Hi !
I joined my project as a zip here.
I have those 3 parts ( one is twice in the assembly ) , I sent those file to a company to 3d print it but the piece don't fit together.
Probably because of the precision of the printer. But the major issue is that all my piece are fitting with each other exactly.
How can I add some wiggle room between the piece ?
Leo Benkel wrote:
1. Probably because of the precision of the printer.
2. But the major issue is that all my piece are fitting with each other exactly.
1. No. There is no manufacturing process known to man that can make perfect parts.
2. See #1.
All designers should be required to do a minimum 3 years apprenticeship out on the shop floor before they are permitted to design anything.
1 yr precision milling
1 yr precision turning
1 yr precision grinding
After a year of working to close tolerancing in the grinding department - they will never forget to add realistic clearances and consideration of realistic manufacturing tolerances.
The Machinery's handbook covers tolerances for standard machining processes.
Given that 3D printing is not particularly precise and varies from process and materials and even orientation of the print - a bit more generous clearance should be considered.
Get some sand paper and a bigger hammer.
As far as adding the clearance during the design process, you can extrude or revolve cut or offset surfaces and thicken for combine-subtract. Other techniques as well, but in the end - be sure to do some section views and make sure that at min/max material condition for mating features that the parts will still assemble.
Think of it this way -
if you make a 10mm perfect pin and a 10mm perfect hole - the pin will not go into the hole without force.
There are molecules or even think down to the atomic level there are atoms occupying that 10mm diameter. Atoms will have to push other atoms out of their position to put the pin in the hole.
Now consider that there is a manufacturing tolerance associated with both the pin and the hole.
Since we cannot make perfect parts you need to consider tolerance and clearance such that the largest pin will go into the smallest hole.
The tighter you make the tolerances - the more expensive the manufacturing process - so specify the most generous tolerances that still result in acceptable function of the parts.
Also, for some reason you have this modeled as two solid bodies?
and as noted, no clearance and perhaps face draft for assembly of mating parts.
J. Mather wrote:
Leo Benkel wrote:
1. Probably because of the precision of the printer.
2. But the major issue is that all my piece are fitting with each other exactly.
1. No. There is no manufacturing process known to man that can make perfect parts.
2. See #1.
All designers should be required to do a minimum 3 years apprenticeship out on the shop floor before they are permitted to design anything.
1 yr precision milling
1 yr precision turning
1 yr precision grinding
After a year of working to close tolerancing in the grinding department - they will never forget to add realistic clearances and consideration of realistic manufacturing tolerances.
The Machinery's handbook covers tolerances for standard machining processes.
Given that 3D printing is not particularly precise and varies from process and materials and even orientation of the print - a bit more generous clearance should be considered.
Get some sand paper and a bigger hammer.
As far as adding the clearance during the design process, you can extrude or revolve cut or offset surfaces and thicken for combine-subtract. Other techniques as well, but in the end - be sure to do some section views and make sure that at min/max material condition for mating features that the parts will still assemble.
Think of it this way -
if you make a 10mm perfect pin and a 10mm perfect hole - the pin will not go into the hole without force.
There are molecules or even think down to the atomic level there are atoms occupying that 10mm diameter. Atoms will have to push other atoms out of their position to put the pin in the hole.
Now consider that there is a manufacturing tolerance associated with both the pin and the hole.
Since we cannot make perfect parts you need to consider tolerance and clearance such that the largest pin will go into the smallest hole.
The tighter you make the tolerances - the more expensive the manufacturing process - so specify the most generous tolerances that still result in acceptable function of the parts.
An excellent post, but may I amend the highlighted part above? "All designers and engineers should be required to do a minimum 3 years apprenticeship out on the shop floor or in the field before they are permitted to design anything."
We had an engineer here specify some really tight tolerances on rebar placement, but he got a whole new attitude after 1/2 day of helping tie it in place. And I've also seen way too many of them spec a certain material without giving a thought to availability or cost. I could go on and on, but I'll stop there.
J. Mather and Glenn Schroeder, AMEN!!!
I'm the chief engineer here at this small company and I wear jeans every single day because I'm on the shop floor so much, particularly making prototype parts. AND I'M A BETTER ENGINEER FOR IT! The folks that just want to stay in their luxurious offices and never get their hands dirty are a different type of person and they have a valid place. But in my world of designing things that have to be manufactured and assembled easily, affordably, and reliably there is no substitute for connecting theory to the real world (and doing the fancy dance when a hot lathe curl finds its way down the collar of your shirt - that was 40 years ago and I'll never forget it!).
Dennis Dohogne wrote:
...(and doing the fancy dance when a hot lathe curl finds its way down the collar of your shirt - that was 40 years ago and I'll never forget it!).
Just ruined another keyboard - maybe I can wash and dry it.
I think I should have gone for the shaved chest look back in the last century. Maybe that was were it originated - someone got tired of trying to dig hot chips out of chest hair.
After working to ten thousands of an inch - I still get upset when someone leans on any working machine while shooting the breeze.
Let me add to what J. Mather said about 3D printing processes. They typically grow the part and by different amounts in the vertical direction versus the horizontal, so orientation will have a big impact. FDM, SLS, and the others will have different resolutions and different "swelling". It pays to actually talk with the vendor doing the work and find these things out. They'll help you because they want you to be happy with the result, but you have to actually talk to them to get this information. You can design in the draft and clearance so that you can reduce the amount of hand work and elbow grease necessary to file and sand the parts. Keep in mind that it is easier to remove material than it is to add it. And threads, unless they are very large such as you might find on a jar, don't even think about doing those in a 3D printer. Print a pilot hole and tap it or plan to glue in an insert for female threads.
hey ! Thanks for all the answers, I read a bit of the conversation, I will go more through all your advises as soon as I have the time.
Just to give you context, I am designing a ring for my engagement, I am not a professional designer or anything, so don't be too angry at me ! I know that my piece won't fit, I am just asking for the tool in solidworks which would allow me to enlarge the connecting part
The core of the ring would be in Tungsten, the Head will be hosting a interchangeable gem and the sides will be interchangeable carved stones. So the ring can be wear day in and night out with all different gem and stones.
All of the prior comments are spot on and offer great advice. Allow me to relate a recent experience, mind you I have more than 40 years in manufacturing, it was simple issue that I just happened to overlook. I had designed a small molded part, not complex at all. I was looking at the threaded insert required and the limited space I had in between the two surfaces. In that the insert and tooling accommodations would be expensive I thought to just drop in a shaped threaded standoff and redesigned the part to accommodate that.
When 3D printed I forgot to allow for the 'overlap' and left it to size. I had to force the insert in for these prototypes. I made changes including a draft that you'll be able to 'see' in the attached picture.
you can extrude or revolve cut or offset surfaces and thicken for combine-subtract.
So I guess those are the feature to use ?
How can I make space around the "edge" piece ? I created it by removing the "core" piece out of it. I tried the options the tool provide to make the extrusion bigger around the piece but it didnt work.
My college did a very good job of Explaining tolerances. The big one for me was the tighter the tolerance the higher the cost. But I think I caught on faster than most since I've been a Mech all my life and worked assembly at many places. The place I work now many years ago I worked on the shop floor . So have a very good Idea how things are made.
could you attach a dumb solid? or add some images to reference the areas that interfere? I am unable to open your asm as I believe it is a future version, but there are multiple methods to add clearance between mating parts.
In general, any part that is being manufactured needs to allow for some amount of clearance between mating parts to accommodate the accuracy of the method used to produce the part. If you model your parts size-for-size then you will always have an issue. You can either start with the high and low ends of your tolerance threshold and adjust based on your prototypes. Or, design your parts size-size and identify critical features/areas that need to maintain a specific size/form and then apply your clearance to the other areas that are not as critical.