Bench grinder recommendation

[Bustedbricks]

I have to buy a bench grinder. In the past I have had one of the cheap 150W jobs but will go for something meatier this time. Question is: Would it be a good idea to get one of those wet and dry types? I need it for grinding lathe tools.

 

[arnoldb]

Hi Bustedbricks

First off, welcome to HMEM

It would be greatly appreciated if you could post an introduction in the "Welcome" section of the forum - That really helps members to put a perspective on where in the world you are, what experience you have, and how best to try and help you when you ask questions Thm:

As to the bench grinder, how big are your tool bits ? - even a cheap & cheerful 6" / 150mm bench grinder is more than capable of grinding up 12mm / 1/2" high speed steel blanks for toolbits. A can of water to the side makes for a great cooling system; nothing special needed there.

Kind regards, Arnold

 

[Bustedbricks]

Hi Arnold,

I have actually been a member for a long time - so long that I forgot my old username and had to register again!

I found that the smaller bench grinders get alarmingly hot very quickly when grinding tool steel. I was wonderring if there was any advantage to the wet stone for getting the tools extra sharp.

Michael

 

[bezalel2000]

Hi Micheal

If you want to fettle a lot of iron gastings bigger is definitely better.

If the stone is getting hot then so is the tool steel and that's not a good thing. Lots of heat has a tendency to anneal the steel, even HSS.
Making sparks for a few seconds at a time giving the tool a drink in between will be helpfull in retaining maximum hardness of the HSS.

If however it is "extra sharp" you are are after, its time to step away from the bench grinder, wet or dry, big or small.

Bench grinder stones are OK for grinding general lathe tools but are relatively course.

All the scratch marks left on the tool edge by whatever stone was used, transfer directly to the cut surface of the job.
So if you are going for an extra clean surface finish lapping the tool surfaces, that meet to form the cutting edge, with very fine abrasive is the way go. A fine oil stone or fine diamond file card or 1000+ wet and dry Carborundum paper (backed by a firm surface) all these will do a better job of "getting the tools extra sharp"

my 2 bobs worth :noidea:

Bez

 

[Bustedbricks]

Thanks for the tips, much appreciated. With the small grinder it is the motor heating up, not the stone. Even with a small load they heat up quickly. Perhaps mine was just a bit too cheap and nasty. A couple of nice one for sale local to me but they are all 3-phase

 

[Tin Falcon]

Well Mike in this hobby and in the machinist trade there are often many paths to the same destination. Sharpening HSS tool bits is no exception. you can buy a wet dry grinder if you like and it should work fine. you can buy a tool grinder if you like. or a 8" bench grinder. One of the things with grinders is the imports come with low quality stones and A quality replacement will greatly enhance performance. that said I have been messing with this stuff for a hobby and some as a trade for about 15 years now. I purchased my first bench grinder 12 plus years ago it is a simple jet brand 6" grinder. with the original wheels. I keep a cup of water nearby when using it. and I use an oil stone to hone the tools when done. It takes time to learn hand grinding the wheels need dressing and the blanks need to keep there cool but. sometimes we just need to be smarter than the tools. Yes there have been times that I have considered getting a new grinder probably a wet dry type. and it may do a better job. but the one I paid IIRC $39 for years ago still works. So do you learn patience and perseverance or put out the bucks. your dime your choice. The right path for you is the path you make.
Tin

 

[Rayanth]

When I faced the decision of buying a bench grinder recently, I was warned about the tool rests. Most inexpensive grinders have flimsy tool rests made if little more than bent sheer metal. If you have a mill, you can tool up some new rests, or you can spend a little more for a grinder with good, solid rests.

My eventual choice was a 6" DeWalt brand grinder, it has cast aluminum tool rests and a stronger motor than most other 6" grubbers. It cost me $100, but I consider it money well spent. I will always stand by DeWalt products, have never been let down by them. Designed for contractors and heavy users, they are a little more expensive, but usually have a sturdier build, powerful motor, and careful attention to mix between form and function.

Not a dewalt salesman or affiliate, just a very satisfied user.

-Ryan

 

[Ken I]

One of the features I look for is if I can dismantle the grinder and reassemble as a wall mount - saves mucking about with a stand or bracket.

I have two that I've done this to - it involves swopping the ends and turning the rotor around to retain the correct orientation of the LH / RH threads relative to rotation.

The one in the photo is a cheapo "Elephant" but has served me well for many years. I have a "Martlett" in my factory shop also turned and wall mounted.

In both cases the "sheet metal" rests are more than adequate / rigid enough for the power to hand (but I have seen some that were just way too flimsy).

Most of these machines have limited duty cycle and will get very hot if run for long periods (more than 20 minutes) - if you really need the heavy duty cycle, you are going to have to spring for an "industrial" type unit.

2c worth.

Ken

 

[ShopShoe]

Bustedbricks,

I second what Tin said:

Buy high-quality stones, perhaps different grits than what was original.

Stones must be dressed, and maybe more often than you think.

If your tool rests are weak, find a way to replace or strengthen them or make new ones.

I add:

The grinder should run as smoothly as possible: Tighten everything up and dress the stones, then watch and listen to it run while looking for vibration. If you have a cup of water for cooling you can see the wave action from vibration there too. If there appears to be a lot of vibration, take it apart and look for the source. On one of my grinders I found the cupped washers that are supposed to help support the stones were seriously deformed. I cleaned them up a little and that helped a lot.

By the way, I found out the hard way that a wheel-type stone dresser only cleans up the edge of a non-concentric stone and doesn't make it any rounder.

 

[Tin Falcon]

I too like the dewalt brand . porter cable is also good . If you have a brand you like lean towards it.
I personal have had not Good experience with ryobi IMHO not worth bringing home. Yes i have used and owned several ryobi tools the price is appealing but that is the only good thing about them.
And i agree make sure whatever you buy has a sodit tool rest unless you want to make one and have the capability. to do so.
Tin

 

[MachineTom]

About 8 years ago I bought a HF tool grinder. It was like $150 at the time. It is still working along. It has real rest table, can run reverse, the table goes around to the other side of the wheel. It uses steel backed side grinding wheels, not cheap but for tool ginding they will last at least 8 years. I put a diamond wheel of one side, and have both a white A/O I purchased and the green S'/C that it came with on the running on the other side. It is not a baldor grinder, but the $500 for a used Baldor is too much. The tilting of the tables sucks, but I have them adjusted to the angles I use for parting tool, and the other for the rest.

Don't know if they are still cheap put this was worth all the money paid and then some.

 

[Bustedbricks]

Thanks for the recommendations. A 6" DeWalt is around £145 here so outside of my budget. Sadly none of the affordable models have decent tool rests so I will have to fabricate something myself.

A couple of really nice grinders were on Ebay and local to me but sadly 3-phase which is not standard in UK houses.