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6th March 2014, 05:16 PM #1
Spark grinder choices for sharpening
I know it's a question of machinery, but much of want I want to ask relates to jigs and so on....hence in this forum.
I'm in the market for an 8" grinder to be used primarily for sharpening chisels and plane blades, and then what ever else comes along. I would like to put a brass brush wheel on one end too, as well as a couple of other things such as calico buff wheels, maybe flap wheels, but primarily I will have a CBN wheel on it.
It seems difficult to get a grinder not made in China these days, and I am concerned that a Chinese jobbie could be full of vibrations. Even Abbot & Ashbury are now made in China.
What I have turned up so far are:
- the usual suspects from Hare and Forbes (all Chinese) including A&A (560-750 watts)
- Creusen (which I hope are still Dutch) from Carbatec at a good price but look a bit under powered at 600w (but probably as powerful as 750 Chinese watts)
- Vicmarc are apparently just about to release a new half speed 8" grinder that they are having made for them (but nothing on the website yet). OOPS, it is on the website already: http://www.vicmarc.com/default.asp?contentID=746 and it's a VERY powerful 1500 watts and 1475 rpm for $247.50 (so I hear). No mention of the Arbor size either.
Then there is the question of sharpening jigs. Fortunately I don't have to worry about turning tools, so the jig would be for flat work tools only. On that score there is:
- Veritas Tool Rest and Grinding Jig
- and a lot of Chinese crap.
- Vicmarc seem to have a lot of turning tool jigs, but I'm not sure if they've heard about flat work tools - no mention of them. Had a look on Carrolls and no mention of them there either.
A small problem with the Veritas Tool Rest is that it designed to go over a 1" wide wheel, and the CBN I'd put on would be 40mm. Should be easily enough solved by filing out the slot to 41mm though.
I assume that I would have to take the guard off a grinder designed for a 1" wheel to fit on the 40mm CBN. I have read that this is apparently quite safe to do as the wheels can't disintegrate or throw bits like a normal AlOx or whatever wheel.
So does anyone have any other ideas, or feedback on any of the above please?
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6th March 2014, 06:50 PM #2
Get yourself some Tormek jigs for use on the spark grinder. I know they are expensive and you really get the full benefit of use if you are running a Tormek at the same time but they make grinding so simple and repeatable that I think it's worth it.
If you don't want to go that way I have a Veritas rest/jig you can have. Don't need it as I have a dedicated Tormek bracket set up on the grinding wheel.Those were the droids I was looking for.
https://autoblastgates.com.au
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6th March 2014, 06:54 PM #3
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6th March 2014, 07:40 PM #4
Vicmarc Grinding Station and Slow speed grinder
Brett will have stock of the new Vicmarc slow speed grinder next week so will see how this goes as my concern with the slow grinders is torque.
If you are using mops and brushes on the grinders you need plenty of torque as you tend to load up very easy, compared to sharpening where you need a light touch.
The Vicmarc grinding station is good for flat toolsJim Carroll
One Good Turn Deserves Another. CWS, Vicmarc, Robert Sorby, Woodcut, Tormek, Woodfast
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6th March 2014, 07:54 PM #5
Goodo, thanks for that Jim. I guess that's why they're 1500 watts then.
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6th March 2014, 08:22 PM #6.
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A few random thoughts about grinders
Like clamps you can't have too many and I have the following
An original 8" Abbot and Ashby on which I run a 6" Scotchbrite wheel (very useful for mat finishing of ally and brass) and a linisher/multitool
A cheap chinese 8" that is ~40 years old on which I run a calico mop, and a 6" coarse white Alox (thats what I use on WW blades)
A Crompton on which I run an 8" green SiC wheel (used for MW lathe tooling) and an 8" wire wheel (this is a very useful wheel for cleaning up corroded metal bits and pieces)
A generic 10" on which I had a generic Coarse grey wheel and an 8" x 40 mm Blue Max but both are about to be replaced. (these were used for MW applications)
As you can see most of these are for MW rather than WW applications
The Blue Max on the 10" grinder was a good wheel until, unbeknownst to me, the generic 10" grey coarse wheel on the other side of the grinder started to wear at the arbor hole (I hardly every used it) which unbalanced the whole grinder and that sent the Blue Max out of round and it was very difficult to true the Blue max. Every time I would go to try up the Blue max I would make it worse. Eventually the grey wheel was so loose it started to grind and spark up against its guard and that's when I realised that it was the problem. A
In terms of other wheels I have a selection of Calico Mops and buffs , a 10" coarse white Alox wheel, and a pile of dust gathering generic Grey wheels, most of which I should throw away.
Most 10" grinders will cope with a 40 mm thick wheel - if not it is not that difficult to enlarge/modify the guards to fit. A problem may arise when the arbor is too short to cope with the thicker wheel. In the case of the Blue Max it had a recessed centre so I was OK.
You don't need a lot of power for chisels and forming bevels on MW tools. Keeping the wheel dressed and using the right pressure and speed and stopping to cool are more significant than power. A powerful grinder can often be a quicker path to wrecking blades.
A belt sander with a quality belt can also be used to form bevels,
The Vic mark unit with the slower speed sounds like it could be a really good one.
Next time I buy/replace a grinder I'm going to get an old 3 phase unit and fit a VFD to it. The advantage of the old 3 phase units is that they have rugged cast iron tool supports instead of the pressed metal rubbish that are provided these days. The 3 phase stuff is also much smoother and quieter than other stuff.
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6th March 2014, 08:42 PM #7
Thanks for that Bob, lot's of good info there.
You mean a 3ph grinder like this one going up for auction on Saddy morning
http://www.advanceauctions.com.au/images/c24.jpg
A bit far for you to pu, and I'm pretty sure Aust.Post would baulk at it.....
It's described as an 18" grinder, but it think there may be a typo there.
ALL of NSW TAFE colleges are apparently selling off their woodworking stuff, one by one, and this is the first to go (it's a small one, as a trial I guess). Bloody ridiculous - it means there'll be nowhere to study woodwork within NSW at a govt level.
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6th March 2014, 09:26 PM #8
With a CBN wheel it seems this is not a problem. See the second pic here, which also shows the new Vicmarc 1475 rpm grinder (1500 watt motor too....)
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6th March 2014, 09:35 PM #9.
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No worries,
[QUOTE]You mean a 3ph grinder like this one going up for auction on Saddy morning
http://www.advanceauctions.com.au/images/c24.jpg]/QUOTE]
Yep
A bit far for you to pu, and I'm pretty sure Aust.Post would baulk at it.....
It's described as an 18" grinder, but it think there may be a typo there.
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6th March 2014, 10:16 PM #10
Ok then, current thinking is two grinders (and not just based upon your plethora of grinders Bob - it's just a really good idea):
Vicmarc Slow speed 8" for edge tools
Creusen (while they're cheap and hopefully still made in Holland) for other stuff like brass brush, mops, flap wheels, scotch bright, yadda
This raises a question: the Creusen's are 6" or 8" (and that depends upon current, and apparently terminal availability). 6" is $162, 8" is $199, but more importantly the ongoing cost of the various wheels is going to be different and usually the 6" could be expected to be less dough.
The question is: how important (or not) is the 8" v 6" argument when it comes to non-grinding operations such as polishing etc with those other non-grinding wheels that I've nominated. This is in contrast to the importance of the hollow grind being smaller radius on a 6" v 8", where an 8" wheel radius is far more desirable on an edge "bevel" for strength amongst other considerations. I understand that a 6" wheel will have 3/4 of circumferential speed compared to an 8".
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6th March 2014, 10:46 PM #11.
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6th March 2014, 11:00 PM #12
Yeah, good observation Bob. The Creusen 6" is only 350w (prolly plenty for edge work) but the 8" is 600w. Cop the cost of the consumables (which should last 4/3 as long anyway).
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7th March 2014, 05:14 AM #13Hewer of wood
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Here's my quick run-down on a few platforms ...
Cheap Chinese: http://www.cwsonline.com.au/shop/ite...ding-jig-cj-04
Broad top, useful mitre gauge. Will deflect vertically with too much pressure. Necessary clearance in mitre track produces a slight angle variation which has to be dealt with by consistent direction pressure, and that's more critical the wider the edge to be ground is obviously. I've used this model for years.
Sabre platform: http://www.cwsonline.com.au/shop/item/sharpening-jig
My turning teacher used one and I've got one in for the 2nd bench grinder. Unlike the pic it has braced legs and will take more downward pressure. It's also a bit shorter and may need packing for the 8" grinder. The skew angle is fixed so if you want to use the sliding skew guide you will likely have to change all your angles. The gouge guide is handy for straight-across grinds. The castings are a bit rough and can do with some cleaning up. The square guide should be more effective for plane blades than the unit above.
Veritas. Nicely made as always. The grinding jig allows a very positive squaring up. It also allows you to fit, just, a single point diamond dressing tool that IMO is the best for cleaning and truing coarse wheels. The platform is decidedly smaller than the two units above and the grinding jig would be essential for plane blades. Not sure about the max clamping width; the website doesn't specify it; will check if you wish. You get an angle setter with the kit; bit fiddly - it's accurate at the very heel of each bevel.
...
Some other comments ...
I've run 40 mm alox wheels without the side cover. Not ideal but OK. It's essential to give them the crack test before fitting obviously. CBN should be fine.
A&A: I have acquired but only test run their Chinese-made 8" industrial duty job (the green model). Has hefty washers. I don't expect problems. 2 year guarantee. 5/8" arbor which is pretty common. The original platforms can be unbolted; don't have to be cut off.
HTH.Cheers, Ern
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7th March 2014, 06:43 AM #14
The Robo Rest looks the goods.
Pat
Work is a necessary evil to be avoided. Mark Twain
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7th March 2014, 06:49 AM #15