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Sophiedoc
03-01-2008, 09:50 AM
My wife is into cutting fabric for quilts and her circular cutter is dull.I figured this is easy to fix.Mounted the blade on an arbor and spun it on the little Unimat holding a very fine spinning emery wheel in the Dremel against it but always got microscopic burrs and or not very sharp.Tried holding a fine Arkansas against it with improvement but still not super sharp.Any better ideas?

Rustybolt
03-01-2008, 09:56 AM
A piece of leather as a strop.

tattoomike68
03-01-2008, 10:00 AM
The V type carbide sharpeners work realy good and cost about $6. they even work on stuff like food processor rotor blades and meat slicer blades.

http://images.cableorganizer.com/klein-tools/48036-knife-scissor-sharpener.JPG

Bob Ford
03-01-2008, 10:10 AM
If IRC the one that I ran about forty years ago had a attachment with a 3" wheel that hollow ground the cutter from one side. If not kept sharp you can remove the temper from the edge.

Bob

smiller6912
03-01-2008, 10:11 AM
My wife is a quilter and uses these quite a bit. In essence they are a razor blade and have an extremely delicate edge. It may be VERY difficult to sharpen due to the radius edge. New ones are fairly inexpensive ($6) and may be the best bet.
http://www.joann.com/joann/catalog.jsp?CATID=cat763845&PRODID=prd46044&source=search

Evan
03-01-2008, 10:22 AM
Try cutting 1000 grit sand paper with it. You may be surprised. It works for scissors.

John Stevenson
03-01-2008, 10:51 AM
If you are grinding or polished make sure you are working off the edge, ie, inner to outer so it throws any burr, however slight off the edge.

Often it's this small burr that produces the fine cutting edge.

True example.
I used to work at a piano factory when I was semi-employable and didn't rant and rave too much :D

We had to make many of our own cutters are they were so special.
Many of jobs were wooden flanges that were part of the support part of the piano action, small pieces of maple or beech with two legs like a yoke.
The space in between the legs of these were alway the same 0.220 to 0.224, yup 4 thou tolerance in wood and we had inspectors to random check samples off the machines with go - no go gauges and if they were off they would lock the machine out.

There are no saws that are 0.220 thou wide off the shelf so we used to get 6" x 1/4" fine tooth milling cutters that were made for horizontal mills and surface grind both sides to finish up at 0.219.
This used to loose all the side clearance and if it was put on the machine like this then it would cut but burn the sides of the legs which wasn't acceptable.

We had equipment that could hollow grind but with hollow gringing to a size you only have one life and this was too expensive a way to go. Parallel grind gets you the whole life of the cutter until it's too small.

So after surface grinding we used to front grind the face of the teeth, half was ground off the cutter and the cutter was turned over the the opposite ones ground off the cutter.
When you measured the cutter it still measured up at 0.219 but on the machine it would cut to about 0.222 with no burning.

As the cutter started to wear it would get tighter and show signs of burning and the operator would call you and you would re grind the faces again but it was surprising just how long they carried on butting on just this burr.

.

Swarf&Sparks
03-01-2008, 10:55 AM
take the burr off the back with a bit of 1200 wet and dry

snowman
03-01-2008, 12:36 PM
buy new ones on Ebay and forget about it.

Serious. It's not worth the trouble.

I'm deathly afraid of the olfa cutters for some reason.

smiller6912
03-01-2008, 12:49 PM
Seriously, Here ( http://cgi.ebay.com/5-45mm-Rotary-Cutter-Blades-Free-Shipping_W0QQitemZ290210690636QQcmdZViewItem?hash= item290210690636) is 5 new blades for $10.50 with FREE shipping.
Do you really want to mess with it for that?
I know "do-it-yourself" is fun and fulfilling but, dude, for $2 each, I just don't think its worth it. And, it is going to be nearly impossible to get it "like-new" sharp.

darryl
03-01-2008, 05:11 PM
Just for interest, I'd like to know how blades are made razor sharp from the factory. An adaptation of that would sure be handy for the HSM where it's prudent to restore an edge rather than replace the blade.

I never have looked at a factory sharp razor blade or xacto type blade under the microscope, but maybe that would give a clue as to the grade of abrasive, angles, etc. I've seen pictures of sharpened cutting edges magnified, and it looks like a mountain range. I can imagine that the smoother it is, the longer it would last because there's more actual edge doing the cutting. It probably hinges on using the finest sharpening medium that can be applied, while keeping heat out of the material, and keeping particles from the abrasive and the material being sharpened from re-cutting.

Maybe a diamond blade and a steady stream of proper fluid to clean, lube, and cool is the answer.

Bob Ford
03-01-2008, 06:04 PM
The unit I was using had a 3/4 H.P. motor to power it. Cuts about 1 inch thick of material. Blade was about 6 inches in Diameter.
If you are talking about the hand powered ones that cut one layer at a time. Blades for them are cheap.

Bob

john hobdeclipe
03-01-2008, 07:25 PM
The only fabric cutters I've seen, in use in a furniture manufacturing environment, had the sharpener mounted on the cutter frame. Thus the blade was sharpened in place, while running.

I think that if you remove the blade and sharpen it then re-mount it on the machine you'll get a bit of runout.

smiller6912
03-01-2008, 07:54 PM
Just for interest, I'd like to know how blades are made razor sharp from the factory....
There was recently a show on Discovery about "The worlds sharpest " or something like that and they showed how factories sharpen things like razor blades and ceramic plastic film cutting blades. It was very interesting. They use a pair of diamond wheels turning against each other and they claimed to be able to sharpen to within a few microns. The microscopic images of the differences between a typical disposable razor and the ceramic blades was astounding.

Rich Carlstedt
03-01-2008, 08:54 PM
I trim/cut all my sandpaper using my wife's old blades and a shop made handle.
They are superb for cutting out smaller sheets for the Oscillating and Vibrating sanders. just cut the back side.
Rich

snowman
03-01-2008, 08:58 PM
Try burnishing the edge with a hardened steel rod to polish it. Maybe a little polishing compound or something as well, prior to the burnishing.

ogopogo
03-02-2008, 10:29 AM
There is very simple and effective tool available made just for this purpose.
It consists of a 3 part assembly with a center ring (of plastic). the blade is first clamped between 2 halves of a simple holder after which it is pressed against the center ring while rotatind it back and forth. A fine abrasive in the ring soon sharpens the blade as good as new.
Yes, the edge is that good. I re-sharpen all my wife's blades , and some
times those of her friends as well.
The one she has is made by a firm called Tri-Sharp and cost about 20$.
A trip to the nearest fabric store (oh Joy!) might find something similar.
Regards.