Hrly Rate for CNC/Virtual Modeling?

[lumberjack]

I've gotta design a bullet mold and accessories for a "customer", then turn around and make it.

The stock is a roll journal that he supplied. The plan is to cut a piece to the correct length, cut it in half (like a hotdog) face the mating surfaces and install a couple of locating dowels.

Then put it together and the external profile back in circularity and cylindricity.

Then machine a recessed flat on each half 90* (external) from the mating surface to locate the C clamp while casting. Then put it in the CNC lathe and cut the internal revolved pattern (bullet mold).

Take it back apart and spot face/counter bore one half and put a threaded hole in the same location on the other half to give provisions for pressing the two halves apart by turning in the screws and machine a recess around the edge of the mating surface to protect the mating surface's edge if it's dropped,

There's some other misc features to be added, but that gives you an idea of that part of the project. The base of the mold will be a copy of the existing mold's base for interchangability, there is no sprue cutter.

I also have to design and make a mandrel for his gas checks to fit the new bullet, no biggy there, but more design time.

My question is what is customary to charge for design time? I'd like to give him a bid rather than an hourly rate.

As far as I figure, the only part that will definatly be cnc'ed is the internal pattern.

 

[CurSedVoyce]

Just asked Katy about her dad and his bidding for the CNC...
He pretty much used his hourly which was between 40-50 an hour union machinist rate on an estimated time of job. He was still on a learning curve at the time so he was pretty much guessing on time on design.. So his hourly did drop on design time through his learning curve.. It would probably help to know how much a standard machinist rate would be for your area also..
Katy is from Oregon... Her dad was contractual country wide through the union.
Often when I did blue prints for parcels I would only charge my plumbers foreman rate to help offset the fact I don't do so much of the blue prints anymore and I am slower than someone that does it all the time.. That rate was about half of her dad per hour.. 20-25 per hour. That was for hand drawn...

 

[Paul B]

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[sawinredneck]

As you are new and learning, keeping the rate low will make you a bit of cash, and not scare them off.
Mos shops I know rate this around $85hr.
They guy I built molds for would charge half up front, then take a percentage of the profit until it was paid in full.

 

[lumberjack]

Since I have access to the CNC mill/lathe and manual mills and lathes, I'll throw most of the machining in.

I'm figuring $4-600.

 

[Al Smith]

They figure around 75-80 per hour machine time on CNC production run stuff .

The rate for regular machine work can vary a tad .I charge 55 myself which is about average I suppose for this area .

 

[lumberjack]

I forgot to mention the bullet I'm designing is a 3" caliber.


Top left is the bottom of the mold.
Top right is a parted off piece of bore from when he had the cannon refurbished.
Bottom left is an as-cast bullet and a "stock" gas check (called a sabot back in the day).
Bottom middle is a machined bullet, swagged and machined gas check.
Bottom right is half the bullet mold.

That mold is 30ish years old, and is for a 2.9" cannon (which he has). The relined gun is a 3" cannon, and he wants a scaled version of the old mold with some slight differences to the bullets geometry and some refinement to the mold itself (mentioned above).

FWIW, he says it takes about 5 hours to make a single bullet, which is excludes things like the bullet cooling off (5 hours at least).

Didn't mean to imply that I was making a standard caliber bullet die, that'd be no biggy.

FWIW the finished bullet picture below weighs 53.2k grains (7.6lbs), and it has some porosity problems. The cannon fires the projo at velocities a 10mm could throw a 135 grain bullet (394 times lighter, 1550fps). The rate of twist is 1:17, that's feet, not inches. The barrel is 72-73" long, best I remember.

 

[CurSedVoyce]

OK that is just too cool...

 

[PCTREE]

Is this for deer hunting???

 

[CurSedVoyce]

Might be hard to set up for deer.... HAHAHA
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[Reddog]

LJ,
If I was bidding this one off job, I would figure 4 hours design/copy time.
Using a cad software we figure 60 an hour. So 240 minimum.

Then for the machining I would figure 6-8 hours at 60-80 depending on machines used. So 360-640 for machining and finishing/polish.

 

[sawinredneck]

Looks like an EDM sink dieing machine would be a good freind to have on that project!

 

[C. Kirk]

Hay there.
I would charge $ 50-60 per hr. for design time. Copying and scaling up should be no more then 4 hours top. Machining $ 40-50 per hr. Machining time 12-20 hrs.

Cut steel in half, square up outside edges, clam 2 halves together, place in mill put in the 2 dowel pins hole, put in dowel pins, flip part bore cut pockets, flip to do the opposed side,
ad in jack screws( top half with threads bottom half no holes on all 4 four corners) this is how i've made low pressure molds at work.

Good luck with this.

 

[squisher]

This looks cool, keep us updated bigguy.

 

[lumberjack]

Thanks for the reminder. Here's the model of the existing bullet as cast w/o the sprue.