Cutting Steel Blanks for Custom Moulder Knives
Recommended cutoff saws, blades, and cutting techniques for sharp, clean cuts in tool steel. December 2, 2006
Question
I have been grinding my own knives for our Weinig moulder. My problem lies in cutting the tool steel bar for my blanks. I have been using a metal chop saw, which has been ruining the temper of the steel. What other means are there for cutting this steel that are inexpensive?
Forum Responses
(Architectural Woodworking Forum)
From contributor M:
Hack saw.
From contributor R:
I think you'll find a hack saw is not going to be the answer you're looking for. Try the 14" Makita non-reinforced chop saw blade at 1/8" thick. The burn area is about 1/8" into the edge. If your grinding axial constant, then your profile doesn't start till the 3/8" mark and there is no need for concern. Water jet will give no burn, but for most folks, the price will end that idea. Try contacting Global Tooling. They have a non-reinforced blade even thinner, at 10" wide, that works really well.
From contributor K:
MSC Industrial Supply sells a magnetic base Kool-Mist system that I use on my little 9" Rockwell contractors table saw for a lot of metal work. It sells for about $100, and will keep the cut cool. It lives on the grinder most of the time, but can be used on almost any tool.
For about $10, you can get a gallon of rust inhibitor to add to the water to keep from rusting the tools. At about 6 oz. per gallon of water, it will last a long time. Some of the tool steel for my lathe tools is 1/4" M2 or 15% cobalt, and when they are real dull, I can hand hold about 1/2" back from the contact with the wheel, and lay into it as hard as I care to without feeling any heat.
From contributor A:
You should be fine with the abrasive cut off saw. We've been doing it that way for about 20 years. The trick is how fast you cut it. Basically, lean on the saw as hard as it will take without stalling. It sounds ugly, but the faster you cut, the less heat develops. Basically, you are trying to shed the heat in the debris, not in the steel blank.
From contributor C:
We use a Makita 14" metal cutoff saw and have cut literally thousands of bars of steel on this cutoff saw over the past twenty years. Years ago we found a triple reinforced wheel that is 1/8" thick that works like a charm.
The triple reinforcement serves many needs. First, it stabilizes the wheel and results in squarer cuts. Second, the two outer reinforcement meshes run only a few inches outside the diameter of the wheel mounting flange. Since there is no fiberglass reinforcement contacting the steel, the end result is a cleaner cut, with less stress to the steel (too much heat will adversely distemper the steel). Third, this wheel cuts very fast! Literally like cutting through butter. This wheel saves us a bunch of time and takes a lot of worry out of the chore of cutting steel.
This is a wheel we (Wood Tech Tooling) also sell. Our part number is A30-1418 and is 14" diameter x 1/8" thick x 1" bore.
From contributor C:
To all: Non-reinforced resin bonded wheels are generally used for saw gumming applications. Reinforced resin bonded blades are recommended for chop saw cut off applications, since these are hand fed operations. Some non-reinforced cutoff wheels are used in precision cutoff applications. These are usually wheels of small diameters and may even be rubber bonded to make it have a milder cutting action. In these situations, coolant is often used to help alleviate overheating.
There are other methods of cutting steel, including wire EDM and water jet.
To further clarify a previous post, the Makita OEM blade I'm familiar with is a triple reinforced blade manufactured by Noritake Sky Hawk of Japan and private labeled for Makita. There is no visible reinforcement mesh on the outer edges of the wheel except those that barely cover the diameter of the wheel mounting flanges. The outer reinforcement layers limit flexing of the wheel and alleviate the pinching that can occur when using non-reinforced wheels. The third central reinforcement mesh run the entire diameter of the wheel and is sandwiched in the middle. This provides wheel stability throughout the full diameter of the wheel. This is important when any side-to-side movement of the wheel when is it up to speed and being used.
From contributor R:
I value contributor C's knowledge very much, as he is a big help in this forum on a regular basis. Here is the number of the non-reinforced wheel from Makita: #724603-3 A 36P BAF. (When I say non-reinforced, I mean no mesh in the wheel.) Cost is under $10.00 each and they are used by hundreds of shops throughout the country. Even Weinig uses this same wheel. Give it a try – I'm sure it will work as well for you as it does for me and others.
From contributor C:
Makita-Direct.com is the USA's largest supplier of Makita Products and spare parts. I've known the owner since kindergarten and his family's been in this business since 1928. They are a discount Makita reseller.
According to my factory rep for Makita, the 724603-3 is indeed a single sheet internally reinforced wheel. I didn't know this until 15 years ago, after I myself had used this wheel for 5 years. As contributor R mentions, this wheel works quite well and is widely used. For our purposes, we found the triple-reinforced after-market wheel to cut faster and cleaner.
Again to reiterate, the use of a reinforced wheel is the safe way to go. It also adds much needed stability and structural integrity to the wheel.
From contributor R:
Thanks for the information. It goes to show that we all learn something new everyday. I don't sell them - I just use them, and they do indeed work well. Contributor C, I would be interested in the wheel you talk about. I would like to try out this wheel as a test.
From contributor G:
Would a horizontal band saw cut this steel? If it would, then all you would need is a cheap one about the same price as a cut off, but you would generate less heat, and could always use fluids to help. I used one of those saws a few years ago. A really cheap one made of sheet metal... And it worked fine on mild steel. Gave a good square cut, too.
From contributor W:
Contributor A's comment is right on per my limited experience. This is the accepted method. You need to lean into the saw. It seems brutal, but it is much cooler. Metal fab shops cut through big pieces so fast it is faster than a cutting torch. Much more of the heat will be blown out with the friable particles of carborundum and steel.
From contributor O:
Contributor A is correct. Unlike cutting wood, you must go through the steel very fast, otherwise heat will build up and the wheel will glaze, creating more heat. Being very aggressive carries away the heat and keeps the cutting edge fresh and sharp by continuously breaking it down. Unfortunately, none of the saws mentioned have the guts to power through the cut at the required speed. There is a way to get around that, however - cut in a series of very aggressive short bursts. The first few seconds, the blade will cut free and fast; right at or before the motor starts to bog down, raise the saw to allow it to recover and repeat until the stock is cut through. This method is fast and effective and if done properly, you should be able to pick the knife up at the end that was just cut without burning your fingers. It’s easier demonstrated than described, so you may have to play with the technique a bit. I have used most of the off-the-shelf saws described in this post and agree the Makita seems to work the best. I’m sure contributor C is right on regarding the blade.
From contributor T:
Contributor A is right on. EDM is "out of shop" and not only costly, but you don't have time for the preparation. (CAD work on your PC). Get the Makita 14" and 1/8" blades from local Ace Hardware and pressure the cut as fast as possible. Have a can of water and a small 6" grinder sitting next to the cut off and chamfer all the cut ends lightly after dropping the blanks into a can of water. Wipe dry and take to the table you use for setting blanks into heads. I spray WD40 on the blanks here and make them nice and clean and easy to set in heads. Spray WD40 on the corrugations in heads and blow dry with air hose. After setting blanks and putting head into the Rondamat, you will feel a lot more professional in that the tools are free from grit, sawdust, and very accurate and clean! The axial setoff will be easier to set and you'll love this system once you set up your tool room benches for it. I can grind a set of tools within 2 to 3 thou and in 20 minutes for a 3 to 4 inch profile, using this procedure, and the moulding finish shows it.
Tip: Get a couple diamond faced files (round and flat) to touch up the grind, keeping the micro grind to about 3 thou and at 15 to 18 degree for hardwoods. Your customers will be coming back "for more like that last job."
Wienig/Rondamat user since 1989.
From contributor T:
I forgot one step, though... Balance those cut off blanks!
