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Knowledge You Can Build On — Est. 1998

Thoughts on grinders

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Thoughts on grinders

#1

Keith Tompkins

Thoughts on grinders

Keith Tompkins

>I have seen a lot of posts recently on grinders, so I'll throw in a couple of thoughts. Most new turners apply WAY too much pressure against the wheel when sharpening. A spray of sparks coming out of the top of the wheel is a good indicator of this.

One light pass on most tools is sufficient to restore the edge....it is not necessary to remove a large amount of material....you can literally add YEARS to the life of a tool with a light touch.

Heavy pressure, a coarse wheel, and a low speed grinder will produce a heavy burr on the cutting edge.....on most of 2030 or 2060 steels, that heavy burr will break off almost immediately when turning, leaving a dull cutting edge and repeated trips to the grinder.

I am one of only a few who advocate high-speed grinders, again the secret is a light touch and a bit of practice.

Re: Thoughts on grinders

#2

One more thing...

Peter Teubel

>Don't forget perfectly balanced wheels with hi-speed grinders.

Re: Thoughts on grinders

#3

Re: One more thing...

Bob Hackett

>I thought I`d post my thoughts on the balanced wheel controversy.While I think anything that helps your equipment run more smoothly and with less vibration is worth looking at I think folks ought to be aware that these balancing systems are NOT a cure-all.

No matter how good the balancing system it will not correct a wheel that is not trued and held securely and correctly.This starts with a close fit between the wheel and the shaft.The fit can be adjusted with bushings as long as the bushings are solid and the fit is a tight one.Then comes those thick,well machined flange washers which also are matched to the shaft and installed with paper between the washers and the wheel(and you thought those were just info labels).The paper is what compresses to make a snug fit and gives the washers something to bed into.

After properly mounting the wheels start the grinder like you would the lathe with an new blank mounted.Stand to the side and flip the switch on and off to check balance and bring the grinder up to speed in steps,this way you won`t have to chase it around the shop if things are out of whack(actually I just pull the plug,I`m too slow to chase).

After the grinder`s up to operating speed you need to true the face.If the grinder runs smoothly now that may be all that needs to be done.If there is still some vibration then the wheel may need to be trued along the sides back to the flanges,I leave it up to you if you`re up to this or not as it takes a light touch and alittle engineering to make a proper support to allow it.Sometimes it`s just easier to mount another wheel.

Once all exposed surfaces of a wheel that has been properly mounted are trued I have never had any problems with vibration and never saw the need for any of the balancing systems.The wheels will stay smooth and balanced as long as you keep the face true and don`t allow them to move on the shaft by loosening the retaining nut.

Out of habit and training I always take a new wheel and rest it on a tool such as a screwdriver shaft and LIGHTLY strike it with a piece of wood such as a hammer handle to see if it has a clear tone.If it has the same tone as when you hold it by it`s sides between two fingers(dull tone)then it may be cracked and will fly apart when mounted.You never know what the boys in shipping or the warehouse did to that wheel before it came to you.I test all used wheel like this before buying.

That`s the basics on what I know about proper grinder setup,hope someone finds it of help.

Mainely,Bob

Addy protocol-2 years as set-up man and head of centerless grinding dept(night shift)at NY Twistdrill.4 years as maintenance mechanic at a large aluminum extrusion plant(VAW of America)where I was the "grinder guy" and maintenance welder.10 years at Sample`s Shipyard where I set up and repaired all the equipment including grinders(I did most of the sharpening too).Other than that it`s just real world experience.

Re: Thoughts on grinders

#4

Re: One more thing...

Wally Dickerman at Green Valley, Az.

>Thanks Bob. Some very good information here. I've never found it necessary to use a balancing system. A little fiddling with the wheels has always done it for me.

Wally

Re: Thoughts on grinders

#5

Re: One more thing...

John Lucas

>Me too Wally. I use brass shim stock if needed to make the wheel run true from side to side and true up the face. As far as speed. I don't see any difference in the cutting action of the tool between high speed and slow speed. I do agree that you need to have a very light touch when sharpening. I will admit however that I've never owned a 2030 or 2060 tool and they may sharpen differently. The main reason I use slow speed is mostly because I have a cheap grinder and it takes a lot longer to come up to speed when I use the 3400 setting.

Re: Thoughts on grinders

#6

Keith Tompkins

Re: One more thing...

Keith Tompkins

>Bob is correct on this one. Many times, even with a balancing system being used, vibration is still a major problem.

The reason is that the wheel can be out of balance on two different planes. Static balance and dynamic balance. You can think of static balance ooccurring in a single plane, the resulting imbalance would be a steady thump, thump, thump. Dynamic imbalance is a side to side imbalance that will make your grinder dance around, even if it's bolted down. A wheel that wobbles from side to side when in motion is dynamically imbalanced.

By trueing up both the face of the wheel and the sides, Bob is eliminating most of the imbalance in the wheel. Thanks, Bob!