[spcutler]

Hello--
I'm looking to have a part machined out of steel (probably 8620). Starting material will probably be 2" diameter rod, 8" long. Final product will look something like a Christmas tree (a cone on a cylinder), but with a rectangular spiral groove on the conical part.

I have a pretty low budget and I don't quite know where to start. A local place offers design classes, and I'd bet I can design the part myself, but I have nowhere to get it machined. I'm guessing it'll need a 5-axis machine but I don't really know that for certain. If I manage to produce a design in Solidworks, can I expect to hand the file off to someone and get it machined without too much extra effort on my part?

At this point I'm pretty much just exploring options, so if others have alternative suggestions (lost wax casting or something?) I'd like to hear those as well. I don't need super-high dimensional tolerance or surface quality; cost is the main criterion. Thanks for any help!

- Scott

[DareBee]

If I manage to produce a design in Solidworks, can I expect to hand the file off to someone and get it machined without too much extra effort on my part?

Yes

Have you got $1000 for your christmas tree?

[Jim Estes]

How deep is the rectangular spiral groove? I think this could probably be done on a 4-axis machine. Just involves rotating the cone as the groove is cut. You would get a slight radius in the bottom of the groove that would result from the cutter traveling down the angle of the cone.

[mactec54]

Hi spcutler

You can do this part on a manual 2 axes lathe with a taper attachment, we used to make a part like this for wood splitters

[universalfab]

This is definately sound like a turning job. Can you post a picture or your part?

[Dualkit]

This is definately sound like a turning job. Can you post a picture or your part?

The guy said he had a LOW BUDGET, if you continue to interact with these people I suggest you go get your blood pressure checked. It seems you are going out of your way to find ways to stress yourself out.

[Tormachmaster]

Post a picture. This is the only way you can get any type of quote on this part.

[universalfab]

The guy said he had a LOW BUDGET, if you continue to interact with these people I suggest you go get your blood pressure checked. It seems you are going out of your way to find ways to stress yourself out.

Thats a good way to look at things and your probabley right.

[spcutler]

Thanks all for the advice so far. I haven't had time to draft a picture yet (the design is mostly in my head at this point), hopefully in the next day or two I can put something together.

All I have at the moment is this:
http://www.scottcutler.net/images/spiralconefield.png

The left of the image is the center axis (ignore the curvy gray lines; those are magnetic field lines). The part outline is in blue. Note though that the grooves are not circular; they form a spiral.

These proportions aren't final, either, but hopefully it conveys the gist of the design. I'll post a full drawing later. This is for a hobby project (hence the budget constraints) so I have no problem with posting this stuff publicly.

- Scott

[irrational]

Hey Scott, are you doing something with Ferromagnetic Liquid?
Kinda like this [ame="http://www.youtube.com/watch?v=eDnrFgd7yfo&feature=fvw"]YouTube- Amazing Magnetic Art Sculpture!![/ame] ?

-IM

[spcutler]

Hey Scott, are you doing something with Ferromagnetic Liquid?

Oh my, you've spoiled my surprise ! You deductive skills are excellent, as that is exactly my intent. The spiral cone shape turns out to be a "perfect" shape for making ferrofluid do neat things due to the way it directs and concentrates the magnetic field.

Well, now that the "secret" is out, to anyone that's interested, your video shows the basic shape that I'm shooting for. Below the surface of the fluid is an additional cylinder that the electromagnet is wound around, but the complicated portion is visible.

Another variable is that I'm not dead-set on a size--if it turns out that the cost is too high for the size I want, I maybe be willing to go with something smaller, such as 1" or 1.5" in diameter.

By the way, here is a vid of my own experiments with the stuff (much less nifty than your vid, but neat in a scientific way):
[ame="http://www.youtube.com/watch?v=KaUnubDdouc"]YouTube- Ferrofluid demonstration[/ame]

-Scott

[universalfab]

That is going to cost you more then a low budget.

[spcutler]

That is going to cost you more then a low budget.

Out of curiosity, where do the bulk of the costs from? I can't imagine that this part would take even close to an hour on an automated machine. By my math, a $100k machine amortized over 5 years is something like $15 an hour. Tool wear costs can't be too much on a part like this. Machinist costs are what--less than $50 an hour, I'd suppose? I guess I don't see why a relatively simple (for a CNC machine) part like this can't be done for something on the order of $100-150 instead of $1000 if the design is done.

Okay, maybe my cost estimates are way off since I literally know nothing about the industry. Maybe things aren't set up to do one-off items relatively cheaply. That sounds like a market opportunity to me, but maybe the demand isn't there.

- Scott

[DareBee]

Funny guy.
A machine that programs and sets itself from a mental image.
What a great idea.



What about heat, electricity, rent, taxes, computer, administration(quotting & billing at minimum), cutting fluid, workholding fixtures, toolholders, money to replace or repair the machine, tooling, CAD and CAM software, etc, etc, .... and most importantly some profit to stay in business with (and feed the kids).


You want 1000pcs made from C12L14 - how about $35 each.

[universalfab]

Out of curiosity, where do the bulk of the costs from? I can't imagine that this part would take even close to an hour on an automated machine. By my math, a $100k machine amortized over 5 years is something like $15 an hour. Tool wear costs can't be too much on a part like this. Machinist costs are what--less than $50 an hour, I'd suppose? I guess I don't see why a relatively simple (for a CNC machine) part like this can't be done for something on the order of $100-150 instead of $1000 if the design is done.

Okay, maybe my cost estimates are way off since I literally know nothing about the industry. Maybe things aren't set up to do one-off items relatively cheaply. That sounds like a market opportunity to me, but maybe the demand isn't there.

- Scott

Your cost estimate is way off. Look at the ammount of hacking that has to be done. I think you need to leave your opinions home, because that bit of tallent is completely worthless to everyone here. And if your such a mathmatician and machinist it sounds like there is no need for any of us here, why don't you just whip up one of these things in a jiffy and show us all how a real brainiac does it?

[spcutler]

why don't you just whip up one of these things in a jiffy and show us all how a real brainiac does it?

I'm not trying for force my opinions on anyone; I'm genuinely curious. So I don't really understand the reason for your tone. If the answer is just "there's a lot of time I'm not accounting for, and this is really more like a one-day project", I'd be satisfied (if disappointed). Maybe my opinions are clouded by all those YouTube videos of machines spitting out ridiculously complicated parts in minutes, and that there's a huge amount of setup time I'm not seeing.

As I said, this is a hobby project. My time is worth almost nothing, so I'm happy do as much as I can on my own. In fact, I'm willing to pay more to do it myself--a local place called TechShop offers classes on CNC and rents machine time. The classes would be fun and I might take them anyway. But I'm not sure their equipment is quite what I need. And my own small manual 3-axis mill definitely isn't up to the task.

- Scott

[spcutler]

Funny guy.
A machine that programs and sets itself from a mental image.
What a great idea.

Didn't I specify that I would produce a design in Solidworks (or heck, whichever package is requested)? I have options available here. Though I don't know how that is ultimately translated into CNC instructions.

You want 1000pcs made from C12L14 - how about $35 each.

In other words, this is a good approximation of the cost of electricity, machine wear, and all the other things aside from fixed overhead, right? I've encountered other industries (such as PCB manufacturing) where one-off parts can be done for a small multiple (say, 3-5x) of the raw cost as long as the design work and such is done upfront. If machining is different, I can accept that, but I still find it curious.

Another thing is--and perhaps this is an invalid assumption of mine--I guessed that there are people here looking for side work and have access to machines (either self owned or from (with permission) their employer). Presumably these people have little to no overhead. I occasionally do contract programming outside of my day job and I'm able to charge way less than any professional house (still with a healthy profit).

Anyway, I certainly didn't mean to get anyone riled up, and I apologize if I did. I just like to understand thing when reality is out of line with my expectations.

- Scott

[mactec54]

spcutler

Don't take to much notice of these guys hacking on you, they do it to everyone,Your part is very easy to make How deep & how wide do the grooves have to be & what shape can the grooves be square bottom round bottom

[universalfab]

I'm not trying for force my opinions on anyone; I'm genuinely curious. So I don't really understand the reason for your tone. If the answer is just "there's a lot of time I'm not accounting for, and this is really more like a one-day project", I'd be satisfied (if disappointed). Maybe my opinions are clouded by all those YouTube videos of machines spitting out ridiculously complicated parts in minutes, and that there's a huge amount of setup time I'm not seeing.

As I said, this is a hobby project. My time is worth almost nothing, so I'm happy do as much as I can on my own. In fact, I'm willing to pay more to do it myself--a local place called TechShop offers classes on CNC and rents machine time. The classes would be fun and I might take them anyway. But I'm not sure their equipment is quite what I need. And my own small manual 3-axis mill definitely isn't up to the task.

- Scott

Hey Scott, I see now where your comming from, you just don't know. Thats great you admitted that. Your part as Mactec said is a easy part, but it still takes time to do and electric, and blah blah blah. The only thing your paying for is time, material and shipping. At least thats all I charge my costumers. What gets me though is your not willing to spend the money for someone elses invested time and money, but your willing to spend way more then a fair price I'm sure to learn how to do it yourself.

[spcutler]

What gets me though is your not willing to spend the money for someone elses invested time and money, but your willing to spend way more then a fair price I'm sure to learn how to do it yourself.

I absolutely respect other's time and money, and if this were a professional project I'd pay to have professionals like yourself do it from start to finish. But being a hobby project changes the equation. I can't justify $1000 on something that I'm not going to sell. But I do have spare time, and so I'm willing to put in some work myself. And I'm willing to spend a little on classes that will help me with both this job and the 3-axis mill that I own.

But if the price is right I'd still rather get it done by someone who knows what he's doing. I'm sure the quality will be much better than I can do on my own, since nothing beats experience in the end.

-Scott