Slitting saw - how to choose

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martik777

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I need a saw that will cut thru 4140 occasionally .190" thick but usually .040" thick.

I've been using 40mm x 1mm x 72t but the teeth dull quickly.

Would a thinner blade wear less? How about less teeth? I don't need a fine finish. I've used angle grinder cutoff wheels but they tend to not cut straight as they are too thin and flexible.

Here's some I am looking at:

tinyurl.com

US $3.15 28% OFF|Useful 80mm Outer Diameter Thickness 1.2mm HSS 72T Slitting Saw Cutting Edge Tool Y1K9 For Home And Production Saw Tool-in Saw Blades from Tools on Aliexpress.com | Alibaba Group

Smarter Shopping, Better Living! Aliexpress.com
tinyurl.com tinyurl.com

tinyurl.com

US $4.18 25% OFF|30T Circular Metal Slitting Saw Blade Cutter 105mm x 20mm|Saw Blades| - AliExpress

Smarter Shopping, Better Living! Aliexpress.com
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Slower rpm, light feed and lots of lube. Thin saws will wrinkle during a heavy feed, the flex will cause a crack. Watch out if your table has stick slip.
 
I would be running that size of blade at around 180 - 200 RPM in 4140. Much faster eats teeth quite quickly.
 
Ah,
Are those to be used on a horizontal mill?
Angle grinder?
No key slot.
 
martik777 said:
I need a saw that will cut thru 4140 occasionally .190" thick but usually .040" thick.

I've been using 40mm x 1mm x 72t but the teeth dull quickly.
Click to expand...

I have same saw.
I run mine at 70 RPMs with a <slow> drip lube system on to the top of the blade.
 
I hope I'm not stepping on any toes here but this thread is relevant to my needs so I'd like to post an on topic question.

I'm working on a small project that requires a slit cut into the end of an aluminum round of 0.750 diameter. The slot will be across the face (like a nock on an arrow) to a depth of 0.875" and width of 0.114".

So I've read that one should choose a saw blade that has as small a diameter as possible that still allows the depth of cut. Now what about tooth count? Usually we like a larger tooth with a bigger gullet for cutting aluminum, right? Or maybe smaller teeth are better because the feeds should be pretty slow for slotting/slitting?

I've never slotted before and this will be attempted on an Atlas lathe with the milling attachment. I have more questions regarding the actual process but I figure I'd start with choosing equipment!
 
To get that depth of cut, you will need a saw around 3 1/5" - 4" in diameter. What is the lowest RPM of your machine? Good thing it's aluminum. I'd keep it way below 2000 RPM, with lots of kerosene or WD40. Aluminum can heat up in a slot and expand to grab the blade. I'd tend to go with the courser tooth. You'll never use a blade that big on steel.
 
The lathe I'm gonna try this on has back gears so it can go pretty slow. I never had a manual for it but from searching around on the net I think the slowest it goes is probably around 28rpm. That seems maybe too slow?

Also, hypothetically speaking, if you had to make this cut in steel, what could you use?
 
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