Estimating engineering time on machine design

There is a pretty radical variety in the complexity of some of my components. For example, just today I finished detailing a fixture plate with 196 features. I probably have 6 or 7 hours just in detailing the crazy thing. Other parts I can design and detail in half an hour.

What I try to do is break the project into a list of tasks and estimate those. Tasks include things like adding fasteners, drawing check, plumbing, travel, etc. Any of those tasks can be broken out for each major segment of the project.

What makes it hairy is how much the customer wants in the 10 lb bag. A very crowded design seems to require a multiplier that only experienced judgement can determine.

-------------------------- Quite right, and I know my question is simplistic. I'm just wondering how others begin. There are no easy answers, but I'm looking for GENERAL approach "rules of thumb" that might be useful.

'Sporky'

I don't like quoting on jobs 'cause it's so hard estimating on something that isn't even it ya head, but I will give and estimate on the hours.

Most clients have an idea of what the whole job should cost and I have found over the years that the design and detail costs are between 10% and 20% of this.

Single parts vary alot in their complexity. I've just spent a couple days on a complicated bearing housing, but then some parts may only take a few minutes.

Just my thoughts....

Cam

Hey Mark-

I'm like Dale, I try to break the project into tasks; part creation, assembly analysis, drawing annotations, file conversions, etc. Then, for each task, I estimate how many hours it will take. "It always takes longer and costs more"

Best Regards, Devon T. Sowell

Yup, agreed. Sorta/kinda done that already. But in the typical mix of prismatic parts, both complex and simple, what do you estimate for a baseline design and documentation time?

In round numbers, I use 4-5 hours per detail for providing a ballooned assembly,

100% bill of materials, 100% dimensi>I'd just like to compare notes with a few machine designers about how

Hi Spork, I am not in machine design, but in my business we would estimate on a project by how many drawing sheets we estimate will be produced. This is then factored by 10 to give the total design hours, it works out over a project as some sheets are minor details and some major assy drawings.

That's interesting. Stress analysis won't be required on this project, and self-checking is typically de rigeur on machine design of this sort (although I agree that self-checking is in general not a good idea; it's a luxury to have a checker when you're doing competitive bid). We're working in tandem with a machine shop in this case. They're handling the hardware bid and we're handling the design bid. It would be easy to screw ourselves here by either overbidding or underbidding, but not as easy as if we were doing the whole thing.

Thanks (to all) for comments. More comments welcome.

'Sporky'

assembly, 100% bill of materials, 100% dimensioned

someone else's assembly, I get 2 hours because

Wow. The time you get would be a real luxury in my world. I'd love to bid that much, but I'm afraid we wouldn't get the job.

'Sporky'

assembly, 100% bill of materials, 100% dimensioned

someone else's assembly, I get 2 hours because

Just a note..you don't NEED to get every project. Some would be best gotten by your competitor. I look for a ratio of 1:4 gotten vs quoted. An example of what I'm taking about happened recently; I quoted a project for $210K while a competitor went in for $167K because he listened to what the customer was making the most noise about, not what he actually said. The customer told us both that he only had $170K repeatedly but turned right around and told us what his justification was. The number of people he was to save yearly actually justified something over $225K. The other guy, a friend of mine, shipped about $30K with the project and has the customer mad because of trying to get the additional money. I know you've been at this long enough to have an idea of what an AVERAGE designer can do and you have to quote the AVERAGE, not the fastest. You sound like you're quoting what YOU can do..are YOU going to do the project? You've got good ones and bad ones working for you and you can't make any money if you only quote the good ones. Sooner or later, YOU'LL end up doing ALL the projects and STILL not making any money. You really want to quote the worst you have and get the good ones to do it. You make money by quoting the worst you can get by with, then using the good ones, if possible, to do the project. In my years, I've only lost money on one or two projects and those were less than 5%. The size of the projects ran, when I was working full time, in excess of $10m total with the spread of work at approximately engineering 17-20%, fabrication labor

42-50% and material 35-41% of the total project. This figure for engineering will include the concept, the cost estimate, all engineering meetings both before and after contract award, total design, total details, all controls, pneumatics, installation & debug of the equipment on our floor and at the customers, any follow up at the customers, corrected "as built" drawing and full operator & maintenance manuals with CD's. Of late, I don't do projects that exceed $200-300K..it's too much work for ME as a project manager. If I do just the engineering, most projects are less than $50K to my company though a few have exceed that for some past companies that have been good customers. AND, if your quoting against another firm, your rate should be different than if you're the sole bidder..sales if the art of finding out what the customer CAN spend, pricing the project for that amount and talking the customer into your price, not what the project is actually worth. R. Wink

On Sun, 20 June 2004 18:36:16 GMT, R. Wink wrote:

deliverables and pays for the sales end of the

I probably don't use the same rate as your

wrote:

assembly, 100% bill of materials, 100% dimensioned

from someone else's assembly, I get 2 hours because

I agree, and I noted that 1 1/4 hours was minimum. I really meant ABSOLUTE minimum, but it's possible to do on some kinds of things. I think 2 hours and then add 15%, as a simplistic approach. And I don't believe in taking simplistic approaches, but "rules of thumb" are useful to a degree.

Thanks, Amigo

'Sporky'

you're quoting what YOU can do..are YOU going to do the project?

Absolutely agree. And yes, it's me doing the project.

by your competitor. I look for a ratio of 1:4

quoted a project for $210K while a competitor

noise about, not what he actually said. The

and told us what his justification was. The

The other guy, a friend of mine, shipped

the additional money.

Why would anyone p*ss off a customer because it took 15% time more than quoted, unless the customer was somehow to blame by changing things from what was originally quoted or whatever?

Best regards, Spehro Pefhany

Well, it's the reality of the situation, Spehro. Customers get pissed off for no justifiable reason, and they do it predictably and almost on cue. They get even more pissed off if it's their own fault. The only way to prevent it is to come in on time and under budget . . . and then they'll find something wrong with what you've given them and demand that you make it up on your own nickel. Reality bites, but the alternative is unthinkable.

'Sporky'