not going to see more then 7 HP out off it.

fabricator · « **Reply #26 on:** May 03, 2011, 09:45:27 PM »

Exactly.

zvizdic · « **Reply #27 on:** May 03, 2011, 10:01:07 PM »

I like to build safe machines and i am all against small trailer hubs.

My 10' shaft is a 1 3/8" no keys.

methanolcat · « **Reply #28 on:** May 03, 2011, 10:02:31 PM »

I agree, I don't see any problem with 1.5" shaft, the shaft on my motor conversion is 1 3/8 and its been swinging a 15 foot prop with no problems at all.

jarrod9155 · « **Reply #29 on:** May 03, 2011, 10:14:43 PM »

That's good to know your motor conversion is holding up with a 15 foot prop .
Just finished the stator install so all I have left is to build the tail, maybe this weekend I can fly this machine .

zvizdic · « **Reply #30 on:** May 03, 2011, 10:19:11 PM »

What is voltage you wind for?
How thick is a stator.

jarrod9155 · « **Reply #31 on:** May 03, 2011, 11:12:40 PM »

The stator is 1/2 and wound 12 coils 18 awg 315 turns 70 volts ac at 60 rpms max voltage around 220 volts dc before furling should start to slow it down .

Janne · « **Reply #32 on:** May 04, 2011, 09:19:37 AM »

Hi all,

The 1% value has been presented as a safe value for the main shaft in the in the homebrewn wind turbine guide. The guide is written back in the 90's by the Finnish wind associations self - build department, by some of the hobbyists that build big DIY turbines at that time for heating purposes, in the 10-20kW range. Smaller than that should of course be ok with good planning (as has been witnessed here). In my opinion, as I'm not too much mechanically inclined, I'd use a shaft near the suggested value, as in the overall cost it's not a very big issue, and considering the major problems it might cause later on.
The guide tries to elaborate the point with a picture of a failed 60mm shaft, that has snapped under the strains of 11m diameter rotor, after a few years of running

My 2(â‚¬)c worth.

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Author Topic: New direct drive on a solid shaft (Read 25759 times)