80% build tips

[notazombie]

That's something I've noticed. A brand new bit cuts great and will do 1 or maybe 2 lowers for me. Once they get a little worn they have a tendency to ball aluminum up in the flutes. Then they like to chatter.
I've just decided to use a new bit for each lower. YMMV.

 

[11Charlie]

That's something I've noticed. A brand new bit cuts great and will do 1 or maybe 2 lowers for me. Once they get a little worn they have a tendency to ball aluminum up in the flutes. Then they like to chatter.
I've just decided to use a new bit for each lower. YMMV.

I wonder if there is a way to clean them?

 

[etrain16]

Looks good! I've got to get a few more things before I can start my first, but I'm excited to do it!

 

[Ura-Ki]

The compressed air should help clear out chips an keep your bits sharper, longer. an Oil bath would be ideal, but not practical!
For more serious milling work, doing more lowers, you can get super grade mill bits from ether Palm Abrasive in PDX or from Hall Tool!
They also have a tool sharpening service to renew worn bits! may be more cost effective then replacing bits every few uses! May also slow the router speed and see if that helps, try it out on some scrap until you can get the speed just slow enough with out shatter!



@SKrueger, I wasn't trying to be critical of your work, just trying to make suggestions, Looks great and will serve you well!

 

[The Heretic]

Some of the vids I have seen guys are using cans of aero oil, spraying the work liberally. I personally like Kroil.

 

[11Charlie]

The compressed air should help clear out chips an keep your bits sharper, longer. an Oil bath would be ideal, but not practical!
For more serious milling work, doing more lowers, you can get super grade mill bits from ether Palm Abrasive in PDX or from Hall Tool!
They also have a tool sharpening service to renew worn bits! may be more cost effective then replacing bits every few uses! May also slow the router speed and see if that helps, try it out on some scrap until you can get the speed just slow enough with out shatter!



@SKrueger, I wasn't trying to be critical of your work, just trying to make suggestions, Looks great and will serve you well!

Your good brother I didn't take it that way in way shape or form

 

[11Charlie]

Some of the vids I have seen guys are using cans of aero oil, spraying the work liberally. I personally like Kroil.

After doing this first one I feel like oil of some sort would help the bit. But would also make a mess as you get further into it.

What might be smart is to spray a oil on to the bit itself every time you change the depth of the router.

 

[Ura-Ki]

A water Bath might be a more viable option, but working with electrical tools would need extra care in handling and operations!
Be careful of what oil you might choose to use, some of them can be flammable!

 

[The Heretic]

After doing this first one I feel like oil of some sort would help the bit. But would also make a mess as you get further into it.

What might be smart is to spray a oil on to the bit itself every time you change the depth of the router.

Kroil is very light (although IMO it is a bit more lubricant than other aerosols), as are most of the aerosol sprays, they tend to evaporate faster than the usual oil used on a milling machine.

 

[Ura-Ki]

There is a Cutting oil in spray cans that NAPA auto parts sells, that would be a great one to use, but I cannot think of the name brand! Just go to the local NAPA and ask for cutting oil, they will be able to set you up!

 

[11Charlie]

There is a Cutting oil in spray cans that NAPA auto parts sells, that would be a great one to use, but I cannot think of the name brand! Just go to the local NAPA and ask for cutting oil, they will be able to set you up!

I'll try that on my next one!

 

[etrain16]

There is a Cutting oil in spray cans that NAPA auto parts sells, that would be a great one to use, but I cannot think of the name brand! Just go to the local NAPA and ask for cutting oil, they will be able to set you up!

When I was still in the field, we would keep plenty of cutting and threading oil around - for drilling/tapping steel and AL and for cutting threads in steel pipe. I always had a small can in my tool kit. I would think that kind of oil might be a good idea, since it's specifically formulated for cutting into metal.

I wonder, for threading, we were able to cycle the oil on the parts and reuse it over and over. We had a pump handle and would just constantly pour oil on the part while cutting - we had a collection bin below with a filter screen - the screen would catch the cut metal and allow you to recycle the oil back onto the part. Makes me wonder if you could set up a little foot pump and could just keep cycling a flow of oil onto the piece and keep things nice and cool. Would probably be a bit messy, but would certainly help extend the life of a mill bit.

Oil was this type (various brands):



This is the oiling bucket we used:

 

[Ura-Ki]

When I was still in the field, we would keep plenty of cutting and threading oil around - for drilling/tapping steel and AL and for cutting threads in steel pipe. I always had a small can in my tool kit. I would think that kind of oil might be a good idea, since it's specifically formulated for cutting into metal.

I wonder, for threading, we were able to cycle the oil on the parts and reuse it over and over. We had a pump handle and would just constantly pour oil on the part while cutting - we had a collection bin below with a filter screen - the screen would catch the cut metal and allow you to recycle the oil back onto the part. Makes me wonder if you could set up a little foot pump and could just keep cycling a flow of oil onto the piece and keep things nice and cool. Would probably be a bit messy, but would certainly help extend the life of a mill bit.

Oil was this type (various brands):

View attachment 420883

This is the oiling bucket we used:

View attachment 420884

Now that's a great idea right there! I would imagine a visit to TAP plastics should net some clear plastic sheet and a feller with a heat gun and some pop rivets could make a deflector around his work station to allow this to work extremely well! I'm steeling this idea @etrain16, and Thanks!

 

[etrain16]

Now that's a great idea right there! I would imagine a visit to TAP plastics should net some clear plastic sheet and a feller with a heat gun and some pop rivets could make a deflector around his work station to allow this to work extremely well! I'm steeling this idea @etrain16, and Thanks!

The main issue with this process is the high-speed of the router, which is going to make the oil fly/spray far more than the low speed we used for threading. If you can make up a splatter shield and still maintain visibility of the part details, it could certainly work. I'd love to see you make up a rig that would do it.

Here is a video that better shows how the setup works. At about 4:40, he gives a good look at the bucket and at 13:50, you can see it actually being pumped onto the part during threading. This is the exact same setup we used in the field - same threader too.

 

[11Charlie]

I'd love to see you make up a rig that would do it.

Me to cuz all I see is a very large mess to clean up.

 

[ammoeba]

A brand new bit cuts great and will do 1 or maybe 2 lowers for me. Once they get a little worn they have a tendency to ball aluminum up in the flutes. Then they like to chatter.

I wonder if there is a way to clean them?

When I'm dremel'ing metal with carbide cutting bits, I try to get the speed right so the material doesn't heat up too much and stick in the flutes. It still happens some no matter what, though. Keep a small jeweller's screwdriver on hand to periodically scrape the flutes out, and you'll find the going much smoother and the bits last a lot longer. It's much easier to clean than you'd expect the first time.

 

[70cyclone]

If you are doing a bunch of these or other frequent metal work this can be your best friend...

Kool Mist - Portamist Cooling System by Kool Mist Spray Mist Coolant Systems, Mill Coolant, Tool Coolant, Lathe Coolant, Machining Coolant
or
Kool Mist - Kool Mist Lite Duty Coolant System Spray Mist Coolant Systems, Mill Coolant, Tool Coolant, Lathe Coolant, Machining Coolant
and the recomended coolants
Kool Mist - Coolants Kool mist 77, Koolmist 78 Spray Mist Coolant Systems, Mill Coolant, Tool Coolant, Lathe Coolant, Machining Coolant Flood Cooling

you can run straight air or with coolant. If you run a water based coolant it is much easier to clean up than any oil(oil is great for cutting or rolling threads) based.
I recommend you cut aluminum wet(not just water) at all times. The heaviest cut you can control will tend to give you the best finish and avoid galling. Conventional milling allows for better control of the tool vs climb milling and running coolant will help improve the finish and increase tool life.
some info on conventional vs climb milling: http://www.harveytool.com/secure/Content/Documents/Tech_ConventionalMillingVsClimbMilling.pdf

 

[11Charlie]

Well @The Heretic I finished my first 80. Lower went together almost flawlessly. Ran into a little snafoo that @Kruejl helped me out with. But it turned out to be a nice looking rifle.

 

[SIG34]

Honestly biggest waste of money & Time... I build a 80% AR15 lower and honestly $49 Anderson lower will do just fine

 

[11Charlie]

Honestly biggest waste of money & Time... I build a 80% AR15 lower and honestly $49 Anderson lower will do just fine

I think you're missing the point. But hey to each their own