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Bench grinder/polisher/shapener advice

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Martin Brundell15/05/2011 17:34:03
29 forum posts
Looking to buy a Bench grinder for my small workshop - has anyone got any recommendations?
 
I want it primarily for sharpening hss drillbits, grinding and polishing.
 
Any help will be appreciated
 
thanks
Ramon Wilson15/05/2011 18:02:30
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1655 forum posts
617 photos
Hi Martin, looks like you're not at Harrogate either
This topic has recently been aired on here - take a look here.
 
Regards - Ramon
Martin Brundell15/05/2011 20:12:30
29 forum posts
Thanks for the reply or though i dont quite understand the harrogate quote?
Ramon Wilson15/05/2011 21:02:06
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1655 forum posts
617 photos
Well I guess that's where most will be this weekend - the Harrogate ME show
Alan Worland15/05/2011 22:49:27
247 forum posts
21 photos
My grinder is a very old Black & Decker which runs well with its 6 inch wheels.
Having had some experience of these 'low wattage' grinders from the DIY outlets I would stear away from them - they seem quite gutless compared to mine which uses about 600 watts. This is mounted with wing nuts onto a wall frame and removed and taken outside for dressing the wheels which is a very dusty process.
For polishing and wire brushing I have a Brooks motor 3/4 HP running at 2950 rpm. I made a mandrel for this so that I can fit either a wire wheel or a selection of buffing wheels - just don't get the work caught up in the wheels as it wont improve it!
Lawrie Alush-Jaggs16/05/2011 10:39:32
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118 forum posts
32 photos
Hi Martin
 
I have for many years had a 200mm 1 HP bench grinder which has served me well through knife making and general metal work. I've added various wheels and mops from time to time and always been pleased with the result.
Recently I decided to make a T&C grinder and because it is only ever going to be light work, bought a second hand GMF grinder on Ebay. The grinder has done about ten hours work at the most, cpst $40.00 and from what the bloke told me, done mostly wire brush work.
 
I would be sizing the grinder to the predominant type of work you will be using it for.
The 200mm grinder takes 100mm sewn mops very well. I used them extensively for polishing stainless and found I could really push the knife into the mop without slowing down the grinder. When I put on 150mm mops, I find, naturally enough, that it is easier to load the motor.
So in my opinion, if you are primarily after a grinder for tool grinding, something which requires reasonable power ~450-500watts you need good bearings. The bearings are hugely important for a T&C grinder, after all, you don't want the wheel flopping about like a prick in a shirt sleeve.
If on the other hand you intend to put some real muscle into rough grinding great thick lumps of rich chewy mild steel, then I would suggest the 200mm ~750+ watts.
As a grinder will last you for ages - there is nothing to break except for the capacitor and the switch, save your sheckles and buy a really decent one. Stay away from bunnings or B&Q, go to a machine supplier and spend twice as much but get ten times the satisfaction.
You may also want to consider what else you want to do. If you want to run a linisher off the grinder, that will mean that really you only have one wheel available to you.
A 200mm grinder with linisher and a 60 grit Aluminium Oxide wheel will give you plenty of grindiness and if you team that with a really well put together 150mm for tool grinding, you have an excellent and much less time consuming setup.
 
 
Lawrie
Steve Wan16/05/2011 12:48:01
131 forum posts
3 photos
Hi Martin
 
Look for Tormek grinder. This grinder runs at low speed and will never burnt out the hardness of the HSS...also building your very own grinder to sharpen mill cutters and drill bits?
 
I did and tested my grinder with good result. My design has the influence of Quorn and Deckel SO. Visit Steve's workshop photo album.
 
Steve
Martin Brundell16/05/2011 13:23:02
29 forum posts
 
I would be sizing the grinder to the predominant type of work you will be using it for.
The 200mm grinder takes 100mm sewn mops very well. I used them extensively for polishing stainless and found I could really push the knife into the mop without slowing down the grinder. When I put on 150mm mops, I find, naturally enough, that it is easier to load the motor.
 
-------------------------------------------------------------------------------------------
Hi thanks for the replies - my primary use will be for sharpening HSS tool bits and HSS drill bits - I do very little heavy grinding (if at all). My main worry is buying a grinder that is too harsh for drill bits (I do a lot of mild steel and Stainless drilling).
 
*** oooh forgot I do need to be able to ploish stainless as well
 
Hence I would also need advice of type of stones needed.
 
@Steve
Building your own? not something I'd thought of. Any info on your poject?

Edited By Martin Brundell on 16/05/2011 13:33:40

Edited By Martin Brundell on 16/05/2011 13:34:13

Martin Brundell16/05/2011 13:36:24
29 forum posts
Posted by Steve Wan on 16/05/2011 12:48:01:
Hi Martin
 
Look for Tormek grinder. This grinder runs at low speed and will never burnt out the hardness of the HSS...also building your very own grinder to sharpen mill cutters and drill bits?
 
I did and tested my grinder with good result. My design has the influence of Quorn and Deckel SO. Visit Steve's workshop photo album.
 
Steve
 
A little too involved for me Im afraid I need something off the shelf. Nice tho thanks

EtheAv8r16/05/2011 13:48:18
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111 forum posts
3 photos
Martin
 
I was in similar position ans posed a similar Q last week.
 
I was just about to go for the Record bench grinder - with a 5 year warrenty it looks excellent value and is low cost and will almost certainly do all I need - I just consigned myself to the fact that I would have to make a better tool rest.
 
However at the last moment I thought 'so what'... (re cost), and went mad and ordered a Creusen HP7500TS Powerline Grinder (Slow Speed).
 
Should arrive tomorrow.
Martin Brundell16/05/2011 14:02:00
29 forum posts
Posted by EtheAv8r on 16/05/2011 13:48:18:
Martin
 
I was in similar position ans posed a similar Q last week.
 
I was just about to go for the Record bench grinder - with a 5 year warrenty it looks excellent value and is low cost and will almost certainly do all I need - I just consigned myself to the fact that I would have to make a better tool rest.
 
However at the last moment I thought 'so what'... (re cost), and went mad and ordered a Creusen HP7500TS Powerline Grinder (Slow Speed).
 
Should arrive tomorrow.
 
Please let me know what you think asap. I like the idea of the HP7500TS + the extension spindle http://www.axminster.co.uk/creusen-creusen-extension-spindle-r-h-prod21052/?src=froogle so I can put a polishing mop on it. Then to any big grinding I'll pick up a cheap throw away grinder fom machinemart. If the HP7500 is OK I'd just need a drill bit sharpening rest - would the standard do? or should a get a more specialised rest?
 
thanks

Lawrie Alush-Jaggs16/05/2011 14:47:12
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118 forum posts
32 photos
Hi Martin
 
Steve mentions the Tormek. A friend has one and it is a woodworkers tool, not a metal workers. It is low speed and which is fine for carbon steel tools. It has a 50mm wide wheel and rests which allow you to sharpen chisels, gouges, plane and planer blades up to about 200mm but it is too slow for the sort of metal removal you need for HSS cutting tools. It is also set up expressly for grinding on the periphery and does not take other wheel shapes.
 
I would as I said earlier go for a six or eight inch grinder.
 
For HSS get either white Aluminium Oxide wheels or diamond wheels. The white AO are specifically made for grinding HSS and have high removal rates with minimal tool heating. You have to keep the tool in one place for quite a while with the pressure on to burn it. I was quite suprised when I first used one, having previosly used Silicon Carbide wheels which are really rubbish for HSS.
 
Diamond wheels are better for TC than HSS though there are many who will dissagree with me. In the past, HSS has tended to load diamond wheels and destroy the diamonds more quickly. I haven't used one for some time so that may have changed and there are others here who may be able to correct me on that point.
White AO wheels tend to be cheaper than diamond wheels so that may be a factor for you too.
I would have a plain wheel and a cup wheel in 60 grit and possibly one each in 80 grit. Use the fine grit for smaller tools like drill bits 3mm and under.
 
100mm cup wheels here in AU cost about $26.00 each and 200mm plain about $32.00.
 
Whichever way you go, you will have to make up arbours for the wheels to get them spinning accurately. And in a trap for young players, different manufacturers have marginally different spindle hole sizes which means they are not interchangable.
I have several white cup wheels from Norton which all fit the same arbour. I recently purchased a pair of Kinik green wheels which are nominally the same but will have to make new arbours for them.
Most manufacturers nowadays ship their wheels with stepped nylon bushes to account for different spindle sizes. They are okay for general purpose grinding but for tool grinding you are better to make your own.
All of the above can be acheived very well on a 150mm grinder, However........
 
For polishing you need a minimum 750 watt 200mm grinder. Get a taper arbour (about 8 pounds) and several mops. Before taking the taper arbour away, ask to see it running on a grinder so that you know it runs concentrically. I have been caught out several times in the past. Decide which side of the grinder you are going to use for polishing because the arbours are available in left and right hand thread.
 
My experience of polishing stainless is that once you have worked through your abrasive grades on the linisher down to a blunt 400 grit, a sewn mop with some green stick will give you a mirror finish. I have found that a leather wheel just heats the metal up too much and that an unsewn mop does nothing at all except spit out of fluff into your face.
 
When you set up for polishing, make sure the machine is well bolted down and that you have plenty of room all around. If you mount the grinder on a bench, make sure that the polishing end of things hangs over the edge as far as possible so that if the peice you are pilishing gets caught, you can let it go and it should just fall to the floor rather than bounce off the bench and stab you in the guts. You also need plenty of room to move your workpiece around the mop.
 
Don't wear gloves.
Wear eye protection.
Wear a leather apron.
Don't smoke.
Eat your greens.
Don't touch strong drink.
Keep it in your shorts.
 
Lawrie.
 

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