Looking for a primer on using a slitting saw

[great white]

As in the title, I'm looking for some good gen info on using a slitting saw. I've never used one before and just ordered one with an r8 shank to use in my drill/mill (cx600/g0704).

I guess I'm looking for info on speeds for different materials, depth of cut on a pass, oil needs, possible jamming concerns, etc. Types of saws, what they 're used for, can you cut gears with the slitting saw arbor, what other uses it has, etc.

Any info on proper use would be appreciated.

Thanks.

 

[bill stupak]

Feeds and speeds I can't help you with, but on an older Tom Lipton (OX Tools) video he recommends full depth cut with slitting saws. This has worked for me.

 

[ps15toolroom]

Conventional mill. Lubrication and chip removal from teeth are the biggest factors in success. Keep brushing the saw as it cuts. When used properly you can take one or two passes.

 

[benmychree]

For slitting, use coarse tooth saws, NOT fine tooth screw slotters. I agree, about full depth cuts, speeds according to general tables of cutting speeds, feeds by feel, don't crowd the cutter nor feed too fine.

 

[Chewy]

This is a case for a mister or coolant flow to keep chips out and the blade cool. A stream of air will help if you don't have coolant. You can hand brush the coolant but a steady flow will increase the cutting speed. You will probably be in the low couple of hundreds speed. I cut to full depth on first pss. When you buy the saw blades, subtract the arbor size from the diameter. A 3" blade on a 1" arbor will give you around 13/16" - 7/8" depth of cut. You have to subtract the outside dimension of the arbor. There are some ways to approach from both sides and finish by hand when you run out of depth. I find 1/16" blade most useful and just ordered a 4-1/2" diameter.

 

[homebrewed]

I have a Sieg SX2 benchtop mill with an R8 spindle. I have an R8 saw arbor and I always have been pretty conservative when using it, due to the machine's relatively low power. My choice of depth of cut really depends on what I'm cutting. Plastic like derlin or acetal is basically a plunge cut to depth. When I cut aluminum I go down to .010" per pass -- obviously, multiple passes. This is based on observations regarding swarf clinging on to the blade when it re-enters the cut, because it causes a noticeable "whang" when that happens. I drop down to .005" per pass when cutting steel. Lubing and cleaning the blade as it turns -- yes, all the time.

I think some issues regarding feed rate are greatly affected by the saw arbor. Cheap saw arbors like mine don't do a good job of aligning the blade so only parts of it really cut -- so swarf only accumulates in that part of the blade. That increases the effective feed rate, with attendant issues depending on the material being cut.

 

[Larry$]

I've got an R8 commercial arbor that I rarely use. The bottom part of it is too big and limits where I can use it. Easy to make arbors and there are several good videos. Stefan G has one. So does Blondihacks. Since the rotation may tighten the screw, put some oil or anti-seize on it. I use a needle tip applicator & WD40 for slitting aluminum and oil for steel. Be generous with it. Aluminum welded into the teeth of the saw is a real pain to clean out.

 

[compact8]

The followings are based on my limited experience with slitting saws :
- use the smallest diameter that can do the job, this minimizes flexing and reduces the load on the machine.
- pay attention to flexing of the blade if the thickness is small. E.g. Most of my blades are only 0.5 mm thick. HSS blades this thin are too flexible so I use carbide blades but still I can end up in having one side of the slot higher than the others because of blade flexing. The problem can be alleviated by making several passes starting with shallow DOC and gradrally increasing it as the blade goes deeper.
- the machine will chatter when the limit of DOC or rate of feed is reached so listen to it.
- check the radial and axial run out of the blade edge with DTI after mounting. If it's excessive, either the blade or the arbor is bad. My practice is to try different angular positions of the blade and pick the one producing minimum axial run out.
- use lots of oil

 

[SLK001]

I cannot stress the importance of lubrication and chip removal during cutting. Without it, your blade will seize and damage a) the machine, b) the work, or c) the blade. Sometimes all three. You will want to go slow, both with speed of machine and feed rate.

 

[WobblyHand]

For a PM25 class machine make sure you have the pulleys in the lowest speed range. Small mills don't have that much torque. Mine would stall if used in the higher speed range.

Use the smallest diameter saw you can get away with. The RPM you can use is lower than an ordinary end mill. If the blade speed is too fast you will dull the blade. If you are cutting steel, use the SFM for steel and calculate the RPM based on the blade diameter. There's lots of speeds and feeds calculators online, I use the one on little machine shop.

I used to take tiny cuts, but now take the whole slice. Lube all the time while cutting and use the lowest gear with the correct SFM is the trick. Feed by hand to get an idea what is acceptable. Your mill will tell you, it's quite communicative, but you have to listen.

Edit: Each material has a SFM (surface feet per minute) rate for it. There is a range, but low carbon steel is about 100, where as aluminum is about 400 for HSS (high speed steel) cutters. You can use about 3x faster SFM if you have a carbide blade. The equation for RPM is:

RPM = SFM * 3.82 / diameter (inches)

As a short cut you can use 4 in place of 3.82. 3.82 = 12/pi. As a beginner, I wouldn't recommend a carbide slitting saw blade as they are brittle and can break.