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For the machinists - What type of endmill for extractor slot?

LVLAaron

LVLAaron

Gold $$ Contributor
I have the need to install some M16 extractors.

I'm not the best at selecting mill tools. What type of endmill should I be looking for to cut the 1/4" slot for the extractor? How many flutes?
 
 
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Walt Krafft said:
If you try to hog it with the exact size endmill it will be oversize. I use a 6mm 4 flute.
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That's why I was looking at the variable helix / variable index cutters. Allegedly they don't have that problem because only one flute is contacting at a time.

I'll do some test cuts...
 
Edge prep is the most important thing for what we are doing. Usually far lower speeds than the tools are designed for. So a sharp edge helps. Some tools are intentionally not razor sharp to increase durability, that does not work out well for us with manual tools. In my experience, non coated end mills are the sharpest. I dont think at our speeds and feeds we really need the coatings. At least with end mills. The cheap non coated ebay end mills do as good as the expensive ones for the type work we do. 4 flutes for steel 2 for aluminum, wood, or composite is what I do. Because the stocks dull the endmills so fast and we are not using them at the correct feeds and speeds we go through them faster than we should so I prefer cheap. But not china cheap ;)
 
Alex Wheeler said:
Edge prep is the most important thing for what we are doing. Usually far lower speeds than the tools are designed for. So a sharp edge helps. Some tools are intentionally not razor sharp to increase durability, that does not work out well for us with manual tools. In my experience, non coated end mills are the sharpest. I dont think at our speeds and feeds we really need the coatings. At least with end mills. The cheap non coated ebay end mills do as good as the expensive ones for the type work we do. 4 flutes for steel 2 for aluminum, wood, or composite is what I do. Because the stocks dull the endmills so fast and we are not using them at the correct feeds and speeds we go through them faster than we should so I prefer cheap. But not china cheap ;)
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Hertel is my "go to" for mills and drills. Coated stuff is definitely not as sharp.

A stock with glass/filler will turn an endmill into cheese pretty quickly. I really like this tool for stocks. Sharp enough... lasts forever.
https://www.mscdirect.com/product/details/84509389


For slotting the bolt...I'm sure the fancy variable endmill will do fine with shallow cuts and high rpm. I'm looking forward to the half dozen little micro splinters I'll get from it.
 
LVLAaron said:
That's why I was looking at the variable helix / variable index cutters. Allegedly they don't have that problem because only one flute is contacting at a time.

I'll do some test cuts...
Click to expand...

The cut is .255", so 1/4" works fine. I actually used a 1/4" carbide that I bought off of a guy that had an oil barrel full of mills from a CNC operation. I think 50 - 1/4" carbide end mills were $25, they still cut great.
 
LVLAaron said:
I'm looking forward to the half dozen little micro splinters I'll get from it.
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Oh man, there’s one job we do at work, thankfully not frequently, with a stainless alloy that creates those tiny, sharp little splinters that embed in fingers and cause pain all out of proportion to their nearly microscopic size. The machines we use for this job are manual vertical mills all hand cranked and the only way to try to avoid the shards is gloves and long sleeves which of course are a big no-no. The alloy is non-magnetic so you make sure you never get one in an eyeball, safety glasses at all times, chip brushes, shop vacs only no blow guns, and we spend time with magnifiers, tweezers and those razor blade-like splinter removers trying to get the splinters out of hands and fingers. You can sure feel the pain they cause but they’re nearly impossible to see.
 
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AccelR8 said:
Oh man, there’s one job we do at work, thankfully not frequently, with a stainless alloy that creates those tiny, sharp little splinters that embed in fingers and cause pain all out of proportion to their nearly microscopic size. The machines we use for this job are manual vertical mills all hand cranked and the only way to try to avoid the shards is gloves and long sleeves which of course are a big no-no. The alloy is non-magnetic so you make sure you never get one in an eyeball, safety glasses at all times, chip brushes, shop vacs only no blow guns, and we spend time with magnifiers, tweezers and those razor blade-like splinter removers trying to get the splinters out of hands and fingers. You can sure feel the pain they cause but they’re nearly impossible to see.
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I run a good shop vac with a clean filter when I’m milling for that reason. I hate the mess a mill can make.
 
AccelR8 said:
You can sure feel the pain they cause but they’re nearly impossible to see.
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You need a cheap dissecting microscope in the shop. I have two, one in the shop and one in the house. The initial purposes were for other things but they get used most often removing foreign bodies out of my fingers. Both of mine are nice classic Wild’s but cheaper imports can be had that’ll do the job. So much easier than using magnifiers. I use hypodermic needles to wiggle the tiny bits out. A dissecting scope gives much more room to work in over a traditional scope.
IMG_1481.jpeg
 
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Here's the patient. And old 722 action/bolt. This thing probably has 100k rounds on it. The bolt body is out of round by 20 thou... has grooves worn it in from the action.

Fred Sinclair built this for my dad 45 years ago. It was a wildcat, "30x40 Sinclair" - Basically a .308AI and was a 100/200 yard varmint BR gun.

Hoping to get some life back in it. Got it centered up based on the shroud threads and firing pin hole. Silver soldered the sleeves and ring in the bolt head... Onto the extractor...


23-08-23 19-59-07 1005.jpg
 
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