Need some ideas for my DIY RCM motor - - diyAudio
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Old 22nd July 2009, 12:17 AM   #1
diyAudio Member
 
Join Date: May 2009
Default Need some ideas for my DIY RCM motor -

Ok, my RCM project has finally made it to the top of the to do list. I believe I have some good ideas, sort of going to go off of these plans, here with my own deviations of course, such as using a windshield washer pump for the fluid and a few other changes.
My problem - first, I am not a very creative person. I am using the faux marble plinth from a Kenwood KD-3055 table. Been tinkering with it and have all the holes drilled and i was just going to use the original motor. Problem was, it did not have much torgue. I pulled the motor out of a Sherwood turntable and tried it, but it is about the same. Figured if I am doing this, may as well try and get a motor that will work when suction is applied.
So, had an idea, but not sure how to implement it, this is where I need some ideas from all of you great DIY'ers.
A long time ago, I was in Tractor Supply and they had this 1/2 hp 3450 rpm motor on clearance. I bought it just because it was so cheap, thought maybe i could use it for a swimming pool filter motor. Never did of course.
So, was thinking (which gives me a headache and can be dangerous), how about trying to use that as the motor for the RCM.
I was thinking I could hook it up to a variable switch to slow down the RPM's (is 3450 RPM), but it will still have the torgue to spin when suction is applied.
But how do I hook it up to the platter.
I would really like to use the Kenwood plinth, going to look pretty cool actually. Is a pretty simple set up, spindle sets in a bushing, platter sits on spindle.
The 1/2 HP motor. What I have to work with is a threaded shaft.
As I am the least creative person you will ever find, I need to figure out how to hook up the platter to the threaded shaft.
I was thinking about mounting the motor vertically in the same place the original turntable motor was - but then I will have to rely on a belt to spin the platter and was thinking, when suction is applied, good chance the belt may just slip, motor will be turning but the platter will not.
So, sitting here staring at this thing, not wanting to do the tubes until I get the motor squared away, I thought who better to ask then the real DIY'ers themselves.
Anyone have any ideas ? Would be really appreciated
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Old 22nd July 2009, 01:27 AM   #2
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Join Date: Feb 2006
Location: Chicago, IL
Donberry,

Looks like a pretty good plan except for that giant honking motor, which will be like using a V-8 on a skateboard.

Not only is it physically large and heavy, but a motor speed control is not going to get the rpms down to the 5-30 RPM you're going to want. Belts and pulleys can be used to reduce the speed, but you're talking about more than a 100:1 reduction, and all that stuff is going to take up a lot of space and take a lot of effort to put together.

There are small gear motors all over the place in the surplus houses. Just do a search on "gear motor" on eBay and you'll see them in every voltage, speed and size, for cheap. You can find one with a 1/4" shaft and use a shaft coupler (try McMasterCarr.com) to attach a presentable shaft if the one that comes on the motor is too short.

Even a small motor can generate a lot of torque when geared down, so it won't take much, maybe one the size of soda can--or slightly smaller. If you get one about 30 RPM, you can use a speed control to slow it down effectively.

Let us know how it progresses.

--Buckapound
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Old 22nd July 2009, 09:34 AM   #3
diyAudio Member
 
Join Date: Jan 2002
Location: France
Default RCM motor

I used a windshield wiper motor for my RCM. Small envelope, lots of torque, and the right speed. All you need to do is supply it 12V at a few amperes, and find a way to connect the splined output shaft of the motor to your platter. A few dollars at a scrap yard.

In my case, I made an adapter block, and a coupling for the shaft. This is when friends who have access to machining tools are handy )
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Old 22nd July 2009, 01:36 PM   #4
diyAudio Member
 
Join Date: May 2009
what great idea - I never thought of the windshield wiper motor - I am going to have the 12 volts there anyway for the windshield washer motor - down side for me - I have a garage full of woodworking tools, no machine tools tho - although I do have a machine shop close by - thanks for the idea, will get a motor and see what is what - would love to see a pic of how u did it if you ever get a chance...
thanks
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Old 23rd July 2009, 04:30 PM   #5
diyAudio Member
 
Join Date: Aug 2005
I used an old microwave turntable motor in mine.
3 rpm, loads of torque.
Attached with pvc tube to the bottom of a video player head spindle.
As with all my projects, rip something to pieces and recycle

John
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Old 23rd July 2009, 07:34 PM   #6
diyAudio Member
 
Join Date: May 2009
great idea on the microwave turntable - may actually be better then what I am doing now. Went to goodwill and got a breadmaker- Now that has some torque - trying to figure a way to mount it now. Hardest part is trying to keep the plinth to the Kenwood KD-3055 intact. From a distance look like an original Kenwood table with some real funky arms......
I have pitched the big motor idea (for now) - once I get everything figured out, I am planning on some pics of the progress.
Can't thank you guys enuff - great ideas......I am slow, but given a push, I can do it
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Old 26th July 2009, 06:44 AM   #7
Stuey is offline Stuey  Australia
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Join Date: Mar 2006
Location: Perth, Western Australia
Quote:
Originally posted by offanonone
I used an old microwave turntable motor in mine.
3 rpm, loads of torque.
The only problem is the bell going off at the end of every record...

What did you do to gear it up?

Stuey
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