Motorizing your console - How to reduce rpms using belts and pulleys

Started by warmcanofcoke, Jan 21, 2013, 04:04 am

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warmcanofcoke

I have a problem - most of the motors I find that could be used to make my Tardis console's Time Rotor move up and down have too many RPMs. The motors I come across are usually several thousand revolutions per minute. I'm probably looking for something that is more along the lines of tens of revolutions per minute. Specialized motors of this sort become rather expensive or hard to find second hand.
I have often been told there is a way to step down a motor's rpms, but I have never seen a diagram before. Recently I came across this article. It describes how to motorize a manual meat grinder. OK obviously this isn't the sort of thing you would normally think to look for when trying to solve this problem. However I feel it may solve the very problem I'm describing.

http://www.sausagemania.com/grinder.html

Quote
    How to Motorize Your Manual Meat Grinder -- Easy Instructions from SausageMania.com!

    This is what you can do with a standard Chop-Rite #22 bolt-down hand grinder....this baby is compact, powerful (3/4 HP) and heavy (55 lbs). It grinds at the rate of five (5) pounds a minute, hour after hour, and, because of the ball-bearing speed brake, it is very quiet and vibrationless. The speed brake reduces the motor speed of 1,725 rpm to a grinder speed of about 75 rpm. The base is oak, and there is a lengthwise 2" x 4" oak spine running left to right under the middle of the base, so that the platform will not "flex" during operation, thus preventing belt slippage. The V-belts are tensioned not too tight, however, so that they will slip if you hit a chunk of bone, instead of breaking a grinder part -- the motor mount is slotted, and the main base beneath the grinder mounts is slotted, allowing them to slide for proper V-belt tensioning. See below for exact motor, pulley and belt specifications.

    The flywheel is available from Chop-Rite by special order only -- contact the company for prices, ordering information and safety instructions -- a motorized grinder is a potentially dangerous machine! Note: Chop-Rite recommends a 1/3hp, 1700 RPM motor. When I motorized my grinder many years ago, the company was under different ownership (and OSHA didn't exist yet). I bought the flywheel at Odegaard's Hardware in Billings, MT, and there were no directions at all. So I was completely on my own. After several prototypes, I came up with the design shown below. It's a machine that will last 100 years, I am certain.
    Motor, Pulley, Speed Brake and V-Belt Specifications:

        Motor: Dayton Capacitor Start AC Motor, 3/4 HP, 1725 RPM, 115/230VAC, 11.67/5.8 Amps, 60 Hz

        Pulleys: Motor shaft = 1.5"; small speed brake pulley = 1.5"; large speed brake pulley = 4"; grinder flywheel = 13"

        Belts: Motor to speed brake: 19"; speed brake to grinder = 42"

        Speed Brake: Two cast-iron pillow blocks or mandrels to take a 1/2" shaft. I used a sawed-off 1/2" bolt for the shaft and ground it flat where the pulley set screws bear, so that even if the set screws loosen a little, the pulleys will not slip. I recommend pillow blocks with ball bearings rather than with sintered bronze bearings.

    In the last 25 years, this machine has seen several tons of meat pass through its mechanism! It cost $160.00 to build in 1976.

03grinder3_zps5821c9b5.jpg
Top view, showing array of matched plates and knives. (Plate at right is for sausage stuffing.) Note weatherproof switch.
04grinder2_zps493ed519.jpg
Stuffing tube in place. Motor mount, speed brake mount and grinder base mount are slotted to allow adjustment as belts loosen with use. The anti-warp spline (not seen) is 2 x 4 oak.
05grinder4_zps9cc99956.jpg
This rear shot shows the relationship of flywheel, speed brake and motor.
07grinder5_zps086cedc8.jpg
And here is a detail of the ball-bearing speed brake. Motor shaft pulley is 1.5". Large speed brake pulley is 4". Small speed brake pulley is 1.5". Grinder pulley is 13". This reduces the 1725 RPM of the motor to about 75 RPM at the grinder. Note zerk grease fittings for the bearings. Short V-belt = 19", long V-belt = 42".



There is also an article that may give added insight.  http://www.ehow.com/how_7901912_reduce-rpms-using-belts-pulleys.html

It is my hope that this information may lead to an article here on Tardis builders that would be useful to future console builders. Perhaps some of our more technically minded members would care to add detailed instructions or advice. As always I would like all of our members to be safe and take precautions to not damage themselves in any way.

Nathan aka warmcanofcoke
why doesn't the Guide mention them? - Oh, it's not very accurate.
Oh? - I'm researching the new edition.

galacticprobe

I don't know if this will be of any help to you, Nate (or anyone else), but there are also "gear motors" that can do the same thing, but without all of exposed the pulleys and belts. The reduction gears (a.k.a. red-gears) are contained within the motor housing (and I think they take up much less space). They give low RPM with high torque.

I found this while poking around: http://www.ehow.com/about_5313147_gear-motor.html. There are more articles dealing with gear motors in the links on the right side of that page.

Dino.
"What's wrong with being childish?! I like being childish." -3rd Doctor, "Terror of the Autons"

warmcanofcoke

Thank You Dino, I am now looking into Gear Motors online. Is there a good diagram or photograph that shows how these motors work?

I am interested in the Pros and cons of both systems.
why doesn't the Guide mention them? - Oh, it's not very accurate.
Oh? - I'm researching the new edition.

warmcanofcoke

How many of the Tardises that we know of, have a appropriately moving up and down column? This problem must have been solved before. I know that type55tardis has a good system - however I'm sure there are many brilliant things going on in his design that I'm not seeing. I need a step by step "how to" tutorial - I would like to understand the mechanics and the principles involved.

I just found a Motor for sale that has 32 rpm 1/20 hp, 1.2" shaft and has a 90lb load - is this a good motor? of will I waste my money? I would like to know more.


Not to sound like I'm the toy designer from "Flight of the Phoenix" who tries to fix a real airplane - but here is the diagram used by Dapol to make the Toy console for the 25th anniversary.
dapolset5_zps9d7f1963.jpg
http://doctorwhotoys.net/dapoltardisconsole.htm
why doesn't the Guide mention them? - Oh, it's not very accurate.
Oh? - I'm researching the new edition.

Scarfwearer

Well http://tardisbuilders.com/index.php?action=profile;u=160 has produced a tutorial here: http://tardisbuilders.com/index.php?topic=1329
But don't look at me: although my console had a pulley system much as you described the ceiling fan  motor I used was nowhere near powerful enough and it barely worked at all.
I've looked at gear motors but they're pretty expensive when new. Lungman's wash-tub motor idea looks good.
http://tardisbuilders.com/index.php?action=profile;u=159 also did one recently - perhaps he'll chime in.

Crispin

warmcanofcoke

Thank you Crispin - I'm not sure how I missed this article- I'm sure I've read it once before - some how I lost track of it.
why doesn't the Guide mention them? - Oh, it's not very accurate.
Oh? - I'm researching the new edition.

Scarfwearer

It's getting to be a big site :) Though it still appears small by most standards... I guess we just pack a lot in a small space.... definitely bigger on the inside.

Crispin

Theta Sigma

Quote from: Scarfwearer on Jan 21, 2013, 02:49 pm
It's getting to be a big site :) Though it still appears small by most standards... I guess we just pack a lot in a small space.... definitely bigger on the inside.

Crispin


I took inspiration from Lungman as well when I retrofitted this old console's rotor mechanism.  

http://tardisbuilders.com/index.php?topic=472.0

"I just put 1.795372 & 2.204628 together." - 4th Doctor

warmcanofcoke

I do like that old console =D

would you like to draw a diagram of the mechanism or add your advice to others interested in building a similar system?
why doesn't the Guide mention them? - Oh, it's not very accurate.
Oh? - I'm researching the new edition.