What factors do you weigh most when evaluating a bench grinder? I’ve started comparing models, but they don’t all list the same set specs. E.g., one lists the number of amps but not horsepower, and another lists horsepower but not amps.
I need to polish metal. Before this, I used a cheap electric drill with a buffing wheel, but the noise was terrible, even when no-load. I wore ear plugs *plus* headset and worked in the basement, but my family still complained about the noise. A quiet bench grinder (okay, relatively quiet) is high priority.
Which of these factors affects the amount of noise the grinder produces?–Amps, watts, horsepower, wheel diameter, spindle diameter, induction motor. For each of these, does “higher” mean “quieter”?
Edited 9/19/2002 1:41:22 PM ET by DWREAD
Replies
For polishing metal you are better off with a buffing head rather than a bench grinder. Grizzly makes such a thing. I'd also be looking at sites that are metal oriented rather than woodworking such as artmetal village or a yahoo group.
The noise came from the gears of the drill. A buffer is relatively quiet because it's a direct drive unit with no gears. You will barely hear the buffer run. The small amount of noise will be from the buffing pad on the metal.
Edited 9/19/2002 2:11:06 PM ET by rsl
I did a search on buffers, but they were all hand-held tools (except for the Baldor 662R). I need both hands to hold the piece against the buffing tool. What do you think of the Baldor?
The Baldor is nice but I'm sure it's more than the $69 for the Grizzly dedicated buffer. You will need to get the catalog...the unit isn't pictured on line. They have a pretty decent selection of buffing machines, buffs and compounds in the catalog. Enco sells the Baldor buffer for $148.50. It doesn't say what size in the catalog...probably 6". The Grizzly is an 8" and I'm sure the Baldor is a better unit but the Grizzly might be all you need. Also for doing web searches...from what I've been told by my computer wizard and read in the computer magazines, the best search engine will only pull up 15% of what's out there plus proper phrasing increases search potentials.Rick
Edited 9/19/2002 4:01:51 PM ET by rsl
Edited 9/19/2002 4:02:06 PM ET by rsl
Rick, I thought plug-in motors were AC and battery-op were DC. And now they talk about induction motors without specifying if it's AC, DC, or some other animal. Is one better than the others?
Also, is a more expensive grinder/buffer quieter?
I think you are making this way too complicated. A more expensive buffer won't be noticably quieter. I don't know your exact needs but for $ 69 the 8" Grizzly should pay for itself in a short time. I'm pretty sure most all buffer and grinders are induction type motors and run on AC if they plug into an outlet versus battery type (DC) which I haven't encountered on buffing machines of this type. Whatever you get will be a step up from a drill by a longshot and far quieter. You will barely hear the buffer. What you will hear is the air displaced by the buffing wheel and when you apply pressure of the piece you are buffing to the wheel.
I don't think you will find anything cheaper for the money than the Grizzly.
Edited 9/19/2002 6:39:09 PM ET by rsl
Thanks, Rick and PlaneWood. It will be a treat to have the proper tool.
He means a DC motor that would use a DC drive. It converts AC to DC (usually 90 volts). The benefit of the DC motor is high torque at low speeds. If you have unlimited dollars, the better choice is a vector motor and Flux Vector Drive drive. It is a special Variable Frequency Drive that gets feedback on motor rotor position from an encoder mounted on the motor shaft. If the drive knows the positions of the rotor windings in respect to the stator windings it can provide full torque at ZERO speed. It is wild to see a fixed motor shaft that tries to fight you back if you try and move it.
In any case the big benefit of that is that it is great for sharpening. Keeps your Tool Cool (which is always good)
Buffing and Buffers need higher speeds and good strong bearings. The load of the part against a wheel way out on a longer arbor, well that's a lot of bearing stress.
I have no opinion on this stuff, I just jumped in because I knew an answer for a change :-)Steelkilt Lives!
Rick, I went to the Grizzly site and found the $69.95 buffer (http://www.grizzly.com/products/item.cfm?Product_ID=17103&&User_ID=2174421&St=1175&St2=63320980&St3=-78732810&DS_ID=1) The arbor size is 3/4"! Come to think of it, sometimes I pressed the metal into the buffing wheel pretty firmly.
Is this a good price?
Try the el-chepo Delta 23-665 model at Home Depot. Use it as a leaning tool then graduate to whatever better suits your needs. Sell it on Ebay when done with it. I use that model to polish small brass pieces and to clean up small steel/iron pieces. Little to high rpm for my grinding needs.
Would be nice to have a variable speed grinder with a DC motor with a calibrated digital led RPM readout. One that is balanced would be nice too!
PlaneWood by Mike_in_Katy
PlaneWood
PlaneWood, is your Delta fairly quiet, i.e., do you need to wear ear protection?
I hadn't considered Delta grinders because of some negative comments on Amazon. Problem is, I don't know if they are statistically significant. Have any of your projects ever taxed the motor?
Grizzly is generally a pretty good value. You are not buying the best, but for a third of the price you'll get something that performs better than the cost would suggest. I've only bought a couple of Grizzly items (dust collectors) and they are doing fine. I'd think a buffer or grinder would fall into the category of "too simple to mess up." I will say that you might as well save yourself the trouble of unplanned downtime and just go ahead and replace the capacitors if you're buying single phase. That's been the weak link consistently for me on Grizzly motors. But, hey, a good capacitor is only a few bucks and easy to replace. If you can spare the extra money, get a Baldor buffer. I've got a 3/4 HP model as well as a 10" grinder and they will go and go. Smooth and quiet. Know two metalworkers who have several of the same type. By the way, they say ENCO is the source and when they run specials on the Baldors, it is the deal. Buy or build the heaviest base you can deal with. A buffer should be free standing and you want it anchored.
I use an old Sears double-extended shaft power tool motor, with shaft arbors I bought from Grainger for about $4 each, one left hand thread, the other right. It runs at 1725 rpm, and is all but silent. Those old Sears motors (40's through 50's) are particular good because they have an on-off switch built into their cast iron base, and the end bells are rounded. But you can use any old induction motor with a base. And don't worry about clogging the windings; if you blow it out once in a while, it will last forever. This is hand work, after all, not production work on automatic machinery, and the tendency is for the polishing jetsam to fling off away from the wheel. Total cost, since I have a pile of old motors laying around, was $8 plus wheels. If you don't have any old motors you can use, call your air conditioning contractor and ask them if you can come to their shop and salvage a motor from a belt-driven blower. They're going to the scrap yard anyway, and I've gotten many for free that way. A few companies also sell belt drive mandrels for polishing, which gives you the ability to determine the speed via pulley drive ratio, using your own induction motor. http://www.prairietool.com/ has a good selection of such parts, along with motor arbor adaptors, wheels, and the like. Or just go with the Grizzly. It looks like a good deal (and it probably doesn't have a capacitor; most small grinders are split-phase and therefore don't have start capacitors).
Be seeing you...
TDKE, speaking of air conditioners, noise, and motors....Our house has two units that look identical but differ significantly in noise level. This is a cookie-cutter neighborhood with the same kind of a/c in every house, so I asked our neighbor if our system were particularly noisy. She said that one of her units was noisy, too, but the only thing the a/c service did was put some kind of baffle around it.
Muffling the noise doesn't address the cause. Is the sound level of a motor design highly variable from unit to unit? Or is noise more likely to be caused by one of the linked components?
If you are referring to the condensor unit (outdoors), there are 2 motors; the compressor, which is hermetically sealed, and the fan. The fan motor itself would normally make virtually no noise, and they operate at 1200 or 900 rpm, but the fan blades can make a lot of noise, especially if they're small and fast-turning. (As a general rule, when moving X cfm of air, small and fast fans are louder and less efficient than large and slow ones.) Most of the noise from the compressor is just that; noise from the compressor, not the motor. Put a typical small induction motor with nothing connected to it on a bench and run it, and it just hums. So, to answer your question, it's probably not the motor(s), but the connected equipment.
Be seeing you...
DWREAD: Check out http://www.craftsman.com, they have a 6 inch bench grinder with a stand, includes a work light & wheel dresser for only $69.99 model # is 00924126000, its there 75th year special..
Take Care... ToolDoc
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