Pictures of things made in Home Shop CNC

[MontanaAardvark]

Very cool! The finish on the mold looks like the drawing on the top of the bait's body.

That's going to be hard plastic, right? I know next to nothing about injection molding, but is that what you're going to do here?

 

[Groundhog]

I've made a lot of similar lead molds for a buddy that makes bass jigs. The ones I make are small (1/2" to 3/4") and have slots to lay hooks and swivels that get molded into the lead. There are usually 3 or 4 jigs to each mold. I don't have any pictures of the finished products but will try to find a drawing or two from the cad drawings.

Here is a finished jig.

 

[Robert LaLonde]

Very cool! The finish on the mold looks like the drawing on the top of the bait's body.

That's going to be hard plastic, right? I know next to nothing about injection molding, but is that what you're going to do here?

That particular one is going to be used with a polyester casting resin. I'll have two models. One for gravity casting, and one with no gate or sprue for rotomolding.

 

[JimDawson]

If the customer had come to me and asked me to design a box that would be the most difficult and expensive to machine this design would have been it. We'll be doing a design review and cost reduction on the next 100 units. These were built to customer specs, not our design, and customer supplied material. All they do is hold a circuit board. About 3x4x1 inches. The customer showed up on Saturday afternoon and wanted the parts Monday morning. My son ran these while I was busy doing other stuff.


So start out with a block of Delrin


Rough pocket the center


Then start on the internal features with a 3/16 endmill


These little pins had to be done carefully so they didn't break off, about 0.130 dia.



Another view


Then build a fixture, flip the part over and pocket the bottom


Then profile the outside. The fixture was a tight fit to keep the walls from collapsing while machining.


Top view


Bottom view


And it fits



Then fit an aluminum heat sink. These were a bit of a pain to machine, nothing to hang on to. Used carpet tape to hold them.


The other part of the order were these two aluminum housings. About 2 x 3 inches.





Anchor them down with a couple of slugs that fit the pockets and profile the outside.


And the finished parts.


We got them out the door on Tuesday morning. About 9 hours of machining time, and an hour or so of programming and setup. The customer was a bit shocked (OK, more than a bit) at the price, but we are not going to work for free, especially when we have a lot of other work to do.

 

[TomS]

Nice work! I've experienced many times in my career selling custom steam turbine parts where customers design a concept components but have no idea what it takes to make it. They usually fall out of their chair when I gave them price and delivery cycle times.

 

[MontanaAardvark]

Nice stuff, Jim!

I was looking at that and thinking that it seemed at least 95% of the Delrin was machined away and it got me thinking - is Delrin recyclable? I've been keeping my aluminum chips (well, the bigger ones) with the idea I'm going to make a forge and make something out of them. Can you melt down Delrin and make a block? Is it even worth the time?

 

[RandyM]

If the customer had come to me and asked me to design a box that would be the most difficult and expensive to machine this design would have been it. We'll be doing a design review and cost reduction on the next 100 units. These were built to customer specs, not our design, and customer supplied material. All they do is hold a circuit board. About 3x4x1 inches. The customer showed up on Saturday afternoon and wanted the parts Monday morning. My son ran these while I was busy doing other stuff.

So start out with a block of Delrin

Rough pocket the center

Then start on the internal features with a 3/16 endmill

These little pins had to be done carefully so they didn't break off, about 0.130 dia.

Another view

Then build a fixture, flip the part over and pocket the bottom

Then profile the outside. The fixture was a tight fit to keep the walls from collapsing while machining.

Top view
View attachment 249159
Bottom view

And it fits

We got them out the door on Tuesday morning. About 9 hours of machining time, and an hour or so of programming and setup. The customer was a bit shocked (OK, more than a bit) at the price, but we are not going to work for free, especially when we have a lot of other work to do.

Hey Jim,

I am a little confused, if the part ended up hollow, why not just machine a contoured slug out of it rather than machining it all into chips?

 

[Robert LaLonde]

Nice work! I've experienced many times in my career selling custom steam turbine parts where customers design a concept components but have no idea what it takes to make it. They usually fall out of their chair when I gave them price and delivery cycle times.

As a contractor I often solved problems with specialty systems that other contractors couldn't or wouldn't solve. The thing is there is almost always a solution if the customer is willing to pay for it.

As a **machinist I get nearly impossible to machine problems as well. Especially since I specialize in a narrow scope of mold making. Sometimes even when I can come up with a solution they customer proceeds to make it impossible because they want it laid out a simpler way or with fewer piecs. Some people seem to have a problem with the basic conscept of making a square corner with a round cutter, or worse they just don't understand that you can't machine a spiral into the thickness of a piece of metal. Only along its face. I come up with answers and a price, and then they will waste days of my time arguing about how to do it if I let them.

Nice stuff, Jim!

I was looking at that and thinking that it seemed at least 95% of the Delrin was machined away and it got me thinking - is Delrin recyclable? I've been keeping my aluminum chips (well, the bigger ones) with the idea I'm going to make a forge and make something out of them. Can you melt down Delrin and make a block? Is it even worth the time?

I have been saving my aluminum as well, but after doing some research I've found that 6061 (my primary aluminum) does not cast well. It tends to form large crystalline structures. There are some tricks, but I have not had time to try them just yet. I thought to simply to cast rough bars and rough rounds for non critical parts like feet and fillers. Anyway, one of the tricks to casting 6061 I have read seems to be rapid cooling. I'm not sure what that means, but once I get aorunf to building my foundry I intend to do some experiments. I want to see the "large crystals" for myself, and then I plan to try various methods of cooling and maybe even extruding to see what I can do. My foundry furnace might come sooner than yours as I have all the materials to build it except the burner on the shelf.

I seem to recall that Delrin can be injection molded, but I don't recall finding Delrin pellets to go in my injection machine readily available. I have a small plastic injection press... still in the crate on the shelf. LOL. I guess I have a too busy shop.

** Caveat, according to some folks I am not a machinist. I'm just a hack, wannabee, self taught, button pushing, shade tree machinist. LOL. I admit I am not a highly skilled manual machinist, but I often make satifactory parts for job types I have never done before. The funny part is sometimes folks are just happy to have somebody who takes them seriously and will make their part.

 

[MontanaAardvark]

Thanks for that, Bob. I'm aware that the T6 in 6061 is a description of the thermal treatment, but that's about the limit of my knowledge.

Casting my chips myself seems like a better idea than trying to sell them.

 

[Robert LaLonde]

Thanks for that, Bob. I'm aware that the T6 in 6061 is a description of the thermal treatment, but that's about the limit of my knowledge.

Casting my chips myself seems like a better idea than trying to sell them.

I think it might. One of the other things with casting aluminum seems to be a large amount of oxidation, and that the more surface area the more aluminum oxide you have to skim off. Chips would be amoung the worst for that, but then aluminum cans are recycled in home foundries, and they would be nearly as bad. Maybe worse due to the plastic liner and paint. I think that part might be manageable with the right combination of flux, and a reducing flame to get the right heat while burning all the oxygen that enters the furnace. I'm all arm chair when it vomes to foundry work so far though. There is often a huge gap between theory and practice. Since I do 99% custom work I have a lot of "mistakes" in my scrap cart. I'll probably start with drops and mistakes before I tackle chips.