help with some tapered cavities

Buy a Wolhaupter boring head on ebay? Those things can bore a taper, I believe.

GWE

Lloyd E. Sp> I'm working on a mould that has a platen with nine cavities. They're simple

I looked one up, and unless it's to be used like a circle cutter in some configurations, I don't see how it could. It tilts, it expands, it follows a pilot, but I can't see how it would change its diameter as it cut. Never used one, so I certainly may be wrong.

One thing, though... it's big. These are only 1.75" holes.

LLoyd

Make a single flute cutter on the grinder with the proper taper. Or, 3D machine on a cnc, or, ram burn on an edm.

Hey Lloyd,

Any possibility of using plugs. Make the 9 cavity holes say 3", straight sided. Turn 9 "plug" inserts 3"OD on the lathe with the proper diameter and draft angle ID, then weld them in place into the tool.

Just a thought.

Brian Laws>I'm working on a mould that has a platen with nine cavities. They're simple

Well, yeah... so far that's my only option. But the tool is (almost) a throw-away, so I'd hate to do the extra 9-up machining if I can machine the taper directly into the cavities during the boring cycle.

LLoyd

Shopmade D-reamer. Or for a hole that big you could make a single flute reamer with an inserted tooth. Use a square tool bit for the insert and grind the appropriate rake and relief on the edge.

Ned Simmons

Used end mills are cheap. You might buy one and have a tool & cutter grinder grind the taper on it. There is one on Ebay 7578883449 with a buy it now price of $1.25 and $8. shipping. And seller says he has more sizes. I don't think it would cost too much to grind. Jim

I have a Wolhaupter (I'm from of Wohlhaupter-land) and it can make tapers.

BUT: This works only if you can adjust the RPM of the spinde and the feed of the table (Z-axis I guess) in a way that fits the taper. Wohlhaupters have buttons you press (4?) and each pressed button either increases or decreases the diameter of the hole by 1/100 mm per revolution of the spindle. Now if feed and RMP match the taper you can get what you want, or even conical threads.

No problem with that. I did made holes (cylindrical) of about 10mm. Depending on the bit, you can make 4mm to 200mm (or so) diameter.

Very nice tool!

Nick

You are probably thinking of the Tree boring head, which does tapers. So far as I know the UPA series of Wohlhaupters does not. They are things of beauty, though.

INCREASING?!?!?! Larger at the bottom than at the top? On a manual mill? Wow.

If the holes were to have normal draft--smaller at the bottom--I can think of a couple of ways to do it without breaking the bank. But larger at the bottom? What the heck is it that the platen does? What kind of mould uses a hole with reverse draft?

Heh, heh! I wondered if anyone would catch that. Actually, with a bit of oddleg fixturing, I can invert the platen during machining... it's just got a bunch of 'interference' all over the top.

This mould has material applied from the top, then pressed out by ejectors through the bottom. That's the 'why' of the inverse taper.

LLoyd

I think this may be my best solution... Somehow it never occurred to me that I could do it with a single flute... but I guess I don't see why not.

LLoyd

OK--I agree with the D reamer concept. I've used them myself for oddball tapers. Also made a few fluted reamers over the years.

Here is one more possible method, assuming you have DROs on your mill: Purchase a tapered endmill in the appropriate taper. Get one with a little size/stiffness to it. I use a 3/4" x 3" long 2 degree for a lot of draft work on thermoforming moulds.

Rough in you holes to the minor diameter. Figure your "toolpath" as a bolt circle, the more points the better. Circle diameter is minor diameter minus tip diameter of cutter. Machine then hand blend as needed. If you use a large cutter, very little blending is required.