View Full Version : Slitting Saws - how to?
12-05-2009, 08:32 PM
OK I was going to be clever and use a slitting saw to make rail grooves on my bolt extension. WOW what a mess! The saws aren't able to cut into the metal for very long before (A) getting super-hot super-fast, and (B) dulling themselves in just a few passes. Destroyed two saws in about 15 minutes then gave up and finished with the dremel and a small file.
Is there a special kind of slitting saw that is intended for steel work vs. plastic/aluminum work? That's the only thing I can think of - that these aren't really for steel, rather softer materials.
I got a handful of these used off of eBay for about $1.50 each. Yes, they are fine tooth.
12-05-2009, 09:36 PM
Slitting saws for steel are usually made of highspeed steel. Sounds like you are either spinning the saw too fast (60 rpms ??), cutting too deep (no more than the blade thickness deep), not using flood coolant, pushing the cut too fast, or a mix of the above. Also possible is that the metal you are cutting is a tough alloy or has some residual hardness (file test ??).
The flood coolant helps clear the fine saw teeth of chips as well as cool things down.
I have burned up a number of thin saw cutters spinning them way too fast. Check for the proper surface speed of the teeth. Using a slitting saw in a mill is a "form cut" not single point. Form cuts require much greater attention per above as they cause a higher chip load.
Last resort... yes, you could use fiber abrasive discs in your mill (at higher RPMs) but with shallow cuts and/or slow feed. Those fiber abrasive discs are available in many handy sizes. Even Harbor Freight has them. Keep the sliding mill surfaces protected and cleaned of grit/dust.
Do check the hardness of your slitting saw discs with a file. The file should slip over them without scratching the blades. A Dremel with abrasive discs and some patience you can re-sharpen your slitting saw blades. The small purchase price you mention sounds terriffic.
12-05-2009, 10:09 PM
Jerry -- I can break anything but just used one to deepen the ejector slot cut in a bolt.
Like Viper, my suggestion is slow it down.
12-25-2009, 03:18 PM
FYI that seemed to do the trick - I cut some aluminum and at the slower speed it seems to work much better. Haven't attempted steel again. :)
Great machining videos from MIT.:headbang:
MIT TechTV – Machine Shop 5 (http://techtv.mit.edu/genres/24-how-to/videos/84-machine-shop-5)
This one shows how to use a sliting saw.
12-28-2009, 08:18 PM
That's a nice video - thanks! I'm going to add that page to Favorites.
He says 500 RPM but it looks like he was cutting aluminum. Only recommends .020" per cut "until you figure out how it works". Gotta love that :)