Help with designing a tool (jig) which would hold my work piece in place 1

[dejan95]

I have just started my first job (mechanical engineering design) after graduation. As my first "big" project I need to design a work station. On this station i need to create a tool which will hold my work piece (a motor) in place. I would love to hear your insight.


Because the bottom part of the motor is made of plastic, I don't want to put stress on it. That is why I thought I would hold it in place with four pins (I might replace one pin with a sensor, so the station knows when the object is in place). The problem i see with this idea (you can see it in the pictures) is that it is hard to position the part, which doesn't make it perfect for fast production.


Do you maybe have any different ideas?


Thank you very much!

 

[desertfox]

Hi there

Where are the pictures?

“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein

 

[dejan95]

 

[desertfox]

Hi

Keep the pin idea but why not put a groove in the blue portion to orientate the motor and locate it on its edge as shown in your diagrams

“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein

 

[Jboggs]

Tip from old white hair: Just because you have four holes does not mean you need four pins. Two pins is all you need to fully locate the motor in one plane. The problem with more pins is that it just complicates the fit with small dimensional variations. Pick the two most critical pin holes and use them.

 

[JohnRBaker]

What sort of loads/forces are going to be on the motor while it's in the fixture? Are they rotational or translational in a particular direction? What sort of operation(s) will be performed while the motor is in the fixture?

John R. Baker, P.E. (ret)
EX-Product 'Evangelist'
Irvine, CA
Siemens PLM:
UG/NX Museum:

The secret of life is not finding someone to live with
It's finding someone you can't live without

 

[mfgenggear]

not a clue to what your are trying to do, what are you doing to the motor?
machining, and machining what, why are you holding it in a fixture?

 

[dejan95]

Hi. There will be just a little bit of torsion, when the pipe will be mounted at the top with three screws. So the part needs to be fixed in the tool without rotation. I have attached a picture of the current idea.

 

[desertfox]

Hi Dejan95

I was thinking of the groove being just being half the height of the base and not wrapping it around the base edges but what you have is fine. Are you supporting the body on just two pins as suggested by Jboggs because that’s a very good tip. What are the silvery coloured strips fastened to the blue block, is it to clamp the motor base?

“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein

 

[dejan95]

Hi @desertfox

Thank you for your insight. The silver strips are to clamp the motor base yes. I added a top view in attachment.

I will probably support the body on only two pins, the only worry I have is that the motor goes through the hole in the tool (so the bottom part which is made of plastic is not damaged)

 

[IRstuff]

I think you are burning way too many calories on the precision of the fixture; there are no accurate alignments to be made, so the cutout for the bottom and the 4 pins are sufficient to keep the unit from turning.

And, the turning force is small, since you ostensibly are turning 3 screws to something like 60 in-lbf of torque.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

https://www.youtube.com/watch?v=BKorP55Aqvg

faq731-376 forum1529 Entire Forum list

http://www.eng-tips.com/forumlist.cfm

 

[dejan95]

Hi @IRstuff

The cutout in the bottom is just so the plastic part is not under pressure. Therefore in should not be used as a turning block. And I also forgot to mention that a plastic part is being mounted in the middle of the pipe at this station. (A plastic part is placed in the middle of the pipe and turned with a tool - bajonet lock).

 

[RRiver]

Yes, I think you're way over thinking this. First, your design is forcing the operator to pick the motor up to insert it in the jig when it's not necessary. You can use the shape of the motor to keep it from spinning and a simple De-Sta-Co clamp to hold the motor in place. A simple V Block shape on its edge with a clamp should work fine.

https://www.ebay.com/i/193492406725...25&pmt=0&noa=1&pg=2386202&algv=DefaultOrganic

 

[desertfox]

Hi dejan95
The bottom where the plastic goes through, the hole can just be rectangular I don't see a need to shape the hole to the plastic.
Why do you want to clamp the motor base to the jig?

“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein

 

[Jboggs]

More tips from white hair (because I learned these things the hard way):
1) As they said above - KISS!! This cannot be said too many times.
2) The BEST source of advice on how to design your fixture is the people that will have to use it. If you bring them in to the design process early on you will learn what has not worked in the past. You'll learn what is important to them. You'll see things from a different perspective than you do now. There is an indisputable fact in manufacturing: if the users do not want something to work, it will NOT work. Period. The opposite is similar: if they want something to work it is much more likely to. Nothing will gain a young engineer more respect on the shop floor than asking those folks without the almightly degree how they would do something. Show them the respect they deserve after years of having to use some engineer's impractical dream designs. One of the most common phrases on the shop floor is "if the guy that designed this had to use it he would have done it very differently". Listen to them and take their advice to heart.

 

[dejan95]

Thank you all for your advice. I will talk to the production line workers and try to take full advantage of their experience. When I come up with a better idea, I will post here for some additional advice. You all seem to know quite a lot, so I might as well take advantage of it Thank you!

 

[mfgenggear]

Dejan
A suggestion
What is the scope of what the objective
Of this tool or.
Test stand
Additional modification of the motor.

Then engineers can can give better answers.

Questions is this tool has to be moved or is it semi permanent.

How big is fixture, how heavy,
What is the material,

Another suggestion talk to the lead production supervisor on the floor.
Who is in charge of the floor.
Careful with who you talk to
You being young you really need a mentor
In engineering to help you.