Estimating engineering time on machine design

I'd just like to compare notes with a few machine designers about how
they figure time on machine design tasks. I personally find that about
1 1/4 hours per fabricated part is minimum to estimate for design and
detailing, and that's really a very conservative minimum. 1 3/4 hours
to 2 hours is probably more realistic unless the task is very
straightforward. Then one has to figure in time for changes and time to
do assembly drawings. It's not quite a simple as that, but that's where
I begin. How about you?

Thanks for any feedback

Mark 'Sporky' Stapleton
Watermark Design, LLC
www.h2omarkdesign.com

 

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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
www.3-ddesignsolutions.com

 

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% dimensioned
details on my customers paper with a CD and manuals. For detailing only from someone else's assembly, I get 2 hours because
of the fumbling to figure out what they were trying to do.
R. Wink

 

Mark-
I agree with the 2 hours per part as a good starting point.
Devon

 

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.

BTW we factor by 20 to get the whole project completed, this includes all
factors to get it completed, ie 20% design time is allocated for checking,
then 30% for stress analysis etc. etc etc.

 

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'

 

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'

 

Been at it for nearly 40 years. I pick and chose what I work on as I'm semi-retired.
Note the numbers include all the engineering..from initial concept to final deliverables and pays for the sales end of the
projects too. I have 5-6 shops that don't have any problems with my costs but I probably don't use the same rate as your
shop either.
R. Wink

 

1.25 hours per part is really flying. Depends on what you are doing. Depends
on what the deliverable is. If the customer requires prints for assemblies
and details then you have to allow time to update each level of subassembly
as well. Just drawing with minimal design would be 2 hours per drawing.
This is assuming simple machine parts and not something like an injection
mold.

 

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

 

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'

 

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

 

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'

 

Sorry, I didn't mean to rant about this but Sporky's dead right about this. Customers (and particularly this customer) go
ballistic over anything over HIS budget (irregardless if he has more money or not) or that is late. That's one of the
reasons I don't drop my price of his projects. My friend shipped his own money with the project (lost money!!) and was
looking for any way to get to a "break even" situation. Any time you "ship money" on a project, you shouldn't have taken it
for the price YOU quoted. YOU SCREWED UP and if you do it on a regular basis, you'll go broke (NOT GOOD). Your
relationship with the customer will tell you (before you get the project) what you can or can't do..either you know them or
you don't...and you SHOULD quote accordingly.
By the tone of your question, it would appear that your customer are the other people in your companies engineering
department rather than for your own business..somebody else is writing your paycheck rather than you having to do it (correct
me if I'm wrong here).
If Sporky is doing the project that started all this his self, I'd be using about 2 hours per detail for straight detailing
work (from an assembly) , 1 hour per detail for assembly generation and ballooning, 1/4 hour per detail for Bill of Material
(to their spec) generation. Sales and project management costs are something NOT based on detail number but I use 5% for the
project for sales and project management is on a "as needed" cost basis. I also get paid (by the shop I'm working with) for
quoting the project (amounts to about 0.5% of the project). Note I don't consider hardware as a detail unless it's modified
in some way and requires a drawing.
R. Wink

 

Sporky I have a set of "rule of thumb" that I developed and used while I was selling custom production machinery. Costs have
changed a great deal but the overall ratios should still be the same. Would you like to have a copy? It's in Word format.
R. Wink