# Slitting Saw Depth of Cut



## Nyala (Mar 9, 2019)

I'm looking at a future small scale project that will require the use of a slitting saw, something that I have never used.  The question that I cannot seem to find an answer for in my research is in regards to blade diameter.

I will need to cut a .125" slot in 1/2" aluminum, about 1.25" deep. 

When I buy a blade, how deep can I expect it to cut?  I know that I'm not going to get a 2" deep slot with a 2" blade, but how deep can I expect a 2" blade to reach?  Perhaps I need a 3" blade, or a 2.5" blade.  

There is lots of talk on the forum and Internet about the depth of individual cuts but I couldn't find anything related to the overall reach of any given diameter blade.

Can anyone advise?

Thank you.

Denny


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## Latinrascalrg1 (Mar 9, 2019)

The depth of cut will be Exactly half the diameter of the saw blade minus half of the diameter of the mandrel/mounting post that drives the blade.

I would get a 3" blade to cut the 1.25" slot you need assuming the drive post/mandrel is no larger then 1/2" diameter.


This reminds me of a riddle from my childhood which ask this question.........How far into the woods can a wolf chase a rabbit?................................................. Answer, Half way!  Once the rabbit reaches the center point the wolf would then be chasing the rabbit Out of the Woods!


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## MarkM (Mar 9, 2019)

Why not just use a two flute endmill with successive cuts until depth is reached being aluminum?


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## 4ssss (Mar 9, 2019)

MarkM said:


> Why not just use a two flute endmill with successive cuts until depth is reached being aluminum?



Because you can plunge saw the part in a less than a quarter of the time it would take you slot it with an end mill without worrying if the end mill will break


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## benmychree (Mar 9, 2019)

Latinrascalrg1 said:


> The depth of cut will be Exactly half the diameter of the saw blade minus half of the diameter of the mandrel/mounting post that drives the blade.
> 
> I would get a 3" blade to cut the 1.25" slot you need assuming the drive post/mandrel is no larger then 1/2" diameter.
> 
> ...


Most slitting saws that could achieve that depth of cut would have a much larger arbor hole than you suggest, and allowance needs to be made for the collars and whatever else holds it on the arbor, that means that the slitting saw would have to be on the order of 4" diameter.


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## kb58 (Mar 9, 2019)

There are other forums here much more appropriate for this thread, because you're only asking people that own PM gear with it hear.


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## Nyala (Mar 9, 2019)

My thanks to all.  Now I have a place to start.  I will only need to cut two parts but using an end mill wouldn't give any experience (newbie here) using a slitting saw.  Plus, I wouldn't have an excuse to buy more tooling : )  I'll buy the blade and arbor together to I can have a good idea of the capabilities.


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## darkzero (Mar 9, 2019)

MarkM said:


> Why not just use a two flute endmill with successive cuts until depth is reached being aluminum?



Do 1/8" endmills with 1.25"+ flute length exist? I would prefer to use a slitting saw also.


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## MarkM (Mar 9, 2019)

I don t think you d have any issues using an endmill to save the time and money to purchase the appropriate saw and arbour for an open slot in a Aluminum.  Proper speeds and blow your chips but I Completely understand why you want to proceed the way you do.
Kb 58 I think your way off base here.  There are plenty here with more than enough experience and quality equipment.
Yes they do exist.  At times you need the reach a corner of a pocket or something but here you would just take your time since your not cutting a 1.25" depth in one shot even if the flutes don t reach the 1.25" depth.  Good enough here!  Blow your chips out and you should be fine.


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## pstemari (Mar 9, 2019)

Probably. I have a 3/8” end mill with about a 2" cutting length, which isn't quite as extreme. You'd definitely want carbide, though.

My experiences with sitting saws have been unpleasant. The thin ones I've used had a bad tendency to bind.

Sent from my Pixel XL using Tapatalk


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## mikey (Mar 9, 2019)

Nyala, you can get slitting saws with really small center holes, down to 1/2". However, they will not be as stable in the cut. Your best bet is a blade with a 1" center hole, which means the holder will be somewhere around 1-1/2" OD. So, half the OD of the arbor is 3/4", plus the 1.25" depth of cut is 2", so at minimum you will need a 4" blade or possibly a 5" blade. You want to have at least 3 teeth in the cut at all times you're looking for a blade with a lower tooth count. Hollow ground blades work fine for aluminum and the lower tooth count will help clear chips better. When you cut, take the cut at full depth and use a lot of cutting fluid to reduce binding. 

Have a look at the Sierra American slitting saw holders. They work very well, have the minimal diameter needed and are fairly priced.


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## Nyala (Mar 9, 2019)

Thanks Mikey.  I'll look at Sierra American and take your advice on blades.  Up until a couple of days ago I didn't know what a slitting saw was, so all of this information works to educate me on their use.  I have so much to learn about machining.  

Denny


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## mikey (Mar 9, 2019)

Nyala said:


> I have so much to learn about machining.




Yeah, me too!


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## mmcmdl (Mar 9, 2019)

Do you have an R8 spindle ?


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## mmcmdl (Mar 9, 2019)

kb58 said:


> There are other forums here much more appropriate for this thread, because you're only asking people that own PM gear with it hear.



Not sure where this came from . Actually , many of us here don't know what PM stands for .  Oh , you're talking about the thread location .


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## Latinrascalrg1 (Mar 9, 2019)

mmcmdl said:


> Not sure where this came from . Actually , many of us here don't know what PM stands for .


Doesn't PM mean "post meridiem" aka After Noon?


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## darkzero (Mar 9, 2019)

mmcmdl said:


> Not sure where this came from . Actually , many of us here don't know what PM stands for .



Aside from the time of day, PM on forums always brings Private Message to my mind. That's what it's been called for most forums forever but Xenforo decided to call it Conversations which I hate. Now a days with social media, all the kids say DM (direct message). It kind of erks me when I hear people on forums say "DM me".

But to the point of your question, I believe what @kb58 was trying to say, may have been better to post this question in general etc for more exposure since it's a machining question rather than in the PM forum here. The question has nothing to do specifically with Precision Matthews machines.

Depends how you view new posts though. Some people only view specific sections. I view by the New/Recent Posts feature so where ever it's posted doesn't matter for me.


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## Nyala (Mar 9, 2019)

I'm using a PM-25MV with an R8 spindle (also with DRO).   My current project is motorizing the Z axis.

I've had it set up for a little over a month and have been doing small things but no real projects.  I watched a number of YouTube videos and selected some small projects to get my feet wet and downloaded some prints.  I am using the mill in connection with a South Bend Model C, 9x20 lathe.  The lathe was build somewhere between 1937 and 1942 but was completely rebuilt by Dad.  He even made all the missing gears for threading.  The bed was scraped in by him and the lathe works like a charm, but it's small.

I inherited the lathe and a ton of tooling from Dad while he was still with us.  Dad was a life long machinist and have some tooling that is way to big for me to even use (1" boring bar a foot long), but 99% of it will all work for me.  Most of his tools were Starrett.  If I look hard enough, I might even find an arbor for the slitting saw.  I have tools that I don't even know what they are.

One thing I am looking at is a QCTP for the lathe.  It's far too hard to work close to the chuck with the lantern style tool post and small things often do not extend out very well.  I do not have any collets for it so I have to be careful not to run into the chuck.  I sometimes extend the part or the tool out further than I want to avoid the chuck.  

I tried cutting a taper by offsetting the tailstock and turning between centers using a lathe dog.  Sometimes I was successful and sometimes I simply broke the part.  I have a bunch of broken parts.

I create small things that I can use and will not likely ever create anything major with these small machines.  

I really do appreciate everyone's help.  I received some basic lessons on the lathe from Dad, but I'm going cold with the mill.

Thanks for everything.

Denny


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## mmcmdl (Mar 9, 2019)

I have R-8 arbors and many saws if you wanted to try one for hahas . As long as I get it back , you could use it .


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## mmcmdl (Mar 9, 2019)

darkzero said:


> But to the point of your question, I believe what @kb58 was trying to say, may have been better to post this question in general etc for more exposure since it's a machining question rather than in the PM forum here. The question has nothing to do specifically with Precision Matthews machines.
> 
> Depends how you view new posts though. Some people only view specific sections. I view by the New/Recent Posts feature so where ever it's posted doesn't matter for me.



After reading his post , I understand what he meant .  He was referring to the thread in which it was posted and not the members responding . So , what does PM mean ?


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## darkzero (Mar 9, 2019)

mmcmdl said:


> After reading his post , I understand what he meant .  He was referring to the thread in which it was posted and not the members responding . *So , what does PM mean ? *



Private Message.  

It can mean whatever, doesn't matter to me, as long as I'm not around when it has a S at the end!


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## MarkM (Mar 10, 2019)

I suggested to go with the endmill (carbide for less flex) knowing there is a better solution.  Slow and easy to save some time and money for this one off.   May I suggest a staggered tooth cutter and make sure it is a slitting saw not a slotting saw.


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## jwmelvin (Mar 10, 2019)

MarkM said:


> ...make sure it is a slitting saw not a slotting saw.



What’s the difference, please?


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## MarkM (Mar 10, 2019)

Slitting saws or more for depth with the proper clearance to the bore.  Slotting saws are more for shallow cuts like a screw Head.  As I have always thought.  Your looking for lots of room for chip removal!


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## projectnut (Mar 10, 2019)

If you have an R8 collet system you can get a stub arbor for 1" cutters from Shars for $31.95 plus shipping.  





						1" Stub Milling Machine Arbor
					

Shars Tool




					www.shars.com
				




I just purchased one for use on my Bridgeport.  I normally use the cutters on my US Machine tools horizontal mill, but the parts I need to cut for my current project are about 40" long.  Way too big for the little horizontal mill.  Even on the Bridgeport I'll need to refixture them a couple times to get the full length of cut


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