18 Degree Half Face Cutter

Ultimately I would also be able to cut all three parts in only 4 setups with this home made cutter.

Yes, I am aware there is a 4th piece in my sketch, but its just a nominal machine to fit cap when the main stuff is done.

I'm having this crazy idea of making a D-bit or rather slightly less than half D-bit with an 18 degree (144 degree include angle, but only one leg of it) cutting lip on the face.

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If you have a surface grinder and an end mill fixture of the type Snag is making, you can regrind a standard end mill to cut the 18 degree angle by clamping the fixture in a small insert vise. I used my fixture to grind the edges at the back relief tilt angle (like a drill bit) so the end mill could rough cut deeper with only the end edges, leaving the harder-to-sharpen side flutes sharp. Like this:

Set up the angle with solid rods in the fixture and mill collets and 15 + 3 degree angle blocks between them. Rotate the end mill about 5 degrees off vertical to add back relief. I'd rough grind the end mill manually to reduce the amount the surface grinder has to remove. This is a good use for dull, chipped or undersized reground endmills.

Some of the thick steel in my scrap collection was flame-cut and has hard spots unless annealed in the wood stove, which roughens the flat surfaces. I rough cut it in ways that allow easily resharpening the end mills, such as nibbling with plunge cuts, as there are no longer any nearby stocking industrial suppliers to buy new ones from, only a second-hand store that sells used tools from auctions. They are usually high quality brand names, but dull or damaged, so salvaging a few US endmills and large taps paid for my surface grinder.

I do this with HSS because carbide tooling chips too easily on my 1960's machines. AFAIK it should work the same way with a diamond surface grinding wheel. I have only one and don't risk it experimenting.

15 + 3 degree angle blocks ...

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I should mill an 18 degree angle block, it's close enough for carpentry purposes to the 4 in 12 slope of my roof.

I do have a surface grinder, but not an end mill sharpening jig. I also do not have a diamond wheel for the surface grinder, and nearly all of my end mills are carbide. I do have a diamond cup wheel and a diamond cut off wheel for the D-bit grinder.

I also do have angle blocks, sine bars, and even a sine vise, but I have found generally I get better results even with questionable methods if I can cut a part in a single setup. I would prefer not to have to tilt the pieces to orient the planes if I can find a work around like an 18 degree angled face cutter. Even with a single flute it will be much faster than tens of thousands of incremental passes with a standard tool.

Remember my net time is my goal here. If I make an endmill jig, order a diamond wheel for the surface grinder (or buy some quality HSS mills to modify), and learn to grind end mills on the surface grinder it will likely take longer than making a carbide tool on the D-Bit grinder. One I pretty much have the stuff and already know how to make... more or less. I'm still struggling with height settings the tool in the machine. Creeping up on it really isn't a great option.

I've been saving my broken and worn out carbide mills for years. I made other tools from some of them even before I had a d-bit or surface grinder. Carbide ground to a cone makes a decent drag engraver and holds up better than diamond tip tools that pop off when you hit any slight irregularity. Anyway...

Your do have a good argument for adding a jig/fixture to my tools and learning to use it at some point though.

I normally use bright uncoated 3 flute end mills: Preferentially. My goal is good chip removal and decent material removal rate in the aluminum most of my paying work is done. Of course I have other mills for steel. Mostly AlTiN coated carbide 2 and 4 flute.

HOWEVER: Back when I was getting started I did a lot of work with what other people "told me" was best. I bet I have some worn out and broken

2 flute uncoated end mills in the bottom of my bucket of broken carbide. From back in the day... I bet I can use the T&C (D-Bit) grinder to put an 18 degree chamfer cutting edge on the face of one faster than I could cut a d-bit mill. A 3 flute or 4 flute would probably be more challenging for my skill level. With a 2 flute I can just get it dialed in once, and use the 180 degree stops.

AND.. having two flutes I can feed it faster. It the point geometry is a problem I can always grind off one flute completely and I will have a fancy looking equivalent of the D bit I was going to make.

Well, this afternoon I either make the cutter, or I start setting up the job with angle blocks.

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It doesn't need to be pointed or center cutting unless you intend to also drill with it. The beveled tips on my 1/2" endmill are only about 0.1" wide, with the center sharpened normally. It's sized for the comfortable DOC of my Clausing mill in steel, specifically milling a wrench hex on threaded rod which can rotate in the collet from high cutting force, not for cutting a wide slope, for which the bevels could be wider at the cost of lower SFPM toward the center.

If you can change the angle to 18.435 degrees the Z rise will be 1/3 of the X run, which might be easier to set up precisely.

Sharpening to a point and then removing the point gives me the ability to know how to set the tool height. Within a couple thousandths anyway.

Pictures Posted Here:

If it works I'll let you know. Probably just have to listen to me bitch about it if it doesn't.

Pictures Posted Here:

If it works I'll let you know. Probably just have to listen to me bitch about it if it doesn't.

Bob La Londe CNC Molds N Stuff

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The item in the photo looks like a hose tee, or perhaps the pattern for molding them. If it is, why 18 degrees?

I ask because I make odd-sized hose adapters fairly often, one last week. I've gone away from sharp-edged barbs because in most cases I want to be able to remove the hose without damaging it, for instance to drain and dry a gas tank for off-season storage.

I tried glycol-based CRC brake caliper grease on sticking valve O rings and it freed them nicely, time will tell if it degrades them.

Weird. If I click the link and it goes directly to a post with 3 images of a "D-Bit" cutter.

Since you mentioned the T which is in a totally different post. Its s

3/16 1/8 3/16 reducing T. The only one I found was a plated brass one on eBay for 24.50 shipped plus tax. The 1/8 inch leg didn't have any type of barb or sealing ridge. I will probably leave the web behind the barb effectively making it a round barb instead of a sharp barb. On tube I do the same thing with a double flaring tool. It will get ear type crimp on hose clamps so I think the seal will be just fine.

Yes I checked McMaster. I also checked auto parts sources. There is a packet of misc vacuum fittings in the over priced "HELP" line of parts that contains the correct size T, but I have not been able to confirm the are gasoline safe, and that's what I used last time a few years ago rebuilding this stack of carburetors. It broke upon reassembly.

18 degrees has nothing to do with the T fitting. Its about the D-Bit cutter.