New setup advice - Pinsetter

[Dsuffern]

My son has been building various (very) mini pinsetters with Legos (including some elaborate ones powered by Mindstorms), though not quite as fancy as this one. We're looking to take it to the next level into a small scale bowling setup. Actual scaling ratio (1/2 or 1/3) doesn't matter much. Given his primary interest in the sweep wagon and pinsetter functionality, I'm hoping those of you with experience will help us get started on the right track.

• First: Pins - Seems like the overall sizing of the pinsetter is based on the pin size. What are you recommendations for small scale pin manufacturers and places to buy (and matching bowling balls)?
• Second: String vs Free Fall - I'm a little biased to the "realness" of free fall but don't want to rule out string pinsetters if that's significantly simpler.
• Third: Automation Level - Looking for advice on levels of automation, understanding fully automated is significantly more complicated than manual. I'm hoping you have recommendations for semi-automated that makes sense (i.e. you load a new set of pins into the table, but the pinsetter manages everything else). Recommendations for stepper motors, motor drivers, etc? We've got a working familiarity with Arduino and Raspberry Pi at this point.
• Fourth: Ball return - Seems simple.. just getting the gravity/drop right, but maybe I'm wrong here.
• Fifth: Lane material - Assuming cheaper cost is more desirable than appearance, is there a reason not to use plywood with a healthy amount of urethane on it?

I'm a mechanical engineer by training so I'm excited to work on this with my son... just trying to get an idea what we're in for and hoping to take advantage of your good ideas ) Thanks in advance!

[mr.badwrench]

Welcome to the forum.
There are old threads here with links to places that sell mini pins.
I'll skip the second and third based on your using the term sweep wagon. That's GSX stuff I know nothing about.
Ball return: Probably a surface return will be simplest. No power lift or calculating how much the ball can rise at the front and make it every time. Maybe cut up a piece of a urethane foam mattress for the ball to bump against at the end of the ball tray.
You could use plywood or OSB with lots of urethane. Make sure the trailing edge of each panel is a tiny bit higher than the leading edge of the next panel. 005" to 015" is enough. If a leading edge is higher the ball will jump.

[Mr. Blister]

To get your feet of the ground about going semi-automatic, look up "Brunswick model B-10". This is the predecessor to the Brunswick automatic pinsetter models. There was a renowned bowling alley where I am (in Chicago) that recently closed down that was one of the last places that utilized these semi-automatic machines.

They require an attendant & were not designed to pick up any remaining pins the bowler happened not to knock down (they don't pick up spare pins & sweep the fallen ones away), which I can only assume, is a feature you are wanting to include about your mini-pinsetter.

In which case, you would likely have to design a clutching/actuating & mode differentiation implementation into your machine for the difference in functions for whether there are pins still standing or not. The way in which your machine handles a "standing pins" or a "strike throw" can be automatic in its sequences of movements, but initiated manually (so, in essence, you would still have what is considered a semi-automatic machine).

Get ready to use some basic shop math and include lots of room in your budget for trial & error LOL!

You most likely will want to run several operations off of one AC single-phase motor. To assign separate movements to several different small AC motors or even DC servo motors can be done too, but to do things the DC way you would have to work with a lightweight (plastic or mostly polymer instead of metal) design primarily due to the weaker-by-comparison nature of DC motors.

[coasterp]

I have 1/2 size pins for sale. If you decide to use that size pin, while true half size balls are available, I recommend using candlepin balls. The pin acttion is VERY true to scale with candlepin balls and they are only 0.25" too large. As for the complexity of the pinsetter you are wanting to build, you mentioned you're a mechanical engineer. I'm thinking you can design a machine, however, what is your experience with industrial automation or controls? The mechanical part is one aspect but controlling everything is the other part to consider.