Which slitting saws

[Keith MathesonParticipant @keithmatheson47708]

Hi, I’ve never had much luck with slitting saws. I struggle to get the speed right, they jam, and the cut also drifts away from where it should go. Clearly trying to do this with an assortment of random slitting saws I acquired is adding to my issues ( I guess itS sort of the same question as ‘ I can’t get a decent finish on this material I’m turning, To which the more experienced ask ‘ what material exactly is it? Answer I don’t know! I’m planning to purchase some new blades and start with the right blade for the job. I would need to slit aluminium, stainless steel and regular steel. I have a gift voucher for Chester so plan to use them. To this end which blades (diameter and teeth ) should I purchase? I enclose a screen shot of the blade options they have. Many thanks in advance

[Keith MathesonParticipant @keithmatheson47708]

[Anonymous]

They all seem to be fine tooth saws, so only really suitable for shallow cutting, such as slotting screw heads. For deeper slots you need coarse tooth saws. Here's a picture of several saws (all coarse tooth apart from bottom right) for comparison:

Ideally for deep cuts with a coarse tooth saw the saw needs to hollow ground to reduce rubbing in the slot.

Andrew

[Howard LewisParticipant @howardlewis46836]

If the cut wanders, you may be trying to feed too fast, (saw jams is another clue ) and a fine tooth saw wis more likely to clog if over fed.

HTH

Howard

[JasonBModerator @jasonb]

If getting from Chronos then go with the 3" x 30T if you want imperial widths, none of their metric offerings look that fine (they do use one photo for all) so if you want metric then I would go to say ARC who have coarse ones.

[EmgeeParticipant @emgee]

Keith

As well as tooth count you need to take note of the hole size compared to saw diameter, a 2.5" diam blade with a 1" bore will seriously limit the depth of cut the saw can make, you have to have a big enough diameter on the arbor and securing nut to provide sufficient grip, without a keyed drive the saw will slip on the arbor and is sure to jam in the cut.

I think you will be best served by a 1/16" thick blade, any thinner and they can easily wander off course if fed too fast.
If you can use flood coolant to keep the chips clear the finer tooth blade will give good service, if no coolant you will need to go with the coarser tooth count as stated by others.
Carbide are far better than HSS but cost a fortune.

Emgee

[SteviegtrParticipant @steviegtr]

Hardest thing is finding an arbor that is central. I have a stack of various saws from good makes. 3 arbors that cut on maybe 6 teeth if I am lucky. Note to oneself. Make an accurate arbor for the saw's.

Steve.

[JasonBModerator @jasonb]

Stevie, the blades never seem to run true even on a true arbor.

[SteviegtrParticipant @steviegtr]

Posted by JasonB on 20/05/2020 07:15:15:

Stevie, the blades never seem to run true even on a true arbor.

Steve.

[Nigel McBurney 1Participant @nigelmcburney1]

Keep within the recomended cutting speed and do not feed too fast,drip some high duty cutting oil eg Rocol on the saw teeth when cutting stainless.Remove the key from the arbour when using thin saws its better for the cutter to slip than shatter into lots of pieces.Make sure the collars on either side of the cutter are the same diameter to avoid distorting the saw.

[AdrianRParticipant @adrianr18614]

I can't remember where, but recently I read that it is better to use course blades than fine. This is because each tooth needs a feed, so the more teeth the faster the feed rate and hence easier to feed too slow and rub blunt.

Made me feel better about the course blades I have.

Adrian

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Steviegtr on 20/05/2020 09:19:05:

Posted by JasonB on 20/05/2020 07:15:15:

Stevie, the blades never seem to run true even on a true arbor.

Steve.

.

I thought we had the makings of a useful discussion about this, but it seems dead in the water [until next time someone asks]

MichaelG.

.

Ref. https://www.model-engineer.co.uk/forums/postings.asp?th=162992&p=2

Edited By Michael Gilligan on 20/05/2020 09:48:42

[Anonymous]

Posted by AdrianR on 20/05/2020 09:34:36:

I can't remember where, but recently I read that it is better to use course blades than fine.

Both have their uses. It's all to do with the size of the gullet. With a fine tooth saw a large depth of cut is a problem as the gullet may get full of swarf, which will cause the saw to jam. For a shallow depth of cut (like slotting a screw head) a fine tooth saw is fine, and can be feed at a higher rate as it has more teeth. For a deep depth of cut a coarse tooth saw has a much larger gullet which will be less prone to jamming.

Andrew

[SillyOldDufferModerator @sillyoldduffer]

Another thing I may be doing wrong apart from trying to take deep cuts with saws designed for shallow slots is how best to tackle the job?

I feel it's best to go through with a series of shallow cuts, going deeper with each pass until the job's done. Results aren't wonderful: the blade and/or swarf tend to jam in the slot, the cut wanders, and finish is erratic.

Is my technique a mistake due to learning with the wrong blades! Now I'm wondering if it's better to cut clean through with a single deep pass and a suitably relieved coarse saw. Any experts able to comment?

Dave

Edited By SillyOldDuffer on 20/05/2020 10:25:38

[John BaronParticipant @johnbaron31275]

Hi Dave, Guys,

It was not understanding slitting saws that caused a jam up when cutting aluminium on the mill, destroying the teeth on the plastic gear.

If I have to do a longish cut in any material I prefer to use the bandsaw. Otherwise its slow and steady with lots of lube. Trying to do a cut in one go doesn't take into account that as you cut the stresses in the material tend to cause the blade to become trapped. The slit closes up, the material twists and all sorts of weird things happen.

As an example, I milled a long 8 mm wide slot 10 mm deep in a piece of material, about 12 mm from one edge. Lovely cut no issues at all. Until I came to refit the workpiece. The slot had opened up and the outer edge had twisted several mm, preventing the piece from fitting back into the frame of the slide.

[Mike DonnerstagParticipant @mikedonnerstag]

Just a thought following using a fine-tooth 2.5” x 1/8” slitting saw today to do a deep cut on 1” EN3 steel with a Sieg SX3 mill. Does a fine-tooth slitting saw apply greater pressure on the work, therefore demandIng greater rigidity in the mill and setup, when compared to a coarse-tooth saw?

[JasonBModerator @jasonb]

It will when the gullets of those fine teeth fill with swarf, keep the fine ones for shallow cuts or thin material.

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