Thanks for detailing the experience.  Maybe others will chime in with some undocumented features and steps.

WD40 is an absolute shit milling lubricant, why anyone reccomends it is beyond me. Ideally you would use actual machining lubricant, tapping fluid, or 3-1 oil all of which are cheaper and work millions of times better than WD40.

This is what I use in my home shop and in our development lab at work and one bottle lasts a long time.

I've been using ETP Gold Cutting Foam and it works great. The foam hangs there for a while providing lubrication when regular cutting fluid just runs off.
Unfortunately it's not widely available as it seems to an item exclusive to Lawson Products. If you can find a can, give it a try.

ETP Gold Cutting Foam

double tap

Ya, when I read the OP, I was like "WD40? What is he....ohhhhhh. Seriously? Why?" I've always used Tap Magic. It averages about 60% of the cost per ounce, so it is cheaper compared to WD40, and it smells a lot better.

I don't understand why someone would even be tempted to use WD40, except out of ignorance. No offense intended, but people seem to do a lot of things without any real research into what they're doing, anymore.

Back on subject, to the jig, itself: Was there any issue with those pins that hold the receiver in the jig?

WD-40 is not a lubricant, it is a Water Displacement solution.

I use oil when I mill a receiver or use nothing at all, these lowers are so easy with a mill, you can actually do it without any type of oil.

When I was young, 16-18 we all kept WD-40 in our cars, reason being, if you went through a deep puddle in your car, you could pop the distributor cap, spray the inside and get your car to fire again.

It displaced water, but it did not lubricate.

Of course that was back in the day you used to have to file and adjust your points in the distributor cap!

The only reason I even use oil is because my endmills are loud and it keeps chips from falling back down into holes a little bit, otherwise the endmills I ordered from McMaster "for work" cut through the aluminium like butter.

The people who make it seem to think that it is a lubricant as well.

From their website

WD-40® MULTI-USE PRODUCT FULFILLS FIVE BASIC FUNCTIONS:
LUBRICATES: The product's lubricating ingredients are widely dispersed and tenaciously held to all moving parts.
PENETRATES: WD-40® Multi-Use Product loosens rust-to-metal bonds and frees stuck, frozen or rusted metal parts.
PROTECTS: The product protects metal surfaces with corrosion-resistant ingredients to shield against moisture and other corrosive elements.
REMOVES: WD-40® Multi-Use Product gets under dirt, grime and grease. Use it to remove gunk from tools, equipment and vehicles. WD-40® Multi-Use Product in liquid form (e.g., gallon) also dissolves adhesives, allowing easy removal of excess bonding material.
DISPLACES MOISTURE: Because it displaces moisture, WD-40® Multi-Use Product quickly dries out electrical systems to eliminate moisture-induced short circuits


I have done at least a dozen receivers using WD40. A quick spritz after each pass works very well. While it may not have the higher lubricity of a cutting oil, it flushes out chips and cools better than the thicker oils. Both important considerations.

I found this thread on the subject on the practical machinist forum. Most agree that WD40 works well when machining aluminum.
http://www.practicalmachinist.com/vb/general-archive/wd40-aluminum-80456/

Obviously any type of lube is better than no lube at all, but I wouldn't poo-poo the use of WD40. It is even mentioned in the Modulus instruction manual as a recommended fluid.

The description of WD-40 has evolved over the years to try include the lubricating features of it, we tested it while I was in the service and it caused more problems than it solved on duty weapons.

They can call it what they want, and don't get me wrong I have used it during milling, but there are less expensive and far more effective solutions out there for milling.  Now with aluminum water will lubricate if that is all you have, but it is not the best solution.

My partner, who owns the milling business won't even let anybody bring WD-40 into the shop, because it gets used incorrectly.

One thing I have used WD-40 a lot for is starting small gas engines works just about as good as either, but not quite a explosive, quick spay into the carb in the spring and the lawn mower starts right up!