×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Machine shops and metric drawings

Machine shops and metric drawings

Machine shops and metric drawings

(OP)
So I had this meeting today with SMC, a machine shop and material manager and have any of you guys ever experience a fabrication house that says "...well the reason the we're late on deliveries is because the drawings are all in metric and we're not use to that standard, if they were english, things would go smoother" Now I'm being asked by SCM (supply chain) to change all the drawings to english, my response "I'll look into it"; but what I really want to do is give SCM and the shop the middle finger and then say a number is a number regardless if its imperial or metric, or we'll find a new shop

RE: Machine shops and metric drawings

I've heard lots of excuses, but never that one. Pretty lame.

John Acosta, GDTP S-0731
Engineering Technician
Inventor 2013
Mastercam X6
Smartcam 11.1
SSG, U.S. Army
Taji, Iraq OIF II

RE: Machine shops and metric drawings

Lame indeed. If they want to stay in business, they need to be more up to date with the trends. I suppose they still base their manufacturing on scaling dimensions from the print with a ruler?

John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems

RE: Machine shops and metric drawings

LONDONDERRY,
You mean you have some choice as to who your suppliers are? I would get your Purchasing Manager to call the machine shop manager to get him to change his way of thinking. That's almost as bad as the shop complaining that all the holes in a surface are not ordinate dimensioned to save on having the machinist to do arithmetic!

Tunalover

RE: Machine shops and metric drawings

I hate this; to me that translates as "it was late because we are not very good at certain parts of our jobs, if you came over here and did part of our jobs for us (for free) we might be on time." OK that might be the cynical version but the spirit is spot on.

I've gotten a version of this a few times (enough that without this forum I would think that I'm the crazy one for thinking the way I do). It's usually up front at the time of order in the form of a request from the job shop for me to produce a metric drawing, or for me to approve their re-creation of my drawing to a metric/JIS standard. Most of the time, their re-creation is filled with errors like bad tolerancing, and missing dimensions and dimensions that have been just plain converted to metric incorrectly. (It makes me wonder about the attention to detail on a finished product if you can't just multiply 20 or 30 dimensions by the same conversion factor and get the correct answer 100% of the time.)

I understand that some people are working to JIS/ISO etc. and may not be familiar with the particulars of ASME GD&T (I don't claim to be a master myself) but the solution IMHO is for the job shop to learn the standard, ask the questions needed to understand it up front, or just no-quote the part. Customizing your prints to cope with a particular manufacturers ability to read it is a nightmare and the first step down a bad path of wasted resources and quality compromises. The SCM should be made aware of this as well; I've seen it happen and it has always ended up costing more than the perceived savings (time/cost etc.) was worth.

On a related note, I design a fair amount of cylindrical parts. Every time I get one of my drawings back that has been converted to JIS, they move one of my diameter datum feature callouts to the centerline of the part; I call them up and we play the datum/datum feature game before finally agreeing that they can make whatever print they want to manufacture, but acceptance/rejection will be based on my print.

Is attaching datum label directly to a centerline (common centerline) allowable in JIS? How is this to be interpreted if so? Or is this just a case of poorly prepared drawings?

RE: Machine shops and metric drawings

LONDONDERRY, when we were revising standards when I first joined the company we looked briefly at this and consensus was that most of our current or likely machine shops were more comfortable with inches so all* drawings were to have linear units in inches, even if the threads etc. were metric.

To my mind this is one area where it makes sense to work with supply chain and say 'what are our machine shops more familiar with' and then go with that as general policy.

* exception for certain items such as optics where metric dims are more common.

Posting guidelines FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm? (probably not aimed specifically at you)
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?

RE: Machine shops and metric drawings

I good machinist, or fabrication house, will know both and know how to translate unit.
We had to drop one because they refused to follow GD&T.

Chris, CSWA
SolidWorks 14
ctopher's home
SolidWorks Legion

RE: Machine shops and metric drawings

I would just find another shop capable of working in metric.
Nothing will get their attention faster than loosing a customer.
Why would you do business with a company using such a lame excuse?

RE: Machine shops and metric drawings

A big part of an SCM's job is finding shops that can work with your documents.

Asking you for a wholesale change of your documents to help out an incompetent shop suggests rather strongly that the SCM is just as incompetent as the shop, and needs to be discharged immediately.

Mike Halloran
Pembroke Pines, FL, USA

RE: Machine shops and metric drawings

Truly, whoever wants to do the job, is looking for ways and means, who doesn't is looking for excuses.

RE: Machine shops and metric drawings

(OP)
Oh but you see I'm the new kid in the company and SCM, materials manager, config manager all think I work for them and love to dictate what they want me to do.

RE: Machine shops and metric drawings

Could you argue that the reason your drawings were delivered late and had several errors was because drawings were converted between the systems back and forth?

RE: Machine shops and metric drawings

The "You sent us Metric and we work in inches", excuse has not worked in shops for the past 10 years. Unless that shop is still working in the "stone axes and bear claws" days. Most machines these days have digital readers that can convert from inches to metric at the flick of a switch. Even tape measures can be bought with inches on one face and centimeters on the other, other measuring devices such as digital micrometers, calipers, and height gages can also switch scales.
B.E.

You are judged not by what you know, but by what you can do.

RE: Machine shops and metric drawings

Let me make it clear that if you've already got a drawing I wouldn't propose redrawing it - it shouldn't be that hard to work around as almost everyone above suggests.

However, I am suggesting that for future new drawings it's worth chatting with other drawing users in the business & supply base to see if one or another system appears to be preferred. I'm also suggesting that as the new guy you probably should have done this before starting to create drawings for your new employer - though it's not necessarily something that immediately springs to mind amongst all the other stuff going on as a newbie.

Posting guidelines FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm? (probably not aimed specifically at you)
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?

RE: Machine shops and metric drawings

In my opinion, units should never be an issue. I have never worked at a place where the units of a drawing ever determined or even influenced any decision of any kind.

John Acosta, GDTP S-0731
Engineering Technician
Inventor 2013
Mastercam X6
Smartcam 11.1
SSG, U.S. Army
Taji, Iraq OIF II

RE: Machine shops and metric drawings

The supplier quoted the job and knew before it accepted the PO the part design(metric), quantity required and due date. They should have not accepted the PO if they couldn't meet your companies expectations. They should have no quoted the part if the design was not acceptable. Tell SCM if they had a qualified supplier they should be able to make the part. My company including the large multi-national above my local plant purchase over 20 billion dollars of metric parts/materials every year.

This supplier must be a favorite company for someone in SCM and gets special considerations. Good luck Londonderry.

Bill

RE: Machine shops and metric drawings

Quote (BillPSU)

This supplier must be a favorite company for someone in SCM and gets special considerations.

The one that puts in the lowest bid almost always gets special consideration...

RE: Machine shops and metric drawings

What a pickle. As a company, they misrepresented their side of the negotiation. Either they really can't use metric or they are late for some other reason and are using this as an excuse. Perhaps the people involved are nice, but if a company is going to be a legal person, this one is not a nice person.

Often the contract is so large or so far behind, SCM can't move the contract elsewhere so it gets taken from the engineering budget to make what SCM did look OK by making what will be called 'easy changes.' It means a chance for engineering to add errors during this rush to save the outside firm, but SCM gets to look good in saving a bad situation and then it's engineering's fault for any delays due to any errors. I hate that.

If someone, up front, said 'we can save $XXXX and it will cost $YYY to change the design, so let's change the design', that's OK. Unless it really takes $YYYY to make the change over the $YYY budgeted. Free overtime! Yeah! So SCM can golf on Friday afternoon.

But come in late and then make this suggestion? That's not OK.

Please, save the middle finger for filling job applications. Waving it around with the other fingers on your way to a new job will feel much better than waving it alone on your way to a new job search. I know you know this. Just reinforcing the thought.

RE: Machine shops and metric drawings

(OP)
Often the contract is so large or so far behind, SCM can't move the contract elsewhere so it gets taken from the engineering budget to make what SCM did look OK by making what will be called 'easy changes.' It means a chance for engineering to add errors during this rush to save the outside firm, but SCM gets to look good in saving a bad situation and then it's engineering's fault for any delays due to any errors. I hate that.

Wow thats exactly what happens here I was warned by my boss the SCM has lots of pull. The metric issues is just a small one. I've been here for just abotu 1 year and from concept design to fabrication is a mess

RE: Machine shops and metric drawings

In the mood for a joke? I'm in SCM and we know you've been posting and we're in a meeting to talk about it. Bwwaahaahaahaa.

Just kidding.

It sounds like SCM is putting the fun in dysfunctional. If they were to involve engineering and planning (have you got planners?) in the selection of suppliers, the costs to the company would probably go down as well as anti-acid consumption and so would schedule volatility with your own customers. Otherwise it's like a dramatic movie with a frightened couple trying to distract guests from kidnappers that promise to kill everyone if the police find out they are hiding there.

RE: Machine shops and metric drawings

(OP)
Hahahaha...
The people in SCM are nice enough, but as an engineer if you ever want to see how bad it is come here. I've never seen where a groupo of people can take a simple design and act like we designed the Space Shuttle. I get into more debates with how they want BOM's structed, ECO workflow process, how they burn vendors, ordering, etc.

Or put it this way. in September of 2013 I released a simple packaging design, most off-the-shelf componetts. As of today we still don't the product and the PM has to go back to the customer (state BTW) to beg forgivness. Nowhere!! were I ever worked would this ever happen, people would be fired. In regards to a planner, oh yes we hired one of those does nothing but add to the problem by acting as a middle man between engineering and the vendors.. Did I mentioned that the company I has over 1600 people,

RE: Machine shops and metric drawings

We tried an experiment one time with metric vs imperial dimensioned drawings sent to outside vendors for quotes. The part was the same one, just dimensioned differently. The metric dimensioned part was quoted higher to make than the imperial dimensioned part.

"Wildfires are dangerous, hard to control, and economically catastrophic."

Ben Loosli

RE: Machine shops and metric drawings

We do everything in metric and have for more than the 30 years I've worked here. I've never had a vendor say it would take longer to get a metric dimensioned part but I've had plenty of shops take perfectly good metric drawings and redimension everything in imperial dimensions. They they do a layout of the part and report the imperial measurements. It infuriates me because I have to take the additional step of converting all their data back to metric. We recently worked with a custom machine builder who asked us "Is it OK to work in metric?". I almost kissed them.

----------------------------------------

The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.

RE: Machine shops and metric drawings

You need to dust off or create a set of engineering standards defining how inormation will be presented from the engineering department. This also applies to the earlier post you had on engineering BoMs and supply chain BoMs. Even if you have legacy drawings in imperial units, you can draw a line in the sand "as of August 1, 2014 all new parts and installations will be documented in metric"

RE: Machine shops and metric drawings

I don’t see how having metric drawings would cause a project to be late, especially if that is what they quoted against. It could be different if you quoted on imperial and got metric.

Buying is stock can be a problem or the extra machining required, if something is designed in metric then all unimportant features would probably be stock metric sizes the same applies to shafts, holes, etc, it probably doesn’t matter in many cases if something is 12mm or ½” but if you have to machine from stock rather than being able to buy off the shelf I can see that is a problem.

I guess this is only a problem in the USA as the rest of the world is metric, or at least to the best of my knowledge. I assume even for American companies that sell world wide everything is in metric? There does seem a fairly obvious solution to the problem.

RE: Machine shops and metric drawings

Oh, there are other countries: the industrial giants Burma (Myanmar) and Liberia still use imperial units. I think you can still buy a pint in an English pub too but that is a special exception.

----------------------------------------

The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.

RE: Machine shops and metric drawings

(OP)
Short Story,
I was once employed at a very small biotech startuyp and we designed a small desktop instrument that was sent to EU for customer evaluation, with a sales team. It was during that time, there was a mechanical issue that required removing english SHCS. Because we didn't expect any issues, no tools were brought and we didn't have field tech position. Being the instrument was in the EU we couldn't quickly buy english hex keys or SHCS. It was a mess and after that I assured all designs would be in metric from that point on.

RE: Machine shops and metric drawings

LONDONDERRY, while we aren't as consistent with it as I'd like generally policy here on new products is to as a minimum use metric fasteners for all of the ones the customer is likely to touch. Second line is that it's good to have all fasteners our field service are likely to touch be metric. Finally, if we're really on a role we'll try to make all the fasteners in a product metric.

Never quite works because some catalog parts or legacy reused parts end up having inch fasteners or for some of the more specialized small screws there isn't a readily available metric option.

However, requiring metric fasteners does not in any way require use of metric dimensions on the drawing for other linear features. So our drawings are generally 'inch' but often have metric threads.

Posting guidelines FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm? (probably not aimed specifically at you)
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources