remember that loop-da-loop ramp?

I may have talked about this in an old post.. turns out to keep centrifical force constant, a loop is not circular, but rather an ellipse:
http://gizmodo.com/why-roller-coaster-loops-are-never-circular-1549063718

This is mostly done for the purpose of reducing g's on the human body.  I figure if you're talking about a pinball with constant velocity (IE: same force holding it against the ramp as it goes around), this is also ideal.  If the force changes, that could be what makes it >pop< out of the track.

SO!  Now that 3d printed pinball parts are popping out of my machine, it's time to revisit that concept in PLA.  So let's look at the loop ramp I started before:

From the side, it's a perfect circle:

We want an ellipse.  But how to model that?  Solidworks can model screws of all kinds, but they are based on a round shape.  I found one complicated tutorial of how to create something, but then  I found an easy out.  Take my existing shape, and use the scale command but only in the Y-axis:

Going to print it tonight since it's a 4.5 hour job even on fast speed.  I'm going to try to print as a single piece without support.  In theory because of it's shape it should be self supporting.

3d printed ramp

Getting a 3d printer (especially once you've dialed it in) can be quite liberating.  No longer are you fumbling around for "how the hell am I going to fabricate that?!", so long as you have solid modeling skills.  So for grins, I decided to model up a simple straight test ramp.  Basically a v-shape, cut out the bottom to save material and build time (since the ball only contacts in the middle), not to mention create an opening so it doesn't block the playfield so much.  Add 2 bosses on each side so I can connect multiple ramps together (my build plate is only 6"x9"), and realistically there's no limit to what I can build.  Did a test print last night, and it worked NICE!  I mean it's smooth, smooth like the monorail ramp on simpsons pinball party (just as I expected).

I just used some self tapping screws I had lying around (had to drill clearance holes on one side), but it's a pretty solid structure.  If I were doing real ramps, I'd probably use brass inserts and machine screws so it can be taken apart over and over (and probably an even better joint).

So now I can basically model my waterfall ramp just how I want it, make a cut every 6", add bosses, and print each section then join them all together.  I will get exactly the ramp I want without complicated metal fabrication.  Each ramp section costs me 84 cents to print!

3d printed parts made, plywood cut, assemble time

So I finished printing my parts, I cut my plywood with basic tools (a 1/2" spade bit and a basic jigsaw).

 

My intention is to make starting a playfield (lower end) quick and easy.  I don't have a coil mounted to the bottom of the trough yet (soon), but from a geometry and structure standpoint it worked out fairly well.  A few things:
1. Holes need more clearnace than you think.  For whatever reason 3d printers suck at making holes, they are always smaller (shrinkage?).  And since by default slicers fill the inside with a grid instead of solid material you want to make sure your holes are sized appropriately
2. Try to make as few pieces as possible that will still fit in your printer.  I MAY be able to make the trough as one piece to simplify alignment.
3. Always make sure you have mounting holes for everything.  In my rush, I neglected to add mounting holes for the shooter lane part.

Considering I printed everything without support and the fastest speed, it turned out pretty well.  I think if I ran parts at medium speed, I'd get better quality.

To see a quick video, click below:
https://youtu.be/61cx1U71XZU

3d print design progressing

So I've added walls, an updated shooter lane, a wall to prevent the ball from popping out of the shooter lane (but allow a plunger to go through).  I've also split the trough into 2 pieces.  The entry ramp goes up to the surface so the ball doesn't drop and wear out the edge of the playfield.  This dumps into a main trough.  I've got everything 3d printed but the 2 left walls (which I just finished modeling).  If you're curious why some walls are split up, it's because my 3d printer platform is 6" x 9" (as most are unless you have a TAZ printer which is only marginally larger).  I'm going to cut plywood tomorrow, and only 10" of height because I have a scrap piece of wood I don't mind using to test out proof of concept.  I also need to buy some 1/4" x 1" balsa strips for the side rails.  I know typically 1/2" is used, but I think using #6 wood screws that 1/4" should still work for walls and conserve space.

don't like it? 3D print it!

So I'm really not liking how the flow is going with my current layout, plus I feel like it needs that a hook that makes it different enough.. not (oh look, stock parts on the lower half).

So here's my new plan.. and it's based on the fact that cutting playfield geometry on a playfield sucks so I'm trying to eliminate as much of it as possible when I start fresh.  That includes cutting the groove of the shooter lane, the complicated  cutout of the old single ball trough I have.  I also don't want to restrict myself to the geometry based on off the shelf parts.  That being the ball trough and the stock williams or SEGA lane guides.

1. Ball trough - I'd like to 3d print this.  This allows me to control the ball path.  The trough itself costs me about $4 to print (once I design a scoop to direct the ball into the shooter lane), but of course I also have to add switches, and a vuk coil.  It will still be far more cost effective than off the shelf, and based on the initial sample I printed, I don't see any issues of it breaking or wearing (at least not on the low plays a homebrew pin will get).  If it does break, I can always reprint it.
2. Inlanes - outlanes - You'll notice I have 2 inlanes and an outlane on each side.  That's accomplished by making the shooter lane also the right outlane.  If someone should plunge light and drain, I'm certain I can include script that says "if player scores nothing, give the ball back".  You'll also notice the lanes look strange.  In order to optimize enough space for this many lanes, typically Stern has to go back to wireforms (those U-shaped things that shove right into holes on the playfield).  This takes precison, and even when you have precision it's a pain to stick those in or take out when you need to shop out a playfield.  My design mounts from the top using the 3 posts from the slings.  I 3d printed a single piece (which in itself isn't terrible, but the walls are slightly flimsy).  On the real version I intend to use PETG sheet on the top, and the walls will be bent pieces of aluminum that will secure using screws.  I'm expecting this to be plenty stiff, especially if I anchor the cottom corner.
3. Apron - Though you can't really see it now, I'm going to be borrowing the design from Bally Spectrum.  It technically has no apron, it simply has walls, and then a piece of plastic shaped like an apron that mounts to bosses.  I like this for 2 reasons:
  A. It means you can have the apron off, and still function because all the walls still remain
  B. The top just being a cover (which is clear), I can print whatever decoration on the inisde

So the left outlane now becomes a direct path to the lower playfield, and it comes back up a hole next to the ball trough.  I'm going to start cutting this new lower half soon.

Fresh Start

Been thinking about this project a lot.  Lots of ideas going on, just need to get them down on paper.  No I'm not throwing out the baby with the bathwater (lots of concepts will carry over), but I might be cutting a new playfield.  More to come soon...

long time no blog

I haven't given up, I promise.  Lot going in my life lately.  Did a ton of work on the house because we were getting it appraised to refinance.  Things I should have done long ago all stacked up, but I got most of them done and the appraisal is over with.  Combine that with staying busy with mods.. Not only am I helping work on mods for Mezel Mods, I'm getting contracted directly by Sparky (who has a big backlog for his stuff, but I'm not going to say no to easy money).  Heck, just last week I had a guy from the next town over contract me to model up a mounting bracket for a tanneau cover for his pickup (apparently the part doesn't exist anymore).  Couple hours of modeling and a quick print and I'm $40 richer.   He found me because I made an account on makexyz.com (local 3d printer vendor list).  None of this is going to make me rich, but it's sure nice to have a side job to fund things.  I also have a backlog of LCD mods, of which I cannot really work on until they start shipping raspberry pi zeros (should be anyday now).  They had to move their factory to another facility to keep up with demand since the pi3 is also selling really well (and has slightly higher margins).

Anyway, now that I'm catching up on things I'd like to get back into this.  I've tried to sell my treadmill to make more space, but I refuse to sell it for the $100 people are offering on craigslist (I originally paid $1200 and it's barely used), so that may be staying.  However, since the house is clean and purged of useless stuff, I may be putting a rocking chair that's taking up space down here upstairs in the library.  It belongs to my wife, but it used to belong to her grandmother.

After hearing the interview with Mission pinball (boom go podcast), I really want to try this framework out.  I've watched videos in the past (getting demolition man up and running in a couple hours), but hearing in depth talk of it makes it more clear what it does and what it doesn't do.  Hugh shipped me the latest rev2 boards about 3-4 weeks ago, and I hate to see it just sitting there.  I still need to tweak my layout a little but I have some ideas.  Also I came up with a way to make quick wireform ramps using 3d printed brackets:
https://www.youtube.com/watch?v=w2ocsm5AkkU