# New using saws in the milling machine



## Alberto-sp (Mar 21, 2022)

Hello.

I have a small milling machine  (70 kg) with brushless motor 750w and morse taper MT2. I have bought a milling arbor for circular blades 16mm internal hole diameter.

But I have no idea what is the best outer diameter and thickness for the blades. I use the milling machine for hobby, small parts of aluminum or mild steel. 

I know wthere is a lot of options, but for general purpose what diameter and thickness should I buy to start?

Thank you

Best regards


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## Lo-Fi (Mar 21, 2022)

For diameter, choose the smallest you can use for the cuts you need. The bigger they are, the slower you have to drive them and the greater tendency to wander.
Width, 0.5mm to 1mm on a small mill. Thicker saws have less tendency to wander. You could try thicker, but might find it tax the small machine.
For tooth count, at least three teeth in contact in the cut. Too small and they'll clog up with chips. Too big and the workpiece will get stuck between the teeth and probably break stuff.

Hope that helps!


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## Alberto-sp (Mar 21, 2022)

Thank you for your answer!

Around 0,7 mm thicker for example. And 50 or 63 mm it is OK?  I don´t know the size of the cut I´ll need but that diameters are OK for that size of milling machine?


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## Lo-Fi (Mar 21, 2022)

Yep , that all sounds pretty reasonable. Just take it steady and you'll be fine. Try and get the saw running as true as you can too. Sometimes clocking the arbor in the spindle and the saw on the arbor can improve things if it's running out a lot.


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## Alberto-sp (Mar 21, 2022)

Thank you!


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## Lo-Fi (Mar 21, 2022)

You're very welcome


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## homebrewed (Mar 21, 2022)

I have a similar mill and a saw arbor + a selection of blades.  Most of mine are 3" in diameter and range from 1/16" to 1/8" thick.  One thing I never do is to climb-cut when I'm using one.  On these smaller manual machines with noticeable backlash I think there's a greatly increased risk of breaking teeth or damaging the work....or both....when climb cutting.  I also lock the unused axes when cutting.

When setting up your saw and work, you need to be aware that the attachment collar on the arbor projects below the plane of the blade so there's a possibility of fouling the collar on your vise.  Saw arbors vary in how much the collar sticks out.  The ones that can accommodate different-sized arbor holes seem to be the worst for this.  Mine is bad enough that I have strongly considered making a slimmer replacement for it.


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## Alberto-sp (Mar 21, 2022)

Thank you.  I´ll buy diferent thickness and I´ll try the behaviour, because even the power and the weight, is not a very rigid machine. For example I bought a face mill 50mm diameter with 4 inserts and for example, facint a section of 2 cm wide on aluminum, 0,7mm DOC the machine vibrates so maybe try with not very thick blades.


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## Road_Clam (Mar 21, 2022)

A few comments. Slitting saws NEED rigidity which unfortunately benchtop mills do not. Slitting saws need very low rpm's and PATIENTS. I've jammed and ripped more than a few parts out of a vice trying to use a 3" blade on a Bridgeport. Cutting oil is a must use as well. I honestly don't think you will have success. A Morse taper setup is also a disadvantage as there is no postitve drawbar to help add retention and rigidity to the arbor. Cutting vibrations could cause the taper to release and that will end up real bad.


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## homebrewed (Mar 22, 2022)

Road_Clam said:


> A few comments. Slitting saws NEED rigidity which unfortunately benchtop mills do not. Slitting saws need very low rpm's and PATIENTS. I've jammed and ripped more than a few parts out of a vice trying to use a 3" blade on a Bridgeport. Cutting oil is a must use as well. I honestly don't think you will have success. A Morse taper setup is also a disadvantage as there is no postitve drawbar to help add retention and rigidity to the arbor. Cutting vibrations could cause the taper to release and that will end up real bad.


+1 on the patience and cutting oil.  When cutting steel with one of these my max DOC is .010", about .25mm, and feed rate = SLOW.  That's with a fairly thin blade.  This one of the operations where a power feed attachment, despite its additional cost, starts to look worthwhile.

That said, the resulting finish can be quite good.

While It shouldn't need saying, slitting saws can be dangerous.  If something gets caught on a tooth and pulled into the cut slot, it's going to get hurt.  Be careful out there.  I learned the easy way, by getting a brush I was using to apply cutting oil caught and sucked into the slot.  The bristles got a real rad haircut out of the deal.  Fortunately it just stalled the motor but.....it made me think, yessirree!


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## Firebrick43 (Mar 22, 2022)

Road_Clam said:


> A few comments. Slitting saws NEED rigidity which unfortunately benchtop mills do not. Slitting saws need very low rpm's and PATIENTS. I've jammed and ripped more than a few parts out of a vice trying to use a 3" blade on a Bridgeport. Cutting oil is a must use as well. I honestly don't think you will have success. A Morse taper setup is also a disadvantage as there is no postitve drawbar to help add retention and rigidity to the arbor. Cutting vibrations could cause the taper to release and that will end up real bad.


Just because its morse taper doesn't mean it doesn't have a drawbar.  All the morse taper milling machines I have seen (mainly emco and atlas) have drawbars.


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## WobblyHand (Mar 22, 2022)

Slitting steel on a small mill can be done, but it is slow.  I cut these slots on my small mill using a 1/16" (1.6mm) thick, 4" (100mm) diameter saw.  It took me 2-1/2 hours!  The slots are 25mm deep.  You need a lot of oil.  Wear an apron or some bad clothes, because you will have oil on you.  30mm diameter mandrel made of 1045 steel.  A 4" blade is too big for my mill, but I did not know that when I bought it.


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## Road_Clam (Mar 22, 2022)

Firebrick43 said:


> Just because its morse taper doesn't mean it doesn't have a drawbar.  All the morse taper milling machines I have seen (mainly emco and atlas) have drawbars.


Honestly didnt know the MT spindle option mini mills utilize a drawbar.


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## mikey (Mar 22, 2022)

I've been using slitting saws for 40 years, in a little Sherline mill and a larger RF-31, and have had zero issues with these saws in either mill. I think a benchtop mill can easily use these saws; my Sherline is about 40# soaking wet and it blazes through aluminum, steel, stainless and brass parts with no problems. Same for my RF-31.

I do believe a good arbor is important. Sierra American makes good ones and shop made versions of similar design will also work well. 

Slitting saws are intended to cut to full depth all at once. There is no need to sneak up on a cut. They also are meant to produce a chip. It works best to feed manually so that you feel a slight resistance to the feed, thus assuring the saw is cutting continuously. 

Lots of lubricant is a good thing. You have two sides clamping down on the blade and lube helps reduce friction and heat. 

Always feed conventionally.


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## Alberto-sp (Mar 22, 2022)

Thank you veeeery much for all your help and answers!!

The mill has a draw bar with a M10 thread.

And yes, I´m very carefull using the mill an the lathe. Apron, protection glasses and sometimes a plexiglass mask to cover all the face (I´m ugly enough)


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