![]() | |
| Home Page | Mark Forums Read | Today's Posts | My Replies | Classifieds | Reviews | Photo Gallery | Web Links | Share Files | Advertise With Us | Ad List |
| |||||||
| General Electronics Discussion Discuss basic electronics, power supplies and anything else electronic related here. |
| This forum is sponsored by: |
![]() |
| | LinkBack | Thread Tools | Search this Thread | Display Modes |
|
#1
| |||
| |||
Ok folks I have a ? and hope this is the place to post it. I want to build a non-cnc sanding/buffing machine and would like to be able to control the speed of a 1.5 to 3 hp ac motor. I would like the motor to be 220v single ph with max rpm of 1750 but I would like to be able to reduce the speed down to about 600 rpm without loss of torque or damage to the motor. Where do I begin to start looking and what do i look for? Mike
__________________ No greater love can a man have than this, that he give his life for a friend. |
|
#2
| |||
| |||
| If 1hp~746W we are talking about 1150 to 2300W.. There are variable speed boxes for drills and similars, but do not know if they support that power. If you do not find it, maybe a lamp dimmer with support for the Watts your motor eats could work, but again do not know if they exists for that power. If you do not find it you will need any AC voltage regulator with a triac able to support at least 2300W/220V=10.45A. The SM12J45 triac for example is able to drive 12A of AC. hope it helps /U Last edited by Urgundiz; 03-25-2004 at 06:58 PM. |
|
#3
| |||
| |||
| Um, I've done a little google browsing and I've found these little collection: http://www.epanorama.net/documents/l...ghtdimmer.html http://us.st.com/stonline/books/pdf/docs/3566.pdf (look at fig. 11) At least will provide some ideas.. hope it helps /U Last edited by Urgundiz; 03-25-2004 at 07:15 PM. |
|
#4
| ||||
| ||||
| Mike, Your best bet is to go with a 3 phase motor. Whoa, you don't need a 3 phase panel to get some juice . Purchase a variable frequency AC drive. Many of these will allow you to input from a single phase source, yet will produce 3 phase out. However, you do need to buy an oversized drive to accomplish this. In your case a 5hp AC Variable Frequency Drive.Naturally, the VFD takes care of your variable speed requirement. And, they are constant torque up to the full nameplate rpm of your motor, after which the torque declines, because the current must be reduced to prevent burning out the windings as the speed increases. In other words, your motor maxes out at rated hp no matter how fast you dare to run it. You should take care to run the motor at a decent speed to assist in fan cooling. This might mean using a belt drive to put the motor in the 1000 to 3600 rpm range, if it is working hard. Appropriate pulleys will then get your spindle into its desired range. You might be able to reduce the motor size (and VFD size rating) if you do this. This is the reason that a lot of CNC machines have huge motors on them: so they will have enough power to do heavy work at the lower speed range. There is a lot to be said for mechanical gear or belt ranges.
__________________ First you get good, then you get fast. Then grouchiness sets in. (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management) |
|
#5
| ||||
| ||||
Eric
__________________ I wish it wouldn't crash. |
| Sponsored Links |
|
#6
| ||||
| ||||
| Yes, there's a good project for the do it yourselfer with the knowhow: design a DIY VFD drive. I don't really know why these things command the price that they do. They don't seem to be particularly smart devices.
__________________ First you get good, then you get fast. Then grouchiness sets in. (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management) |
|
#7
| |||
| |||
| Thanks U HU Ba! Wow that sounds like a great screen name !!Hu I have a 8 hp ph converter. Would that lessen the cost any? Balsaman when you say universal what exactly do you mean? Are you talking a std x-frame electric motor or something else like an ac servo motor? /U I will check the links and thanks for the help. Any more ideas?? Mike
__________________ No greater love can a man have than this, that he give his life for a friend. |
|
#9
| ||||
| ||||
| Mike, a phase converter isn't a VFD, although you probably knew that. Most "lower" HP VFD's can input 220 1ph, output 3ph variable frequency. These are nice if you don't have available three phase. Other VFD's require a 3ph input, then output a variable freq. 3 phase. In this case, you can use your static phase converter to create the input for the VFD. I guess expense is relative. To many, a $250 VFD is too costly, but if you have $5,000 or more in your mill and motion control hardware, then $250 ain't so bad to get a very solid and reliable variable speed drive. I have experimented with a small VFD, a Hitachi, and am impressed with its capabilities. Most of them have digital inputs for spindle ON/OFF and speed, pretty handy for a CNC controller, and necessary for ATC. |
|
#10
| ||||
| ||||
| Swede, Could you elaborate on "a small VFD" ? I'm relatively a dunce when I see "VFD" . I'm still unraveling its mysteries. But sometime I want to implement a variable speed spindle with CNC and want to know the correct route. |
| Sponsored Links |
|
#11
| ||||
| ||||
A standard ac motor is one like you have for the fan on your furnace. Quiet, and usually 1750 rpm or 3600 rpm, and can not be slowed down by reducing the voltage, as thier speed is a function of the AC line frequency. Eric
__________________ I wish it wouldn't crash. |
|
#12
| |||
| |||
| Thanks for the replies guys. The sad thing is, I had two brand new vfd's a few yrs ago and sold them for pennies on the dollar because "would never need them". My wife complains that I am a pack rat and now I wish I were one! I think I'll do some sufring now since I kinda know what i am looking for. Thanks again. Mike
__________________ No greater love can a man have than this, that he give his life for a friend. |
![]() |
| Currently Active Users Viewing This Thread: 1 (0 members and 1 guests) | |
| Thread Tools | Search this Thread |
| Display Modes | |
| |
Similar Threads | ||||
| Thread | Thread Starter | Forum | Replies | Last Post |
| CNC Controlled Spindle motor speed control | gregmary | General Electronics Discussion | 13 | 02-27-2009 07:01 PM |
| variable speed dc drive | DragnsBane | General Electronics Discussion | 5 | 02-08-2005 08:07 PM |
| S/S Relays and Variable Speed Routers | InventIt | General Electronics Discussion | 1 | 08-24-2004 12:05 PM |
| Spindle Speed & Feed Rates - Question | Moondog | DIY-CNC Router Table Machines | 1 | 07-23-2004 06:24 PM |
| min speed exceeds max speed for axis "x"? | ljoe1969 | TurboCNC | 4 | 01-19-2004 07:49 AM |