3D printers for testing part fit

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jchisolm
Posts: 97
Joined: Tue Jun 17, 2014 9:56 pm

3D printers for testing part fit

Post by jchisolm »

I got one of those $200 3D printers off Amazon. I've been using it to "print" parts so I can check for fit. This works well for small parts you might be having to build or machine or get machined. In the past I would use insulating foam panels from the big box stores. This is kind of OK for larger parts but not great for small parts.

With the 3D printer I can print the part with drill holes included and check for fit before I go to the expense and time of machining the part or having it machined. Or building a mold or just doing a hand layup. (Resin is getting expensive and also hard to get these days). it's not as fast as cutting out some foam but, for me, worth the wait.

Here are a couple of pictures of a part I wanted to check for fit before I actually machined it.

CAD drawing
IMG_20210918_003838278.resized.jpg
Printed result
IMG_20210918_110131848.resized.jpg
I use "draft" or fast mode in printing so you see the layer lines but that's OK for what I'm doing. Finer detail just takes longer to print.
Joe Chisolm
Express CT builder
Marble Falls, Texas
jchisolm
Posts: 97
Joined: Tue Jun 17, 2014 9:56 pm

Re: 3D printers for testing part fit

Post by jchisolm »

I also should mention that the parts are actually pretty strong. I've seen reports where they pull test items and they get around 180-200 lbs. If you need a small trim piece or a switch knob or say a "custom" switch handle you can design and print your own.
The down side is, for PLA filament, it is said to have some UV resistance problems. I've yet to track down what kind of issues. YMMV.
Joe Chisolm
Express CT builder
Marble Falls, Texas
xprsav8r
Posts: 22
Joined: Mon May 08, 2017 5:23 pm

Re: 3D printers for testing part fit

Post by xprsav8r »

That is pretty cool, Joe. I imagine you could wax or paint the part to improve UV resistance. I imagine the parts could be glassed in into the fuselage as needed.
jchisolm
Posts: 97
Joined: Tue Jun 17, 2014 9:56 pm

Re: 3D printers for testing part fit

Post by jchisolm »

I'm not sure what the strength of a bond would be glassing directly to the 3D part. I'll have to try it.
Here are a couple of videos on using a 3D printed part for molds or direct layup over the part.
BTW: this channel has some pretty good instructional videos

https://www.youtube.com/watch?v=KpJdwryFj6k

https://www.youtube.com/watch?v=4ND2WtEZatY

I'm thinking maybe throttle quadrant or such. If I can print a handle for 50c worth of PLA filament vs a couple hundred bucks might be worth it. There is a video of a 3D printed ukulele. The neck and body are strong enough to handle the string tension. I'm just getting into it so I've got a lot to learn. One issue is dimensional accuracy is limited by the layer size. From what I measured X and Y are pretty close, within 5-10 thou but Z axis is controlled by the layer size. For quick printing I'm using .3mm layer size. One part I'm doing is 2" Z-axis and the part is 169 layers. That works out to be about 1.996 inches but the actual part measured 1.976 so it's 24th under. Holes have usually been undersized. I have to run a drill bit through them. For threaded parts most people model the part to accept a metal thread insert of some type. Super glue seems to be one of the preferred methods of bonding the insert to the part.

Overall I'm happy with the parts I'm printing. The biggest obstacle is the learning curve for 3D cad software. There are several different ones. I think SolidWorks has a $99/year package now and EAA may still have their free version. Solid Works does not have a Linux version and it wont run on a Windows VM running on Linux. I've been using FreeCAD now for a couple of years. It's ok and has some bugs but keeps getting better. Down side to FreeCAD is steep learning curve.
Joe Chisolm
Express CT builder
Marble Falls, Texas
282ex
Posts: 43
Joined: Wed Aug 10, 2016 12:59 am

Re: 3D printers for testing part fit

Post by 282ex »

PLA not only has UV tolerance issues but also has a low melt point. I might recommend using PETG as its melting point is higher and has less shrinkage.
Erik Petersen
Wheeler Express Series 90 Auriga
Everett, Wa
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