Speed control for small motors?
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Postmaster
Joined: Jun 2001
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Is there an electrician in the house?
Got a question on rigging up something. As a disclaimer, I will take any advice given and its use, with the understanding it is done at my own risk.
What I am trying to accomplish.
I am planning on doing some port work. I found a heavy duty 1/4" arbor electric die grinder for a decent price new. It operates at one speed, and it exceeds the recommended rpm required for the abrasives. I was thinking of installing a house light dimmer switch (with the round ****), inline of the power cord, to reduce the rpm of the motor.
I understand that some electric motors don't live too long being under powered but I only need it to complete two cylinder heads.
Any reason I shouldn't do this, or another suggestion that wouldn't cost too much? I could get a controller for $40 but I would rather not spend that much on a one time deal, know what I mean? I looked into a variable speed unit and they are not cheap, it would make my doing the work less cost effective. Any thoughts appreciated, later
What I am trying to accomplish.
I am planning on doing some port work. I found a heavy duty 1/4" arbor electric die grinder for a decent price new. It operates at one speed, and it exceeds the recommended rpm required for the abrasives. I was thinking of installing a house light dimmer switch (with the round ****), inline of the power cord, to reduce the rpm of the motor.
I understand that some electric motors don't live too long being under powered but I only need it to complete two cylinder heads.
Any reason I shouldn't do this, or another suggestion that wouldn't cost too much? I could get a controller for $40 but I would rather not spend that much on a one time deal, know what I mean? I looked into a variable speed unit and they are not cheap, it would make my doing the work less cost effective. Any thoughts appreciated, later
Posting Legend
Joined: Sep 2001
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I have built several controllers like that for small universal motors. AFAIK if the motor has brushes like a hand drill motor or Dremel tool it will work OK. If it has a regular squirrel cage induction motor it will not work. Some of the HD setups that use a flex shaft are not of the universal motor type.
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Postmaster
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Yep it has brushes, I may not have to do that at all, I found one that is cheap that operates at 25000rpm (no load) constant and 22000 is recommended so it should work, good to know I can use a dimmer switch if needed though. Appreciate the response, later
Posting Guru
Joined: Aug 2003
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From: Wichita KS.
Disclaimer - I usually have not the slightest idea what I am talking about, I just relate things I've seen done that might work in a given situation. As I am about to here . . .
I remember, when I was younger, a friend of mine built a homemade tattoo gun. The only problem was that the needle went too fast and turned people's arms into hamburger meat. To resolve this problem, he went to the hobby store and bought a model train speed controller. This worked great for him because he could set the speed easily and note on the controller what speeds worked for him.
Don't know how well this would work for you jw, but at least I contributed something somewhat pertinent to the thread.
Good luck.
I remember, when I was younger, a friend of mine built a homemade tattoo gun. The only problem was that the needle went too fast and turned people's arms into hamburger meat. To resolve this problem, he went to the hobby store and bought a model train speed controller. This worked great for him because he could set the speed easily and note on the controller what speeds worked for him.
Don't know how well this would work for you jw, but at least I contributed something somewhat pertinent to the thread.
Good luck.
Lead Driver
Joined: Feb 2003
Posts: 8,140
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From: Oak Harbor, OH
If you are going to go with a dimmer switch, make sure it's rated for at least 20 amps. They may even have a ceiling fan speed control that may work better.
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Posting Legend
Joined: Sep 2001
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Most of those dimmers are rated in watts. I just like to make sure I have 1-1/2 times as many watts capacity than the load to keep the control cool. Volts x nameplate amps = watts. In the case of a dremel tool it is negligible and any control will work. A hand drill or die grinder may be 3 or 4 amps or 500W therefore use a 750W capacity control.
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I think the cheap elec. grinder I am looking at is a 300W. The abrasives I am looking at are for use of max speed 22000, I figured (which could get me in trouble) that the 25000 no load rpm of the grinder would surely drop significantly once I began to work. However, I decided I will be using some form of controller after all, as some pieces can be operated at 22000 but best results are at 10000.
So I will have to give the model train speed controller or dimmer switch or ceiling fan speed control a look. Appreciate everyones responses, so the controller doesn't matter as long as, I keep the rated watts of the controller well above the grinders. Appreciate it, if anyone has another suggestion feel free to throw it out there, later
So I will have to give the model train speed controller or dimmer switch or ceiling fan speed control a look. Appreciate everyones responses, so the controller doesn't matter as long as, I keep the rated watts of the controller well above the grinders. Appreciate it, if anyone has another suggestion feel free to throw it out there, later
Posting Legend
Joined: Sep 2001
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Those speed ratings on your abrasive probably have a safety factor but they could explode at 25000rpm.
When I build my controls I use a double gang plastic box and a deep cover for wiring room. I put a duplex socket in one side and the control in the other. Use a grounded 6' electrical cord. I wire one socket for full voltage and control the other with the dimmer. I have made these for several people that use them for hobbies. If I had a camera here I would post a picture.
When I build my controls I use a double gang plastic box and a deep cover for wiring room. I put a duplex socket in one side and the control in the other. Use a grounded 6' electrical cord. I wire one socket for full voltage and control the other with the dimmer. I have made these for several people that use them for hobbies. If I had a camera here I would post a picture.
More Turbo
Joined: Sep 2003
Posts: 630
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From: Northeast
JW:
I have purchased two "Router Speed Controllers" from either Harbor Tools or Northern. They were on sale, for, I believe, $13.00. I plan on using them for a different project.
Now, I'm no Nikola Tesla, but I'm reading about routers lately, and know they range from 1-3hp, with 1.5-2.0 hp. being popular. While I don't know how fast they spin, or if it makes a difference, I would think they would handle the current, which must be more than your grinder's.
They're a small box, the size of a beer can, with a **** and cord.
Perhaps the assembled could comment, as I'm not versed in 'lectrics.
Peter
I have purchased two "Router Speed Controllers" from either Harbor Tools or Northern. They were on sale, for, I believe, $13.00. I plan on using them for a different project.
Now, I'm no Nikola Tesla, but I'm reading about routers lately, and know they range from 1-3hp, with 1.5-2.0 hp. being popular. While I don't know how fast they spin, or if it makes a difference, I would think they would handle the current, which must be more than your grinder's.
They're a small box, the size of a beer can, with a **** and cord.
Perhaps the assembled could comment, as I'm not versed in 'lectrics.
Peter
Posting Legend
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I have purchased a few electrical devices from HF and they are not made very well. I doubt that some of them could actually get a CSA or UL rating even tho many of them carry those approvals. Money must go under the table or they just slap the label on without actual approval. Personally I look for the CSA or VDE approval on electrical items since I feel it is better than UL. I can usually tell if the labels are fake with a quick peek inside.
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BigSix1
Appreciate the response, $13 sounds about what it might cost to rig up something, I guess I might compare prices. later
Torque1st
Do you think the HF product would accurately reduce the rpms by half? If say, I turned the **** half or are you saying that its junk and would be all over the place even if it did hold up?
Appreciate the response, $13 sounds about what it might cost to rig up something, I guess I might compare prices. later
Torque1st
Do you think the HF product would accurately reduce the rpms by half? If say, I turned the **** half or are you saying that its junk and would be all over the place even if it did hold up?
Post Fiend
Joined: Apr 2002
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From: Central Kali
I have a triac speed control I built years ago from a kit. It is rated at 10 amps and has never failed. It has like 4? parts in it.
I also built a scr control for the 220 volt input to my welder. It will handle 60 amps.
I also built a scr control for the 220 volt input to my welder. It will handle 60 amps.
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BigSix1
Would you have a part number or another reference to the controller you menitoned? I couldn't come up with much on the harbor freight site with only putting in "speed controller" or "router speed controller", later
Mike W
Would you have any more details on the controllers you have mentioned? Price, where to buy, etc.? Thanks, and later
Would you have a part number or another reference to the controller you menitoned? I couldn't come up with much on the harbor freight site with only putting in "speed controller" or "router speed controller", later
Mike W
Would you have any more details on the controllers you have mentioned? Price, where to buy, etc.? Thanks, and later