Bench grinder electrical specs

[robsims]

Which motors can i use to make a bench grinder?

[jpanhalt]

Which motors can i use to make a bench grinder?

Already asked and answered. 

Either buy a decent bench grinder which will typically have wheels on each end or buy an arbor for grinding wheels and power it with a separate motor.  In your case, you apparently need a motor rated for continuous duty.

[mag_therm]

I just checked the 20 year old Delta Shopmaster bench grinder here.
It looks like this one currently on Delta site
https://deltamachinery.com/products/grinding-sharpening/23-196#specs.

Delta  home shop machine tools ( I have 3, grinder table saw and drill press ) are a bit above Palmgren in price and quality I think.
I have a Palmgren XY table that is basic, robust and accurate enough.

The Delta grinder  nameplate says 2000 ~3450 RPM, no current or power rating stated, but Class A temp class is stated.
So this one will run at a lot lower surface temp as class A is the lowest temp class (cheapest, lowest quality paper insulation etc.).
Class A might have been used back then because the temperature might have needed to be low anyway  due to human contact rules in USA ( I don't know for sure).

After 10 minute at full speed check today, it is barely above ambient.

Sometimes I run this for 10 minutes or more if doing a lathe tool from blank.

If your new grinder is not meeting expectation, can you ask for refund?

[robsims]

Many thanks guys

[Kleinstein]

The data also give a direct power rating of 1/3 HP which is around 250 W.  This is plenty of power for a bench grinder for most used. Only when sharpening heavy tools (e.g. ax) one may want more power. Even than some 200 W to get converted into heat going mainly to the too is a lot and will heat up the tool quite a bit.
Most of the time the grinder will run essentially idele and thus take little power and thus usually does not get warm.

The 120/230 V are likely different versions - switchable voltage is very rare with such tools. For the motor there is essentially no difference, as the high voltage need twice the windings, but half the current. If at all for small sizes the higher voltage can be a bit more tricky as very thin wire has a larger proportion of isulation. The 1/3 HP size is not that small.
 

[jpanhalt]

I rarely disagree with you, but you need higher wattage when you are using a coarser wheel and rough contouring cutters.  Since the OP indicated he wanted to round off steel, it is possible he may need more power.  For simple deburring and knocking off corners, such a low HP grinder may suffice.  But starting with a 3/8" square HSS cutter for a profile, you may need more power

Take this example: https://www.zoro.com/dayton-bench-grinder-12-in-max-wheel-dia-1-14-in-max-wheel-thickness-3660-grinding-wheel-grit-1fyx2/i/G3077496/  That's 240V @ 10A.

For grinding my TIG electrodes and general work in my barn, my grinder is 1/2 HP.

[mag_therm]

So we know what we are looking at, here is photo of innards of  a well used but servicable motor from Reynosa Mexico.
https://app.box.com/s/5j3m1ic3rmq81lldf5cej74edv6a3c6i
230 V fractional HP Capacitor Run Class B ( 130 C Max insulation) , they are made by the millions for the USA, just south of the border, in all shapes and ratings and shafts.
Mostly automated manufacturing, I had a bit to do one time with the rotor side  automated production machines in these plants, although I was on transformer /inductor design in my early days.
The vendors of appliances and air-con and home shop machines don't make their own motors obviously.
Automated production machines for these motors is usually handled world wide by tier 2 vendors locally.

I suppose there is a very small probability of a wrong or faulty motor of exactly same mounting footprint getting into robsims grinder.
And again, these small motors are typically Class B or H, and impedance is such that the current (hence temperature) does not vary much from locked rotor to no load.
Correct me if I am wrong on this, as I see posts to the contrary....

[Old Printer]

Delta still has a professional line but they also sell junk lines. Jet makes some pretty good stuff as well, but you have to pick and choose. Porter Cable did like Craftsman and sold out to big box stores.. it’s hard to buy by name alone anymore. A decent small tool sharpening grinder should run $150-200. A good quality Jet will run you close to $500 and up. Buy from a company that sells to guys who make a living with their tools if you want top drawer. Even a good midsize grinder will get hot if you lean into 1/4” thick steel for a while.

[robsims]

Thanks old printer. I'm going to save some more to buy a Jet

https://www.amazon.com/577101-6-Inch-Industrial-Bench-Grinder/dp/B00004T9KV?th=1

I think these are the better ones to have. It looks sturdy and i think you don't have to feel all the time if it's getting hotter than an oven  and be afraid it will burn up.

[mag_therm]

Delta Shopmaster 6 inch ( year ~ 2002 model)  : Lock rotor test, set at full speed  Test Date : 22 08 28

Ambient = 26 C in shop , Extech temperature probe at centre top of motor housing
Note: this is not the critical winding insulation temperature which will be higher.
{Time minute} , [Rise Celsius]
{ 0 } , [ 0 ]
{ 5 } , [ 44 approx ]
{ 6 } , Lock off, motor  at no load full speed
{ 10 } , [ 38 approx]  , motor off
{ 50 } , [ 11 ]

[jpanhalt]

Thanks old printer. I'm going to save some more to buy a Jet

I think these are the better ones to have. It looks sturdy and i think you don't have to feel all the time if it's getting hotter than an oven  and be afraid it will burn up.

That looks about right.  Note it is 1/2 HP, and the end bells/guards are cast as are the tool rests (at least they look to be cast).  I don't consider Jet industrial quality, but it is a step or two up from what you have. 1/2" shafts are a little small for industrial, but OK.  You will probably want a pedestal stand.  That stand shown on the listing seems overpriced.  If you have a welder, it is easy to make a stand from some plate and pipe.   FYI:  My drill press circa 1973 is a Jet and at that time was made in Japan.  It's a beast and continues to serve me well. 

[robsims]

Delta Shopmaster 6 inch??  The base of the machine looks so Chinese. They look like the junk bases of chinese bench grinders

https://www.ebay.com/itm/334520823786?hash=item4de2feafea:g:hesAAOSw7J5i6V8d&amdata=enc%3AAQAHAAAA0KLBCyTUWE%2FglSfIjj1wEZWV2sEMZsAifrQTXbAYLKhSN2YOECZzcsiKWFQ6gQizmKoSHiLnB9Y9Uth3UGD56ODTnWPgOlcIj2aQ5NXQRVlq1u5E9Un75fm8zRoVBQ243Pv%2FTAQWAY1lFTOhcG17prwAZkaefpE1qpaGfBzYDZDI2e%2BN6s94aHfVprgp%2BNdKLWcPQQwh7h3Etolttb3kaYgcczdToAS%2BHTDJBezWy7FRZdlWB5GdidnXA2hkQgQIlvnJHTLQgImiqZZuYsGAikg%3D%7Ctkp%3ABFBM1JXKkd1g

https://www.ebay.com/itm/144613970844?hash=item21abaa139c:g:z78AAOSwJ9Bg38x7&amdata=enc%3AAQAHAAAAwNafkx2HpmUG1RRLrbgHhbFHO%2B%2FNXt%2B6x4Aq4TfaxXq4Uv4iDc2uC1D2fwKaYyrkP%2BMuvFyfxZXbFEHYHPwAFhimejTObqjecfa4yty4NtChkPFlHhuXELDQ31S9YMCo2hGSeZwe3LpTVUHi9SUpDeqFMaJoJsFlb0Eh74uxLn%2F5QwhSr1UdMR6jSG87nGCcaVmp%2Ftken3AzMKvkXfZe8snuZdluxRLYJkXIMGlM9T%2Fpjl5KSTyluOCzT0nG4x%2B54Q%3D%3D%7Ctkp%3ABk9SR4zT3ZHdYA