Apologies my PDF failed to send on the last post- please find below.
rotating_table_top_project.pdf (823 KB)
How many teeth has the A gear in page 3?
How much total weight (including whatever objects you will put on it) will have the rotating plate?
I like it !
the beauty is that you can get a motor with reduction as well .
Nice drawings, i wish the schematics often posted here were as good.
Worm gear, that looks like something that fenner might do , they can be expensive.
Sintered gears are much cheaper , IF you can find a suitable one.
How many teeth has the A gear in page 3?
How much total weight (including whatever objects you will put on it) will have the rotating plate?
Hi Blimpyway,
I have written to a couple of companies who make 4” worm gears for a relatively cheap rate. I still don’t know how many teeth it will have but I’m hoping to achieve at least a 100:1 ratio.
The weight of the tabletop is currently 3.1kg – I might reduce this if I need to by routering of excess wood from the bottom.
The table will only hold a glass of water, 0.7kg
Aluminium plate- is in the post so I don’t have an exact weight yet but I estimate it will come to around 1.5kg
Total: 5.3 kg
do you think a Nema 17 sufficient for this?
Nice drawings, i wish the schematics often posted here were as good.
Worm gear, that looks like something that fenner might do , they can be expensive.
Sintered gears are much cheaper , IF you can find a suitable one.
Thanks Boardburner2! Ill look into Sintered gears, I dont mind spending a little bit on the gears to get them right.
I like it !
the beauty is that you can get a motor with reduction as well .
Thanks Dave, the design is largely based on all the advice I've received from your guys, im very gratful for all the help! just gotta try and make it happen now.
The stepper reduction would be a nice touch, but ill have to see if i have enough space first.
do you think a Nema 17 sufficient for this?
I think it's more than enough. The limit isn't as much the motor torque as the axial/radial force limits, if the worm screw is supported only by the motor's axle. https://cdn-shop.adafruit.com/product-files/324/C140-A+datasheet.jpg
No need for further reduction if 10N (2.2lbs, 1kg) applied at the 5cm radius of the gear is enough to turn it.
EDIT At such slow speed, with 100tooth worm gear, a 200step/rotation motor will have to make a step every couple seconds.
I wonder what's the point of such slow movement that is unlikely anybody will notice
Hi All,
I’m writing to give a short update and also to ask if I might get some advice on gears ratios, stepper motor capacity and vibration/noise proofing.
Since my last post I have purchased a very sexy 7.1 inch worm gear from Ed Byers! It still wasn’t cheap! but after many hours of browsing the web and research it seem to be the best option. It has 252 teeth and came with a DC Hurst stepper motor which has a built in reduction gear box of 150:1. See photos attached.
I guess my first question has to do with the motor- I was wondering if you think its up to the job? I have attached the specs to this post, or you can find them here (the model number is: 3008-002)
: http://www.hurst-motors.com/asabsgeared.html#buy
It will need to turn:
Worm gear: 1kg
Aluminum shaft & mount plate: 1-1.5kg
Table top: 4-5 kg
Total= 7.5kg max
My second question is to do with working out the math of the ratios. My target is to achieve 1 imperceptible rotation of the table top every 10hr & 39 mins.
I have done a quick calculation but I wanted to check if my reckoning makes sense?
Worm gear 252:1
Gear box 150:1
Gear box 150 x worm gear 252 =37,800.
Combined I should get a ratio of 37,800:1
37,800 divided by 639 minutes (10hr and 39 min) = 59.1
Which means I should need to programme the stepper motor to rotate proximity once every 0.99999 seconds.
Does that sound right to you??
Lastly, I haven’t had a chance to test the motor yet- as I still haven’t bought or learnt how to use Aduino but I’m slightly worried about the level of noise the stepper motor and gearbox will produce. As I’ve said previously, I’d like the table to turn imperceptibly so it would be a huge shame if you can hear the motor humming away. If my above calculations are correct, do you think the motor will produce audible noise at a rate of 1 rotation per second?- is there any way of reducing the sound of a stepper motor?
And as far as making a mount for the motor is concerned does anyone have any advice on ways/materials to use to damper/cancel out vibration?
Thanks so much for your help,
George
I think you are missing one huge number.
the Hurst 3008-002 has 24 steps per motor rotation, 3,600 per final drive with the 150: gear box.
that stepper has 24 'natural' steps per rotation, and half steps are not nearly as jaring. 1/4 steps are almost fluid.
so, assuming 1/4 steps on a 24 step motor is 96 steps per rotation times 150:1 ratio, times 252 for the gear box. or 3,628,800 steps per table rotation
I get 5678.87323944 steps per minute or about 94.6 steps per second.
but, I also see an additional gear redcution after the motor.
dave-in-nj:
I think you are missing one huge number.
Thanks dave-in-nj that's a very good point, I'd completely forgot to figure in the steps! 3,628,800 is a very big number indeed!!!
lionelwoolfe:
ched.I guess my first question has to do with the motor- I was wondering if you think its up to the job? I have attached the specs to this post, or you can find them here (the model number is: 3008-002)
: AS, ABS Geared Permanent Magnet DC Stepper MotorsIt will need to turn:
Worm gear: 1kg
Aluminum shaft & mount plate: 1-1.5kg
Table top: 4-5 kg
Total= 7.5kg max
Dave do you think the motor is powerful enough?
lionelwoolfe:
Dave do you think the motor is powerful enough?
all depends on rotational resistance. but I expect that there is a lot of delivered torque.
probably more than you need
Thanks Dave, I guess It's best I concentrate on getting these bearings to move as smooth as possible then.
Do you reckon the sound of the motor will be audible at the speed I'll be using it?
lionelwoolfe:
Thanks Dave, I guess It's best I concentrate on getting these bearings to move as smooth as possible then.
Do you reckon the sound of the motor will be audible at the speed I'll be using it?
only way to know is to put it together.
the motor will get hot, so you cannot cover it too much. blower to move heat might allow you to put it in a box if you can hear it.
Hi Everyone,
It’s been some time since my last post, I’m writing to give an update on my project and ask once again for your collective wisdom/guidance!
For those of you who haven’t followed this thread, I’m a complete novice with no experience at all using arduino or stepper motors. My project is part of an artwork I’m making, in a nutshell: I am trying to make a table with a rotating top that moves very slowly- exactly one rotation per 10hr and 39 mins (corresponding to the rotation of the planet saturn). It’s very important that the movement is both accurate and imperceptible.
After a lot of discussion and great advice from this forum I have finally put together the gears and mechanics (see pics attached). The turntable plate is attached to a 1” shaft which is connected to a 252:1 reduction worm gear (the sort they use in telescopes), powered by a Hurst (model 3008-002) stepper motor, which has a built in reduction gear box of 150:1.
Having finally put this all together- I now can’t wait to get it going!!
I wanted to ask the forum what do I need??
What Arduino? – I have seen there are quite a few types available on the market- is there a great deal of difference between them and which would be best for my application?
What driver? –Robin2 suggested a while ago that a Pololu A4988 might be good for my application?
How do I power the motor/Arduino- and can I do this from a single power source?
Is there anything else I have missed??- please even obvious stuff would be great -I’m really new to this!
Thanks again!
George
lionelwoolfe:
powered by a Hurst (model 3008-002) stepper motor, which has a built inThanks again!
George
Can you provide a link to the datasheet for that motor ?
Superb build, congratulations.
Boardburner2:
Can you provide a link to the datasheet for that motor ?Superb build, congratulations.
Thanks Boardburner! its been a learning curve.
I have attached the specs below.
there also available at AS, ABS Geared Permanent Magnet DC Stepper Motors the model numer is (the model number is: 3008-002)
lionelwoolfe:
What Arduino? –What driver? –Robin2 suggested a while ago that a Pololu A4988 might be good for my application?
How do I power the motor/Arduino- and can I do this from a single power source?
Thanks again!
George
From the link that motor can be wired as unipolar or bipolar.
The polou board i think only operates as unipolar.
Any arduino should be suitable.
I am unfamiliar with that board though.
Perhaps someone with better knowledge will come along soon.
You will need 2 supplies though.
One for the motor and one for the arduino.
The arduino could quite possibly be suplied from the motor supply though with suitable protection.
Boardburner2:
From the link that motor can be wired as unipolar or bipolar.
The polou board i think only operates as unipolar.
Any arduino should be suitable.I am unfamiliar with that board though.
Perhaps someone with better knowledge will come along soon.
You will need 2 supplies though.
One for the motor and one for the arduino.
The arduino could quite possibly be suplied from the motor supply though with suitable protection.
Thanks Boardburner that's a great help!
I will have to do some more research into the power 