56 replies to this topic

[DDH69]

I'm investigating building a set of replica chimes (3) that run using 12VDC solenoids.  Research so far has me considering carving up a xylophone and taking out the three notes used by one of the old EM machines and striking those with a 12VDC solenoid hammer.

 

I'm wondering if anyone has done a similar thing and has any advice.  Of course pictures or a link would be ideal.

[MajorFrenchy]

I like where this is going already.
I was considering removing 3 of my contactor and replacing them with a small bicycle bell, but a xylophone.... Mmmmm!
 
We tested 3 home made solution to build a chime for our cabinet.
 
The 1st one was a Cheap 7$ Xylophone that we mounted 3 solenoid on a piece of wood.

I mounted 3 solenoids on the keys i believed sounded the best:

In theory this should have worked, the issue was that the solenoid does not bounce off the keys and it muffles the sound. 
---------------------------------------------------------- FAIL --------------------------------------------------------------------
 
We were not going to stop there, we ordered a different type of Xylophone that has piano keys. 

 
The sound on this one was much better. the solenoids was hitting the piano keys who are hitting the xylophone bars. The sound was quite decent and this could be a cool cheap alternative. The sound is absolutely not even close to an original chime, but it makes noise and can be done under 40$
 
Our Last test was a more traditional way of making a chime. i used a Vintage bicycle bell and a desk bell. 
 

 

 
The sound on this was quite good and this was mounted in my backbox. the small bicycle bell sounds really good.

 

For the desk bell ,  well ... the solenoids  does not hit the bell mechanism fast enough to make a clear sound. Unless i can somehow tell DOF to speed up the execution of the solenoid, i  will have to remove it and replace with another bicycle bell.
 
We did a video of the whole process and if you want to hear some gameplay
https://www.youtube....h?v=SG_a4vZR-l0

Edited by MajorFrenchy, 15 June 2019 - 12:58 AM.

[DDH69]

On the same unit that I'm considering would also be an old fashion bicycle bell (already ordered).  So the "module" I'm looking to build will have 4 solenoids, 3 for chimes and 1 for the bell.

[mjr]

scottacus did exactly that.  He actually took it one step further and fabricated his own chime bars from scratch, using acoustic physics principles to figure out the right geometry.  Hopefully he'll see the thread and tell you about his experience - he's quite a music expert so he has lots of good information on this subject.  I tried to capture some of what he described to me about his project here:

 

http://mjrnet.org/pi....php?sid=chimes

 

One important thing I'll point out is that the resonance chamber is apparently as important as (or moreso than) the chime bars themselves.  The classic Gottlieb units are renowned for their excellent resonance chamber design, which makes them continue ringing for a long time after each hammer strike.  I unfortunately don't have any references to how to design that, but it's something to keep in mind.

Edited by mjr, 16 May 2019 - 06:22 AM.

[BorgDog]

the classic gottliebs do come up for sale on ebay every so often.  used to be fairly cheap, but now fetch close to $100.  I agree they sound the best   but then I may be biased having them in my vp-cab and 5 system 1 machines, oh and my homebrew.

 

sounds like a cool project, be sure to keep us updated.

[mjr]

Looks like scottacus did a nice in-depth write-up at one of the other vpin sites:

 

https://vpinball.com...pic/chime-wars/

[MikePinball]

I wouldn't underestimate the complexity of building your own. As mentioned the two big design areas are:

1. Bars of the right material, length, thickness, and mounting in the correct positions
2. The size and shape of resonance chamber is important

Here are some Chime units built from scratch but notice that the designer only tackled item 1 above. According to his webpage "The chime unit does not have the traditional amplification box. After much experimentation I found the same effect could be achieved by slightly increasing the power of the solenoid coils, thus reducing cost and complexity."

 

As a side note, I looked at buying some used Chime units. I bidded on one untested Gottlieb Chime but it eventually sold at $124. I also found a completely rebuilt and tested Bally unit and that cost $100 including shipping. It looks good and sounds really nice - it should last for many years.

[BorgDog]

yikes, it's gotten worse since the last time I looked.  I'm going to have to start looking for machines to part out just for the chime unit and the lockbar, they are like gold nowdays.

[DDH69]

I bought some aluminium bar this morning.  Hopefully a bit of playing over the (wet) weekend.  I've managed to find some great information around the place.  I'll let everyone how I get on.

[MajorFrenchy]

I bought some aluminium bar this morning.  Hopefully a bit of playing over the (wet) weekend.  I've managed to find some great information around the place.  I'll let everyone how I get on.

You have inspired me DD.

Of course being Add, does not help..

I bought a 15$ kids xylophone ordered 3 small 8$ solonoids and I will build an enclosure and mount it inside the cab. I'll post some pics when I get it set up, and might as well make. Video of the whole process.

Sent from my SM-G965W using Tapatalk

[DDH69]

Mid afternoon on Sunday and have made some progress (I really should be getting ready for the upcoming FX3 Williams vol 4 release, but you know ... toys!)

 

Anyway, I bought 1m of 40mm x 3mm (1.5" x 1/8") aluminium bar for $13.  I cut two sets of three chimes from this.  Why two sets, well there was a lack of clarity of sizes from my research.  I researched a number of sites where people have built replacement chimes and also some musical sites to understand it all properly.  One of the sets was correct, the other just sounded a bit odd.  Testing using a musical note test tool on the mobile phone I got C5 at +10%, D#5 at -5% and F#5 spot on.  I believe its pretty hard to tell anything <15%, and given I'm no musician and they will be inside my cabinet changing the sound anyway, I'm leaving them as they are.  It is possible to file and drill to get them perfect, but I doubt early EM manufacturers did that!

 

I've decided to mount this off the side of my cabinet as I'm pretty much out of space on the base.  Chimes were mainly mounted off the side anyway.  I've decided to use some perspex I had lying around - found out via trial and error how to heat bend it!  I also had some old nylon M4 screws, these are now holding the chimes, it saves using rubber grommets with metal screws.

 

Again via some trial and error I found that a decent air gap underneath lets the sound resonate nicely.  If you mount them close to a flat piece of wood (or other material) the sound is dead.

 

I have 3 x solenoids ready to go, but will now have to wait for some M3 nylon dome nuts.  The nylon dome nuts will strike the chime as you don't want metal on metal ideally, it ensures you get the "ring" without the initial "ding".

 

So for those who want to follow along the details of the chimes are:

40mm x 3mm aluminium

 

C5 = 176.5mm with mounting holes (4mm or 5/32") 39mm from each end

D#5 = 162mm with mounting holes 35.5mm from each end

F#5 = 148.5mm with mounting holes 32.5mm from each end

 

The mounting needs to be 22% of the length of the bar from the end to be on a node.  And when you mount the bar its not done up tightly, it needs to move.  So with the holes make them one drill size over (ie 1/64") - allow some movement but not too much - remember its easy to make the hole bigger, much harder to make it smaller!  And yes, the sizes above to 0.5mm are important - make it the most precise cutting you've done for a while by taking your time.

 

Here are the pictures and a link to the video with sound sound of progress so far. https://youtu.be/Ok7RU718O6Y

 

 

Now it will sit for a while until the rest of my parts arrive.  I will update once I have it all built and in place.

[MikePinball]

Looks like a good start. They do sound a little metallic, however. The rubber grommets might in fact be better than the hard plastic. I suppose some experimentation will help.

[DDH69]

As I wait for my nylon dome nuts and have now screwed some things together after the paint dried, I shortened the spacers a little bit and added a rubber "O" ring (3mm ) ring on M4 nylon bolt.  The sound is a little better IMHO.

 

I will post another video once I've got the rest of parts and solenoids making the strike.

[mjr]

In case you haven't been able to look at a real one close up, the business end of the solenoid plunger (the end that hits the chime bar) is nylon, similar to a replay knocker.  If your solenoids have purely metallic plungers, and the sound you get is too much of a metallic clank, try something a little softer at the striker end.

Edited by mjr, 25 May 2019 - 02:18 AM.

[DDH69]

In case you haven't been able to look at a real one close up, the business end of the solenoid plunger (the end that hits the chime bar) is nylon, similar to a replay knocker.  If your solenoids have purely metallic plungers, and the sound you get is too much of a metallic clank, try something a little softer at the striker end.

 

Thanks mjr.  I thought they were, but there is nothing like confirmation - thanks.  My solenoids come with an M3 metal dome nut on the "push" end.  I have ordered some M3 nylon dome nuts and plan to replace the default dome nuts on the solenoids.  I hope this will give me a good sound ....... we'll see!

[coreduo0099]

Looking very nice.  I got a few size bellhop desk style bells and strike the bell plunger with my solenoids.  They sound authentic unless you have something to compare with side by side or have a great audio memory of a real pin.  Thanks for the measurement details.  Looking forward to how it turns out as it might be time up replace my chimes hack and add MX lighting that I've been thinking about...

[scottacus]

Sorry I don't check this site very often so I just saw this topic.  My post on the other site pretty much sums up my testing of chime units.  If you watch the videos you can see the way the units respond to different cycle times which I thought was pretty cool.

 

Ever wonder why Gottlieb units sound so good while some of the notes on Bally and Williams tables sound clunky but other notes sound OK?  Its because of the location on the holes in the chime bars.  Gottlieb went to the trouble of locating the holes at nodes while Williams and Bally didn't so the Gottlieb units ring out beautifully while some Williams notes go "clunk".  If you put the holes 22% of the length of the bar from the end you will hit a node for any length of bar.

 

The key factors in chime unit cycle times are the weight of the slug, distance of travel to the chime bar and the voltage/current applied to the coil.  I hollowed out my chime slugs and that greatly helped the speed of cycling.  Both Gottlieb and Williams score motors run at about 150ms per pulse so the units were probably designed to fire at this speed.  I bet that if the coils were placed closer to the bars, faster cycle times could be achieved.  

 

The other issue is that these units were designed to run on AC but we feed them DC.  @MJR would the coil field collapse for AC vs DC have much effect of cycle times?  I know that the inductance caused by the AC field cycles increases the resistance shown to the circuit by the coil so by running DC through them they are operating at lower resistances and thus higher currents than the designers intended.  This is why MJR's Pinscape board with the coil cut timer circuit is really critical to preventing coil burn up. 

 

One other thing is that steel is hard but aluminum is soft so as MJR said, the slugs need to have nylon tops to them.  I had one EM machine that I rebuilt that was missing the nylon tip on one slug and that slug cut a perfect hole almost completely through the chime bar from the bottom up.  I went to the hardware store and picked up a nylon bolt of the correct diameter, trimmed it to size and epoxied that into the recess on the top of the slug to fix this (plus cut a new chime bar).

 

Chime units are great additions to our cabs but there is more to them than meets the eye!

[mjr]

@MJR would the coil field collapse for AC vs DC have much effect of cycle times?

 

Interesting question; I don't know the answer.  My intuition is it's not much of a factor, though.  I'd think the dominant factor is the time it takes to get the plunger from point A to point B, and the magnetic field rise/fall times are so short (microseconds?) that they're just rounding errors in comparison.  I suspect that the limiting factor in your cycle time tests is the strength of the return spring, because that's going to limit how fast the plunger pulls away from the chime after a strike.  You obviously can't just crank up the spring strength without also increasing the solenoid strength, but I think the combination of those two forces is probably the main cycle time limiter.

[scottacus]

The solenoids in my test bed with the return springs were DC but the ones in the Gottlieb chime unit are AC coils with gravity as the return for the slug.  I was not impressed with the sound of the chime unit that I built with the DC coils (even though they cycled way faster) because they lacked the mass of slug to get the right sound from the chime bars.   That is why I picked up the Gottlieb unit.

 

I did an experiment with the Gottlieb chime unit about a year ago where I placed increasing lengths of rubber in the bottom of the chime unit to lift the slugs up so that they had a smaller length of travel.  Surprisingly it didn't make much difference in the speed of cycling.  There must be a sweet spot for the location of the slug in regards to the coil in terms of efficiency of movement of the slug in the coil.  If the slug is too high (already within the coil) it seems to lose speed of motion which I think is why there was little improvement in cycle speed.  If the slug and coil were lifted towards the unit it would probably increase cycle speed so long as the duration of the pulse was short enough to not impede the slugs return with gravity or pin the slug up against the bar.

 

The reason why I'm harping on cycle speed is that there can be occasions on the table where a ball cycles rapidly between pop bumpers and it sounds really weird to not get chime rings for all of the hits.  It seems to me that the EM designers took this into account when they laid out their tables.  The score motor acts as a speed governor because it cycles at a fixed rate of about 15ms per pulse and it prevents other score multiples when it is in motion so only single hits are possible when the score motor is running.  Those scores (like pop bumpers under in-lanes at the top of a table) tend to have different point values and use a different chime bar than the in-lane.  Another cool feature the designers used on some of these machines.

[mjr]

I did an experiment with the Gottlieb chime unit about a year ago where I placed increasing lengths of rubber in the bottom of the chime unit to lift the slugs up so that they had a smaller length of travel.  Surprisingly it didn't make much difference in the speed of cycling.  

 

I think that actually makes a certain kind of sense.  I think the model for the motion here is a driven harmonic oscillator.  The cycle time for that kind of system is purely a function of the spring constant and oscillating mass.  The force determines the amplitude of the oscillation but doesn't affect the cycle time, and I don't think constraining the amplitude would affect the cycle time either.

 

 

The reason why I'm harping on cycle speed is that there can be occasions on the table where a ball cycles rapidly between pop bumpers and it sounds really weird to not get chime rings for all of the hits.  It seems to me that the EM designers took this into account when they laid out their tables.  The score motor acts as a speed governor because it cycles at a fixed rate of about 15ms per pulse and it prevents other score multiples when it is in motion so only single hits are possible when the score motor is running.  Those scores (like pop bumpers under in-lanes at the top of a table) tend to have different point values and use a different chime bar than the in-lane.  Another cool feature the designers used on some of these machines.

 

Indeed, there must have been lots of arcane little details like that in the engineering of those machines.  Whenever I look at the innards of an EM machine, I'm impressed at how much more complicated they look than a modern SS machine, with their giant mechanical adding machine filling the interior of the cab.  The slow execution speed of the mechanical computer created all sorts of constraints that a modern game designer wouldn't even imagine.