Slitting Saw Advice Requested

Could some of the more experienced hobbyists please expound on the slitting saw please - use/setup/speeds/feed/depth - any special prayers that must be said, background music that must be playing, exotic coolant that must be sprayed/flowed/misted etc.?

I've got a small project and a bandsaw won't do. I want to make a long thin slot (1/16thish wide, 1/2"ish deep) in a long (15") thin piece of CRS. If you can picture a woodworking backsaw - it would be the spline on top of the blade that stiffens the saw.

thanks
Joe
 
Joe, there is nothing to fear from slitting saws. The mandrel is easy to make if you do not have one. The saw blades can be very expensive if you buy a USA made blade $25+ however the Chinese blades work well. I use regular cutting oil and run the blade at about 400-600 RPM. To make a 0.500" depth of cut you will probably do better by making it in two passes. I routinely do 0.500" cuts but not for 15". I have never broken a blade nor a tooth. I use 2.5" to 3.5" blades, most from Grizzly. Not sure what all the fuss is about. Make a few test cuts on some scraps and I am sure your confidence level will rise substantially.

Jim
 
joe_m, that cut is a rather longish cut. Does your mill have the range to make an uninterrupted 15" long cut? Assuming you can find a way to index the work piece for multiple cuts, here are a few things to keep in mind:
  1. You can make a full depth cut of 1/2". Slitting saws are made for full depth cuts.
  2. Your mill must be trammed carefully or the saw can bind.
  3. The fit of the saw in the arbor has to be pretty tight - no slop - or you'll snap a blade.
  4. The blade should have at least 3-4 teeth engaged in the material at all times. The coarser the tooth count the better but the 3-4 teeth is a minimum. For the cut you cited I suggest a saw without any set.
  5. Speeds depend on the material and diameter of the saw. I will try to attach a pic below to guide you. It's from Martindale - you can look them up.
  6. Feeds should be done manually. It is best to begin a cut slowly until the teeth are fully engaged, and then you can speed up the feed until you settle into a steady pace. You need to feel the saw cut - it should be smooth but with a slight resistance to the cut - and listen to the cut - it will hiss slightly. Any screaming or whining indicates the speed or the feed is too fast.
  7. Coolant is important. Due to the nature of a slitting saw, excess heat will warp a blade fast so a lot of coolant and clearing the chips is important. This is one reason to use the coarsest saw appropriate to the cut. Any coolant you would normally use for the material you are cutting will work fine. You do not need to flood it but a constant drip on the teeth is a good idea.
  8. Be absolutely sure the part is clamped rigidly in the vise. If the part can move the saw will start a resonance that is hard to suppress and you will snap a blade. This is especially true for a long part such as you are contemplating.
  9. Be sure to lock any other axis other than your feed axis before making your cut.

I agree with Jim, slitting saws are not a big deal to use. Just pay attention to alignment, rigidity and cooling and you should be fine. Practicing on some scrap before your project cut will reduce any anxiety you may have.

Here is a table that I hope will help:

SSaws.jpg

Oh, one more thing. Martindale makes some good saws and I like them. Lots of others, though.

Best of luck,
Mikey

SSaws.jpg
 
Thanks - good info and I've printed it out to take to the shop. I have at least 18" of travel on the X-axis so 15 isn't a problem. That's a slower speed than I would have thought to go and I don't use coolant unless I'm reminded to. I have a good sized pile of slitting saws from 1/64 up to about 3/8 (the slot will actually be 1/32, not 1/16) but I've only got holders for the ones with smaller holes. I know I could make one for the 1 and 1.25" holes but I'm just going to order a cheap one and be done with it.
Joe
 
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