How would I make these?

zgoo · Apr 20, 2006

I need help on what would be the best way to machine these parts;

They are made from 316 SS bar stock 1" dia. The length needs to be 2" with a flat .5" radius on one end. There is a turned step down on the other end of .100 and 3/4" long from the end. I also need a slot about .375 wide and.750 deep coming in from the top of the radius in the center of that end. I need to make 50 to 100 at a time. I have a CNC bridgeport knee mill. A cnc shop gave me a price of $13.50 ea T&M and that seemed a lot to me. Since I'm a new to this I willing to learn from you guys? I was thinking that I could take some 1" x 3/4" x 16" plates and put 4 of them against each other and make .800 holes every 1 1/2 along where the plates meet so that I can hold about 20 of the 2" parts standing on end and clamp the set on the mill table. Then using a ball mill cut the .5 radius in the tops by make long passes cutting each part in a pass until the radius is cut. Them cut the slots with end end mill at ringle angle to the radius. Any help with this or comments? How hard or slow will 316 be to machine?

Thanks-Dan

Bobw · Apr 20, 2006

A little hard to imagine what you're describing. $13.50 for the price, I guess it depends, first what are the tolerances, how many did you ask him to make? 316 sucks, so that ups the price, if the guy is busy, he bids it high, if he gets it great if not who cares.

316 sucks, I recently had my first real introduction to it, it makes 304 seem easy. Gummy nasty and if you look at it wrong, it will work harden on you.

zgoo · Apr 20, 2006

+ or - .010. Need 50-100 at a time.

zgoo · Apr 20, 2006

I guess if you stood a 2" lenght on end and milled a .375 wide by .750 deep in the top end and then put a .5 flat radius on the same end. Then cut a .75 set .100 deep on the other end. hope this helps!

Solar71 · Apr 20, 2006

sounds easy to make...
simple geometry...

but 316 SS is ( i think ) about 2$ per pound...

if each units raw stock wieghs 2-3 pounds thats almost 6$ right there...

the price does not seem too high...
because you are ordering such a low quantity...
50 units is sooo low...
even 100 is low for such a small part...

But then again , if you provide the raw stock, thats another story...

good luck

Solar71 · Apr 20, 2006

Send a blueprint and i can have my boss quote it...

tommarow...

no problem...

PS : what does T&M mean ?
Tooling and Material included in price ?

if so, the price seems good

zgoo · Apr 20, 2006

Solar,

T&M time and materials.

The cost of the stainless bar is about .50 per inch so material cost is $1. per unit. max.

PBMW · Apr 20, 2006

online metals has 1" dia 316L for $123 per 8 ft.
That is certainly not .50 per inch
It's hard to imagine what your part looks like from your discription. But I would quote just the material for 100 pcs at $165. Lets say the part ran in four min. that would be $800 in labor. Add in an hour to set it up and program it. An hour to inspect them, package and prepair the shipping documents and an invoice and you're at $1025 total ...
I'm just pulling numbers out of the air, but on the surface it seems to be in the ballpark
No way to tell really without seeing a drawing, but my point is that there are many costs that you may well have not included in your determination that this was toooo much.
Jim

Solar71 · Apr 21, 2006

123$ for 8 feet is .78c per inch

i have never seen material sold per inch...
i only see it $ per pound...

still... .78 x 2 inches = $1.56 per unit (about)

not too bad...

i thought it would be more

htrd6935 · Apr 21, 2006

I think the price is toooooo low. 316 does not like to be machined. But it can be done with the right tools and machines. Which cost a whooool lot of money.

Tumbleweed Tim · Apr 21, 2006

Cut one on your bridgeport then you will feel better about the 13.50 each.

tmt · Apr 21, 2006

Not to be a nit picker, but $123 per 8 ft is approx 2.56 each part. Don't forget width of cut and enough to finish the ends off and it comes out to more like $2.75 each part.

$123/(8*12) = $123/96 = $1.2813 per inch. At least that is the way I learned it in a back woods school.

Solar71 · Apr 21, 2006

tmt...

oops your right...

i did 96 / 123
instead of 123 / 96

my bad...

so whats the weight of 1 inch ?

PBMW · Apr 21, 2006

My bad...you are correct on the material cost.
I've been up since 4:00 this morning

Tumbleweed Tim · Apr 21, 2006

It's coming out of your check Solar.

maxh · Apr 21, 2006

I calculated .227 pounds per inch.

pi * (2.54/2 cm)^2 * 2.54 cm = 12.87 cc

12.87 cc * 8 g/cc = 103 g

103 g / 454 g/lb = .227 lb

zgoo · Apr 21, 2006

In town we can get the SS for a lot less then the online metals. Since I have not tried to run it before, what kind of problem could I run in to with the Bridgeport and what would be the proper cutter to use?

Dan

PBMW · Apr 21, 2006

Zgoo
A pic would REALLY help....

mill hand · Apr 21, 2006

you might be able to do those slots and whatnot in 15mins. but tooling is going to be carbide. :eek:

Anvil · Apr 21, 2006

A .375 slot .75 deep in 316? I'd spend my first coin on a Seco Carboloy Nano Turbo .375 insert cutter. You'll have to turn back the shank a little to get .75 DOC, but these cutters turned a half-hard 304 job into a money maker for me. They're undersize about .01 so you'll have take a clean up pass with a finisher.

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