Advice on a lever weld design 1

[Mech1066]

Advice please,
I designed a 4 piece lever weldment and a shop guy complained that it's too many pieces to keep square.
At my pass company, we always just bolted the pieces together, but this places likes welding.
Anyone with welding experience?

 

[MikeHalloran]

Buy him two carpenters squares and a handful of c-clamps.

I am not kidding. Some years ago, I designed a box structure made of square steel tubing, and had the ends milled square and beveled for welding, in a milling machine, before sending it to the welding department.

The resulting assembled box could be seen to be out of square from across a football field.

I went to the welding department to find out how they could possibly have screwed up that badly.

They had a $5000 heliarc machine, and a $3000 welding platen, and ... nothing else. They didn't have a single dog for the platen, or a c-clamp, or any kind of square.

Apparently the welding department employees had stolen everything they could carry home, and the supervisor did nothing about that, and had the nerve to tell me with a straight face that they had assembled my stuff by holding the carefully prepared parts together by hand while tacking them, and then proceeded to weld them fully even though they could see they weren't square. Had they called me before striking an arc, I would have found them some tooling.

We outsourced our welding after that.
Since there was thus no need for a welding department, we bid those assholes adieu.






Mike Halloran
Pembroke Pines, FL, USA

 

[MikeHalloran]

Since you didn't provide a photo or sketch, it's not possible to evaluate your design for producibility, but one way in which you can do your shop a favor, especially if you are using CNC cutting, is to make your parts "self-fixturing".

... which is a fancy way of saying the piece parts can have features like tabs and slots that tend to hold them together, so minimal or no fixtures are required to keep them in proper alignment.


Mike Halloran
Pembroke Pines, FL, USA

 

[racookpe1978]

I have over 16 magnets and a bunch of vises and clamps and angles and squares .... in my garage. For my personal use.

Have a serious "talk" with this welder. Be polite. But he is wrong. Dead wrong. Might be incompetent, might just be untrained. Might have no suppliers, or has been told that it is "unmanly" or wimpy to use clamps and magnets and straps and jigs. But he needs some education.

At a cheap Harbor Freight, Tractor Supply Hardware store, Northern Tools, Fastenal, Enco, ....

 

[JNieman]

The best investment in a welding department is -good- tables for them to work on. Decently flat surfaces of thick enough steel to resist warping when they tack components to the table for jigs/fixtures. Then just make sure they have the above-mentioned BASIC tools (squares, 45-45-90 magnets and more if needed) and enough scrap metal round and flat bar stock to let them tack up their own jigs.

I'll second the pre-machined aids though. Tabs or keys can go a long way in speeding up a welder, but they will usually still need to set them up against a square or with magnets if it is a piece to be made with a manner of precision.

_________________________________________
Engineer, Precision Manufacturing Job Shop
Tool & Die, Aerospace, Defense, Medical, Agricultural, Firearms

NX8.0, Solidworks 2014, AutoCAD LT, Autocad Plant 3D 2013, Enovia DMUv5

 

[ornerynorsk]

The difference between a good tradesman and a great one . . . good ones complain about having to do something a certain way. A great one will study it, offer an alternative or simpler design if viable, and then get busy and do the job. Bad ones just don't make it that long before getting fired.

It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.

 

[aotellmetalstamping]

I agree with MikeHalloran,

it is better outsourced,and no need for a welding department

metal stamping part supplier in China

http://www.aotell-stamping.com

 

[TVP]

It's days like this when I appreciate Eng-Tips the most. Mike's first email made me laugh out loud here at the office. I believe that this thread offers a great deal of practical information, both specific and general. Likely we've all worked with excellent fabricators and some that were not so good. It's always helpful to work closely with others (machinists, welders, suppliers, etc.) in order to optimize designs for assembly and manufacturing, so good luck on this job!