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| Drumsander question, "rpm question" http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=20926 |
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| Author: | Lars Stahl [ Sat Feb 07, 2009 4:16 pm ] |
| Post subject: | Drumsander question, "rpm question" |
I am almost done with my homemade drumsander its 24". Can´t wait to press "on" . BUT ! I need to understand what size I need to make it as it should be in "rpm" the motor is an old 1.7 horsepower 2800rpm, 50Hz, "using 3pins" 370W" not 220W if this helps ? . As I understand it, it supposed to run on around 2000rpm, so what size of pulleys do I need to get it to run at the right speed.??? The pulley that´s on the motor now is 3" . I will use a 3/4" rod well 20mm to be exact. hope this is enough for the load. any thoughts ?. Lars. |
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| Author: | TonyKarol [ Sat Feb 07, 2009 4:59 pm ] |
| Post subject: | Re: Drumsander question, "rpm question" |
Lars .. you dont say what the drum diameter is ???? I run a 3/4 hp 1725 RPM motor, 3 inch pulley, to a 6 inch drum 6 inch pulley .. so about 860 RPM on the drum. that seems ot work well .. if your drum is adifferent diameter, you might want to figure out feet per minute that the sandpaper hits the wood ... |
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| Author: | Rich Schnee [ Sat Feb 07, 2009 5:09 pm ] |
| Post subject: | Re: Drumsander question, "rpm question" |
Lars…It’s the surface feet per minute that you need to be concerned with. What size drum are you using? Is it 24” in width or is that the diameter? I have seen large dia drums but that would be huge. Choosing the correct pulley in order to get the proper SFM is dependant on the drum diameter or more to the point the circumference. The larger the drum, the lower the shaft RPM. |
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| Author: | Frank Aarre [ Sat Feb 07, 2009 5:38 pm ] |
| Post subject: | Re: Drumsander question, "rpm question" |
if you've got a 6" drum you should be ok with double pulley size on drum vs motor which would give you a ltlle over 2100 fpm. do you have dust collection to handle the sander? btw, i'm just finishing up my own drum sander shooting some paint on it now, turned out to be a bigger project than i initially planned 
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| Author: | Lars Stahl [ Sat Feb 07, 2009 5:44 pm ] |
| Post subject: | Re: Drumsander question, "rpm question" |
the drum size is 3,3/4" (9.5cm) |
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| Author: | Lars Stahl [ Sat Feb 07, 2009 5:51 pm ] |
| Post subject: | Re: Drumsander question, "rpm question" |
the drum size is 3,3/4" (9.5cm) |
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| Author: | Frank Aarre [ Sat Feb 07, 2009 5:52 pm ] |
| Post subject: | Re: Drumsander question, "rpm question" |
4 1/2" on the drum would give 2055 fpm |
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| Author: | Lars Stahl [ Sat Feb 07, 2009 5:54 pm ] |
| Post subject: | Re: Drumsander question, "rpm question" |
great !! thank you soo much. how do you calculate this ?. lars |
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| Author: | Frank Aarre [ Sat Feb 07, 2009 5:58 pm ] |
| Post subject: | Re: Drumsander question, "rpm question" |
Lars Stahl wrote: great !! thank you soo much. how do you calculate this ?. lars well it's late and it seems my math is flawed... but still i think 4 1/2 would work 9,5cm drum gives you 29.83cm pr revolution. its spinning at 2800 rpm which is 83524 cm/m /30,48=2740 fpm correct me if i'm wrong but 3" pulley on motor and 4 1/2" pulley on drum will give 1826 fpm on a 2800rpm motor. as i said it's late here in norway... |
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| Author: | Lars Stahl [ Sat Feb 07, 2009 7:27 pm ] |
| Post subject: | Re: Drumsander question, "rpm question" |
Thanks alot Frank. I am from Sweden. Good to know I have more neighbors guitarfriends.  . Lars. |
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| Author: | Joe Sabin [ Sat Feb 07, 2009 7:53 pm ] |
| Post subject: | Re: Drumsander question, "rpm question" |
Lars Stahl wrote: great !! thank you soo much. how do you calculate this ?. lars Feet per minute on a drum is calculated: Drive shaft D Driven shaft d RPM of motor R Diameter of Sanding drum in inches S FPM=d/D*R*S/4 I'm cheating here since I'm assuming pi = 3, but that's close enough. |
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| Author: | Lars Stahl [ Sun Feb 08, 2009 7:05 am ] |
| Post subject: | Re: Drumsander question, "rpm question" |
Thanks Joe. |
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| Author: | Darrin D Oilar [ Sun Feb 08, 2009 10:32 am ] |
| Post subject: | Re: Drumsander question, "rpm question" |
Lars, you will love the drum sander once you get it up and running and all the quirks worked out. Have you run the motor prior to getting it all hooked up to the drum sander? The reason I ask is because here in the US we run into cheap motors all the time that are 3 phase and most of us dont have that at our houses. I'm just wondering if that is what you have with that motor, hence the specs you were reading. Forgive me in advance if I don't know what I'm talking about as I am ignorant of power supply in Sweden.  Are you using the old clothes dryer/presser thing that you showed pics of when you first moved into your shop for this? I can't wait to see pics as I love adapted use tools. Good Luck. Darrin |
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| Author: | Lillian F-W [ Sun Feb 08, 2009 10:36 am ] |
| Post subject: | Re: Drumsander question, "rpm question" |
Wonderful news Lars. How about some pictures? We would love to see your version of a drum sander. Hopefully you were taking pictures through out the building process. |
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| Author: | Lars Stahl [ Sun Feb 08, 2009 9:38 pm ] |
| Post subject: | Re: Drumsander question, "rpm question" |
Darrin. No not running it by the presses I showed a while back Its a 3 fas. old nice motor at 1,7 horsepower. Haven´t started it yet, waiting for the rod so I can stack the drums and hook it up. Not long til I do though ![[:Y:]](./images/smilies/smiley20.gif "Thumbs Up") Lillian, I havent taken many photos on the sander, but I sure will though. and I will post as soon as I have some on the camera. the thing is that my camera is not working on a macintosh wish I have, so I have to install the photos on a PC and then transfer them over to the Mac !! hmmm grr. takes forever it seem. Lars. |
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