Gallery, Projects and General > Oooops!

I screwed up using a slitting saw..

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ieezitin:
Lads

In the shot below is a set up on the milling machine of me trying to Slit-saw a taper pin expansion rod i am making. The saw thickness is .007 thou x 1 1/8th od, i ran the mill at 150 rpms the part is made out of 304 stainless.

In this shot you see the work in front of the slitting saw, i centered the saw blade to the pin center and i plunged cut in (moving the part away into the blade) .075 thou. that worked fine, i bathed it in Kroil and slowly fed the part onto the blade.

I then needed to slit the other side of it so i just raised the quill and moved the table 180deg, lowered the quill to center height and started to slit this side. 

The device you see poking into the end of the collet block is a stop for the pin up in the hole, my thought was the blade may want to throw the pin out. That will become clearer on the next photos.







Here is a shot of the first side i successfully cut.






Well!!!!!!!!! here is what happened when i did the other-side, i got to about .050 in the cut and the thing turned to Shite, the blade snapped and at the same time gouged the piece which is now ruined.





Here is the shot of the part with the pin included, i installed a sacrifice pin into the arbor for the machining process in slitting, the wall thickness on the taper tube end is around .032 thou






I figured that what i am trying to explain may be a little hard to do in words so i can show you my drawings for you all to get a better perspective.


Linear drawing showing taper reamer and drill, this is to scale.





Detailed drawing.








And a shot of the pin installed before being turned down.



 






What i shall do now is re-make another one and this time just index the pin, as i know it worked in that location.

if anyone has any experience in using very thin slitting saws i would appreciate the advice, i have never slitted anything this thin.

Happy days      Anthony.

vtsteam:
Take everything I say with a grain of salt from a low experience source, who has made a few deep slitting saw cuts on occasion. But who has experience with larger saws. Apologies in advance for treading where angels fear to.

Plunging with a slittling saw like that seems to me difficult, but I can see why you did that because the saw arbor is too wide to allow slitting as a set of traverses from the end of the piece. I make it out that you were running 44 SFPM (if I didn't screw up calculating) which seems slow for 304. I don't know what the sacrificial piece is made of, and also tpi of slitting saw compared to wall thickness. Seems like sacrificial piece, if necessary should be easy cutting but not something that will grab (like brass -- if relief angle is great) or make grabby swarf.

Hope that helps, or at least doesn't interfere!

ieezitin:
V___

thanks for the input.

the sacrificial piece is steel its a shop purchased taper pin. i need to find out what the tooth count was on the saw to give people more information on trying to solve this pesky problem.

again thank you..

Anthony.

vtsteam:
ieezitin, I was thinking about it a little more today while I was working. If you look up my quick change tool holder thread you'll see some pretty deep cuts with a slitting saw, but not stainless and not the thinness of your blade -- so same grain of salt......

But I used a commercial water based coolant and kept a pretty constant spray from a spritzer bottle going while taking small cuts. If that thin blade of yours heats up it probably will warp. And if it does, I think it will jam in the cut.

I don't know about Kroil -- never seen the stuff -- but I think it's an oil based rust buster, not necessarily a coolant, though I'm sure it lubricates. Water based coolants would do a better job I think of actually keeping everything cool.

So, I'm thinking speed and feed should be checked based on your material, blade diameter and tooth count, and then use a real coolant.

And if possible try not to plunge cut. Can you traverse in from the end of the piece towards the other end?

ieezitin:
V----------

here is a little more info... i was wrong on the OD of the cutter its 1.740 and it has 17 teeth per inch.

Kroil is a rust / nut- loose type product but it is thin and between the fingers it gets very slippery, i use it on Ali all the time and works fine. i would have used Tap-Majic if i had some but i did not. Neither do i have any water coolant to be honest i do not usually use any coolant on my machining just a little WD40 and fine turbine oil for drills and reamers, maybe that would have worked. 

I too have been thinking about it more and i believe the coolant had a major roll in the destruction of the cutter. 

I plunged cut because the blade is so thin i just was having a hard time in my mind asking the blade to cope with feeding it inn the piece.

we all live and learn............................  Anthony.

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