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View Full Version : Surface grinder - how tight for spindle nut?



loply
10-31-2012, 09:16 AM
Hi folks,

Got my first S/G set up and running this week and I've got two new Norton wheels for it.

One thing I'm unsure about is how tight I should be setting the spindle nut that holds the wheel on. There is a large 3 or 4 inch 'washer' (a steel flange) between the nut and the wheel.

Should this just be finger tight or should I be nipping it up with a wrench?

Cheers,
Rich

tdmidget
10-31-2012, 09:42 AM
Sounds like a rather large flange. The wheel adaptor nut should be a little more than hand tight, maybe 1 flat with the wrench. What kind of machine?

loply
10-31-2012, 12:31 PM
It's an Eagle Surface Grinder (manual, 750lbs).

The Norton wheels I bought have a 'label' adhered to both sides, but I'm wondering if I should be inserting my own pieces of paper between the wheel and the flanges either side of it, in addition to this?

Cheers,
Rich

Peter N
10-31-2012, 01:35 PM
I had an Eagle Surface Grinder, good little machine and a nice finish if you can get the 2-hand co-ordination right on traverse & cross feeds.
The 'label' on the wheel is called a blotter, if it has the original Norton blotter on then leave it on there. Information from Norton here: http://www.nortonindustrial.com/uploadedFiles/SGindnortonabrasives/Documents/Safety%20-%20Blotters%20-%20What%20Good%20Are%20They.pdf

IIRC the Eagle uses a normal right-hand thread on the spindle instead of the more usual left-hand thread, as the wheel running direction is opposite to normal, so you also need to consider your grinding direction when starting/taking cuts. You will obviously be cutting in both directions of traverse, but the cutting action on a wheel is just the same as a milling cutter when using 'climb' cutting or normal cutting.
As for nut tightness, I used to hold the nut still with the spanner in one hand and then just spin the wheel up to the nut with the other hand. When the wheel stopped itself against the nut this was tight enough for me. YMMV.

A word of advice, as you sound like a newbie to grinding. Take care handling the wheels, *always* ring the wheel before you mount it to check for cracks - a cracked wheel can be absolutely lethal if it breaks up and flies off in many pieces. A large cut on a surface grinder is 0.003", most starting and finishing cuts will always be smaller than this. Don't try and cut using the full width of the wheel on a pass, feed in about 0.020" or 0.5mm (cross-feed) at a time. This will cut using the leading edge, and as it wears a little bit, it automatically presents a fresh edge right behind it. Wheel selection is important too, but this can depend on what you are grinding. Too hard/too soft and it will skip or load up.
There is plenty of advice available on here, so feel free to ask away.

Toolguy
10-31-2012, 03:03 PM
I have used surface grinders for a lot of years, have a nice one in the home shop. I have found that the wheel should be fairly tight so it can't move after dressing. The wheel is a slip fit on the shaft so there is a few thou clearance. My grinder has a Sopko spindle so standard adapters fit the spindle and the wheel can stay on the adapter most of the time. The wheel to adapter is what needs to be fairly tight. The adapter to spindle, snug. On a grinder where the wheel mounts directly on the spindle, it should be tight like an adapter. If the wheel can move on the spindle during grinding you will get an uneven surface and the wheel will be a little unbalanced. You need to have the paper on both sides of the wheel to prevent the flanges from cracking the wheel under pressure. The paper provides a cushioning effect for the wheel. The paper label on a new wheel is all you need. On a used wheel with the paper partially or completely gone you need to provide a new one. If partially gone, clean off what is remaining to make a flat surface for the paper and flanges.

oldtiffie
10-31-2012, 06:50 PM
For a usual wheel which rotates clock-wise (ie "right-handed"), the mounting/clamping thread is a left-hand thread and so is self-tightening. It will "nip" as required on the blotter as soon as the wheel "spins up".

Then and only then dress the wheel and (re)dress it each time the wheel is (re)mounted.

The purposenof the "blooter" (paper) is to fill in any gaps between the wheel (which may not be flat) and the flanges (which are - or should be - flat).

Over-tightening is of no use at all and may cause the wheel to crack and the outer flange (left-handed) to over-tightened which may need a hammer or some-such and a spanner to release it which may both damage the spindle and its bearings.

A good grinder and ham-fistedness as well as a "cheater" (bar) are not a good mix.

Peter N
10-31-2012, 06:57 PM
The Eagle spindles rotate anti-clockwise and use a normal R/H thread (as mentioned above) so the same applies.
Unless someone has crossed the belt drive.....:eek: