Aluminum fixture for cutting molds

[rcferguson]

So I did my first real project on the Carve King today, not counting the test block I was working on. I'm hoping to make injection molds for some plastic parts, so the first step was to make some fixturing I can use for my mold blanks. I made a lot of chips today, everything went great. Didn't have any problem cutting the aluminum, kept with the recommended feed rates, and the 70-75 aluminum is pretty hard/brittle, so no gumming of the cutters. Didn't need to use any lube, just made sure to keep chips vacuumed out whenever it was in a tight spot like boring holes, etc. Aluminum came out very smooth after tramming the router.

Couldn't get my cheap vise very level, but it's OK for making the fixture.

        

Next step will be to bolt this thing down to the bed and surface the two islands where the mold blanks will go... that will ensure that they are nice and parallel front to back.

BTW, the fenders I 3D printed to cover the top front V-wheels worked like a charm! Really kept them clear of chips.

[Bruce]

Congrats on getting your first project underway.

[Derek the Admin]

That looks good! I'm looking forward to seeing the molds that you end up making.

[rcferguson]

Made a couple mold blanks...

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It occurs to me that if I want to remove these blanks from the fixture and put them back on later I won't be able to locate them very precisely, because the hold-down holes I've pre-drilled have some slop in them to accommodate the hex screws I use to clamp them onto the fixture. Maybe not a problem if I do all the machining in one fell swoop, but if I ever need to remove them and put them back on later, say to rework or add a feature, or even to machine a bunch of blanks for later use it will hard to locate them properly. So I will add some precise locating pins to the fixture and pre-drill those holes as well.

Anyway, I'm finding it difficult to figure out what tool path I should be using for what operation. For example, the first thing I tried was to use a 1/4" ball end mill to machine a sprue down the center of the blank. You'd think this would be a simple operation, as it is basically just a slot that goes partway from the edge of the mold to a point past the mold cavity as a path for the injected material to get to to part. Well, the slot command won't do it, so did some Googling and it seems I have to use the Trace command, but I can't figure out how to get it to enter the workpiece from the open end, it wants to drive down to the end of the slot. Back to the CAM videos to see what I can glean.

[viddall]

Jan 17, 2019 5:19:06 GMT rcferguson said:

So I did my first real project on the Carve King today, not counting the test block I was working on. I'm hoping to make injection molds for some plastic parts, so the first step was to make some fixturing I can use for my mold blanks. I made a lot of chips today, everything went great. Didn't have any problem cutting the aluminum, kept with the recommended feed rates, and the 70-75 aluminum is pretty hard/brittle, so no gumming of the cutters. Didn't need to use any lube, just made sure to keep chips vacuumed out whenever it was in a tight spot like boring holes, etc. Aluminum came out very smooth after tramming the router.

Couldn't get my cheap vise very level, but it's OK for making the fixture.

        

Next step will be to bolt this thing down to the bed and surface the two islands where the mold blanks will go... that will ensure that they are nice and parallel front to back.

BTW, the fenders I 3D printed to cover the top front V-wheels worked like a charm! Really kept them clear of chips.

Nice! 
What is the vise your using?

[rcferguson]

Jan 21, 2019 17:44:25 GMT viddall said:

Jan 17, 2019 5:19:06 GMT rcferguson said:

So I did my first real project on the Carve King today, not counting the test block I was working on. I'm hoping to make injection molds for some plastic parts, so the first step was to make some fixturing I can use for my mold blanks. I made a lot of chips today, everything went great. Didn't have any problem cutting the aluminum, kept with the recommended feed rates, and the 70-75 aluminum is pretty hard/brittle, so no gumming of the cutters. Didn't need to use any lube, just made sure to keep chips vacuumed out whenever it was in a tight spot like boring holes, etc. Aluminum came out very smooth after tramming the router.

Couldn't get my cheap vise very level, but it's OK for making the fixture.

        

Next step will be to bolt this thing down to the bed and surface the two islands where the mold blanks will go... that will ensure that they are nice and parallel front to back.

BTW, the fenders I 3D printed to cover the top front V-wheels worked like a charm! Really kept them clear of chips.

Nice! 
What is the vise your using?

El cheapo vise that came with something else... looks identical to one they have on Harbor Freight for $16. I'm probably going to buy a machinist's vice, but trying to find something low profile that won't break the bank.

[rcferguson]

Making some progress now. Had a lot of problems getting things repeatable enough for everything to line up. Moved my router down in the mount because I was having Z problems near the end of travel. Rebuilt my fixture because the machine wasn't square when I made it and that threw everything off. Cutting both side of the mold at the same time now so things line up a lot better.

Here are the first couple molds I made. Injecting with Black Polypropylene, and I'm very happy with the results.

[rowiac]

Wow! Looks like you are making good use of several manufacturing methods: CNC router, injection molding, 3D printing and some woodworking. What is that device in the last picture? Also what are you using as a molding machine?

[rcferguson]

Feb 21, 2019 15:40:45 GMT rowiac said:

Wow! Looks like you are making good use of several manufacturing methods: CNC router, injection molding, 3D printing and some woodworking. What is that device in the last picture? Also what are you using as a molding machine?

It is a quadrant control for flight simming. The parts I've done so far with molds are the quadrant levers and knobs, as well as a detent for positioning (the smaller parts in the mold). Some of the larger parts I can't do because they are over the 1.1 cubic inch limit of my molding machine, so those will be done with liquid resin in silicon molds. I have a couple more molds to do for the quadrant (gears, etc.) and then a bunch of parts for the trim controls which you can see below the quadrant levers.

I use an LNS benchtop molding machine. It operates with a lever, and when injecting close to the the full capacity takes a LOT of strength to operate. I basically have to put an extension lever on the crank and put my full body weight on it to fill those molds. I'm looking into modifying it with a pneumatic cylinder to speed up the operation (and prevent myself from getting a heart attack!).

[Derek the Admin]

That’s great! I’m so glad to see a successful end result.

Excellent work.

[Bruce]

Wow, impressive project. Are you building custom flight simulator controls for sale or just your own use?

[rcferguson]

Feb 23, 2019 19:24:14 GMT Bruce said:

Wow, impressive project. Are you building custom flight simulator controls for sale or just your own use?

Hoping to sell. I already have my USB controller for sale on Amazon:

Gear-Falcon Controller

Gear-Falcon Controller 2

[Bruce]

Interesting...are you still making this unit too?

Gear-Falcon Bomber Commander

[rcferguson]

Feb 23, 2019 20:40:08 GMT Bruce said:

Interesting...are you still making this unit too?

Gear-Falcon Bomber Commander

Haven't released it yet, but plan to as soon as I get my molds made and production started. I started out planning to everything in 2-part cast resin, but just can't get smaller parts to cast consistently, so decided to switch to injection molding instead for quality and speed.

[Bruce]

I think this flight simulator stuff is really cool. Please keep us updated on your progress.