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old mart
11-10-2016, 03:43 PM
I have just got a MT2 arbor of 13mm size which takes 50mm slitting saws. it has a key and I now have a set of saws from 0.5mm to 3mm thick.
I was worried about the key and havn't fitted it yet.
What speeds are best and how big a cut can be taken or are lots of small passes the way to go?
I would use tapping oil on steel and WD40 on aluminium.

dalee100
11-10-2016, 03:53 PM
Hi,

On such thin saws I don't use a key. Friction is enough to hold them. As far as speed goes, I assume they are HSS so, standard formula for HSS cutting speeds. So you are looking at 170 to 200rpms for mild steels. A bit less for tool steels.

The thinner the blade, the less depth of cut. And the deeper you get, the greater the chance of material stress relieving itself and pinching the blade. This is why I don't like key driven slitting saws. Big shell mills are different.

Oil is good for steel and WD40 for aluminium, though I mostly have used flood coolants over the years. Since it was there.

Dalee

fixerdave
11-10-2016, 09:55 PM
I recently hijacked another thread to ask this question. Surprisingly, at least for me, you can take pretty much the entire saw depth in one go. No need to make a whole bunch of light passes. Some people say to watch out for the tooth gullets filling and binding. Another recommended taking a light pass first to make a grove to help guide the blade.

I tried this in steel, one pass 15mm or so deep, and it cut no problem with about a 1.5mm thick saw. It worked surprisingly well, much better than multiple baby-passes at 0.5mm deep. Oh, and I'm using just about the junkiest Chinese wet-noodle lathe/mill combo you can get. No key, just a cheap arbor with a 1/2" Weldon shank.

David...

old mart
11-11-2016, 09:09 AM
I tried mine without the key and left the belts fairly slack. A five mm total depth in about 4 passes in some type of austenitic stainless steel. Used the rotary table and chuck on its side to put 2mm slots like a castellated nut in the end of a special pivot bolt. This is part of the anchorage points to hold a Westland Lynx onto the deck of a ship.
I produced 8 slots in all and the blade jammed twice momentarily, I reversed the feed quickly and everything was hunky dory, no damage noticeable. Glad I ran the belts slack.
I had contemplated using 2mm end mills, likely to end in tears.

Carm
11-11-2016, 10:16 AM
I recently hijacked another thread to ask this question. Surprisingly, at least for me, you can take pretty much the entire saw depth in one go. No need to make a whole bunch of light passes. Some people say to watch out for the tooth gullets filling and binding. Another recommended taking a light pass first to make a grove to help guide the blade.

I tried this in steel, one pass 15mm or so deep, and it cut no problem with about a 1.5mm thick saw. It worked surprisingly well, much better than multiple baby-passes at 0.5mm deep. Oh, and I'm using just about the junkiest Chinese wet-noodle lathe/mill combo you can get. No key, just a cheap arbor with a 1/2" Weldon shank.

David...


All this done with a slitting saw?

J Tiers
11-11-2016, 10:37 AM
Never mind the names......

There are a few types of saws.

1) designed for cutting shallow slots, like screw heads. Small teeth, no dish-relief ground. Don't go very deep with these in one pass, they can bind, and they can fill the tooth gullets and jam. No key may be best.

2) Designed to cut deeper, larger tooth gullets, saw dish-relieved. You can go deeper, but best not to "bury" them in the cut. Less issue with binding and gullet filling. Key wide ones only.

3) Side cutting saws, with teeth on the periphery and also on the sides. Large tooth gullets. Go ahead and bury these, regulate the feed to avoid filling the gullets, but keep them cutting. Key is fine in general, the saw will normally cut its way out of trouble.

old mart
11-11-2016, 12:51 PM
The saws I bought have no side relief or set, the one I used, 2mm, had some eccentricity. I will have to find out if the blades are poor or the arbor. They were at the lower end of the price scale, so I can't complain. The saw I used seemed just as sharp afterwards as it was when unused. I think the mill was at 120 rpm, minimum speed.

fixerdave
11-11-2016, 03:01 PM
All this done with a slitting saw?

http://i1281.photobucket.com/albums/a507/fixerdave/IMG_20161008_175820_zpsetqiezc6.jpg

I know, not the greatest picture. As far as I know, that's called a slitting saw, not dished and not any set to the teeth I can see, and that was one pass. No issues at all.

My questions were prompted by a picture on this thread:
http://bbs.homeshopmachinist.net/threads/71625-Slipping-arbor-on-slitting-saw
http://i5.photobucket.com/albums/y154/mudnducs/slit3_zpsfgwmqpg6.jpg

I'm not an expert here... just saying what I asked, read, and tried. Worked for me.

David...

old mart
11-11-2016, 04:08 PM
What happened when you got to the end of that cut, Fixerdave?

fixerdave
11-11-2016, 04:36 PM
What happened when you got to the end of that cut, Fixerdave?

I did the MT3 collet in the first picture. The second picture was another guy complaining about his slitting saw slipping on the arbor 3/4 of the way through the cut. Obviously, because the blade was getting pinched. I was just shocked that you could cut that much in one go with a slitting saw. Others said it was okay, so I tried.

With the MT3, that was the end... well, that was what it looked like after I put it back in the slot to take the picture that I forgot to do earlier ;)

It was plunged in at one end, full depth, moved to the other end (which was a drilled hole), and then withdrawn. No issues at all. Oh, yes, the slitting saw did not cut perfectly concentric... not all the teeth cut but rather more of a pulsing. But, that seems to be the way with slitting saws.

David...

boslab
11-11-2016, 06:10 PM
I've also found the benifit of sticking a wedge (said fox wedges on box) into the cut to stop it biting the blade, same as they do with timber,
https://www.buckandhickman.com/find/product-is-310392-ROEBUCK-FOX-WEDGE-3-1-2-X-1-X-1-4
Very usefull things and cheap too, though making them isn't hard
Mark