Homebrew Pinball #3, Part 20

Cross posted from the original Pinside thread, this is one of many posts regarding my third homebrew pinball machine, creatively nicknamed 'P3'



My ribbon cable connector idea has solidified into a small custom PCB. I would have liked to have this custom fabricated, but the turnaround time is long, and the board is simple. If I'd known exactly what I needed sooner, I would have ordered it with some other boards a few months ago, but oh well.


My MPU board has a slot for a 26 pin ribbon cable. 16 columns + 8 rows = 24, but 26 was cheaper. I just ran every wire from the playfield to this board, and soldered them to the pins:

Wouldn't have been too bad, except that, since I want to avoid having any left over wire hanging around, I need to be soldering it while it's within an inch or two of the playfield, sideways A lot of careful soldering, but luckily no issues

On a custom board I would have made all the wires come in one side, but with no room to route traces here, it still gets a bit messy. 3D printed some simple brackets and mounted it to the very back of the playfield, and it was good to go

Posted Tuesday, September 22, 2020
at 09:37 AM


Tags: Blog Post, Pinball, Project, P3,

Homebrew Pinball #3, Part 19

Cross posted from the original Pinside thread, this is one of many posts regarding my third homebrew pinball machine, creatively nicknamed 'P3'



Wiring is progressing, not a lot to show...

I'm ending up running two main bundles of wire, one along each outside edge of the playfield, for simplicity. It gets a bit hairy in a few places where mechs are near the edge of the playfield; I need to make sure the wires don't get caught on the cabinet's supports. I guess this is another reason to use a wpc or stern style mounting system... Maybe if I get to a point where I can say the construction is 'done' and I don't need to take the playfield out completely anymore, I'll try to convert. Assuming it fits my playfield...

Trying to keep the switch wiring high enough to clear the mechs, and any future lights that get installed, while also keeping it as far from the coil wiring on the support rails. These stern wiring supports are great, and cheap at PBL, but sadly I only have two on hand. Wasn't planning on getting this far when I did my last parts orders, or if these would be useful, and now we're in quarantine so I'm trying to avoid unneeded orders.

To work around that, I found some random strips of metal I had on hand, and bent them. Seems to work just as well, and probably cheaper too, but I'd probably still use the plastic if I had a choice, just to avoid having random metal things to possibly short stuff against.
This all looks a bit messy right now, but hopefully once I have all the wires in, and zip tied together into a harness, a lot of the slack will disappear and it'll look cleaner. I also have a lot of coil wiring (like that white loop) where I've had to repeatedly rewire stuff as coils get added or changed, resulting in extra too-long lengths and wire nuts that can be cleaned up eventually. The wiring is going pretty well, and is pretty easy as long as I can reach stuff. The biggest pain is doing the connectors for all the drop target mechs. part of me almost wishes I hadn't bothered with them, but I know I'd regret it down the line. They require a lot of extra planning since you need to have both wires ready ahead of time before crimping, and you need to make sure never to have three wires join at a connector, even though that'd be fine at a regular switch.

I'm also realizing another issue: since I salvaged most of my switches from a Gottlieb playfield, they don't have the third lug for the diode. Right now I'm just sticking a diode on one lug, with the other end hanging free, which hopefully doesn't come back to bite me down the road...

One other hurdle to figure out soon is how to actually hook all these wires to the MPU. Right now I'm just terminating everything in the upper left corner of the playfield, which is vaguely where I picture the switch wiring leaving the playfield, since all the coil wiring is on the right side. I'm hoping I can use a big ribbon cable to connect the playfield to the MPU, to avoid having to assemble more connectors and run a lot of extra wire, since my wire supplies are already running low.

Posted Monday, September 21, 2020
at 09:53 AM


Tags: Blog Post, Pinball, Project, P3,

Homebrew Pinball #3, Part 18

Cross posted from the original Pinside thread, this is one of many posts regarding my third homebrew pinball machine, creatively nicknamed 'P3'



Quoted from atum:

Great idea on the rig! What all colors can you do and mark? Are you limited to black stripe? Or can you put a green stripe on red, etc. to get more possible color combinations with fewer solid (base) wire colors?

I bought all the colors at my local staples: black, white, gold, red, and purple. Weird arrangement, but ok. I used black stripes for the rows, since it was a color I was sure could show up on every wire color I was using. For the columns, since there was so much wire, I just left them blank (the sixth stripe color, invisible). Depending on how I handle lights when I get to that point, maybe they'll use some of the other colors.

I've also been using it to mark some of the coil wires. I managed to get 10 feet x 10 colors of striped 18awg fire off ebay that I used first where possible, but 10 colors is much less than my current 27 coils, and it turns out that 10 feet isn't long enough to reach from the bottom of the playfield all the way to the boards, so I had to reserve the striped wire for only coils on the back third of the playfield. My coil drivers are arranged into 4x 8 pin connectors, so I made one of those with no stripe, one with gold stripe, etc and tried to always use the same color ordering for pins. My rows go red-orange-yellow...purple-pink-brown, and so do my coil connectors, minus the random pre-striped wire thrown in. I've got a giant spreadsheet of all my connector wiring, and also use upper case vs lower case to denote 18 vs 22awg wire, which will allow me to reuse my limited stripe options more.
Coils:
Switches:

Posted Sunday, September 20, 2020
at 10:50 AM


Tags: Blog Post, Pinball, Project, P3,

Homebrew Pinball #3, Part 17

Cross posted from the original Pinside thread, this is one of many posts regarding my third homebrew pinball machine, creatively nicknamed 'P3'



I populated the switch matrix components on the MPU board, and they seemed to test okay with any single switch. Still a bit worried about if the way I'm driving the switch matrix will work once I've got lots of switches down, but so far so good. Luckily, the actual wiring of a switch matrix doesn't really change regardless of how you connect to it, so even if my board ends up being bad, that won't mean rewiring the playfield. With that in mind, I started trying to plan out the matrix, which was surprisingly involved. Technically any switch could go in any position, so all that really mattered was what made wiring easier. I'd already wired up all the target banks as individual rows, so that constrained me somewhat, but beyond that I just tried to lay out all the other rows based on what groups of switches were closest together:

Doesn't look too bad so far!
Then I tried to connect up the columns...
That looks a bit worse. Then I realized I was going about this a bit wrong. No matter what, I was basically going to end up with two big bundles of wire going up each side of the playfield, and then joining at the back. So I need to re-order the rows in a way that will minimize how many rows/columns need to be run to the back, since that's where the most wire will be used. I also don't need the rows/columns to all connect together, since they'll join at the connector anyway, so I can simplify that a bit.
That left me with a new, more concrete wiring plan for the rows:
The columns, again, look a lot messier...

I feel like there must be a way to simplify this more, but I can't see any obvious major changes, and it doesn't look too bad overall. I'd love to see inside the mind of someone who designs the wiring harnesses for these games professionally.

I have nine colors of 22awg wire to work with, and the playfield itself uses 62 switches, which requires an 8x8 matrix. To keep things clean, I'd like to stripe the wires, so I can tell the rows and columns apart when working. Sadly I couldn't find any cheap sources of stranded wire online, so I came up with this:

Tried it first with a regular sharpie, but the ink would rub off quickly, so I got some oil based ones, which seem to stay on the wire well once they dry. Stick a marker in the top, pull your wire through the side, and you'll get a messy but usable stripe.

With that figured out, I started trying to assemble a minimal corner of the switch matrix for more testing, which ended up being the first three columns on one side of thee playfield, and two rows:

Switch matrix still checked out fine, so I'm going to go ahead and wire the rest of the switch matrix

Posted Saturday, September 19, 2020
at 03:05 PM


Tags: Blog Post, Pinball, Project, P3,

Homebrew Pinball #3, Part 16

Cross posted from the original Pinside thread, this is one of many posts regarding my third homebrew pinball machine, creatively nicknamed 'P3'



To control the magna save and the outlane saver, I needed my secondary flipper buttons. I took measurements of my Black Knight, WCS, and JM to find out what the spacing should be, and was surprised to find that they were all different! JM's secondary buttons are further back than BK's, while WCS is not only further back, but also isn't 'parallel' to the rail (it looks to be parallel to the bottom of the cabinet instead, which makes it way harder to hit 'in the moment'). Both JM and BK feel okay to me, so I copied BK's spacing.

Luckily, the depression for a williams flipper button seems to be the same diameter as a star rollover, so I was able to use my forstner bit here too.

After I installed these, I realized that, in order to use them, I sorta need a switch matrix! That will be my next step

Posted Friday, September 18, 2020
at 11:17 AM


Tags: Blog Post, Pinball, Project, P3,

Homebrew Pinball #3, Part 15

Cross posted from the original Pinside thread, this is one of many posts regarding my third homebrew pinball machine, creatively nicknamed 'P3'



Mounted the final mech today, the outlane saver. I'm having some trouble with its reliability currently. It keeps going up too high and getting stuck above the playfield. I added a bolt across the bottom to stop it from going too far, but then the bolt got stuck instead. So I added a spring to prevent the bolt from hitting the bottom of the coil so hard, but the spring reduced the travel enough to make the mechanism weak. I'll need to play some with adjusting the lengths of the parts in an attempt to lengthen the travel, or maybe make a custom bracket to allow everything to be longer (currently I'm just using a regular up-post/vuk bracket).

Here's a video of what the saver does when it doesn't get stuck or bottom out:

It's super strong and just sends the ball flying back onto the playfield if you time it right. I like having an outlane saver that doesn't save you completely, it just keeps the ball in play. The magna save does the same thing to a lesser extent, and the mini playfield shot between the flippers also manages pretty well, since your shot tends to go right into the right slingshot and out of control. This can be good or bad, depending on your playfield situation, since chances are once it gets bouncing around it's going to knock down a few drop targets, which will help you complete your hand, but they might not be the cards you want to make a good hand.

If you fire the popper too late though, you'll end up with a ball that, due to its left/down motion, leaves the metal guide sideways, and just flies off to the left. I've had it end up in the left inlane, the left outlane, all the way down in the mini playfield, and even somehow jumping backwards into the trough. I'll have to put up some air ball protection to make sure it always returns to the playfield somehow.

Posted Thursday, September 17, 2020
at 04:07 PM


Tags: Blog Post, Pinball, Project, P3,

Homebrew Pinball #3, Part 14

Cross posted from the original Pinside thread, this is one of many posts regarding my third homebrew pinball machine, creatively nicknamed 'P3'



Next step was adding the diverter to the shooter lane. I have a bally gate mech, but it's designed for low speed inlanes, not very flowy. So I 3d printed a much smoother gate:

This mostly works, but I had issues where very fast balls would somehow get too much horizontal force out of it and hit the top post of the slingshot instead of directing down into the inlane. So I had to take 3 iterations of straightening it and adjusting the curve to get it to a point where even the fastest ball I can manage still goes towards the inlane, while a slow ball that just drops from the end still has a good chance of getting to the inlane.
Original:
Final:
It's a fine line because it needs to be able to fit behind the right drop targets and not block the shooter lane, so it can't be too wide or too straight.

I also added a little guide on the slingshot to smooth the transition, since the ball tended to bounce back and forth before coming down to the flipper

With the diverter and the left inlane done, I now have two more shots I can test.

First, the spinner/orbit:

This works, although it's a bit clunkier than I'd like. The spinner eats up some of the energy from the ball. I'll have to do some more tests with the spinner removed to see if there's any geometry improvements I can do. My upper arch isn't optimally designed, since it has a large flat part, which gives the ball time to 'drop' at the top and not follow the other side curve smoothly. Plus, with the lanes on both sides of the playfield, the shots hit the side walls at a more oblique angle which is probably leading to a less smooth shot. Might need to get the camera in slo-mo to see for sure

Second, the under-ramp/orbit:
I was worried about this shot since the left side curve of the upper arch is tighter than the right due to the ramp and upper eject area being in the way, so the ball had a the potential to hit the wall and bounce off at a ~25 degree angle, missing the curve completely, but luckily this doesn't seem to be the case somehow. In fact, it's smooth. SUPER smooth. And ridiculously fast. I took 20 shots at it, and didn't manage to loop it even once due to the sheer speed of the ball coming down the inlane. But I'm also not very good at that type of repeating shot. Can't wait to get this flipping enough to see some better players take a crack at it.

Posted Thursday, September 17, 2020
at 03:23 PM


Tags: Blog Post, Pinball, Project, P3,

Homebrew Pinball #3, Part 13

Cross posted from the original Pinside thread, this is one of many posts regarding my third homebrew pinball machine, creatively nicknamed 'P3'



Printed some inlane guides, and made a one way gate for the left inverted inlane.

Had a lot of trouble getting the inverted inlane to work properly. I made it with slots so it could be adjusted up and down, but if I put it lower, than a ball that just dribbled into the lane above the separator wireform wouldn't manage to make it over the gap, and if I put it higher to save those balls, then a fast ball coming down from the top of the playfield would hit the back of the slingshot and drain. There was also a weird issue that I could never reproduce by hand where a ball dropped from a middling height would somehow rattle to a stop and then fall down the outlane.

I designed this little gate to make it work at any speed. It works surprisingly well, although I'm sure it's going to break sooner or later since it's quite flimsy. I'll have to come up with a more solid way to accomplish it..

Posted Wednesday, September 16, 2020
at 03:55 PM


Tags: Blog Post, Pinball, Project, P3,

Homebrew Pinball #3, Part 12

Cross posted from the original Pinside thread, this is one of many posts regarding my third homebrew pinball machine, creatively nicknamed 'P3'



Some more small build updates...

Made these little clips for the ball arch. They go on top of the side rails and clamp one long piece of stainless down to the playfield. Eventually I'll probably drill some holes through it to mount it, similar to how williams games do it, but for now this will allow some easy adjustment while I play with the curves

In the spirit of getting as much mounted as possible to figure out placement under the playfield, I started mounting all the rollover stars. Had to special order a 1-3/16 forstner bit (dang, these are expensive!) to cut these. Manually drilled down the proper distance to get them flush, was a big pain.

My biggest innovation yet, a target in front of the spinner wire instead of a mini post. Should be back handable from the right flipper

Threw together a 60 degree kicker for the upper eject hole as it was the only shape mech that would fit with the drop targets so close. Didn't want to pay for a full mech so I used a random plunger from a vuk or kickback, not sure. The plunger was too long, so I just put some 1/2" standoffs under the mech

Needed a down-post for the mini playfield diverter, so I 3D printed one. It just presses up against the bottom of the playfield to stop it at max height, and uses a plunger from a williams drop reset mech that has a built in thread on the end. I had problems with the rubber I put on it sticking in the hole of the playfield, and being too bouncy when up, so I switched later to just a straight plastic post on top.

Posted Monday, September 14, 2020
at 06:08 PM


Tags: Blog Post, Pinball, Project, P3,

Homebrew Pinball #3, Part 11

Cross posted from the original Pinside thread, this is one of many posts regarding my third homebrew pinball machine, creatively nicknamed 'P3'



Bottom of the playfield already getting pretty crowded...

Before I got much farther, I realized I'd forgotten to cut the magnet holes in the bottom. Those will need to be done with the router, which needs some space, so I'll need to remove all the mechs in the area and the support rails.

I very scientifically traced the magnet out, and routed out a depression:

I wanted to hook it up to test, but that meant installing the relay somewhere. When I was looking around for the best place to put it, I realized that this was a bit dangerous, as I didn't know where any of the lights, switches, or wiring was going to go. I tried to mark out roughly where I was picturing things, and that actually left me with no safe spaces to put the relay! I'm sure once it's all done there'll be room, especially in the middle of the upper playfield area, but I have no idea what sort of lights are going to be up there now, so I want to avoid mounting anything there. Then, I realized the one area I knew was safe...

Posted Monday, September 14, 2020
at 09:39 AM


Tags: Blog Post, Pinball, Project, P3,

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