Kehren RW6 How to Remove Grinding Wheel

Burgs · Dec 26, 2017

Hi
I am trying to remove the grinding wheel to rebalance and have come up with a problem.
The manual said to "remove the fixing screw in the spindle", yep did that, left hand thread no problem.
"The supplied extractor screw screwed in instead, (ha no supplied extractor thread). "By driving the latter the wheel collet is removed from the taper of the spindle"?
I can't see how this happens as there is no thread on the collet for the extractor to screw into the collet?
Only thing I can see to do is undo the bolts in the collet and remove the front flange and wheel, then apply some gently heat to the taper. Or remove three of the 6 bolts say, and make up a puller plate that pulls by the collet bolts and bushes on the end of the shaft and try and pull the hub/collet of the spindle?
I want to keep the wheel mounted to the collet to see if the balance is out or if I have another problem.
Wheels should be 16" x 1 1/2" x 5", but either the wheels that came with the machine are worn down or the PO fitted 12", I have 4 wheels and they all measure 12", details on the sides of the wheels have long time gone, 3 white ones one pink?

Burgs

Toms Wheels · Dec 26, 2017

Remove two bolts, make a bar the contains those bolts, add a larger fine threaded center bolt an use that to jack the the hub off the spindle. The Hammer stays in the toolbox. If so tight it does not move, just crank it as much as you can, and leave it overnight, try in the morning, likely will pop off.

Tyrone Shoelaces · Dec 27, 2017

Just to add to Tom's Wheels advice. Replace the locking ring/nut and just leave it a thread or two away from tight. When the wheel and arbor comes loose it can fly off if not restrained.

Regards Tyrone.

Burgs · Dec 27, 2017

Hi
Thanks for the info, backed up what I did.
Made up a puller yesterday morning, used two bits of hi-tensile threaded bar, but a bit weight on the nuts, attached the overhead crank just in case it came off uncontrollably. Nothing fancy just a bit of scrap plate, two studs, and piece of scrap bronze to push on the end of the spindle.
And yes no banging with a hammer, I thought that was a bit rude of Kehren as those spindle bearings are not cheap and there are four of them.
Put a bit more weight on and it popped off easily.
Rebalanced the wheel it was out a far bit, ground a couple of jobs and they look a lot better.
The collets hold two balancing weights should there be three?
It took a bit of messing around to get the balance right.
.

Tyrone Shoelaces · Dec 27, 2017

What do " Kehrens ' say about the number of balance weights ? I've worked on all sorts of grinding machines over the years - most have two weights but some have three. If you can balance the arbor satisfactorily with two weights and you're happy with the finish I can't really see a problem. Is there no provision for coolant on your machine ? I wouldn't be happy using a biggish ring grinder without coolant.

Regards Tyrone.

tdmidget · Dec 27, 2017

Burgs said:
Hi
I am trying to remove the grinding wheel to rebalance and have come up with a problem.
The manual said to "remove the fixing screw in the spindle", yep did that, left hand thread no problem.
"The supplied extractor screw screwed in instead, (ha no supplied extractor thread). "By driving the latter the wheel collet is removed from the taper of the spindle"?
I can't see how this happens as there is no thread on the collet for the extractor to screw into the collet?
Only thing I can see to do is undo the bolts in the collet and remove the front flange and wheel, then apply some gently heat to the taper. Or remove three of the 6 bolts say, and make up a puller plate that pulls by the collet bolts and bushes on the end of the shaft and try and pull the hub/collet of the spindle?
I want to keep the wheel mounted to the collet to see if the balance is out or if I have another problem.
Wheels should be 16" x 1 1/2" x 5", but either the wheels that came with the machine are worn down or the PO fitted 12", I have 4 wheels and they all measure 12", details on the sides of the wheels have long time gone, 3 white ones one pink?
View attachment 216074

Burgs

What's the spindle speed? That will determine the wheel size.

Tyrone Shoelaces · Dec 28, 2017

Burgs said:
Hi
I am trying to remove the grinding wheel to rebalance and have come up with a problem.
The manual said to "remove the fixing screw in the spindle", yep did that, left hand thread no problem.
"The supplied extractor screw screwed in instead, (ha no supplied extractor thread). "By driving the latter the wheel collet is removed from the taper of the spindle"?
I can't see how this happens as there is no thread on the collet for the extractor to screw into the collet?
Only thing I can see to do is undo the bolts in the collet and remove the front flange and wheel, then apply some gently heat to the taper. Or remove three of the 6 bolts say, and make up a puller plate that pulls by the collet bolts and bushes on the end of the shaft and try and pull the hub/collet of the spindle?
I want to keep the wheel mounted to the collet to see if the balance is out or if I have another problem.
Wheels should be 16" x 1 1/2" x 5", but either the wheels that came with the machine are worn down or the PO fitted 12", I have 4 wheels and they all measure 12", details on the sides of the wheels have long time gone, 3 white ones one pink?
View attachment 216074

Burgs

The " knife edges " on your balancing irons could do to be narrower.

Regards Tyrone.

Burgs · Dec 28, 2017

Hi
The knife edges just fit the wheel assembly in, about 3 mm either side, I originally made the knife edges for a single cylinder historic, motorcycle racing engine to balance the flywheels.
The spindle speed is 1450 Rev/min going by the original specifications.
The grinder dose have coolant but the parts I am machining are cast iron although I suspect they are hard, and information I have is that coolant not needed, although today I had a small fire from residue behind the wheel, I am learning :crazy:

I am leaning towards turning the coolant on in order to find a better finish.

Today I fitted one plate up and found that it is none magnetic :eek:

, so will have to make up an adaptor back to steel.
Thanks for you help it is greatly appreciated.

Best regards
Burgs

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