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CHJ

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Just getting back into woodturning after some 50 yrs and need to resharpen HSS tools.

I'm OK with metal turning tools on existing bench grinder (been doing it for years) but am having problems keeping the larger surface area of the wood gouges from overheating.

Has anyone got or had experience of this model:

http://www.rutlands.co.uk/cgi-bin/psSto ... i/scantool

Reason for looking at this model:
First and foremost PRICE (limited stretch in pension) and second ease of manufacturing my own jigs to suit until Santa comes around again. (Assuming I need the bespoke ones that is)

Of the various much cheaper un-cooled Whitestone slow speed grinders around how much of a problem is heat build-up?
 

DaveL

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Chas,

I am not a turner, so have no idea about the problems of sharpening turning tools, but I have bought a wet stone grinder. It looks the same as this one from Axminster. Mine is a Rexon, B&Q had them at 50% off, I paid £39 for it. I have made a couple of simple jigs and its fine for putting the primary bevel on plane irons and chisels. If your into making your own jigs then it could be an even cheaper option. :)

If you do start making jigs, don't let Tony know, he'll sulk as he thinks he’s the jig king. :wink:
 

beejay

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Scantool always scores well in test reports. well made and reliable and although not the cheapest they do what they say on the tin.
Use Tormek myself but did look at Scantool first but cost of the various attachments for Scantool swayed me towards Tormek.
beejay
 

Alf

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CHJ":2impk6aq said:
Just getting back into woodturning after some 50 yrs and need to resharpen HSS tools.

I'm OK with metal turning tools on existing bench grinder (been doing it for years) but am having problems keeping the larger surface area of the wood gouges from overheating.
Chas, might be a cheaper option to try a different wheel on your bench grinder. I use one and have no trouble.

Cheers, Alf
 

CHJ

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DaveL":3fwkueik said:
Chas,

I have bought a wet stone grinder. It looks the same as this one from Axminster.
Thanks Dave, have had a look at similar, certainly a cheaper option just a little concerned as to whether I can modify the Water Bath to allow a "frontal approach" to the wheel instead of the "overhead" which is a bit awkward for gouge grinding.

If you do start making jigs, don't let Tony know, he'll sulk as he thinks he’s the jig king. :wink:
Don't disillusion him and don't tell him my workshop space is bigger than his. (don't tell him I'm currently trying to improve on one of his attachments if not jigs either.)
 

CHJ

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beejay":2djku1p1 said:
Scantool always scores well in test reports. well made and reliable and although not the cheapest they do what they say on the tin.
Use Tormek myself but did look at Scantool first but cost of the various attachments for Scantool swayed me towards Tormek.
beejay
Thanks beejay I too have been looking at the combined total.
thought The Scantool would be easier for homemade jigs.


Alf":2djku1p1 said:
Chas, might be a cheaper option to try a different wheel on your bench grinder. I use one and have no trouble.

Cheers, Alf
Thanks Alf had looked at those and wondered if they were that much cooler running.

Should know all this but spent to many of my latter years just managing a machine shop where everything was done with the latest in coolant running specialist grinders, should have taken up the hobby again whilst I still had the craftsmen and firms reps. around me.
 

Taffy Turner

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Water cooled griders are not normally very popular with turners as they are too slow. I know it would drive me nuts having to muck about setting up and what knot, when I can just give the tool a quick whizz on the bench grinder as soon as it starts to show signs of going dull.

The key, as Alf has rightly pointed out, is the grade of stone that you are using. I used to have a cheap grinder with a bog standard grey stone, and I used to have overheating problems all the time. I now have a Record 8" bench grinder with a 40mm white stone on one end and a 25mm grey stone on the other. The grey stone doesn't get used for sharpening as such - just for re-shaping (you just have to take your time and let the tool cool naturally - don't quench it whatever you do!).

The white stone cuts much cooler than the grey, and I belive that ruby stones are cooler again, and I have also seen blue stones, which are supposed to be the ultimate (sorry - I can't remember which catalogue I saw them in, if I come across them I will let you know).

I hope that this helps.

Regards

Gary
 

Alf

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Taffy Turner":1c65yple said:
I have also seen blue stones, which are supposed to be the ultimate (sorry - I can't remember which catalogue I saw them in, if I come across them I will let you know).
Peter Child. I'd forgotten them.

Cheers, Alf
 

CHJ

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Taffy Turner":37k1o7ye said:
Water cooled griders are not normally very popular with turners as they are too slow.
Thanks GaryThat is a factor that was bothering me, I'm used to shortest possible time 'on stone' as it were.

Taffy Turner":37k1o7ye said:
I know it would drive me nuts having to muck about setting up and what knot, when I can just give the tool a quick whizz on the bench grinder as soon as it starts to show signs of going dull.
Gary
I think I shall have to put up with some jigs and a little set-up time at the moment, on the fingernail gouge at least until I get more used to it.


Alf":37k1o7ye said:
Peter Child. I'd forgotten them.

Cheers, Alf
Thanks for the link Alf, yet another site to drool over.

Will now spend the evening with numerous printouts trying to make my mind up.

You have all put my mind at ease regarding the coolness of the 'better' stones in dry grinding.

Looks like it may be multiple equipment buys from the cheaper but sound build end of the market and concentrate on good replacement stones for specific jobs. A choice made from the red/pink/blue offerings seem to be what I need immediately. As Plane blades have been oilstones only up 'til now, a cheap wet might be something I can sneak in the shop sometime in the future to speed that process up.
 

Chris Knight

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I am not about to argue against something I have never used but it may be worth considering what a guy called Forrest Addy had to say on WoodCentral. He is one of the folk who really do know their onions and is worth listening to. This response by him was to a query from someone who wanted to slow their grinder down as they thought it would cut cooler as a result. However the same logic holds good for a number of situations.

QUOTE

Any way to slow down a 3600 RPM grinder? (Joern Larsen, SF Bay Area, CA)

Why slow down a perfectly good bench grinder when the problem you may be having with overheating your cutting edges is due to your grinding wheels being dull and neglected.

The reason for the success of the newer slower speed grinders (1800 Vs 3600 RPM) is ignorance and pandering. The object of this wasteful purchase is ostensibly to prevent the overheating of edged tools when grinding them. The result is when purchased the problem recurrs as the original factory dress on the grinding wheel dulls.

Dispelling the ignorance:

The reason tools overheat while being ground is friction. When the grinding wheel is clean and the abrasive grains in its surface are sharp, they cut cool and efficiently. Any edged tool dulls in use and that as true with the abrasive grains in a grinding wheel as it is with a chisel or plane iron. When the abrasive grains become dull from use they tend to rub not cut and ever-increasing effort on the tool against the grinding wheel is necessary to sharpen it it. Thus the tool overheats, turns blue and the temper is lost. A tool will overheat as readily on a 1800 RPM grinder as it will on a 3600 RPM grinder.

Solving the problem:

Learn to dress your grinding wheels. Make/buy a diamond wheel dresser on a hand shank so you can dress your grinding wheels, making them round, and thereby removing the dull grains by knocking them out of the bond to expose fresh sharp grains. A suitable diamond dresser would be a small cluster diamond such as found in the link for less than $40.

A suitable shank could be made from a piece of 7/8" round bar 12" long by drilling a 7/16" hole in the end 1" deep and cross drilling and tapping for a set screw. This is a life time tool when used in the home shop for the weekly grinding wheel tune up. Your grandchildren will pass it almost unscathed to their grandchildren and they will use it to dress their grinding wheels into the 22nd Century.

Exposing the pandering: when a market opportunity occurs and a perceived need is fulfilled by selling something useless that is pandering: buy this gadget/product and health/beauty/sharp tools are instantly yours. Magnet therepy, herbal remedies for impotence, beauty products, and slow speed grinders are all in the same class of pandering.

When new, the slow speed grinders work great and why not? The wheels are fresh and sharp and they agressively cut while the work stays cool. You are pleased with the money spent for the problem is solved - until the wheels grow dull and then you're burning the edges again. Then you have to buy another grinder, don't you? Why not? That's how you solved the first problem with the high speed grinder.

Nope. There's good reason why grinding wheels turn as fast as they do. That's the optimum speed established almost a hundred years ago for vitrious bonded aluminum oxide grinding wheels in professional shops. You'll never find a slow speed (half speed, actually) grinder in a professional sharpening shop. They're not productive.

Times haven't changed much since 1912. The abrasive and the bond and the process controls for making grinding wheels are much more refined today but the interaction of the grain with the steel edge is still the same. 5000 to 5500 surface feet per minute is the optimum speed for aluminum oxide against hardened carbon or high speed steel.

The reason you want to buy or make a half wheel grinder is because of deliberately perpetuated ignorance and possibly because the other guys are getting them. Well, you're smarter now. Are you going to make/buy what you don't need and will work properly for a short time? Or are you going to learn dress your grinding wheels and solve the overheating problem forever?

No, you have to use a diamond dresser to make a clean smooth round sharp grinding wheel. There are no low cost options. Trust me. The wheel dress obtained by use of Norbide sticks, star dressers, the abrasive stick are all a distant second best to the silky cool cut of a sharp well dressed wheel dressed with a diamond dresser.

To answer the original question: No. There's no practical way to reconnect a 3600 RPM two pole induction motor so it runs as a 1800 RPM four pole motor.

UNQUOTE
 

Alf

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Forrest is quite right that good wheel maintenance is important, but I disagree that a diamond wotsit is the only way - a devil stone will work just fine, but it'll take longer. I think Forrest is a pro and therefore time is money, but if money is scarcer than time I don't think the diamond is an absolute necessity, although nice to have. Of course the biggest problem with overheating is just too much pressure on the tool into the wheel to "hurry things up". I've done it myself, and it's a daft thing to do. Just letting the tool kiss the wheel and letting the grinder do the work is the key. Bit like letting the weight of a backsaw do all the work in the cut, I s'pose.

I imagine it wouldn't help to mention my hand-cranked grinder that runs slow, has a grey wheel, been dressed, er, not as often as it should have, and has never yet over-heated anything. Kinda spoils the theories a bit really... :roll:

Cheers, Alf
 

Alf

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waterhead37":14gyq0r4 said:
as cheap as the star wheelers.
Cor. Posh. I'm busy conserving a four quid devil stone down here in the Third World. :wink:

Cheers, Alf

1/16" gone, 5 15/16" to go...
 

CHJ

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Hi Chris

Yes I do know the theory of grinding, but a general reminder of the need for clean sharp cutting stones is always helpful.
My last shop reground HSS, Cobalt and carbide coated cutters and all sorts of plasma sprayed materials and aircraft components including gas turbine blades and aircraft brakes.

I have diamond wheel dressers, my existing bench grinder wheels have a regular cleanup and are changed to different grit size/type to suit specific jobs such as tungsten carbide etc. that come to light in general DIY.

This has not prevented me from struggling to achieve a satisfactory control of the edge temperature of my gouges which in the main have a larger contact area on the stone, to give the concave continuous facet required, than I am used to handling in a home workshop.

If I select from my existing stones to achieve cutting speed without excessive heat the surface finish is to coarse for my liking, hence the cry for guidance on what is used by the experienced turners here.

My personal skill is not yet up to matching the light touch required, which Alf refers to, with dexterity to complete the cut in an acceptable time I guess.
 

DaveL

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Alf":2e7g0i8n said:
waterhead37":2e7g0i8n said:
as cheap as the star wheelers.
Cor. Posh. I'm busy conserving a four quid devil stone down here in the Third World. :wink:

Cheers, Alf

1/16" gone, 5 15/16" to go...
Alf,

Look about half way down this page and there is a Diamond dresser for £5. I don't know what its like but Geof is a turner who sells tools that he finds useful.

rogerrabbit":2e7g0i8n said:
Bought my lathe from Geoff Woolvin - nice chap, sensible approach. I'd be happy to take lessons from him.

Roger
Northampton
He has obviously has impressed Roger.
 

Alf

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Thanks, Dave. Funnily enough I was looking at the diamond dressers on Axminster's site yesterday and thinking I was probably being a bit of a tight-wad about it. :oops:

Cheers, Alf
 
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