Author Topic: ametek blades (Read 6164 times)

snake21 · « **on:** February 09, 2011, 10:48:30 AM »

hi friends,i have an ametek 38vdc turbine which has 3x 24 inch pvc blades to charge a 12v battery.the motor need to spin at about 400rpm to reach cut in and its rare to see it reach cut in with the pvc blades.the wind speed need to reach about 30-40 km/h to charge the battery.in average,i can see 8v-10v all the time.i just want to experience my first blade carving for the small turbine.the pvc blades spins as if there is a sort of resistance.i think there is alot of drag in pvc blades.thats why i want to change for wooden blades to see the difference

i have hugh's book on wind turbine and i am just asking if the 4" wooden blades would be good for my ametek.or is there any other design for wooden blades for treadmill turbine.

thanks

gsw999 · « **Reply #1 on:** February 09, 2011, 09:17:18 PM »

You need a set of 3 ALU Blades with a hub , these will fly along with a bit of wind like this...

http://www.youtube.com/watch?v=IDvIq9ZxqRA

those are running on an indiana 24V but very similar to Ametek.

hayfarmer · « **Reply #2 on:** February 09, 2011, 11:33:17 PM »

one of my mills is an amtek 38v also and I lost a set of aluminum blades in a storm flew off didn't short the mill to brake .went to a smaller galvanized blade and am very

happy.great wind site keeping 500 ah battery bank charged along with solar but mill is always humming.

the blades I have catch the wind beautifully,and shes turning even when the flags on the 25 ft pole 150 feet away aren't moving.

hayfarmer

snake21 · « **Reply #3 on:** February 10, 2011, 01:09:45 AM »

hi hayfarmer, thanks for the reply.according to your records,can you please tell me the rpm that the 38vdc motor meet to reach 12v?and what is the average and maximum output that you have ever recorded with your ametek?

have you fabricate the blades yourself or you bought it?if you did that yourself,can i have the dimensions,if you dont mind?
the average wind speed at my place is about 25km\h.my pvc blades seem to slow down very fast after a great spin.do you think that the steel or aluminium blades perform best?

thanks

Flux · « **Reply #4 on:** February 10, 2011, 04:23:30 AM »

If you want to try your hand at carving blades then Hugh's blades for the 4ft machine should work quite well. On Hugh's machine the cut in is below 400rpm but the axial alternator has no drag below cut in. Although in theory you could raise the blade tsr I suspect in real life you would loose out on starting and gain very little.

Using it as it stands should be fine.

Flux

Basil · « **Reply #5 on:** February 10, 2011, 05:08:02 AM »

I had a 38 volt ametek mill with air master fan blades and they worked great.
http://fieldlines.com/board/index.php?PHPSESSID=cf8b9e4aa64b51c2c1eba38c578b4411&topic=144715.msg978857#msg978857

gsw999 · « **Reply #6 on:** February 10, 2011, 06:00:03 AM »

My aluminium blades have easily survived whatever has been thrown at them I think windynation sell them on ebay they are really nice blades rated to 90mph.

klsmurf · « **Reply #7 on:** February 10, 2011, 07:08:08 AM »

I tried those 24" windynation blades. The profile is very close to a set of 8" PVC blades I made. I've seen over 900RPM on my little geared up treadmill. If you use them make sure they are secured well. Their adapter for the hub is very small. (2-3/16 set screws) I milled a flat on the shaft and that helped, but I would recommend a through hole on the shaft to keep them from slipping at those speeds. Kevin

hayfarmer · « **Reply #8 on:** February 10, 2011, 07:54:30 AM »

please tell me the rpm that the 38vdc motor meet to reach 12v?and what is the average and maximum output that you have ever recorded with

Quote from: snake21 on February 10, 2011, 01:09:45 AM

hi hayfarmer, thanks for the reply.according to your records,can you please tell me the rpm that the 38vdc motor meet to reach 12v?and what is the average and maximum output that you have ever recorded with your ametek?

have you fabricate the blades yourself or you bought it?if you did that yourself,can i have the dimensions,if you don't mind?
the average wind speed at my place is about 25km\h.my PVC blades seem to slow down very fast after a great spin.do you think that the steel or aluminium blades perform best?

Hi don't know the rpm at 12v but its very little around 7 mph wind I have a 12v led light attached to tower that comes on when 12 volts is reached.and mill starts up way before that cant hardly feel any breeze. bought blades from husky windmills cnc laser made.the aluminum blades that I had from another mill were too large and long and had a storm with 75 mph winds and the blades ripped right off, didn't last 2 months.my amtek mill is rated at 460 watts @ 28mph between 2 75 watt solar panels and this mill I keep a 500 ah battery string happy. here is a link to where I bought the blades from they have been working perfectly going on 3 years,you can make them yourself the design is simple.http://cgi.ebay.com/3-WIND-GENERATOR-BLADES-SUPER-STRONG-LIGHT-QUIET-OP-24-/130483859642?pt=LH_DefaultDomain_0&hash=item1e6171b0ba
and I recommend shutting down with a stop switch if winds go above 50 mph, and take it down above 75 mph I think the blades are 4 inch by 24 inch rounded corners and 1/4 edge folded thick galvanized.

hayfarmer

Isaiah · « **Reply #9 on:** February 10, 2011, 10:05:57 AM »

Take the rated Rpm of the motor divided by the volts of the motor and multiply that by 15
Im not sure on your motor so this is an example 1750 divided by 38 volts=46 X 15=690 rpm to charge a 12 volt battery.you really want 13.8 volts not 12.
just 12 volts will never bring the battery to full charge is why we use the number 15 to calculate.
hope this helps

snake21 · « **Reply #10 on:** February 10, 2011, 10:26:12 AM »

hi you all,thanks for your reply.
isaiah,i already know the small formula you gave me and thank for that but my ametek is a bit different compared to the normal one coz i rewound it using thicker wire and some more turns compared to the original one.thats why the output of my turbine is a bit different.i had 10 more turns per coil compared to the original one.
the motor was rated 12a 36v and 1150rpm which makes 440 rpm for 13.8 v.with the new winding,i am expecting to get 13.8 at 400rpm.
400rpm is a bit difficult to achieve with normal pvc blades at about 25km/h wind.thats why i want to change for high speed blades

gsw999 · « **Reply #11 on:** February 10, 2011, 10:39:28 AM »

the ametek 30vdc is a better motor in my humble opinion, I have a couple of these but not using them as I have 2 x 24v indiana motors which are better again, may i suggest using a drill on the motor to determine rpm/voltage , again in my opinion this is the best way of doing it.

ghurd · « **Reply #12 on:** February 10, 2011, 11:25:21 AM »

Quote from: gsw999 on February 10, 2011, 10:39:28 AM

better

Careful!
I have an Indiana 24 that reaches 14V at about 1400RPM.
There were so many variations and house numbered versions made, can not tell what is better just by a brand and voltage.
Some RPM were rated loaded, others unloaded, so even with a sticker showing volts, amps and RPM, still not exactly sure what is better.
G-

snake21 · « **Reply #13 on:** February 10, 2011, 12:30:22 PM »

i am experiencing another problem with my ametek,if someone cn help please.

the angle of the motor to the pole was about 90 degrees but the blades were hitting the pole.i then modify the pole so that the motor is about 10 to 15 degrees inclined to the top leaving some more distance between the pole and the blade.after this modification,i then found that the turbine started to vibrate a lot at a certain rpm.

the blades are balanced accurately but i really dont know the source of this vibration,someone may help please?

thanks

ghurd · « **Reply #14 on:** February 10, 2011, 12:56:04 PM »

Does it vibrate at about the cut in RPM,
or when the RPM is faster or slower than about cut in?

If it starts to vibrate at an RPM faster than it was going when the blades would hit the tower, it could be the force bending them back to hit the tower is now bending them back more, and they can start to "flutter".
When my PVC blades flutter, it makes a higher frequency buzzing noise from the blades. When this happens the output amps go down, even if the wind speed increases.

Because it is a brushed DC motor, it is not likely to have the lower frequency "growling" sound that travels down the tower, which is more common with AC output machines.
The vibration from AC output machines also tends to be worst at about the cut in RPM.

Not sure if any of that is important.
G-

hayfarmer · « **Reply #15 on:** February 10, 2011, 01:29:45 PM »

Quote from: snake21 on February 10, 2011, 12:30:22 PM

i am experiencing another problem with my ametek,if someone cn help please.

the angle of the motor to the pole was about 90 degrees but the blades were hitting the pole.i then modify the pole so that the motor is about 10 to 15 degrees inclined to the top leaving some more distance between the pole and the blade.after this modification,i then found that the turbine started to vibrate a lot at a certain rpm.

the blades are balanced accurately but i really don't know the source of this vibration,someone may help please?

thanks

I had the same trouble with mine I watched it vibrate for years until I took it down recently and fixed it link shows the fix and root cause:

http://fieldlines.com/board/index.php/topic,144836.msg980765.html#msg980765

read my post and fixes you may have the same trouble

hayfarmer

snake21 · « **Reply #16 on:** February 10, 2011, 01:39:09 PM »

the turbine does not shake at low rpm,when it reches cut in,it vibrate max and vibration decreases at higher rpm than the cut in.when i stick my ears to the tower,i hear a buzzing sound and it increases or decreases depending on the rpm,more rpm,more buzzing sound down the tower.sometimeswhen i am inside the house,i may even hear the buzzing sound though the concrete roof.

dont know what to do.the reason for me to change the blades are to make it spin faster and to try to stop the shaking.

any advice?

thanks

hayfarmer · « **Reply #17 on:** February 10, 2011, 01:45:17 PM »

guys lines tight?play a tune on them? too much slop on the yaw housing over the tower pipe maybe?

just a thought.
my trouble was caused by distance of top guy lines too far from turbine and possible contributor was a tower pipe at top too small,adding and welding a sleeve at the top stopped my shaking completely.

hayfarmer

gsw999 · « **Reply #18 on:** February 10, 2011, 06:41:10 PM »

Quote from: ghurd on February 10, 2011, 11:25:21 AM

Quote from: gsw999 on February 10, 2011, 10:39:28 AM
better

Careful!
I have an Indiana 24 that reaches 14V at about 1400RPM.
There were so many variations and house numbered versions made, can not tell what is better just by a brand and voltage.
Some RPM were rated loaded, others unloaded, so even with a sticker showing volts, amps and RPM, still not exactly sure what is better.
G-

Both mine stick out well over 50 volts at times , i love them as i can just connect them straight to a 24volt battery setup i dont even use a controller , they just keep on going , somebody said "if you use those blades they better be on tight" no s**t sherlock

, if there isnt alot of wind you can just stick a 12v battery on and they will work fine with that , 20$ ebay inverter and you got cheap lighting.

gsw999 · « **Reply #19 on:** February 10, 2011, 06:44:22 PM »

Quote from: snake21 on February 10, 2011, 12:30:22 PM

i am experiencing another problem with my ametek,if someone cn help please.

the angle of the motor to the pole was about 90 degrees but the blades were hitting the pole.i then modify the pole so that the motor is about 10 to 15 degrees inclined to the top leaving some more distance between the pole and the blade.after this modification,i then found that the turbine started to vibrate a lot at a certain rpm.

the blades are balanced accurately but i really dont know the source of this vibration,someone may help please?

thanks

please put up some clear pics and video if possible , the problem sounds like when you angled the turbine you made it very open to wobble / gyroscopic forces, the motor is likeley not on the top of the tower as secure as it should be or not very well aligned, just my thoughts.

Peace

snake21 · « **Reply #20 on:** February 13, 2011, 10:23:16 AM »

hi gsw,i wont be able to put pics or video,coz i took the turbine down due to those reasons mentioned above.i have well balanced the blades and even that it is vibrating.before i tilt the blades,there was no such problem but after i tilt the motor,it started vibrating with the same blades i was using.

u mentioned allignment ,i couldnt understand what you were really saying.can you please elaborate some more about the problem allignment can cause.

the angle of the turbine to the pole is about 15-20 degrees i think.

here is the youtube link when i first placed the turbine,no vibration at all. http://www.youtube.com/watch?v=7IdPGtsE1V4

thanks

Seekscore · « **Reply #21 on:** February 13, 2011, 10:41:14 AM »

Just some thoughts.

I am not sure what the additional forces are doing for the vibrations when the motor is angled up. But if it worked fine with no vibrations pointed directly into the wind. Why not just move the genny forward to get the blades further in front of the tower and add some weight to the back to keep the weight balance centered over the tower?

Mike

snake21 · « **Reply #22 on:** February 13, 2011, 11:39:05 AM »

thanks for the reply,the problem is that i will need to make another support for the motor on the tower.i think i need to redesign the turbine support

any advice?

gsw999 · « **Reply #23 on:** February 13, 2011, 12:32:34 PM »

you are right about the re design.

you need to take it down .

put a small piece of pipe ( the same size as your tower ie 2" ) in a vice , then you can balance your whole top assembly properly ontop of this ( motor , blades and tail ) , so basically you need to find the centre point of the weight distribution so that everything is weighted and balanced as perfectly as possible, when you have dont his you know for a fact that your turbine will not wobble.

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