| Author |
Message |
ian mckenzie (Ian160981)
Member
Username: Ian160981
Post Number: 1
Registered: 5-2008
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| Posted on Thursday, May 1, 2008 - 9:49 pm: |
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hi everyone, im new to this site and quite new to projects in general. i am building a tv cabinet which the tv/lcd will rise out of. the weight of the television will be about 15 - 20 kg but i would like the motor to be able to lift about 30kg just in case i upgrade my television. i was thinking of the following motor - 24V 200W Geared 203rpm MY7712NZ - Part No: 1471-103. this motor already has an output torque of 9.35nm and an output rpm of 203. i am going to install a 20 tooth gear to the motor which will drive a 40 tooth gear which will be on a 17mm shaft. this is the drive shaft so to speak to which the lifting straps will wrap around. since i am using the gear setup mentioned would i be right in saying my output torque would double and my rpm would half. i hope so because i would like an output of about 100rpm. if i am right then my output torque at the 17mm shaft would be 18.7nm , my overall question is would this torque be enough to lift the desired weight easily. if you think this is too powerful is there a 12volt motor that would lift this weight. the motor must be worm drive to gearbox. |
ian mckenzie (Ian160981)
Member
Username: Ian160981
Post Number: 2
Registered: 5-2008
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| Posted on Thursday, May 1, 2008 - 10:03 pm: |
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hi me again sorry if im boring you with my long story. but i forgot to mention the reason the motor must be worm drive is that the television will be staying at the top position for a considarable amount of time, so i was relying on the gearbox to hold it there while the power was disconnected from the motor. also ( last question - honest !!! ) could you recomend a battery supply or power supply for this 24 volt motor. if it is a battery supply i would need a charger to suit as well so i can charge the batteries automatically while not in use.
thanks for reading and sorry about the vast amount of questions.
thanks |
Admin (Admin)
Board Administrator
Username: Admin
Post Number: 776
Registered: 10-2004
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| Posted on Friday, May 2, 2008 - 8:30 pm: |
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Hello Ian,
Yes the output torque will double and speed halve for the 2:1 reduction you quote. So at 100rpm, you will get 1.9kg/m torque. At 1cm from the centre of the motor output shaft you will get 190kg/cm torque so this is plenty to lift your 30kg. This is the best motor from our range for you especially with the worm drive output.
We have not tried to back drive these motors but we believe it should hold the 30kg load you have without power being applied to the motor.
Whilst you could use batteries, especially given the short running time, I feel a power supply would be better. However, we do not have any 24V power supplies in our range. It is quite likley that you could run the motor at a reduced voltage of 12V (giving 50 rpm) in which case our 13.8V power supplies would be fine.
Regards
Paul |
ian mckenzie (Ian160981)
Member
Username: Ian160981
Post Number: 3
Registered: 5-2008
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| Posted on Friday, May 2, 2008 - 8:40 pm: |
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thanks very much for your quick reply. the information is relly helpful, although if i run the motor from a 13.8v power supply would this not effect my overall torque. and if so do you think it would still handle the weight. and also would running it at 12v not increase the amps drawn by the motor and if so what power supply would cope with this. thanks again for all your help. this is a great site and i will be a long term customer.
regards
ian |
Admin (Admin)
Board Administrator
Username: Admin
Post Number: 778
Registered: 10-2004
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| Posted on Saturday, May 3, 2008 - 12:20 pm: |
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Ian,
No problem, happy to help. Yes, the overall torque will be reduced. Let's assume a 12V supply, the motor speed will half at 100rpm, the current will half to 5.7A, thus power will reduce by a factor of 4 giving 50W. The resultant torque will halve to 4.67Nm. Now this speed may be too low for you so you need to decide whether to have that second stage of 2:1 reduction or not. Without it, the geared motor should be able to lift 47kg/cm so it's close. Maybe a compromise of a second stage reduction between 1:1 and 2:1. As long at the motor load does not exceed its reduced capability by reducing the voltage, the current will reduce as well. Check out our power supplies 1090-016 or 1090-017 which wil be fine.
I hope my theory is right, as a double check I just ran a motor to lift 11kg (the 11kg load was attached by a wire to the output shaft) and it took just 3A at 3V which is only 9W. At between 12 and 19V it took between 3.8 and 5A. I would suggest giving it ago from a 13.8V power supply especially with a second stage reduction.
Regards
Paul |
ian mckenzie (Ian160981)
Member
Username: Ian160981
Post Number: 4
Registered: 5-2008
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| Posted on Saturday, May 3, 2008 - 1:38 pm: |
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thanks once again. i worked out that with the 2:1 reduction at 12 v, i should get an approx movement of 4.5cm a second, so to move the desired height (700mm) it will take aprox 17 seconds, which i can live with, i would prefer it to be slow anyway as to not damage any part of my project especially the tv.
the performance of this motor seems great, especially at the low price. im glad i can run it from a power supply because it would cost more using batteries and a charger. (11kg at 3v) now thats good. thanks again for all this great help.
i'll let you know how the finished product ends up.
cheers
ian |
ian mckenzie (Ian160981)
Member
Username: Ian160981
Post Number: 5
Registered: 5-2008
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| Posted on Wednesday, May 7, 2008 - 6:19 pm: |
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hi me again. just a simple question this time. would i be right in saying the motor ( 24V 200W Geared 203rpm MY7712NZ - Part No: 1471-103 ) has an output shaft diameter of 19mm. if this is the case can you recomend a suitable kind of gear to fit on this. eg - mod 1 or 1.5 or 2. i am still going to go 2:1 reduction but the amount of teeth on each does not matter too much ( i just want to get the cheapest ones suitable ) the larger gear has to fit onto a 17mm shaft.
thanks
ian |
ian mckenzie (Ian160981)
Member
Username: Ian160981
Post Number: 6
Registered: 5-2008
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| Posted on Wednesday, May 7, 2008 - 9:12 pm: |
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just an update on my question, i just noticed that the output shaft of the motor has an internal diameter of 13mm. ( if this is the case could i mount a gear in the inside of the shaft - eg - MOD 1 16 Tooth - Part No: 4710-016, as this gear has a boss diameter of 13mm too. would it be adviseable to mount a gear in this way especially with the weight i plan to lift. the reason i am asking is , these mod 1 gears are cheaper which is obviously better for me but at the same time overall quality and performance are my most important goal. could you please advise me on this when you get a chance.
thanks
regards ian |
Admin (Admin)
Board Administrator
Username: Admin
Post Number: 784
Registered: 10-2004
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| Posted on Thursday, May 8, 2008 - 12:49 pm: |
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Ian,
Not seen it done this way but as it is a solid boss on the 16T, I would expect it to work. Your problem is the second gear going on the 17mm shaft and still getting your 2:1 reduction. A Tbot 30T gear could not be bored out to 17mm but our 4200-015 32T could just about and still leave 4mm wall thickness. |
ian mckenzie (Ian160981)
Member
Username: Ian160981
Post Number: 7
Registered: 5-2008
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| Posted on Wednesday, May 21, 2008 - 2:37 pm: |
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HI ,me again. do you supply pulleys preferably plastic. that would be suitable to attach a 1" wide lifting strap to , the strap is 1.5mm thick and will be wrapping round the pulley 14 times , so the depth of the pulley will have to be about 20mm. the pulley will be attached to a 17mm shaft. the reason i need a pulley is mainley to secure the strap to the shaft, with a plastic pulley i could do this easily i think.or can you think of another way i could attach the strap directly to the shaft. i hope i have explained this well enough. thanks |
Admin (Admin)
Board Administrator
Username: Admin
Post Number: 797
Registered: 10-2004
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| Posted on Wednesday, May 21, 2008 - 6:22 pm: |
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Sorry nothing like that. Can't you just use wrap the strap around the shaft and use some disc's either side to form the pulley with some form of collet to stop the disc's from moving? You could make the disc's using a hole saw of about 60mm diameter. If the disc was made from 10mm aluminium plate, you could always drill and tap it to fix it direct to the shaft. Just a thought. |
ian mckenzie (Ian160981)
Member
Username: Ian160981
Post Number: 8
Registered: 5-2008
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| Posted on Wednesday, May 21, 2008 - 8:43 pm: |
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hi, i was thinking of doing it that way. although i was still presented with the same problem of actually attaching the strap to the shaft securely enough to lift 30kg. i was thinking of drilling and tapping and securing the strap with some form of bolt, but i was thinking the head of the bolt would be above the shafts surface, which means the strap would be secure enough but there would be a high spot when rotating which would affect a smooth operation. im sure i'll think of something though. thanks very much for all your help. so far ive bought a few things from you and i am extremely happy with the service you provide. its a great site. thanks again |
Admin (Admin)
Board Administrator
Username: Admin
Post Number: 799
Registered: 10-2004
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| Posted on Thursday, May 22, 2008 - 7:01 am: |
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Ian, happy to help when we can. If you have access to a milling machine, can you machine a slot in the shaft to take the strap? |
ian mckenzie (Ian160981)
Member
Username: Ian160981
Post Number: 9
Registered: 5-2008
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| Posted on Thursday, May 22, 2008 - 9:33 am: |
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hi. unfortunately i dont have access to that kind of equipment but that is the route i am taking. i thought of it last night and just started drilling a series of small holes which i will tidy up with a hacksaw or file. thanks again for all your help.
regards
ian |
