Using 3D prints as fabrication templates

Discussion in 'Aircraft Design / Aerodynamics / New Technology' started by addicted2climbing, Sep 26, 2018.

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  1. Sep 26, 2018 #1

    addicted2climbing

    addicted2climbing

    addicted2climbing

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    Hello All,

    I have been rebuilding a damaged Zigolo and so far along the process I have been using my 3D printer quite a bit in the build. I had a fair amount of parts that were damaged and had to recreate. I had a 4130 weldment where all the gear connection tabs were bent. I modeled up new tabs in Solidworks and 3D printed templates to be used to make the replacement parts. It worked so well that I did it again with a personal mod to allow me to adjust the seat. This time I took some pics of the process. The cockpit is a bit cramped for tall pilots so the rudder pedals can stay fixed and by moving the seat back it will help lower my knees since I am 6'4" yet it will still work with shorter pilots with the seat in the original location. I used this method to make 4ea 2mm thick aluminum brackets, but easily could have made 10 at a time. Also I just attached template and once I began, there was no measuring, just select the drill and use the template as a drill guide then trim and sand.. Went very quick.

    Single template clamped to part to drill first few holes for bolts.

    IMG_3773.jpg

    2 holes drilled and bolted together, C clamps removed.
    IMG_3775.jpg

    Series of holes drilled.
    IMG_3777.jpg

    Drilling Rivet holes.
    IMG_3779.jpg

    Second template added after all holes drilled.
    IMG_3780.jpg

    Cutting it out.
    IMG_3781.jpg IMG_3782.jpg IMG_3784.jpg

    All templates removed with 4mm drills used to keep alignment while I bolt it back together.
    IMG_3785.jpg

    Sanded up and a bit of skotchbrite on the edges and its done.
    IMG_3786.jpg IMG_3787.jpg

    I have not separated the brackets yet as I have a bit of sanding on one edge to remove some cut lines and then scotchbrite that side.

    This method was so quick and I plan to use it when building the Skylite. My dad and I will be starting the Skylite in the next few months and when we do, I will make enough parts to build 2 airframes. I will draw up as many of the gussets and brackets as possible and then give the templates to my dad who is retired and can just crank them out. When say all the wing fittings are done we start the wings. Also I have used the 3D printing to print actual parts that I need to fabricate and install the print to test it and when I know it fits, I then make the part.

    Thoughts?
     
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  2. Sep 26, 2018 #2

    addicted2climbing

    addicted2climbing

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    Here is the assembly in Solidworks. I only modeled the few items I needed to design these brackets.

    Seat Support Mod Assy - 1.jpg Seat Support Mod Assy - 2.jpg Seat Support Mod Assy - 3.jpg
     
  3. Sep 26, 2018 #3

    BoKu

    BoKu

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    That's exactly D more than how I do it. ;)
     
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  4. Sep 27, 2018 #4

    addicted2climbing

    addicted2climbing

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    Great minds think alike...
     
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  5. Sep 27, 2018 #5

    ScaleBirdsScott

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    Whether 2D or 3D, prints are definitely a crucial part of building.

    I like the use of 3D in that it helps a bit with keeping the drills in alignment, no need to center punch or be too worried about drills drifting or skipping. Just stick it in the hole and go.
     
  6. Sep 27, 2018 #6

    Victor Bravo

    Victor Bravo

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    That's really clever and showcases how useful a printer could be for odd stuff like this.

    I agree with Scott, printing a drill guide is a fantastic way to make sure the drill bit goes through on target and (equally important) straight through the material at 90 degrees. That has the clear potential to result in "good" holes for bolts to go through without having to "clean up the hole" again with the drill to get the bolt through. This also yields a better bearing surface in the edge of the material.

    Building on this idea, you could possibly print alignment tools or jigs, or alignment clamps, to hold aluminum tubes together at the right angle for riveting gussets, or to keep things aligned in one area while you drill/bolt/rivet somewhere else, avoiding warps or misalignment over larger distances.

    Although it has nothing to do with the Skylite or Zigolo, the idea that really jumps out in my mind is that you could model and print an alignment jig to hold all the tubes in place for something really complex, like the V-tail mounting weldment on the Davis DA-5. That one assembly is likely responsible for hundreds of people being afraid to build the DA-5, which is otherwise a very siimple and attractive aircraft.

    So there might be some small cottage industry or income stream for making tube clamping fixtures for complex weldments, or weldments that need to be aligned to close tolerance. That kind of product could be of great value to people building certain aircraft parts.
     
  7. Sep 27, 2018 #7

    Riggerrob

    Riggerrob

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    Great idea!
    What about HBAers sharing 3D Print or cut files for jigs?

    Post files here, then builders on the far side of the country/planet can down-load e-files to make their own jigs.

    Include the caveat that every end-user is responsible for verifying dimensions before flying his/her creation.
     
  8. Sep 27, 2018 #8

    ScaleBirdsScott

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    Another thing is that of course it's possible to waller out a hole pretty quick when it's 3D printed, so if it's a fixture that might see some repeat use (I'd say more than 2-4 times) I'd oversize the holes and use some thin tubing as drill bushings. Also since it's 3D take full advantage and make bosses to locally increase the hole depths and get better alignment. I'd say 1/8 is all you need for the base of such a fixture if it's flat, but anything larger DIA than 1/8" then no reason not to make it locally a taller hole. Or if getting dead dead nuts perpendicular matters, use an even longer alignment boss.

    I like the idea of laying out complex 3D clusters with prints. It's definitely possible. I've 3D printed false leading-edge ribs to define the "intended" leading edge when a particular design has ribs that don't reach quite to the forward tip of the LE, which could then be removed after the metal was drilled and installed. That actually worked quite well. I've also printed a large part I called "The Church" that allowed me to drill spar holes in the fuse from both sides without going off alignment. It worked pretty good, but next time I'm designing the frame where such a contraption isn't required :p
     
  9. Sep 27, 2018 #9

    addicted2climbing

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    Hey VB,

    Yes yes and yes... I have plans for most of this in the Skylite build and also the Zigolo rebuild. I already looked into modeling snap on clips to hold the clusters with the connection far enough away to tack weld. If I get the VR3 pre notched fuselage kit, I can test this. Still unsure if its gonna be cost prohibitive. If so another option is coping widgets similar to what rainbow aviation was trying to do on the EMG. Only issue with this is the Skylite has so many different combinations of clusters and angles that it would require a bunch of coping widgets but I can cross that when I get to it.

    For now printing drill jig/cut templates for sheet metal works well and I will continue to expand on this idea. Scott, I have designed them to use Drill bushings as well here for items at work (mostly oops moments where I need to add a hole and just print out a quick jig to drill 20 holes) and it works great. On the Bearhawk LSA (which I never built) I drew up the wing in Solidworks and the spar has a continuous repetitive hole pattern and I made a 3d Printed block with a drill bushing and a pin so that as each hole is drilled, the pin then goes in that hole and sets the location for the next. It was U shaped so that it was guided by the edges of the material it was referencing.

    Since my only location to build is the EAA hangar and I don't have a garage, I only have 1 to 2 days a week I can be actively building, but the other days and lunch breaks, I am still working on the design and can be printing. This allows me to have everything ready in advance before the day I can build and then all I need to do is stack the templates and start building..

    I am currently working on the Skylite wing in Solidworks and I already have snap in "widgets" designed to hold the spar tubes up off the table a bit for the build and also build in the correct amount of washout at the same time.
     
  10. Sep 27, 2018 #10

    CameronB

    CameronB

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    I have also used PLA as a drill template. I also used a template to trace with a plasma cutter for a steel bellcrank.
     
  11. Sep 27, 2018 #11

    Hot Wings

    Hot Wings

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    I can see some advantages to 3D printed jigs such as being discussed but for the majority of the hole drilling we need to do a simple 2D print (this is what Boku is saying in post #3?) attached to the part with spray adhesive followed by a sharp center punch is going to be far quicker and provide accuracy on par with the 3D jig. In fact the 2D print is going to provide superior holes if the center punched mark is drilled on a drill press with a proper series of starter and finish drill bits. I still have my 2D cad program for these kind of templates.

    If you need accuracy better than this then the parts probably should be drilled on mill table with X/Y feed, or done with bluing and an optical center punch - followed by the drill press routine.
     
  12. Sep 27, 2018 #12

    addicted2climbing

    addicted2climbing

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    Hey Hotwings,

    In some instances I have to disagree on this. I use to do it with 2D and 3M77 and use a drill press and center point and it worked well but I was still eyeballing the center point on the drill press and did not always get it right. The 2D method requires a bit more tweaking and adjusting in the process to get it right and needs to be done for every hole. Than the template needs to be peeled off and coated in WD40 to remove the sticky. Also when cutting metal on a paper template it lifts and deposits metal cut dust making cutting it out after harder. This can be avoided by just cutting it exact with Scissors than tracing it in permanent marker just in case the paper template pops off mid way. The 2D method is faster to iterate should the first one not work you just make the quick change an print a new one without the waiting of a 3D version.

    However, with the 3D version. Yes it takes longer to have the template and a bit more planing in advance. Ie easy to do while I am at work but if I need another and I am at the airport I need to go back to a 2D version. I do have a portable paper printer for that. But having done both methods, I can say that the 3D template had so many advantages that I would prefer it 100% of the time. The ability to just select the drill and not use a center drill and just drop it in the hole and go was such a time saver. I aligned it first power off than turned on the drill press and drilled. Also having the plastic template on both sides helped a lot when sanding the metal on the belt sander. I was able to get it very close to nominal then remove the templates and do some quick final sanding and scothbrite after. No issues with heat affecting the template either as I took my time sanding.
     
  13. Sep 27, 2018 #13

    BoKu

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    When I get newbies in the shop, one of the things I regularly teach is how to hit the center of a hole +/- 0.005". It's easy once you get a little bit of practice.

    * If the print does not have a crosshair for the hole center, clamp on a piece of stock with a pre-drilled hole of the same size. Then either drill or transfer punch through the pre-drilled stock.

    * Every shop must have a set of transfer punches. No clue how folks survive without these things:

    https://www.harborfreight.com/28-piece-transfer-punch-set-3577.html

    * If the print has a 0.010" thick crosshair for the hole center, place the template on your vice anvil and use your centerpunch and lightweight hammer to make the tiniest little dimple where you think the center of the crosshair is.

    * Evaluate the dimple by eye.

    * If the dimple is a bit off center, use the next tap with the centerpunch and hammer, slightly more firmly than the first hit, to drift it towards the center of the crosshair.

    * Iterate the prior two steps until the dimple is exactly in the center of the crosshair.

    * Give the dimple one more tap, straight down, to upsize it to something that a #30 drill will center on.

    * Drill the hole #30 (the one stuck to the drill press with a magnet), then updrill it final size (most often #12 or 1/4").

    It sounds like a lot of steps, but it's really only a handful of seconds per hole.

    --Bob K.
     
  14. Sep 27, 2018 #14

    addicted2climbing

    addicted2climbing

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    Hey Bob,

    When I did the 2D method, I made sure to have a crosshair for the center of all the holes. I would use a spring loaded punch to make the dimple for the drill. My drill would still walk occasionally but that was likely due to my cheap set of HF drill bits. I found on this project that my drill closest to 6mm was unusable and I need to spend the money for a proper set.
     
  15. Sep 27, 2018 #15

    ScaleBirdsScott

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    Being able to do the 2D method as described above is invaluable and perhaps necessary. The 3D print method does come in handy when you have multiple parts because you can slap a few into the fixture and you're starting each one the same.

    With a 2D template bonded on method you either need to print multiple templates (which, is fine) or you make one as a master and copy the rest off of that one (which is also fine) so it's not like this is some super new ability. It's just cool and kinda fast in the shop. Which, I will admit, if you have limited workshop time but plenty of CAD time it does make sense to do as much as possible in the latter to maximize the former. If you can do 20 brainless transfer holes in a printed fixture in the same time as 5 artfully eyeballed on-a-2D template holes, and you can print your template while at work or doing other stuff, it could add up over time to saved time. Plus you still have that template so if you've gotta make another identical bracket or a second plane that fixture cost time is sunk.

    And with more and more people having little 3D printers in the home, I see these methods as potentially legitimate use of that level of 3D printing for expediting the construction of a homebuilt. Not in directly making structure, but in making what structure you have to fab, that tiny bit faster or more accurate or more repeatable with less effort.

    And the good news being it's all a bit extra; not strictly necessary, but nice when available for those interested.
     
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  16. Sep 27, 2018 #16

    Hot Wings

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    It does, but I agree it does go pretty quickly.

    The only variation from your method that I use is to start drill with a good 1/16" bit. That long flexible bit tends to self center in the center punch crater - so much so a quick by hand is often good enough. The piece can then float into place on the drill press or guide the free-handed successive bit into the proper spot.

    But if you have a 3D printer and the time to wait for it to print.......then what ever works for you is good.
     
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  17. Sep 27, 2018 #17

    specter22

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    I do a lot of tight-tolerance fabrication for prototypes at work. We've got a small CNC 3-axis mill, a manual lathe and a manual drill press. Anytime I can, I print out paper templates for drill locations, center punch, center drill, and drill to size. If the hole locations are tighter tolerance than +- .005", I'll center drill them in the CNC, then finish on the drill press, using only the center drilled divot. We've tried using our 3d printer for precision templates and precision dummy parts, and even with our nicer printer, the results are often +- .010" - especially when it comes to holes. Even more so if the printer starts a layer on a hole edge - you can end up with "nubs" sticking into the hole, and when you try to drill it out, those nubs put enough pressure on the drill bit to move your hole out of tolerance. For me, doing a good job of setting up the drill press and pricking accurate holes is a heck of a lot faster *and* more reliable. That being said, if you want to wait for a template/drill guide to print, and you can get good results, good job finding a creative solution to your problem.
     
    Last edited: Sep 27, 2018
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  18. Sep 29, 2018 #18

    proppastie

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    I use Rubber cement for the paper, does not wrinkle the paper, and rubs off when done. that all parts that are assembled together are drilled at assembly absolute location is not an issue, .010 is good enough, I also like the spring loaded center punch.
     

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