Convert a bench grinder into a disk sander?

[Duncan DiSaudelli]

hello All

please can you help me wit some advice concerning:

1) I have a Hilka 350W bench grinder motor which has an arbor sticking
out of each end, comprising an M10 nut on a threaded portion, and a 1/2"
diameter section on which the grinding wheels fitted.

I want to fit some sort of 6"-8" diameter rigid plastic/aluminium disk
to it so that I can stick emery cloth disks to it and bear down on the
face of the disk, using a tool rest, so I can smooth/shape bits of wood
and plastic.

What sorts of search terms ought I to use to find something suitable? I
can find lots of things to fit M14 spindles on angle grinders but that
won't do.

2) Also - my other 6" bench grinder is intact and does have a coarse
and a fine wheel fitted. is it safe to use the outer face of said
disk(s) as an abrasive surface for softer materials (wood, plastic,
perhaps aluminium)? I can fashion a suitable tool rest but I a worried
about forces acting out of the plane of rotation, compared with the
normal mode of use i.e. when the outer edge is the grinding surface.


In pictures:

I've got two bench grinders rather like this, one without wheels and
covers, and the other intact:
http://pop.h-cdn.co/assets/cm/15/05/54cb16d1c8206_-_bench-grinders-01-0713-lgn.jpg

I want to turn the incomplete one into something like this:
http://www.cnccookbook.com/img/OthersProjects/Tools/DiscSander1a.jpg

This man's DIY is something similar to my aspirations:
https://woodgears.ca/reader/hessam/disk_sander.html

I want to stay safe, but I also want to make use of the spare motor, so
any advice would be welcome.


DDS

[harry]

The bearings in a bench grinder only takes radial forces.
The thing you want has taper bearings to take axial forces.
So forget it.
Just go out and buy one.

[tabb...@gmail.com]

or use a drill


NT

[Duncan DiSaudelli]

>> I want to stay safe, but I also want to make use of the spare motor, so
>> any advice would be welcome.

> The bearings in a bench grinder only takes radial forces.
> The thing you want has taper bearings to take axial forces.
> So forget it.

I hadn't realised the difference in bearings. Thanks for the info - idea
now forgotten!

DDS

[Graeme]

In message <ej74md...@mid.individual.net>, Duncan DiSaudelli
<D...@attention.now> writes

Slight tangent. I have a few hand sized metal bits to clean, and first
thought was to hold them in a vice then attack with a rotating wire
brush in an ordinary B&D drill. However, I do have a pillar drill.
Could I mount the wire brush in the pillar drill, and hold the metal
bits against the brush or what that also risk ruining the pillar drill
bearings? The pillar drill is a cheap but great for my simple needs
Silverline.
--
Graeme

[newshound]

A more significant point is that bench grinders usually run faster than
disk sanders.

I am fairly sure that my cheap Machine Mart combined disk and belt
sander is based on a standard electric motor with simple has deep groove
ball bearings at both ends. The axial load (and also the bending moment)
which you apply to a disk sander is usually not particularly high, and I
would not expect any problem with deep groove bearings for normal
domestic use.

The "drive end" bearing is often larger than the non-drive end. Also,
the drive end bearing is usually the "locating" bearing. At the other
end, one race of the bearing will usually be a sliding fit with no
shoulders either on the axle or in the housing, to accomodate thermal
expansion.

[Capitol]

If it's a ball race, it won't make any significant difference, Harry
has sleeve bearings in mind I think.

[newshound]

Its not ideal because the access isn't particularly good, but unlikely
to do much harm. Do you mean one of the "disk" type brushes or one where
the "bristles" stick out at the end opposite to the spindle?

[harry]

Tapered ball bearings.
Commonly used on car wheels.
Can be adjusted with the centre nut.
Or anything else where the shaft has axial forces as well as radial. Eg Lathe.
Often can be completely dismantled.
https://www.google.co.uk/search?q=tapered+ball+bearings&tbm=isch&imgil=iAqea8ILLc34pM%253A%253BLPWkJuJ1O-dQQM%253Bhttp%25253A%25252F%25252Ftaperrollerbearing.blogspot.com%25252F2015%25252F10%25252Ftapered-roller-bearings-definition.html

[harry]

Pillar drills usually have a thrust/tapered bearing at the top of the shaft and a "normal" bearing at the bottom (next to the chuck).

[Graeme]

In message <-vadnRCO09X6DVPF...@brightview.co.uk>,
newshound <news...@stevejqr.plus.com> writes

>On 3/19/2017 10:41 AM, Graeme wrote:
>> Could I mount the wire brush in the pillar drill, and hold the metal
>> bits against the brush or what that also risk ruining the pillar drill
>> bearings?
>

>Its not ideal because the access isn't particularly good, but unlikely
>to do much harm. Do you mean one of the "disk" type brushes or one
>where the "bristles" stick out at the end opposite to the spindle?

I mean the type with bristles sticking out at 90 degrees to the
shaft/spindle.

I'm talking about Victorian door furniture which has been allowed to
rust over too many years. Plan is to remove all traces of old paint and
rust, then treat with gun blue or Zebo.
--
Graeme

[Capitol]

Harry, they're tapered roller bearings. Only sometimes used on cars,
generally on the front axles.

[John Rumm]

There are quite a few DIY from scratch disc sanders on youtube:

https://www.youtube.com/results?search_query=disc+sander+build




--
Cheers,

John.

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[tabb...@gmail.com]

Search youtube for rust removal, there are easier more thorough methods.


NT

[harry]

There's both shown on the link.
They both serve the same purpose.

[newshound]

+1. The exact method does very much depend on exactly what you want to
clean, though.

[newshound]

Taper/tapered roller or angular contact ball bearings are the usual
types used for increased thrust load capacity.

Hary's link is particularly useless. In those pictures there are taper
roller, spherical roller, needle roller, deep groove ball, angular
contact ball, thrust ball bearings, and also a crossed roller bearing.

Incidentally Google will give you all sorts of bollocks about Conrad
bearings, including Wikipedia showing you a picture of a self aligning
ball bearing and calling it a Conrad. An American term, not used in the
UK, even though Conrad was a Brit.