Bench grinder woes

[KimG]

I have an old "ish" (25yrs) B&D professional 6" bench grinder that has served well for all that time, but the wheels have reduced to less than 5" so I decided to get a new wheel for the fine finish, I got a 120 grit wheel and although it came with a slightly oversized bush, I was able to knock it out and also the old wheels bush and refit it to the new wheel, and it is a nice snug fit, I mounted the wheel between the two clamshell washers and turned it on, and was a bit gutted to see it wobbling, not just back and forth (which I can dress out easily enough) but also from side to side, at first I though I must have a dodgy stone, but after removing it all, carefully cleaning the clamshells and remounting it, it was the same, so then I tried putting the old wheel back, and now it wobbles too! I am at a bit of a loss to figure this out, I can only think that the Clamshells are poorly machined because I can think of no other way it can go off centre like that, is this a common experience?

I am therefore thinking of replacing the whole thing, choices seem to be between an Axminster for £50 odd, or Record Power 6" for similar loot, an 8" for £75, or even further upmarket for a Creusen at £170 (the cheapest I could find so far at least)

I imagine the Creusen is by far the superior bit of kit, but does it convey a significant advantage over the others?

Given a choice between the first three only, what would you go for?

Anything I may have missed when it comes to refitting the wheels, after all, if there is a set process that does get them centered I may save myself some loot!

All replies appreciated, I have been turning for all those years, but this is a new one, we are always learning!

 

[CHJ]

Are both clamping washers identical, i.e. does one have a different bore or locating step in it, have you got them round the correct way ?

If you place the two clamp washers on the shaft with a piece of spacing wood (turned) in between does it all run true ?

You say

I was able to knock it out and also the old wheels bush and refit it

Was the central bush just a loose fit plastic item or was the bushing a tight fit hard substance in the centre of the wheel.
If it was the latter then I think you may have wrecked both wheels.
A lot of wheels especially older ones have a filler substance poured/molded into the centre of the wheel and the bore machined in this to ensure true running.

 

[nev]

A quick search of the forum will give you a 1001 answers...
search.php?keywords=which+bench+grinder&terms=all&author=&fid
... and probably leave you more confused than before :wink:
but i think the best advice is buy the most expensive one you can afford (or bear to part with the cash) from a reputable supplier, such as the likes of the Toolpost, Peter Childs, Axminster, Rutlands, and the for sale section of the forum .
if you want local(ish) Brian at Timberman in Carmarthen is very helpful and more than reasonably priced.
personally i have a record 6inch (cos it was in my price bracket at the time) which serves me well and has since been improved 100% by the addition of a wolverine jig. I still cant quite understand exactly why but adding a proper jig made my tools a significant amount sharper :?
Apologies if I've added to your confusion

 

[KimG]

Hi Chas, thanks for your reply, I went out to double check everything, the bush for the old wheels it a push fit plastic one with a serrated outer edge, the bush for the new wheel is a nylon multi fit type, you push out or push in whichever fits, the old bush fitted just right so I am confident that is out of the equation.
There are no marks on the washers, they are identical but have a small amount of play on the shaft, a few thou or more, but I did not think this would prevent them from tightening into a tru configuration, I did try the spacer test, it was difficult to tell, the amount of wobble on the wheel is barely visible at the outer edge, yet it makes a big difference at speed.

In the end after much experimenting with slight changes in the relative positions of the washers to each other (in an attempt to cancel out and possible unevenness) I noticed that the inner washer was wobbling very slightly, this was seen slow rotating with the wood spacer, looking at the back of the washer I could see a slight groove where it sat against the flange of the shaft, suspecting that this, along with the play might lead to improper seating, I ground the back of the washer till the wear was gone and it was flat (on a diamond wetstone)
I then held the washer against the flange and rotated the shaft, there was a distinct wobble generated, so the flange itself was not true, I tried to correct this with the diamond wetsone, but it is too small an adjustment and would need to be done on a metalworking lathe, I can't see it would be feasible to strip the thing down for that, even if that's possible, literally there seems little I can do, as far as I can tell it is worn out so to speak.

In which case it seems likely I may well have to buy, which brings me to part two. What are your various preferences?

 

[KimG]

Thanks for that Nev, interestingly enough I bought my current lathe from timberman some 15 years ago, he was a nice guy to deal with for sure.

I can only really go for the Creusen if the other two have much negative comment, I wouldn't want to buy something that nobody liked, so it's one to the record power so far!

thanks for your reply!

 

[woodyturner]

Have you considered the Axminster or the creusen slow running grinder I have been using the creusen slow running grinder for about 15 years and it is still going strong
http://www.axminster.co.uk/axminster-ax ... rod460432/
http://www.axminster.co.uk/creusen-creu ... slow-speed)-prod22331/

 

[CHJ]

I take it the clamp washers are just pressed steel, these are notorious for being out of true.
I have made several replacements to overcome these for my own grinders.
You used to be able to get some good machined versions from Peter Childs, don't know if he still supplies them but it's worth an e-mail. http://www.peterchild.co.uk/

One thing you can do to reduce side wobble with the pressed steel washers is to make up some tapered paper washers.

Take some thick card, I used to use beer mats or the like.
Cut out some washers big enough diameter to accommodate the clamp washers.
Sand them down to a taper about half their thickness across their width.
Now assemble the wheel with the steel washers each side and lightly clamp wheel and keep adjusting their rotation until the wheel wobble is eliminated.

 

[KimG]

The Axminster slow runner looks promising Woodyturner, thanks for the link. The Creusen is out of reach though.

You're right Chas, they are indeed pressed steel, that is useful to know and thanks for the tip about the card washer, I will definitely be giving that a try, it sounds like an ideal solution.

 

[CHJ]

Would save you on additional expediture seeing you have already purchased new wheels.

Although a good quality brand grinder is ideal if you have the pocket money, the quality of the wheels is the main criterior and even a cheap motor as long as the bearings and shaft are balanced and of reasonable power is just as good at spinning them.
Mine are the cheapest of cheap but have benifited from my ability to balance and true the wheels well. (as supplied they were not good).

 

[TEP]

Would save you on additional expediture seeing you have already purchased new wheels.

Although a good quality brand grinder is ideal if you have the pocket money, the quality of the wheels is the main criteria and even a cheap motor as long as the bearings and shaft are balanced and of reasonable power is just as good at spinning them.
Mine are the cheapest of cheap but have benefited from my ability to balance and true the wheels well. (as supplied they were not good).

+1 for this post! I have 2 Machine Mart grinders which I have had for close to 20 years for one. Would still be using them if I had not had the opportunity to buy a 8" Record which I use now.

All have had the wheels replaced with after market white stones, and have never let me down. IF you can blow a couple of hundred £'s that's fine. But in my opinion they won't sharpen tools any better than the cheaper machines with a good stone fitted. In the end it really comes down to the ability of the operator, and what chisel shape he is aiming for, and how to use a standard speed grinder properly.

 

[KimG]

Both Chas and Tam make an excellent point, and I am optimistic about the tapered card washer being an effective cure for the wobble, I won't be able to try it till next week but I will certainly post up the result when I get to it. Many thanks to all who read and replied.

 

[wcndave]

I have an axminster with significant wobble out of the box. The clamshells seem an odd way to do it, as you can tighten the wheel on at any angle barr true it seems!

I just fiddled and fiddled until the were roughly right, bit like trying to get the gimball straight in apollo 13.

Now i think i just need a diamond dressing stone to true up the front.

Is there something we are missing with these clamshell washers, it's like trying to put a billiard ball on a kitchen top with the dot facing exactly to the right place, and tightening it usually causes movement....?

 

[CHJ]

90% of the problems are due to the pressed steel clamp washers, although I have seen some wheels of unknown pedigree with the central mounting holes way out of true and even the recessed portion of wide wheels out of true with the rest of the wheel, goodness knows what sort of production control was used in their molding.

Obtaining a set of good machined clamp washers with a good fit on the shaft and its location collar gives a far more realistic chance of getting a vibration free and true running wheel. They take away the clamping and location and leave you with just the wheel balancing and truing to contend with.

Machined Clamp Washer and Pressed one off a cheaper grinder.

Note just how far out of true the pressed steel one is, at least double the thickness of the steel rule.

 

[paul-c]

hi kimg
i have the 8" record grinder and am very pleased with it - especially as i got it at a reduced show price.
best of luck getting sorted.
cheers
paul-c

 

[KimG]

Well I tried the tapered washer which I really thought would do the trick but despite careful adjusting it seemed completely random, sometimes running nearly true, a slight adjustment and it was out by a mile again, my pressed washers are not warped like Chas' pic, I ground both faces flat, I think that they are slightly oversized in the hole and the grinder shaft isn't not providing a true backstop, I can't fathom the reason for the erratic behaviour any other way. I ended up buying an 8" RP grinder, I may ask a metal turning friend to machine up a couple of washers though, just to see if it makes a difference.

I very much appreciate everyones help in this thread. Thanks!

 

[gregmcateer]

This may be useful;

http://www.ebay.co.uk/itm/Creusen-H...Home_Garden_PowerTools_SM&hash=item35be29cfe8

seems to be shop-soiled / ex-demo from Axminster

Greg

 

[chipmunk]

Also looks to be 110V

Jon

 

[KimG]

I have already ordered the RP 8" so it is pretty much moot anyway, but thanks for the link.

 

[Phil Pascoe]

This may be useful;

http://www.ebay.co.uk/itm/Creusen-H...Home_Garden_PowerTools_SM&hash=item35be29cfe8

seems to be shop-soiled / ex-demo from Axminster

Greg

10v - 3.50w - no wonder they want rid of it!

 

[toolmaniac]

I have three bench grinders fitted with different wheels & mops for sharpening, general grinding and cleaning/polishing.
1 is an 8" Creusen, 1 6" a Wickes own brand, and one is an unknown 20-odd year old 6" Taiwanese machine bought on eBay.

The only one I have trouble with is the Creusen. The rests are pathetic for such a large (and expensive) machine.
The nuts work loose on the shafts, and it is currently out of action for a sheared roll pin. When it's working well, it's fine, but...

The best one is the Taiwanese - old, solid & powerful - £20 well spent.. The Wickes is OK, but a bit puny.

I know they are supposed to be the best, but I wouldn't buy another Creusen.