Who uses a milling machine for slotted guards

D

Diggerdog

Joined
Aug 30, 2005
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173
I just received a micro mill from Harbour Freight. I don't have it set up yet but I'll get right on it tomorrow. I spent over 3 hours today making a slotted guard and towards the end I was so frustrated I got a bit sloppy. With a milling machine can you just use an end mill to make the slot. Seems like it would take minutes and be very precise instead of taking hours the other way.
 
Here is a little hint on how not to break small end mills. Small end mills break VERY easy cutting sidways so when I slot a guard I do as follows. First scribe the shape of the slot you want then drill a hole through your guard just smaller than the end mill you are using. Now use the mill to make plunge cuts (like a drill press) moving sideways about .010" at a time. This takes the side load off the end mill. All that is left to do is take a few thousands on each side and your slot is done. I still have the first two 1/8" end mills I started with and I have made a lot of slotted guards. Maybe it's because I'm Scotch:D
 
Yup. 5 minutes.

Before you mill your guard slot, make sure your blade is profiled, ground and nearly finished to the point where you may only need a few touch-up strokes by hand. The main reason to do this is to make sure the slot dimension is going to be correct. Too many times have I milled my slot and then set about to grinding, HTing and rubbing the blade only to have the slot be too wide now when I go to assemble it.

Ideally, a nice firm slip-fit is the best way to set up a milled guard slot, but we always can't have a perfectly plane surface on the guard area of the knife - especially if we don't have a surface grinder. So another method I use is to mill the guard a little oversize, and use a press to firm it right up neat to the blade.

Try to get the slot-to-blade fit completely perfect before you shape and finish the rest of the guard. You'll be more precise in drilling and pinning the guard if it still has nice square dimensions.
 
jhiggins said:
Yup. 5 minutes.

Before you mill your guard slot, make sure your blade is profiled, ground and nearly finished to the point where you may only need a few touch-up strokes by hand. The main reason to do this is to make sure the slot dimension is going to be correct. Too many times have I milled my slot and then set about to grinding, HTing and rubbing the blade only to have the slot be too wide now when I go to assemble it.

Ideally, a nice firm slip-fit is the best way to set up a milled guard slot, but we always can't have a perfectly plane surface on the guard area of the knife - especially if we don't have a surface grinder. So another method I use is to mill the guard a little oversize, and use a press to firm it right up neat to the blade.

Try to get the slot-to-blade fit completely perfect before you shape and finish the rest of the guard. You'll be more precise in drilling and pinning the guard if it still has nice square dimensions.
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I used a Taig minimill for about 3 years and got very good results once i learned that the smaller cutters are not strong enough to handle the side load. Now that I have a bridgeport and I learned how far I can push a cutter before it snaps it is even better. Mini mills are good, Bridgeports are great.

By the way Jeff, I can do it in 4 minutes.:jerkit:
 
I use a Sherline mill with good results. Would like to get a larger mill one day.
Thanks for the info guys, I learned a thing or two.
 
thanks for the plunge cut tip im sure i would have just snaped a ton of end mills and just got pissed off
butch
 
I like to use a carbide ball mill or burr to cut slots. They do the plung cut with less chatter. There is no need to drill a pilot hole if you do this. Jams, Fred
 
You could also plunge cut with with a smaller end mill, then come back again with an on size for the finish cut. This will leave your slot closer to the finish size. I also remove some of the metal in the slot by taking a single cut down the middle with a band saw.
 
You will have to run a small end mill at a high speed to help prevent breakage. Take light cuts if you are side milling (.005-.010). You can use a pair of dial calipers to check slot size as you cut. You can also check the width of the guard from the slot to each side with the calipers to keep the slot centered in the guard. I would suggest using carbide. Sometimes you can get them pretty reasonable by bidding on them on ebay. If possible, when you are milling check to see if you have a smooth cut in the slot. If it's not you might try keeping the cutter on the same surface and reverse the mill and see if it smooths up. Sometimes you will see small chatter marks in the cut. Use a light weight cutting fluid also. Just a drop helps with the cut. I usually try to leave the slot .001 smaller than the tang and then tap it onto the tang for a snug fit. Good luck
 
Thank you all for the information. I'll let you know how I make out with the new milling machine. Doing it by hand is so slow and frustrating, I can't imagine doing another one that way. Dave
 
i just bought a 6" cnc boring mill. the table has a 120,000 lb capacity. it has 14 feet of x and 13 feet of y. however the shop owner has already told me, mining equipment only. lol it does look cute with an 1/8 2flute hanging out of a 6 inch spindle
 
I use a Enco mill and slotting saw blades. I usually cut 8 to 10 guards at one time when using n/s or brass and using a norton surface grinder on the flats, then a variable speed disk and they usually come out so I press witn a 2 ton arbor press.
 
FYI; Just make sure your endmill is a center cutting one if you are going to plunge. One of the flutes on the end mill (if you look on the bottom), will go across the centerline of the endmill. If endmill is HSS, then cutting fluid is a must, just remember, that stuff like Rapidtap is NASTY when it smokes, so wear a respirator, or ventilate well!!
 
sinawalli said:
FYI; Just make sure your endmill is a center cutting one if you are going to plunge. One of the flutes on the end mill (if you look on the bottom), will go across the centerline of the endmill. If endmill is HSS, then cutting fluid is a must, just remember, that stuff like Rapidtap is NASTY when it smokes, so wear a respirator, or ventilate well!!
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I've been using a Kool Mist rig. Best $150 I ever spent. Parts come out cool and clean. It also blows the chips away so you can see what you are doing.
 
jhiggins said:
I've been using a Kool Mist rig. Best $150 I ever spent. Parts come out cool and clean. It also blows the chips away so you can see what you are doing.
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What machine are you using the kool mist on? Would it be worth getting if the machine isnt used for production?
 
adammichael said:
What machine are you using the kool mist on? Would it be worth getting if the machine isnt used for production?
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I use it on my lathe and my mill whenever I suspect a work-hardening/heat buildup is going to happen. This typically will happen when I machine my shoulders on the blade, or when using NS or stainless guard material. The mist is a little funky to get used to, but very little mess afterwards. Definitely no smoke, and no weird fumes in the shop. I used to flood cool, but its a pita. Now I use my little Kool Mist rig, and I am happy as a clam at high tide!

Michael, if you start shopping for one, there are a few different types out there now. I bought the kit that comes with a stainless steel reservoir, magnetic stand, hose, and nozzle. It was something like $150 or so. There are cheaper versions out there that you could just dunk the siphon hose into a jug and go for it.
 
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