bench grinder - advice please

[Cliveshep]

Just get into and use it. It will be much safer than an angle grinder.
If it is old you may find the edges of the wheels are not flat but perhaps have a groove or low area in the middle. This doesn't matter so much if you are just grinding or smoothing metal. Move the job from side to side and with use you may get it flatter. If not then you might need the dressing tool. You need it flat for drill bits. New stone wheels are not so expensive and can be bought for all sorts of jobs.

Sharpening drills is easy. The trick is to start with a large drill 8 or 10mm that is in fairly good condition. Look closely you will see the cutting edge and angle. You grind the whole face ie edge and angle to improve the cutting edge. Note that the cutting edge must extend right out to the outside edge. They often wear on the outside where they have been used to make a hole bigger. The grinder will take a lot of metal off quickly so just a short touch then check. Keep the drill cool as already said by dipping in water.
good luck olewill

Just to add to this excellent and informative post - "clearance. clearance, clearance" meaning that with any edge cutting tool, milling bit, drill bit, lathe cutter, the proudest part must always be the cutting edge, with a clearance slope away from this. Otherwise the tool will just polish itself and make the work hot. The exception is drill bits used for countersinking aluminium.

 

[sarabande]

I'm deeply grateful for all the advice on this post. Tried out all sorts of metals yesterday with lots of different spark lengths and colours. And I'm getting somethings to cover the wooden bench !

CS. Can you expand a bit on "clearance angle" please ? I am a bit confused with terminology from a couple of grinder instruction sites.

 

[dam747iam]

grinder

do not grind wood/brass/alloy as they clog the stone, also good idea to wear gloves as material can get hot.

 

[William_H]

Clearance angle

[

CS. Can you expand a bit on "clearance angle" please ? I am a bit confused with terminology from a couple of grinder instruction sites.[/QUOTE]

The clearance angle is in effect the angle the cutting surface has to the work. It is exactly like the angle of a plane blade or the angle you hold a chisel. ie too steep will cut to deep and grab or stall while too shallow will not cut at all. About 30 degrees or less seems to be right for most work. However drilling perspex needs a very small cutting angle to stop it biting in.
On a drill bit it has 2 cutting surfaces and the cutting angler (clearance angle) needs to be the same on both.
Holding a drill bit up you will see from the side the cutting edge and the clearance angle which is the area of metal behind the cutting edge which must be clear from the material being cut.

It is all obvious if you look at a large good drill bit. good luck olewill

 

[DJE]

I'm deeply grateful for all the advice on this post. Tried out all sorts of metals yesterday with lots of different spark lengths and colours. And I'm getting somethings to cover the wooden bench !

CS. Can you expand a bit on "clearance angle" please ? I am a bit confused with terminology from a couple of grinder instruction sites.

See here.

 

[Deen79]

Hi to everyone after having a look on some of the advice given on here I thought why not try and see if anyone can answer the question to this enquiry.
I bought a 6inch Delta bench grinder but trying to find this same model with the same extra features it has on it can't find anything about it anywhere and when I put the model number in will bring me to a page where a 120v Delta bench grinder but nothing on the 230v I have also the other different it had was the variable speed on the 120v is 2000 to 3450rpm but the 230v I have is 1720 to 2850rpm which I think is on the more high end model plus another many different this Delta bench grinder have then the 120v is the wheel stop time when turning it off normally on the 120v and many reviews on this take up to 4 an half minutes to come to a stand still but with this 230v it's not the same up & down switch the 120v Delta has but the more expensive range with the green & red square buttons with dust protection and once pressed will shut down the wheel stopping in less the 15 seconds which is a real big improvement from the 120v one. So my question is do you think this one I have was specifically made to order by the company cause it even as the label from Delta of all the specs at the back of the grinder...

 

[Deen79]

This one everyone Delta 230v bench grinder!

 

[jim.howes]

I would like to add to the post regarding what materials NOT to grind on a bench grinder. You should only grind mild steel or high carbon steel on a grinder. You must never grind non ferrous (aluminium, copper, brass, stainless steel etc) material because as said earlier they clog the wheel but they not only clog the wheel it can actually load the wheel and can/will put the wheel out of balance and when travelling at nearly 3000 rpm they can explode causing the user an awful lot of damage. It was a sackable offence if found to be using a bench grinder for the wrong material.

 

[Norman_E]

One of these is essential

http://www.axminster.co.uk/product-Axminster-Star-Wheel-Dressers-23607.htm

I am no fan of the wheel type of dresser. One of these is OK POWERTEC 71003 Diamond Grinding Wheel Dresser : Amazon.co.uk: Business, Industry & Science
but my preferred type is a single diamond point like this Model Engineering and engineering tools online from RDG Tools Ltd Home Page (Engineering Tools) Tel 01422 885069 /884605

 

[ghostlymoron]

I too was given one which I use a lot. Sharpening chisels, redressing screw drivers. I have a stone on one side and wire brush on the other for general cleaning. I'm thinking of getting a polishing bonnet? for use on silver, brass and other metals.
Mine is a bit under powered. Always use safety glasses and keep tight grip on the tool or piece being worked.

 

[Fr J Hackett]

Grinding wheels, one of life's most abused tools perhaps next only to the screwdriver as witnessed by Bouba's recent post of fixing a circular saw blade to one . As I will probably be entering the world of wood turning where tool sharpening takes on an extra dimension I am currently debating whether to change my primary sharpening set up to CBN (carbon Boron Nitride) wheel and jigs or go for a slow speed grinder or even go the whole hog and buy a Tormek or belt grinding system which could get very expensive indeed.

 

[superheat6k]

I always keep the rest gap below 2mm, and always, always, always with full goggles on, not just safety specs. If you leave a pair dedicated for grinding on the grinder there is never any excuse not to wear them.

As soon as the face becomes uneven at all, or if any clogging occurs it is time to dress the wheel. Using a diamond dresser the process is akin to grinding the flat end of a bolt, gently apply the diamond tip and move slowly left to right and back across the full face of the wheel, and expect a cloud of grit dust as you dress it.