4 x 36 grinder/sander

Pretty much all of these sanders are belt driven, so you could do a pulley setup. Anything else would likely be cost prohibitive.
 
Sorry about the lack of info, It is a delta 1/3 hp the type you would get at Lowes it seems to have plenty power considering, but it just runs to fast. it heats metal up fast.
 
I have one of those for my router will it work on the sander also. I looked for brushes on the sander motor and could not find any.
 
22h2 said:
I have one of those for my router will it work on the sander also. I looked for brushes on the sander motor and could not find any.
Click to expand...
Yes been using one for years on my two , have not smoked a motor yet .
 
I hate to admit it, but I used a variac on my first grinder for a couple of years. You have to use light pressure and go slower, but it helps you learn to grind with patience.
 
Here is a trick to convert a disc/belt sander to a variable speed belt sander.
Many of those lighter duty rigs have the disc on one end of the motor, and the drive wheel on the other. Get a variable speed motor setup (I like DC rigs) or a step pulley set for a standard motor you have. Take the disc off the unit and mount a pulley on the shaft. Drive the pulley with the external motor ( just cut the cord on the internal motor to avoid a problem). What you are basically doing is using the motor as a shaft and two bearings. You can change the speed as needed now. Good thing is that when you need the variable speed motor for a better setup, you just unhook it and away you go.
Stacy
 
I tried the controller for the router it did slow it down but It would stall out when I tried to grind. I will look into step pulleys I have never had this thing apart so I don't have a clue how it is made. I would think that someone would make a variable speed drive for lower Hp motors that would not sacrifice the power.

thanks
 
The problem is one of economy. You can get a VFD for it, it's just going to cost you more than the whole sander. There isn't a big enough market for speed controllers to further the tech and mass produce reasonable quality ones at a fraction of the current cost.
 
Was trying to hunt down a 110v out controller for you, seems that there's not much market for one. The cheapest solution would probably be to got to a 220v motor and controller. You could probably get a cheap motor in the 1/2hp range (what most 4x36's have) for less than $50. You controller would probably cost $200-400 and would not have a NEMA enclosure.

Here's an example of a 1/2 hp 110v motor with a speed controller -
http://surpluscenter.com/item.asp?UID=2007122723361834&item=10-2352&catname=electric
It's a nice motor, but you can see it's not cheap. The manual says it was designed for economy, which tells us that either the technology is extremely expensive or that the market supports the cost. I'm guessing it's the latter.

Here's about the cheapest new controller you'll get if you go 220:
http://www.driveswarehouse.com/Drives/AC+Drives/Micro+VFD/L100-004MFU.html

I think this is why we see so many more DC motors on small variable speed tools. Big DC motors and controllers are expensive, but the smaller ones aren't quite so bad.
 
I used a 4 X 36 grinder for a long time when I started. It kind of defeats the purpose a bit, but what I did, and how I have mine set up now for handle work, is.......

Remove the disk attachment (not that great anyway), take off the geared pulley that's on there and get a standard V-Belt pulley (I used a 2 inch one with a 1/2 inch bore).

Then get a 3/4 hp variable speed (220Volt DC) and controller (I got 3-4 of them on Ebay for around 100$ each with controllers). Use the frame of the original grinder to house the rollers, pulleys, belts etc..., and use the new motor to power the grinder. I just left the old motor in there as it would take longer to remove it and it didn't serve a purpose to do so. So now you'll have to have a little more room to have the external motor.

You'll need 2 small (2 inch or so will do fine) V-Belt pulleys with a 1/2' bore. That's the best way to do it. It requires a little leg work on your part, but controllers for AC motors rarely work well or last, and if you find one, it probably will be expensive and it will not give you full power (more like 2/3 power).


MT
 
thanks
AcridSaint and Mark I believe I will try DC motor and controler or step pulleys, I really appreciate the help and advise.

Ted
 
Most really cheap AC motor speed controllers are really just dimmers. They work by chopping up the sine wave of the AC current which effectively limits the amount of energy available to the motor. The problem you will run into with one of those setups in a motor that is not commutator controlled is the field rotation getting out of step between the rotor and stator. Most AC motors I have run into if I am not mistaken depend on sine wave frequency to control rotational speed (1750 rpm is 60x60/4-field slippage, 3400rpm is 60x60/2 - field slippage) if you try to regulate speed by merely limiting effective current supply you lose torque dramatically. I think the step pulley idea is the least expensive and most usable solution

-Page
 
Page is correct about what the HF controller does. They are only meant for small single-phase AC motors. Sometimes it will work for you. Other times, it won't.

For real speed control, doing what Stacy and Mark suggest with a DC motor and controller is your best bet if you are on a tight budget.

Otherwise, you can hook up a three-phase motor and a corresponding drive (VFD and ASD are common industry terms). The Hitachi drive that AcridSaint linked to should work for you. Better still would be the Lenze one that Texasnewf found in the following thread. It is dust tight so your chances of blowing it up are greatly reduced. If I recall, they sell a variety of drives with different hp ratings.
http://www.bladeforums.com/forums/showthread.php?t=519051

Phil
 
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