I have had a lot of requests for detailed Tumbler plans, how to choose pulley's for the motor and drive shafts and where to get the stainless steel pins from.
I have combined all three posts that I have done recently into one source for easier reference.
Finished Product:
I used a treadmill motor with dc motor controller and variable speed pot. You can also use any ac motor that will fit with the correct pulleys. I explain how to choose the correct pulley's bellow.
Plans:
I used 1 1/4" Steel Tubing for the frame.
I used 1/2" size Pillow Bearing Blocks that had a 1/2" mounting holes. I have seen some with 3/8" mounting holes but these were on sale so they will do.
The important part is that when you mount the pillow bearings the center to center measurement of the 1/2" shafts are 5" apart. In my case I drilled the first 1/2" bolt hole 2" from the end and then measured the distance of the holes in the bearing blocks to ensure when they were mounted I got the 5" that I needed. In most cases the center to center holes on the bearing blocks are 3 3/4" but check yours first to see if there is a difference. You can see that the mounted blocks are almost touching. The little piece of brass with the roller wheel between the shafts is to prevent the tumbler drum from hitting the end and keeping it on the shafts. My friend that has a lathe is making me up a bearing mounting post for a more permanent installation.
For the feet I used a 3/8" x 1 1/2" long threaded Chair Leg. I drilled a hole in the frame and put the nut on from the inside and then just tack welded it. I put a rubber cup over it to keep the tumbler from moving but weight alone I am sure it wouldn't go anywhere anyways. I tack welded the 1/2" pillow bearing mounting bolts for easier installation.
Another look from the pulley side.
How to choose the Pulley's for the motor and drive shaft.
To calculate the size of the pulleys needed with a certain speed of the motor we can use this simple formula.
Motor RPM x Motor Pulley Diameter = Driven Pulley Diameter x Driven RPM
After we are done figuring, this only gives us the speed of the driven shaft on the tumbler
Since we want the speed of the driven shaft on the tumbler we can re write the formula as:
Motor RPM x Motor Pulley Diameter
---------------------------------------------- = Driven Rpm (Speed of the driven shaft)
Driven Pulley Diameter
Then you use the speed of the driven shaft on the tumbler to figure out what the speed of your Tumbler’s Drum is going to be. I combined both formulas into one to make it easier to figure out the speed of the drum. I made up some letter designations to make it easier to follow the formula and here they are:
Motor Rpm= M
Motor Pulley Diameter= MP
Driven Pulley Diameter = DP
Diameter of Driven Shaft = DS
Diameter of Tumbler Drum = TD
Driven RPM of the Drum = DR
M x MP x DS
------------------- = DR or the speed of drum on the tumbler.
TD x DP
Lets try one .
You found a motor at the dump that has a sticker on it that says it turns at 1725 RPM.
You go to Princess Auto and find a pulley that fits the motor and it has a diameter of 2”.
You buy some bearings for the shaft to run on and they are ½ “ size for your ½” shafts.
You buy a 6” pulley for the driven shaft for the tumbler drum to run on.
You make a 6” tumbler drum out of a empty plastic jar.
How quick will your tumbler drum be turning at?
With our handy dandy formula we can plug in some numbers and find out.
1725rpm x 2” x ½”shaft
--------------------------- = 47.9 RPM or about 48 RPM the tumbler drum will be going.
6” drum x 6”pulley
The Thumlers regular speed is 30 rpm and the high speed is 40 rpm. We don’t want anything quicker than 60 rpm because the brass and contents will just stick to the outside wall due to centripetal force. So in this case we guessed correctly for the size of drum we want and the pulley needed to obtain that speed.
So let’s say we find some 5/8” bearings on sale and our drum size is 8” instead of the 6” we had before.
Using the same motor and pulley sizes what would be our drum speed?
1725 x 2” x 5/8”
------------------- = 44.9 RPM So 45 RPM is right in the ballpark .
8” x 6”
You can always buy an adjustable pulley for the motor that varies so you can fine tune the speed of the drum but figuring out what size of drum you want to make and the smallest size of the motor pulley, you can mix and match the size of the shaft and pulley on that shaft so you don’t have to spend extra money experimenting on what you want.
If you know the size of your Drum that you want to make and the size of the motor pulley then with algebra we can manipulate the formula to come up with the size of the pulley on the driven shaft.
M x MP x DS
---------------------= DP (The size of the pulley needed to put on the driven shaft)
DR x TD
Let’s try one out.
You have a 7” drum, a 1725 rpm motor with a 3” pulley on it and you have some 7/8” bearings and 7/8” shaft to use for your tumbler. What size of pulley do I need to put on the 7/8” shaft to give me 60 RPM for the Drum?
1725 RPM x 3” x 7/8”
-------------------- = 10.8” (You would need about a 11” pulley)
60 RPM x 7”
It would be hard to find an 11” pulley so your better bet would be to drop the 3” pulley on the motor to a 2” pulley which running it thru the formula again would give you about a 7” pulley which is more realistic.
You have the driven shaft pulley diameter of 7” on a 5/8” shaft and you want to know what size of pulley I need to buy to put on the motor to give me 55 rpm for my 8” drum.
Manipulate the formula to give you this.
DR x TD x DP
------------------ = MP (Size of the pulley needed on the motor shaft)
M x DS
Let’s try it.
55RPM x 8” x 7”
-------------------- = 2.85” ( You would buy a 3” pulley and that will get you close)
1725 RPM x 5/8”
With an adjustable DC motor like on a treadmill then just buy any two pulley's that you need and you can adjust the speed of the motor to get what you want.
How much to make the Tumbler?
3” pulley 6.00
4.5” pulley 9.00
½ “ shaft for 5 ‘ 9.00
½” Pillow Bearing 13.00 each (52.00 total)
½” heater hose 4.00
Base mounts 12.00 (rubber cups I put over adjustable screw in legs)
1 1/4” Square tubing $30.00 for a 8 foot length and I had 4” left over
Motor found at scrap yard
Total $122.00
Source of Stainless Steel Pins
There are several sources out there that can supply the needed stainless steel pins. You want the ones that are magnetic for easier clean up when you drop a few.
Cheapest ones that I have found are from Pellets LLC (http://ww w.pelletsllc.com/) and the ones you want are SCW-41 / .255 at $6.00 per pound. How many pounds will determine what USPS flat rate box you will need to have them shipped in.
Drum
For the drum I used a piece of 10" PE pipe that I get from work that is thrown out. I cut a piece of Plexiglas that I already had and mounted it on one end with some gasket cork and RTV Silicone seal.
On the inside I mounted with brass screws some strips of plastic that I had laying around to help with mixing the brass and pins up.
On the top I glued RTV on the PE pipe then put a layer of gasket material on top of it then another layer of gasket material and then glued the Plexiglas on top of that. So I had glue/gasket/gasket/glue and Plexiglas. Drilled holes all the way around and drove long screws thru it all into the PE pipe. When it was dried I had a flat surface with gasket on the PE pipe and a flat surface on the Plexiglas. I cut out the inside of the gasket on the pipe and now I have a perfect water tight seal.
When I make another drum I will change the top Plexiglas to metal instead. I screwed one of the screws to tight and cracked the Plexiglas and had to start over as you can see in this picture.
If you need anymore info drop me a line.
I have combined all three posts that I have done recently into one source for easier reference.
Finished Product:
I used a treadmill motor with dc motor controller and variable speed pot. You can also use any ac motor that will fit with the correct pulleys. I explain how to choose the correct pulley's bellow.
Plans:
I used 1 1/4" Steel Tubing for the frame.
I used 1/2" size Pillow Bearing Blocks that had a 1/2" mounting holes. I have seen some with 3/8" mounting holes but these were on sale so they will do.
The important part is that when you mount the pillow bearings the center to center measurement of the 1/2" shafts are 5" apart. In my case I drilled the first 1/2" bolt hole 2" from the end and then measured the distance of the holes in the bearing blocks to ensure when they were mounted I got the 5" that I needed. In most cases the center to center holes on the bearing blocks are 3 3/4" but check yours first to see if there is a difference. You can see that the mounted blocks are almost touching. The little piece of brass with the roller wheel between the shafts is to prevent the tumbler drum from hitting the end and keeping it on the shafts. My friend that has a lathe is making me up a bearing mounting post for a more permanent installation.
For the feet I used a 3/8" x 1 1/2" long threaded Chair Leg. I drilled a hole in the frame and put the nut on from the inside and then just tack welded it. I put a rubber cup over it to keep the tumbler from moving but weight alone I am sure it wouldn't go anywhere anyways. I tack welded the 1/2" pillow bearing mounting bolts for easier installation.
Another look from the pulley side.
How to choose the Pulley's for the motor and drive shaft.
To calculate the size of the pulleys needed with a certain speed of the motor we can use this simple formula.
Motor RPM x Motor Pulley Diameter = Driven Pulley Diameter x Driven RPM
After we are done figuring, this only gives us the speed of the driven shaft on the tumbler
Since we want the speed of the driven shaft on the tumbler we can re write the formula as:
Motor RPM x Motor Pulley Diameter
---------------------------------------------- = Driven Rpm (Speed of the driven shaft)
Driven Pulley Diameter
Then you use the speed of the driven shaft on the tumbler to figure out what the speed of your Tumbler’s Drum is going to be. I combined both formulas into one to make it easier to figure out the speed of the drum. I made up some letter designations to make it easier to follow the formula and here they are:
Motor Rpm= M
Motor Pulley Diameter= MP
Driven Pulley Diameter = DP
Diameter of Driven Shaft = DS
Diameter of Tumbler Drum = TD
Driven RPM of the Drum = DR
M x MP x DS
------------------- = DR or the speed of drum on the tumbler.
TD x DP
Lets try one .
You found a motor at the dump that has a sticker on it that says it turns at 1725 RPM.
You go to Princess Auto and find a pulley that fits the motor and it has a diameter of 2”.
You buy some bearings for the shaft to run on and they are ½ “ size for your ½” shafts.
You buy a 6” pulley for the driven shaft for the tumbler drum to run on.
You make a 6” tumbler drum out of a empty plastic jar.
How quick will your tumbler drum be turning at?
With our handy dandy formula we can plug in some numbers and find out.
1725rpm x 2” x ½”shaft
--------------------------- = 47.9 RPM or about 48 RPM the tumbler drum will be going.
6” drum x 6”pulley
The Thumlers regular speed is 30 rpm and the high speed is 40 rpm. We don’t want anything quicker than 60 rpm because the brass and contents will just stick to the outside wall due to centripetal force. So in this case we guessed correctly for the size of drum we want and the pulley needed to obtain that speed.
So let’s say we find some 5/8” bearings on sale and our drum size is 8” instead of the 6” we had before.
Using the same motor and pulley sizes what would be our drum speed?
1725 x 2” x 5/8”
------------------- = 44.9 RPM So 45 RPM is right in the ballpark .
8” x 6”
You can always buy an adjustable pulley for the motor that varies so you can fine tune the speed of the drum but figuring out what size of drum you want to make and the smallest size of the motor pulley, you can mix and match the size of the shaft and pulley on that shaft so you don’t have to spend extra money experimenting on what you want.
If you know the size of your Drum that you want to make and the size of the motor pulley then with algebra we can manipulate the formula to come up with the size of the pulley on the driven shaft.
M x MP x DS
---------------------= DP (The size of the pulley needed to put on the driven shaft)
DR x TD
Let’s try one out.
You have a 7” drum, a 1725 rpm motor with a 3” pulley on it and you have some 7/8” bearings and 7/8” shaft to use for your tumbler. What size of pulley do I need to put on the 7/8” shaft to give me 60 RPM for the Drum?
1725 RPM x 3” x 7/8”
-------------------- = 10.8” (You would need about a 11” pulley)
60 RPM x 7”
It would be hard to find an 11” pulley so your better bet would be to drop the 3” pulley on the motor to a 2” pulley which running it thru the formula again would give you about a 7” pulley which is more realistic.
You have the driven shaft pulley diameter of 7” on a 5/8” shaft and you want to know what size of pulley I need to buy to put on the motor to give me 55 rpm for my 8” drum.
Manipulate the formula to give you this.
DR x TD x DP
------------------ = MP (Size of the pulley needed on the motor shaft)
M x DS
Let’s try it.
55RPM x 8” x 7”
-------------------- = 2.85” ( You would buy a 3” pulley and that will get you close)
1725 RPM x 5/8”
With an adjustable DC motor like on a treadmill then just buy any two pulley's that you need and you can adjust the speed of the motor to get what you want.
How much to make the Tumbler?
3” pulley 6.00
4.5” pulley 9.00
½ “ shaft for 5 ‘ 9.00
½” Pillow Bearing 13.00 each (52.00 total)
½” heater hose 4.00
Base mounts 12.00 (rubber cups I put over adjustable screw in legs)
1 1/4” Square tubing $30.00 for a 8 foot length and I had 4” left over
Motor found at scrap yard
Total $122.00
Source of Stainless Steel Pins
There are several sources out there that can supply the needed stainless steel pins. You want the ones that are magnetic for easier clean up when you drop a few.
Cheapest ones that I have found are from Pellets LLC (http://ww w.pelletsllc.com/) and the ones you want are SCW-41 / .255 at $6.00 per pound. How many pounds will determine what USPS flat rate box you will need to have them shipped in.
Drum
For the drum I used a piece of 10" PE pipe that I get from work that is thrown out. I cut a piece of Plexiglas that I already had and mounted it on one end with some gasket cork and RTV Silicone seal.
On the inside I mounted with brass screws some strips of plastic that I had laying around to help with mixing the brass and pins up.
On the top I glued RTV on the PE pipe then put a layer of gasket material on top of it then another layer of gasket material and then glued the Plexiglas on top of that. So I had glue/gasket/gasket/glue and Plexiglas. Drilled holes all the way around and drove long screws thru it all into the PE pipe. When it was dried I had a flat surface with gasket on the PE pipe and a flat surface on the Plexiglas. I cut out the inside of the gasket on the pipe and now I have a perfect water tight seal.
When I make another drum I will change the top Plexiglas to metal instead. I screwed one of the screws to tight and cracked the Plexiglas and had to start over as you can see in this picture.
If you need anymore info drop me a line.
