Variable speed bench grinders

[Kscardsfan]

Does anyone have any advice on what to look for when buying one of these? I’ve been thinking about getting one for a while now, but just want to make an informed decision.

 

[tool_scrounge]

I would buy a quality 3 phase used grinder and add a VFD ( variable frequency drive) and you will have variable speed. What are you trying to grind?

 

[macgee]

Tool_scorunge made a good suggestion. Look for an industrial grinder that uses 3 phase, preferably 230V and then add a VFD to it.

Finding a belt driven belt grinder and converting it to variable speed might easier to do in your area.

 

[Kscardsfan]

I would buy a quality 3 phase used grinder and add a VFD ( variable frequency drive) and you will have variable speed. What are you trying to grind?

I do some amateur blacksmith stuff on nights and weekends and would like to dial it in when I have to keep temper. I also got charged with keeping all the family lawnmower blades sharp, and I’d like to not free hand it with a flap wheel.

 

[macgee]

By the sounds of it, you'll ideally would want a 2" wide x 72" VFD belt grinder, they're not cheap but you could get away with a more common 1" x 42" belt grinder to start off with, convert it to variable speed. Check out the knife forums, they'll have way more info on this subject than on GJ.

 

[exmaxima1]

Tool_scorunge made a good suggestion. Look for an industrial grinder that uses 3 phase, preferably 230V and then add a VFD to it.

Finding a belt driven belt grinder and converting it to variable speed might easier to do in your area.

+1
If you are making an investment like that go for a belt grinder instead. Wheels are dangerous and obsolete for most modern applications.

 

[Renegade1LI]

I bought a jet grinder and polisher, both are variable speed 8" and you can add a 2" belt to it. The grinder is IBG-8VS, has a breaking resistor and dust collection hook up.

 

[Renegade1LI]

I just looked you can buy it a complete package
Jet 577248 IBGB-248VS 8 in. Variable Speed Industrial Grinder and 2 x 48 in. Belt Sander

 

[Renegade1LI]

Here's a link to a multitool grinder, same one I just ordered.https://www.trick-tools.com/Multito...er_Attachment_8_inch_Contact_Wheel_MT8CW_1164

 

[whateg01]

Here's a link to a multitool grinder, same one I just ordered.https://www.trick-tools.com/Multito...er_Attachment_8_inch_Contact_Wheel_MT8CW_1164

I've looked at those to add to one of my, uh, more than one or two bench grinders. One thing that keeps me from doing it is the notion that it should have 1+ HP per inch of belt width. None of my bench grinders is more than 3/4 HP, so I haven't done it. Sure does look quicker than building a belt grinder from scratch and cheaper than buying one, though!

 

[EchoBravoSierra]

I bought an Ironton variable speed bench grinder from Northern Tool. I've used the grinder wheel a little, the wire wheel a little more, but mostly used it after taking the grinder wheel off and used 8" buffers to polish some cast aluminum parts. Burned the motor up after having it just a little over a year.

There's my $0.02, and I'll be following responses to help me decide how to best replace it.

 

[APEowner]

What is the benefit of a variable speed grinder? In my experience abrasives need a fairly high surface speed to be effective and cutting rate and surface temperature are best controlled with pressure and/or coolant. What am I missing?

OP. I apologize for the potential thread derail. I thought about starting a separate one but I thought the answer to this question might help you in your decision making process.

 

[Renegade1LI]

What is the benefit of a variable speed grinder? In my experience abrasives need a fairly high surface speed to be effective and cutting rate and surface temperature are best controlled with pressure and/or coolant. What am I missing?

OP. I apologize for the potential thread derail. I thought about starting a separate one but I thought the answer to this question might help you in your decision making process.

Not knowing what the op intends to grind or sand I know if I am shaping aluminum I use a slower speed. If you go on blade forum it seems to be a nice option to have but not totally necessary. I feel if it's an option you may think you will use get it, it can't hurt to have it.

 

[macgee]

What is the benefit of a variable speed grinder? In my experience abrasives need a fairly high surface speed to be effective and cutting rate and surface temperature are best controlled with pressure and/or coolant. What am I missing?

OP. I apologize for the potential thread derail. I thought about starting a separate one but I thought the answer to this question might help you in your decision making process.

APE,

Its a massive benefit. You can dial in the speed for the material you're working on. Its just the same steel and not really caring its use, then usually the standard fast speed is fine.

But if you're sharpening expensive blades, working with other materials like wood and plastics as well then dialing in the needed speed really benefits you. While not completely related but there's a reason why RO sanders (& similar) all have variable speed. Also, think of why you have two very different bandsaws, one for wood and one for metal.

Of course you can get a way with it but once you experienced it you'll never go back.

Go check out Knife forums sites and see all of the many threads about variable grinders speeds and you'll see what I mean.

 

[Renegade1LI]

Just out of curiosity I was looking over at trick tools, most of their belt grinders are variable speed & $$$$$ You can spend some serious coin for a grinder.
https://www.trick-tools.com/Knifemaker_Grinders_363

 

[Kscardsfan]

Here's a link to a multitool grinder, same one I just ordered.https://www.trick-tools.com/Multito...er_Attachment_8_inch_Contact_Wheel_MT8CW_1164

That website might be very dangerous for my finances. Wow.

 

[seber]

One thing to consider is that most of the conversions do not have provisions for a tool rest. Depending on your use this could be a show stopper. I've made knives without a tool rest and I'm here to tell you, it is a LOT harder without.

 

[iajonesy]

Just a little PSA. If you are using a bench grinder DO NOT GRIND aluminum,plastic, or other soft material. The wheel can easily clog with the material and it can build up enough heat to explode. Ask me how I know.

Mike

 

[kelpaso1]

I would get a cheap HF belt sander and use aluminum oxide belt for metal. Belt sanders are way better and faster. I haven't used my bench grinder in 20 yrs to grind metal except to use a wire wheel.

 

[Kscardsfan]

I would get a cheap HF belt sander and use aluminum oxide belt for metal. Belt sanders are way better and faster. I haven't used my bench grinder in 20 yrs to grind metal except to use a wire wheel.

I’ve kicked that idea around as well. I’m just exploring options right now as much as anything. My grinder mainly gets used for rough work and wire wheel stuff right now due my worrying about losing temper and overheating my steel. But a true belt grinder is outside of my budget and space restrictions right now. So I’m looking at what’s out there for me to use in the confines of a packed two car garage and driveway.

 

[whateg01]

I would get a cheap HF belt sander and use aluminum oxide belt for metal. Belt sanders are way better and faster. I haven't used my bench grinder in 20 yrs to grind metal except to use a wire wheel.

I'm going to half disagree with you on that. I have one that I bought years ago when my focus was on wood. I still use it for metal but I can stall it even on small pieces of wood or metal. It's better than the bench grinder for most things but I intend to put a 1.5 or 2 hp motor on it and add variable speed. I still use the bench grinders (yes, plural) for stuff, but if there's a lot of material I use the belt sander. Just know it's not the best machine in the world for metal removal.