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Jaakko Fagerlund
04-09-2012, 06:41 PM
I'm restoring an old pencil grinder (new bearings, new shims) and run in to a problem. There is 4 small vanes in the rotor that appear to be something like printed circuit board material or the like, I'm just not at all sure what material they exactly are. The original color is (deep) brown, resembles bakelite.

The dimensions are 0.65 mm thick (up to 0.75 mm will do), length about 20 mm and height of 3-4 mm.

Does anyone have a good idea of a material that I could use, as I need to replace all the vanes? Getting spare parts is out of the question, as the manufacturer is not in operation anymore.

Here is a picture of the vanes, though I don't know if it helps at all: http://aijaa.com/006559972079

bborr01
04-09-2012, 06:56 PM
The ones that I have seen look like Micarta. I think that is also what is used for circuit boards.

Brian

sasquatch
04-09-2012, 07:02 PM
I can't help you out with your'e question, but that is an unusal project to me anyway, but still very interesting!!

Any pics of the sharpener??

GadgetBuilder
04-09-2012, 07:22 PM
Tufnol is another trade name, like Micarta, for cloth or paper impregnated with phenolic resin. Strong stuff, turns to dust when machined.

John

jkilroy
04-09-2012, 07:26 PM
You are correct that most air motor vanes are made of Micarta, or generically known as Phenolic Resin Cotton Sheet Materials. The stuff should be available through a wide range of suppliers at reasonable prices.

Tait
04-09-2012, 07:35 PM
Some of the knifemake suppliers, such as alphaknifesupply (http://alphaknifesupply.com), have some thin sheets available in small quantities.

delagem
04-09-2012, 07:50 PM
Faced with a cost of $1500 for a rebuild kit for a Vimex Gas Detection pump for a commercial oil tanker installation, we took a stab at making our own vanes.

Seriously? $1500 for 4 vanes, and a paper gasket!

Micarta, or Garolite, cut to size, worked fine.

http://www.mcmaster.com/#garolite/=h1bmts

Michael

armedandsafe
04-09-2012, 07:58 PM
My first thought was brass shim stock. My second thought was concerning the weight differential between the two substances.

My third thought was "You don't know what you're talking about." :D

Pops

darryl
04-09-2012, 08:16 PM
I would probably grind some segments out of a used bandsaw blade. These are vanes with a sharp edge to shave the pencil back to sharpness, are they not? I think that's what you are talking about. HSS blade material would last a long time in this app, as long as you can make pieces of it that will fit.

John Stevenson
04-09-2012, 08:16 PM
Jaakko is from Finland and is probably confused by trade names.
What is know in one country isn't know in others.
No one here has a clue what Micarta is here, Phenolic Resin is another hardly heard off product but everyone in the UK engineering field has heard of Tufnol or Resin impregnated cloth.

Be interesting to know what it's known by in Europe / Scandinavia ?

John Stevenson
04-09-2012, 08:18 PM
I would probably grind some segments out of a used bandsaw blade. These are vanes with a sharp edge to shave the pencil back to sharpness, are they not? I think that's what you are talking about. HSS blade material would last a long time in this app, as long as you can make pieces of it that will fit.

Actually vanes in an air motor.
Pencil grinder is a name for a small thin grinder, not what it does.
Also called a die grinder.

Toolguy
04-09-2012, 08:26 PM
I would probably grind some segments out of a used bandsaw blade. These are vanes with a sharp edge to shave the pencil back to sharpness, are they not? I think that's what you are talking about. HSS blade material would last a long time in this app, as long as you can make pieces of it that will fit.

What they are talking about is an air powered slim line grinder like a skinny Dremel tool. They are not sharpening pencils. The vanes are pushed by the compressed air to spin the spindle.

lynnl
04-09-2012, 08:29 PM
Actually vanes in an air motor.
Pencil grinder is a name for a small thin grinder, not what it does.
Also called a die grinder.

:D
I was wondering, what's the big fuss over a pencil sharpener. :D

Ah.. the joys of language!

John Stevenson
04-09-2012, 08:44 PM
This is a pencil sharpener. :p

http://www.stevenson-engineers.co.uk/files/new%20pointer1.jpg

Does 7,000 per hour and that's slow.

Only does 7,000 because it cuts the pencil with rotating knives as the pencils are made from recycled plastic [ including the 'lead' ]

Commercial sharpeners work by rolling the wooden pencil at an angle along a large diameter linishing drum and can do 24,000 per hour.
You can't do plastic on these as it melts.

Black_Moons
04-09-2012, 08:44 PM
:D
I was wondering, what's the big fuss over a pencil sharpener. :D

Ah.. the joys of language!

lol! Nah, much cooler then that.
http://users.tpg.com.au/agnet/bigger.jpg

Typically 50,000 rpm spindle speed.. For scale, thats a 1/8" shank bit. I think the diameter is somewhere around 5/8" to 3/4"?

Great for getting into tight spots and overall fine controlled work. Does wonders with a small carbide burr if you can keep it from skittering out of control and don't mind being covered in thousands of little needles. Can get at the transfer ports of small 2 stroke engines..

Black_Moons
04-09-2012, 08:54 PM
Also can be (ab)used as a toolpost grinder.. Sorta :)
http://users.tpg.com.au/agnet/tpg2.jpg
More for hard materials and nice surface finish then high accuracy I would assume.

darryl
04-09-2012, 09:05 PM
Well that makes more sense then. I guess I should have eaten before trying to think :o

Ok. Circuit board material is commonly epoxy/fiberglass or phenolic resin. I don't think either one would be good for air motor vanes. There is a phenolic resin layered with cloth, but not fiberglass, and this is a common vane material. This is, or used to be used a lot for electrical connector boards. It's the same material that's used for the rubbing block on points in a distributor.

In the air motor application, you'd want to get it in the exact thickness required, since it's unlikely you could mill it to thickness without interfering with it's lamination.

Other vane materials look like some form of cast carbon- I know they are crisp, not bendy, and have some built-in lube of some kind. Not sure if you could get this in a sheet that you can cut pieces from, but maybe.

John Stevenson
04-09-2012, 09:11 PM
Probably not a lot of help but these are the people I use.

http://www.directplasticsonline.co.uk/TufnolSheet/Whale/1mm/

1mm is the thinnest they do.

gwilson
04-09-2012, 09:19 PM
I thought Micarta had paper laminations,not fabric as some other phenolic products do. At least the Micatra I have bought several times is stacked paper.

The Bowie knife I posted months ago has a Micarta handle. It obligingly turns yellow,like old ivory. But,it is easy to spot from real ivory anyway(if you know ivory!)

sasquatch
04-09-2012, 09:38 PM
Re: The pencil sharpener:

Oh well, now i learned something else NEW again on the HSM site!!:D :D

dian
04-10-2012, 04:11 AM
conrad has carbon sheet starting at 1 mm as well as epoxy sheet starting at 0.3 mm.

davidh
04-10-2012, 09:03 AM
try "gator products" in the "states" they have vanes for nearly everything and they work with samples that i have sent to them also. . . .

Duffy
04-10-2012, 11:14 AM
Nobody has suggested graphite impregnated material. I know that the stuff used for "improved" bandsaw blade guides sure LOOKS like laminated fabric, and it sure is slippery. No idea where one would find it, but it is also supplied with an adhesive backing for use on the plattens of belt sanders.

Harvey Melvin Richards
04-10-2012, 11:32 AM
I have several vacuum pumps that use carbon for the vanes. I don't know if that would work for a pencil grinder.

I have a Suhner LSA 81 80,000 rpm pencil grinder that I bought in a pawn shop for $20. It's missing the vanes, but Suhner is still in business so I should be able to get replacement parts.

Jaakko Fagerlund
04-10-2012, 12:07 PM
Thank you for everyone for the suggestions, I'll go check out what I can find from those suggested :) And yeh, it's a grinder, not a sharpener ;)


I have a Suhner LSA 81 80,000 rpm pencil grinder that I bought in a pawn shop for $20. It's missing the vanes, but Suhner is still in business so I should be able to get replacement parts.
The other die grinder I have is the exact same model :) Very nice and lightweight model, I like it very much. It was around a year ago when I changed the bearings on it (off the shelf 686 and 624 bearings), has worked flawlessly (those bearings are listed as "54000 rpm", so I don't see how they work there or if the machines 80000 rpm is actually true).

ikdor
04-10-2012, 02:10 PM
Another name for the phenolic circuit board material in Europe is Pertinax, or Hartpapier in German. It's not cloth based but paper based.

It's dirt cheap, available from places like Conrad etc.

Bearings can in general be run faster than their catalog rating. If the air is cooling them and you don't need 50.000 hours of operation you can extend the envelope, 80k is pushing it a bit though....

Igor

Lew Hartswick
04-10-2012, 02:59 PM
The material is "Phenolic" there are two basic types "Cloth filled" and
"Paper filled" . The old terminal boards (things that actually held the
components like resistors and capacitors before "printed wiring"
boards existed) were made of it. I mounted and wired many many
of them. Ought ot be available as sheet stock in thicknesses from
about 30 or 40 thou ( 0.03 inches ) up to several inches thick.
I have some at school but it's about 1/2 inch.
...Lew...