Eight days since my last post and the backglass is finally getting close to being done. Working with bleeding edge mpf has been slow and frustrating and I am very much looking forward to getting back to making saw dust and solder smoke. I have literally spent days getting to this point.

Currently the backglass has 20 second cut scenes of each of the 10 bosses with a 3 second animation between them. The display is divided into a static topper, middle video section and lower scoring section. I've gone through multiple versions before deciding on the current one. In game play the full length videos of the 10 bosses are played at random with the theme song for each boss matched up to the video.

There are many animations and scenes that play during the game including, CUP/MUG drop targets and the 10 soul contracts that are collected for clearing the banks, SOUL top lanes, Dash saucers, Knockout, Perdition entry x 3 and more.

The latest addition was that as of yesterday the dev version of mpf now supports "digital_score_reels" which are zip files with a png animation sequence of a score reel with transitions between digits. At present the system will advance a "nines rollover" as soon as the points are scored so that looks a little funny (score 50 points and it goes 00180, 00290, 00200, 00210, 00220 not 00180, 00190, 00200, 00210, 00220) but all in all getting this to work has taken a ton of time and looks pretty awesome.

I've got all of the code written that I think I need at this point in time so now I'm just waiting on the last few parts to arrive before starting making the playfield. One aspect of game play that is very important to the design of the game is the "Dash" shot. There are two "Dash" saucers that are expected to kick the ball up towards the top of the table.

This is one of the problems with bringing a VP game to reality is that in VP you can make playfield devices do things that are not what they are designed to do. A saucer kicker (or hole kicker) is just meant to capture a ball and kick it back into play. There is no expectation that the ball will travel far from the hole.

I picked up three matched Williams kickers from E-bay with the hopes that all will kick the ball with the same strength. Today I built a test bed to see just how far a hole kicker will kick the ball. I set the angle of incline to 4 degrees and powered the coil with the same 35v DC that will be used in the actual game. With a 1/2 piece of plywood and no bevel cut into the hole edge the ball would only go as far as the first line in the video, with a bevel cut into the hole edge the ball will make it to the second line. Both of these distances are only about 4 inches and are way short of what the game design calls for.

I then got to looking at the kicker mechanism and I figured that if the throw of the slug for the kicker arm were increased, maybe the ball will kick further out of the hole. I added a couple of 1/4 washers under the bracket that holds the coil and tried again. The results can be seen in this YouTube video.

Does anyone know why the designers of these kickers put the spring loaded coupling between the part that actually kicks the ball and the part that is connected to the coil slug? It seems to me that this would dampen the kicking strength of the unit but I'm sure that there is a very good reason why they used a much more complex mechanism. I just have no idea what that reason is?

At any rate it is reassuring to know that the Dash kickers can be modified to get more distance from a saucer kicker!
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Still waiting for the playfield inserts to arrive so time to design parts for holding the LED lights to the playfield. I used F360 to make a clip to hold the ws2811 lights through holes in the playfield so that the light bulb section sits proud to the surface of the playfield.

I bought a bunch of ws2812b light chips with the hopes of custom wiring them up so that the wiring harness exactly fits the playfield. The chips have two sets of three solder pads for +5v, gnd and data lines and these look tight to each other and it will be hard to hold the wires in place while they are being soldered. I designed these two holder parts in F360 to hopefully help out with soldering and installation. The chip holder section has two sets of three channels in it to index, space and hold the wires for soldering. This chip holder's sides have a bevel to them that mates up with a matching set of bevels in the mounting bracket so that the two slide together and lock. The mounting bracket has two holes for screws to attach it to the bottom of the playfield where they will project through translucent white inserts. The white inserts will let me change the colors of the inserts during light shows.

We'll see how well all of this works out in reality when the playfield is made...

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Started making saw dust today, here's the white board playfield with the side rails, apron and top arch mounted to it.

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Thanks! I think it looks pretty sweet too but I'm handling it way more than I would like to at this stage. It still doesn't have any clear coat on it since I was planning on hitting it with Spraymax when I clear coat the playfield.

At any rate it is great to see this start to come together. Even though it's only a blank piece of 1/2" plywood it still looks like progress after over a month of just working on MPF.

I made a Photoshop poster of the playfield at 1 to 1 scale and put it on the blank plywood to work out the details of how everything was going to go together. There are a ton of details that needed to be worked out like how will the playfield mechanisms fit under the playfield and not block each other, switches or lights. My mechs are ALI and have different geometry from what Onevox used for his VPX layout so that had to be taken into consideration as well.20210101_100400 (resized).jpg

After all of that had been worked out, I printed out circles with center holes on transparency film and used that to mark the centers of the 3/4", 1" and 1 3/16" inserts with an awl. Once everything had been marked I pulled back the paper overlay and drilled 3/32" holes for each mark. The areas that could be reached with the drill press had that used otherwise these were hand drilled. 20210101_100446 (resized).jpg20210101_101817 (resized).jpg

For those who haven't used Forstner bits before, they cut an flat bottomed hole but first cut around the edge and then clean up the middle. They follow a center point until the perimeter starts to cut and then the perimeter guides the bit. Because of this you never want to cut all the way through the wood from one side because it will badly splinter out the bottom side unless it is supported very well. For this reason it's common practice to drill part way through from one side and then flip the board and finish the hole from the bottom. You have to leave a center hole for the second side so you have to not bore so far though from the first side that you mess up the center hole.

I bored out the bottom insert profiles with a Forstner bit that was 1/8" smaller than the insert itself. This is because inserts need a shelf under the to restric how deep they sit in the hole. I bored about 2/3 of the way through the playfield and did the bottom side first because that way the center plug will be drilled down onto the bottom hole when the top insert section was bored. This would leave a cleaner finished product than boring it out the other way.20210101_100523 (resized).jpg

The inserts that could be drilled with the drill press had the stop on the drill press set to stop the top hole at exactly the right depth. The holes that could not be reached by the drill press were hand drilled and I needed a way to know when to stop. I designed a part in F360 that could be 3D printed that fit around the Forstner bit, had a depth stop that was adjustable with a set screw and also had clean out sections on the sides to let the wood removed by the bit clear the bit. This worked very well and I was able to get all of the 3/4" and 1" inserts bored and temporarily set. I'm waiting for a 1 3/16" Forstner to arrive to bore the last two inserts.20210101_132758 (resized).jpg

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Sure PM me your email address and I'll send you the stl file. It fits my 1" Forstner bit but I used it on my 3/4 bit as well and although it was slightly off center the bit was run at such a slow speed that it wasn't an issue.

Today I finished up most of the playfield cut out work including cutting the shooter lane groove. This one is a complete rip off of a technique from @borgdog. As he had told me in a PM it is very hard to find a 1 1/16" round nose router bit so I went with a 1" bit to cut the groove.

The trick is to make a sled for your router base with a slot in the middle that is wide enough for the 1" bit and set up fences on either side to guide the router down the middle. On the far end you put a slat of wood that is the same thickness as the deepest cut of the groove and then set the router to just touch the table at that end where you want the end of the groove to be. All you then have to do is run the router the full length and presto, you're done. Works like magic!

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I had picked up a four ball trough from Terry at Pinball Life a few weeks ago and today I figured out how to mount it. I looked at a few modern Stern machine playfields and saw that they cut a large rectangle for the trough which is what I did as well. I didn't think to buy a scoop for the trough since I wasn't exactly sure how all of the geometry would work out so today I spent time designing scoops in F360 and printed them from ABS. It took a couple of tries to get the geometry right and the scoop is printed is draft resolution with 50% infill for a quicker (2 1/2 hour) print. The actual part will be 100% infill with a finer layer height.

Since I used the original ALI metal trough back guide I could only mount the scoop to one side on the play field. The plan is to drill holes in the metal guide, tap holes in the player side of the scoop and mount it on that side via screws through the metal plate.

Here are s couple of photos of the trough, scoop and playfield and a quick video of the scoop in action (minus the inner shooterlane wall).

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Sure PM me with your email address.

Well as I said in a much earlier post, I'm going to show the successes and failures of this build.

I started off populating the underside of the playfield by starting with the lighting. I figured that you populate a PCB starting with the lowest components like resistors so why not start with the lowest component on the playfield, lighting. Everything was going along great until I saw that some light brackets were going to interfere with roll over switches so I figured that those switches and other components like kickers, dts, pops, ect should go on first.

I started with the three bank drop targets since they looked like they would cause the biggest problems because of their size, I was right. I bought two really nice old gottlieb 4 bank dts and figured that I could pull one target and use those as 3 dt banks. I spent half a day working on getting those to fit using different orientations, configurations, I even cut one down to be a three dt unit (they are kind of modular) and it still wouldn't fit with the Dash kickers. The reason for this is that the coil that resets the dt's sits out to the side of the unit and increases the footprint of the unit. I needed to find another solution or I would have to change the geometry of the playfield layout. Something that I REALLY don't want to do since I know this layout should be good.

I took a look online and saw that Pinball Life sells a "modern" 3 bank dt where the coil sits within the footprint of the dt bank. I called to get the dimensions of the bank and it looked like it would fit so I drove down to Huntley to pick up two of them. They cost more than my donor machine...

I hooked up the DT to my 35v PS to see how it would reset and it didn't. It could reset 2 dts but not the full bank of three. It was then that I realized that these coils were designed to work at 50v not 35v, so now I was faced with either making a 50v ps for the table, increasing the coil strength or decreasing the return spring strength of the dt mech. More to come on this

On a positive note I have found a way to increase the kicking distance of saucer or hole kickers. If you raise up the coil of the kicker, the kicker's arm can move further along its arc and kick the ball a longer distance, here's a video of that in action. This means that the VPX Dash kicker shot can be reproduced in real life!

This post is intended for mature audiences only, please so not read this and drive as this can cause drowsiness.

I really don't want to add a 50v PS to the cab and finding springs with lower tension for drop the targets will probably be very difficult/impossible so I figured that my best bet would be to try to increase coil strength. I have no use for these coils so if I destroy one, oh well.

Coil magnetic field is determined by three factors, Current, Number of Windings and Length of the coil. Increasing the current or number of windings increases coil strength while increasing the length of the spool will decrease coil strength. One trick that I've used in the past is to cut a coil and pull some windings off as a means of increasing coil strength. You might think, "that's crazy, you're decreasing the number of windings so you're going to decrease the coil strength!" Well that's correct but if you think about the geometry of a coil, the last windings take the longest distance around the core of the coil because they sit on top of all of the other windings. If you pull those off you will have the most favorable decrease in resistance per loss of windings.

A coil's resistance value is determined by the gauge of the wire and the length of the wire. The coil that came with the DT unit is a Williams 26-1200 which has 26 gauge wire and 1200 windings on the spool. The bigger the gauge number, the narrower the wire so 26 ga wire has a diameter of .016 while 20 ga is .032. As you decrease wire cross sectional area, you increase resistance so 26 ga wire has 40 m ohms of resistance per foot while 20 ga has only 10 m ohms per foot. By pulling off windings you decrease the resistance of the coil which increases the current (I = V/R) so if you increase the current faster than you decrease the number of windings, you will increase coil strength. That's why this only works for the first windings because they have the longest path around the core.

I started by pulling off 75 windings and the bank reset the dt's better but would not set all three so I pulled off another 75, better still but not all three. I kept on pulling off groups of 75 to see what would happen knowing that this would probably not work and the targets continued to reset more and more briskly until I got down to about 750 wraps at which time the sparks were getting pretty large and there was no added benefit. Oh well, it was worth a try because I had no idea how much coil strength would be needed and maybe I could get one of these coils to work.

Next I calculated the amount of coil strength in milli Teslas (mT) that 50v would provide with an intact 26-1200. Using ohms law I calculated the current at 4.6A and with a coil length of 35mm and 1200 windings that should be around 198 mT. At 35v I was generating 138 mT with the original coil. By pulling off windings I was able to hit a peak of 145 mT at 825 windings and around a whopping 7A of current. This goes to show that when these manufactures design a coil they are shooting for the best combination of lowest current with the best number of mT's.

Next I took a look online to see if there is a stock coil that will deliver over 200 mT at 35v. Pinball life sells a Stern coil that is 24 gauge with 940 turns. According to an online coil resistance chart this coil has a resistance of 5.72 ohms which at 35v is 6.1A and by my calcs should deliver 205mT. I ordered a couple of these from Pinball Life and we'll see how they work out. I also ordered a 1 pound spool of 24 ga magnet wire from Remington Industries (BTW a great online source for wire of all types) so that I can rewind the coil that I destroyed to put it back in service should the Stern coils not be strong enough.

Sure but I already have a beefy ALI transformer and my CobraPin board is set up for 35v so I'd like to stay at that voltage.

I love it when the math works out! Full three bank reset with 35v DC and new Stern 24-940 coil that should generate over 200 mT of field strength.

AD72 good point. Higher voltage makes interfacing with modern equipment much easier but the downside is that it makes the older equipment run hot. If you're reusing parts or buying old scrapped parts like I am then lower voltage and careful coil selection may be the better way to go.

I've got an old presentation slide projector that I hook up to the computer and project onto poster board taped to the wall with that.

More work on lighting. As I mentioned earlier I designed a holder for the small chip 2812b's that spaced out the three wires going in and the three wires going out.

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These could be slid into a couple of different sized holders that could be screwed down to the playfield.

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Some of the LED's had to be installed under playfield devices so those were inserted into routed out channels

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I put together some mpf code to drive the LED's as a test, there are about 12 left to go...

After nearly 300 solder joints, I am now done with light wiring! The GI lights were run and used the little under-playfield clips to hold them in place. Thus far the clips look to work well but we'll have to wait until the game has been played for a while to be sure that they are a good solution. I added in sections of wire to lengthen the GI strand if more than one light would need to be turned off to bridge a gap between holes. If only a single light would not be used to make the span, I just zip tied off the light and turned that position in the strand off in the mpf light configs.

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I set the GI lights to 255, 197, 143 but I think that they still need more amber to them. I stressed the system by running 50 GI lights on full white while running the insert lights on an attract pattern. There were occasional flashes in the GI strand so I pulled out the 2200uF cap on the input of the 5v buck converter and put in a 10,000 uF cap and that removed any flashing.

I put a single chip 2812b into each of the pop bumpers and that seems to be doing a nice job with lighting. These are connected by 3 pin molex so the pop bumpers can be removed while the rest of the light strand stays on the playfield. If anyone is looking for a good excuse to buy a 3d printer, check out all of the black ABS parts used in the lighting section of this build. I also printed low profile wire retainers to guide the wires around playfield mechs.

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@cobra18t, me too!

Bord the light show that I thought would look so cool is a little underwhelming so I'm going to try to re-do them with strobing the inserts top to bottom and side to side to see if that looks any better.

@Zitt, thanks for the offer! The bumpers are ALI with their plastic base and I'm not sure about the bodies but they look a lot like the ones I've worked with on Williams and Bally EMs. The lights are chip 2812b's and if you ream the channels for the original light wires up by one size from what just fits down the channel (sorry don't remember the bit size) you can still leave a small portion to mate up with the lower section and three 22 gauge wires will fit up the channel.

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This is what the modern Stern dt's look like. I'm going to put some super tough vinyl stickers on them for the CUP and MUG.

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Today's job is to figure out a way to get leaf switches behind the DT's. The new DT mechs fit perfectly but they leave no room under them for mounting standard EM through playfield leaf switches. I took the switches apart and tried all kinds of different geometries to see I could make them fit including mounting the bracket on top of the playfield but nothing would work. I ended up boring and tapping new holes in the mounting bracket to raise the switch by about 3/16" and them trimmed off about 1/4" from the top of the large front leaf so that it can fit under the plastics.

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I'm amazed at how well Onevox 's playfield geometry works with actual pinball parts. The cutout for the dts and switch was exactly the right size for the parts. This makes me pretty confident that the geometry of VPX tables and parts is very good.

Sorry I haven't worked on a machine newer than RaB, they have optos for rubbers?

Zitt you're right I was thinking about the Stern coil that I juiced them with, they are these parts from Pinball Life
https://www.pinballlife.com/mm5/merchant.mvc?Screen=PROD&Product_Code=PBL-100-0083-00

Yes but do you know your customer number. All kidding aside, Steve is a font of knowledge.

Thanks Wally, you were a big inspiration to me for undertaking this project! Seeing your shop and playing the games that you've made gave me the bug to try something like this. I've looked all over for Two Brothers Pinball beer here in Janesville but have yet to find any.

For those of you who don't know, Wally is a home builder legend and also happens to be a really nice guy. Over the years he has hand built a bunch of classic pins like Medieval Madness, Cactus Canyon Continued, Scared Stiff and Monster Bash to name a few.

Today a few of the last "problems" to be solved for the table came together. I need a spinner for the left lane and bought a used one (Middle Earth?) that unfortunately is fairly wide and I couldn't figure out how I could mount it and get a hole in the playfield for the drive shaft.

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I found a modern style spinner at Pinball Life that just came yesterday. It has a microswitch that sits above the playfield so that should make finding real estate for it easier. I printed heavy vinyl artwork and applied it to both sides.

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I also printed out CUP and MUG art for the drop targets.

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Lastly, when Bord and I worked on Onevox 's VPX table, we added in a two ball mutiball and needed a way to block off the Perdition lane until one ball drained. Bord came up with a post that could be dropped and raised to take care of this and I looked all over for a mechanism that could fit this bill. I found an "up post" on ebay that was from an old 2" flipper EM that also came yesterday. I stripped and cleaned it and printed stand offs to raise it up enough to fit in the tight space that is available for it under the play field. I had some leftover fiberglass tubing from stunt kite repairs that fit the post like a glove so I cut that to length, mixed up some epoxy that was dyed black and did a pour to fill the tube and glue everything together.

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For those who have never done this, you can add a drop or two of dye to epoxy and not effect the cure or strength of it. It is a very common way to do mother of pearl inlays with the black epoxy holding in the MOP and filling any gaps in the inlay routes.

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