Guesstimating part costs before RFQs (as a designer, [not RFQ])

Generic Default · Mar 2, 2017

I have a whole set of parts that I'm going to get made in fairly small quantities (15-60 of each part). It won't be happening for a long time, so I don't want to send out RFQs yet since I'll probably I tweak the designs between now and then. I always machine my own prototypes before I send out RFQs.

But I still want to have a ball-park price range for the parts during the design process. I know how much the raw material for each part costs, nothing fancy, just 6061 flat bar and/or plate. Prices for the blocks of aluminum are $30 to $85 from online retail sources.

The parts are simple, blocky, and can easily be machined in any VMC in a 6 inch or 8 inch vise. I know the exact amount of material that needs to be removed from the stock for each part. Features are simple slots, profiles, pockets, counterbored bolt holes, a few tapped holes, and facing. Parts shown below; the blocks are 10 inches in the largest dimension.

My best guesstimate is to find the approximate cycle time per part, multiply it by an assumed shop rate of $100 per hour, and then add the cost of the raw material to it. Plus a little bit more for shipping, CAM time, anodizing, ect... spread over the total batch size.

For example, one of the blocks with the large center hole starts at 240 cubic inches and ends up just over 120 cubic inches. If the shop hogs out the part at a decent rate (15hp?) the total cycle time for the entire part, front and back, should be less than 10 minutes.

So 10 minutes = $17 shop time + $80 material + (setup hassle time) gives a final part cost of roughly $115 per part

The reason I'm posting this here is because I want to get your expert machinist/shop owner advice on pricing this stuff. Am I correct in my estimating logic? What am I not accounting for? I'm early on in a manufacturing career, and I plan on doing this type of stuff for the next few decades, so give me your best advice and guidance!

m98custom1212 · Mar 2, 2017

Generic Default said:
So 10 minutes = $17 shop time + $80 material + (setup hassle time) gives a final part cost of roughly $115 per part

The reason I'm posting this here is because I want to get your expert machinist/shop owner advice on pricing this stuff. Am I correct in my estimating logic? What am I not accounting for? I'm early on in a manufacturing career, and I plan on doing this type of stuff for the next few decades, so give me your best advice and guidance!

You got it really nothing to it from that being said now where you may see pricing variance could be from the following

- Lead Time Short or Long Time
- How busy is the Shop in question
- Do they cut this material frequently
- Shipping/Distance from you
- Tolerances

Next you have the Factors
- Pain in the Ass Factor
- Flat out I don't really want it Factor
-You're whiny and need your hand held thru the whole project which takes time which cost me money

EPAIII · Mar 2, 2017

I think you could possibly refine the design to make the parts less expensive to machine. One has an inside corner with what appears to be a zero radius. That can be done but will probably require a second set-up. Another has features on two sides that will probably require a second set-up. The small one on the middle-left seems to have slots that go across an inside corner. Again it will need two set-ups and still may be problematic if the corners of those slots have to be completely square. Even if you come at that corner from both sides with an end mill, it will still leave something in those corners. I am not sure how that could be done.

Perhaps some of these parts could be divided into two parts for easier manufacture.

If you want a low price, you need to consider how the parts will be made while you are designing it. The earlier you think about these things, the better.

Limy Sami · Mar 2, 2017

MMMM? ;- Some thoughts of mine - others may disagree and YMMV

Well now - 10'' parts are not exactly small, therefore they take more time.

+1 for what EPA III said - cutting out the twiddly, fancy and awkward 2nd op bits saves $$$$

Likewise, no mention of tolerances, every zero after the decimal point increase costs - same goes for finish - the finer the more $$$

15 - 60 offs are not big lots, and that is reflected in the price, .set up time can be the killer, the larger the batch the less set up time per part.

My VERY ROUGH rule of thumb, for run of the mill jobbing work - take the cost of the material and multiply that by 2.5 to 3.

HuFlungDung · Mar 2, 2017

You're allowing $35 to make it, you forgot the Pi factor, which means 3.14 x $35 = $110

I think you are overlooking some stock prep time: large chunks of plate or extrusions are not flat and to size, so there is most likely a facing and squaring up step to do before you are ready to plunk the part in for the real machining. Deburring, cleaning between parts and inspection takes some more time. And bigger parts just cost more because they're bigger, because you sell them for more, because they're bigger.

gustafson · Mar 2, 2017

labor is twice parts

really

other than a bracket with two holes drilled in it you have to cover replacement of the stock

then you have to buy a length of stock cause no one can be bothered figuring out what is the most economic way for you to save money

is there any feature that is tighter than +- .005? add BS factor

anyone who would charge $17 labor on $80 stock is crazy

most of those parts have a radius all around, meaning either 2 ops or a fixture

If I was doing 15 of an 80 dollar stock[it won't cost 80 bucks if it fits in a vise btw]

1 hour program
1 hour setup
15 minutes per piece run
1 hour post

and a piece of aluminum that will fit in a vice is more like 25 bucks, so lookie there 45 bucks in labor 25 in stock, and since I would mark up the stock my net would be 75 each, labor twice parts.

And I did not figure that out in advance, really

Feeny · Mar 2, 2017

I think your machining numbers are good (from the extremely little information given on the part, a picture really tells nothing). I would add a 1 hour set up for each part # and a 1 hour programming per part # if it is more than just a simple hole or two.

If someone walked in with that picture and asked me to ballpark for QTY 15-60, I would say $100 - $400 per part.

Bobw · Mar 2, 2017

For example, one of the blocks with the large center hole starts at 240 cubic inches and ends up just over 120 cubic inches. If the shop hogs out the part at a decent rate (15hp?) the total cycle time for the entire part, front and back, should be less than 10 minutes.

So 10 minutes = $17 shop time + $80 material + (setup hassle time) gives a final part cost of roughly $115 per part

Yeah... NO..

I'll be dipped in shit if I'm making parts for less than half the material cost, unless its a bandsaw
cut and deburr.

Your looking at a qty of 15-60, so lets say 50 of 'em.. That's $4k I've got to front for the
material, and I'm going to get $1750, after turning the material into parts...

If I'm buying material, I'm marking it up.. Just like at the grocery store, or the garage
changing your brakes.... Have you ever argued with the cashier at McDonalds about the price of
french fries.. "But there is only 6 cents of potato here, why is it $1.99??, should be 8 cents".

I'm also going to buy a few extra pieces, set up piece, and any oops.. The tighter the tolerances,
the trickier the part, the more extra material I'm going to buy...

So now I'm going to make $750 for making the parts.

But I had to get quotes and order the material, put the bill in the system, and cut a check... Then
I had to receive the stock, get if off the truck, get it in the building, I'm assuming its coming out
of plate, so now it needs to be deburred, and odds are it will need at least one skim cut to true
it up so I can hold it really well..

Now I'm down to making about $500 and I haven't even started drawing, or programming, or buying
tools, or setting the machine up... And then still have to make the damn things, QC 'em, bill 'em,
package 'em and ship/deliver 'em..

Material removal is NOT a good way to guess parts prices, unless its literally just a hog out
with no features... I do some castings where I'm making over $100 per cubic inch of material
removal, and I earn every penny of it.

I'm not trying to be a dick (it comes naturally

), Just pointing things out
that you may not have thought of.. Everything always looks cheaper from behind a desk...
I'm guilty of that also..

The one thing that burns my ass, when a customer says "That should be eeeeaasy"...
I'll tell you if its going to be easy or not, you just make sure I get a check..

Onepass · Mar 2, 2017

Plus on all the others posts ! A lot depends on any relationship you have with the shop you go to. I gotta take a gamble on you being slow pay or a deadbeat or you gonna be cod?

Generic Default · Mar 2, 2017

The small one on the middle-left seems to have slots that go across an inside corner. Again it will need two set-ups and still may be problematic if the corners of those slots have to be completely square. Even if you come at that corner from both sides with an end mill, it will still leave something in those corners. I am not sure how that could be done.

Perhaps some of these parts could be divided into two parts for easier manufacture.

If you want a low price, you need to consider how the parts will be made while you are designing it. The earlier you think about these things, the better.

I designed these parts in CAD starting with a block, and every feature is a hole, pocket, or slot that is identical to what can and will be made in the mill (I even label my CAD features with the tool names that will make them). All of the features can be made with standard tooling that every shop already has on a cart; the endmills are either 0.25, 0.5, ect. Drills are standard tap chart sizes, nothing that a shop would have to order. I assume every shop has at least one facemill and rougher already in the tool magazine.

This bar shaped part should be easy, the pockets you mentioned can be milled with a 0.25 endmill 0.75" deep, after the main slot is hogged by a larger endmill. So you put it on parallels and run the first op, then flip it and press it up against a basic work stop for the bottom side edge radius.

The part below also gets set on parallels. Face the back, pocket the back, then flip it and run the main hogging cycle on the front (along with drilling, counterboring, ect).

Should take less than 10 minutes for both cycles on any modern VMC. I already ran the numbers for chipload, rpm, horsepower, ect.

Limy Samy, Bobw, gustafson,

They are big, simple parts. No crazy tolerances, everything gets done in 2 ops so all of the features are guaranteed to be accurately positioned to within a few thousandths (and that would be on a badly worm machine). Yes, they're mostly big parts. But the cycle time is a fraction of an hour per part. They shouldn't need any hand finishing other than a quick deburr maybe.

Multiplying the part cost by a factor of 2.5-3 is exactly what I'm trying to avoid. I'll probably end up buying all of the material, cut to length, and shipping it to whatever machine shop I end up using. That way there's no liability on their part, and no mark up that gets passed on to me. It's cheaper to send them a few extra blocks of each size, assuming they scrap the first part or mess up at some point. I know I always pay bills ahead of time, but shop owners don't (until they get the check). You guys are giving me the impression that a sizeable chunk of machine shop costs come from a distrust of the customer's payment and the initial cost of materials that the shop has to buy before they can even get started.

On the last big order I did, I offered to pay the shop owner with a briefcase full of cash, no joke. He actually preferred cashiers checks so I did that instead. He must have read that pablo escobar book or something.

Slightly different from the machining...... What about anodizing?
Everything I've anodized in the past has been small swiss lathe kinda stuff. Anyone who has had similar parts anodized, was the anodizing cost excessive for bigger blockier parts? Everything in the picture will be basic type 2 black.

Techguy · Mar 2, 2017

You might post a couple of your parts on here with dimensions and tolerances and ask what price range they would be in. That would give you some ideas for budgetary purposes. I think you have assumed way low with setup, programming, and scrap. Are these cosmetic parts? That adds to the price.

Will you take overages say 10%? I expect like most customers you don't want shortages. That requires me to make at least one extra and buy material for at least a couple extras because of set up scrap.

I won't make any part for less than a 3 to 1 ratio of part cost to material cost. I can't afford to make parts at a negative price if the platers screw them up. Most turn out to be 10 to 50 to 1 material to final part price here. My raw materials costs are generally low.

Post a couple drawings with details including if they are cosmetic and I am sure some of us will give you price ranges.

Good luck,

Dan

Limy Sami · Mar 2, 2017

MMM? well you did ask!

Perhaps the alternative would be for you to set up your own shop to make them yourself, .........then perhaps come back to us with a true breakdown of your time inputs and costs, ......... and we can compare them with the prices mentioned in the first post.

m98custom1212 · Mar 2, 2017

Generic Default said:
I designed these parts in CAD starting with a block, and every feature is a hole, pocket, or slot that is identical to what can and will be made in the mill (I even label my CAD features with the tool names that will make them). All of the features can be made with standard tooling that every shop already has on a cart; the endmills are either 0.25, 0.5, ect. Drills are standard tap chart sizes, nothing that a shop would have to order. I assume every shop has at least one facemill and rougher already in the tool magazine.
View attachment 192552

This bar shaped part should be easy, the pockets you mentioned can be milled with a 0.25 endmill 0.75" deep, after the main slot is hogged by a larger endmill. So you put it on parallels and run the first op, then flip it and press it up against a basic work stop for the bottom side edge radius.

The part below also gets set on parallels. Face the back, pocket the back, then flip it and run the main hogging cycle on the front (along with drilling, counterboring, ect).

View attachment 192553
Should take less than 10 minutes for both cycles on any modern VMC. I already ran the numbers for chipload, rpm, horsepower, ect.

Limy Samy, Bobw, gustafson,

They are big, simple parts. No crazy tolerances, everything gets done in 2 ops so all of the features are guaranteed to be accurately positioned to within a few thousandths (and that would be on a badly worm machine). Yes, they're mostly big parts. But the cycle time is a fraction of an hour per part. They shouldn't need any hand finishing other than a quick deburr maybe.

Multiplying the part cost by a factor of 2.5-3 is exactly what I'm trying to avoid. I'll probably end up buying all of the material, cut to length, and shipping it to whatever machine shop I end up using. That way there's no liability on their part, and no mark up that gets passed on to me. It's cheaper to send them a few extra blocks of each size, assuming they scrap the first part or mess up at some point. I know I always pay bills ahead of time, but shop owners don't (until they get the check). You guys are giving me the impression that a sizeable chunk of machine shop costs come from a distrust of the customer's payment and the initial cost of materials that the shop has to buy before they can even get started.

On the last big order I did, I offered to pay the shop owner with a briefcase full of cash, no joke. He actually preferred cashiers checks so I did that instead. He must have read that pablo escobar book or something.

Slightly different from the machining...... What about anodizing?
Everything I've anodized in the past has been small swiss lathe kinda stuff. Anyone who has had similar parts anodized, was the anodizing cost excessive for bigger blockier parts? Everything in the picture will be basic type 2 black.

And this where you ran into trouble telling us how to machine your parts

david n · Mar 2, 2017

Bobw said:
The one thing that burns my ass, when a customer says "That should be eeeeaasy"...
I'll tell you if its going to be easy or not, you just make sure I get a check..

Yup......all summed up right there.

Generic Default · Mar 2, 2017

m98custom1212 said:
And this where you ran into trouble telling us how to machine your parts

The reason I attached the pictures in that post was to clear any confusion; the second person to respond to the original post was saying that one of the parts was nearly impossible to make due to a zero-radius inside corner.

RC Mech · Mar 2, 2017

Generic Default said:
You guys are giving me the impression that a sizeable chunk of machine shop costs come from a distrust of the customer's payment and the initial cost of materials that the shop has to buy before they can even get started.

This is a business, and not even a lucrative business. The prices you're coming up with are the prices you should expect if you were to purchase a milling machine, gather years of experience and tooling, put a significant chunk of capital towards measuring and gauging instruments, take small business management courses, hire employees and then get put through the ringer chasing deadbeats for payment after you've delivered your product and above all, DO IT ALL YOURSELF. If you've calculated chip load and material volume (both of which are merely OUTPUTS from any decent CAM package), clearly you know what you're doing. So just, do it. Simple, right?

You say "no crazy tolerances" but then abstain from giving a numerical example. This has got PITA written all over it. You should be so lucky as to have a shop only tax you 2.5-3 times for the pleasure of having to deal with this. As was said before, $80 chunk of material, $17 to add value such that the hunk of ignorant material is actually worth anything to anyone. :nutter:

m98custom1212 · Mar 2, 2017

Generic Default said:
The reason I attached the pictures in that post was to clear any confusion; the second person to respond to the original post was saying that one of the parts was nearly impossible to make due to a zero-radius inside corner.

Pictures have nothing do with it.. It's this "Should take less than 10 minutes for both cycles on any modern VMC. I already ran the numbers for chipload, rpm, horsepower, ect." Please tell me more with your vast experience in programming and running a vmc

david n · Mar 2, 2017

You will have a minimum of an 1-2 hrs in just programming and setup. I'd be charging at $200 before a single part comes off the mill. Then there's milling it. First article will be more like 30 mins instead of your 10. Another $50-$100. Then we have inspection, clean up, paper work, packaging. Another $50. Ah, let's say another $75. So there your $115 part is more like $325-$375. 'Course that is for a one off, you will have to order a lot of parts to get that price down.

Limy Sami · Mar 2, 2017

Cynical bitter and twisted lot us machinists - aren't we

Or as one of my old mentors used to say ''any twat can draw something and read a book Sami lad, .................much the same as any twat can lose money.''

gustafson · Mar 2, 2017

My friend, we have been doing this for years, there few billionaires among us. WE have given you our opinions, on what we would charge, and what our customers likely would bear, that is all

When one of us says that for 15 minutes of machine time, it takes 2 hours,please, show us the respect to believe it is the truth

You will not be sending anyone here a bunch of pre cut stock, I can buy it for less, cut it to size on my fully automatic non ferrous cold saw, and have enough stock to either make it all over if i screw it up, or make you one for a bargain price if you screw up, all without you being aware of anything interesting going on

At the end of the day, there is a reason that a part made with 80 dollars of stock costs 250 dollars, and if you do not understand that, then please, buy machines and come kick our collective asses, that is capitalism

Guesstimating part costs before RFQs (as a designer, [not RFQ])

Aluminum

Stainless

Diamond

Diamond

Diamond

Diamond

Plastic

Diamond

Hot Rolled

Aluminum

Hot Rolled

Diamond

Stainless

Diamond

Aluminum

Stainless

Stainless

Diamond

Diamond

Diamond

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