The Dale C. Maley Family Web Site

I like building hand cranked marble models or games.

So far, I have used several ideas for lifting the marbles about 16" above the base of the model:

1. Two 4-bar linkages lift 1 marble at a time

2. Marble pump

3. Three large wood gears lift the marbles

One other method I had an idea for was to modify the grain elevator concept to lift the marbles. On a grain elevator, a belt runs vertically, often for 50 to 100 feet up.  Bolted to the belt are steel buckets. The grain drops into the buckets from a horizontal auger, then the buckets carry the grain to the top, and when they go over the top the buckets drop the grain down into an auger leg to a bin, wagon, or truck.

It would not be realistic to use a belt on my model because I want stuff to be all wood if possible, and I could not achieve the tension needed on a belt like that. But, I could use a wood chain instead of a belt, and I have built a wood chain before.

I am pretty sure of the load geometry because it was at ground level and I could see it as a kid on the farm in the 1960s.  I am not as sure of the unload geometry since it was 60 feet in the air and I only saw it once when I painted the elevator.

I could borrow the loader concept from the big 26-marble machine. You push up about a 1/4" on a piston, that the releases 1 marble. The chain will be moving up at the load station.

This loader concept has a lot of complexity.  What if I just blocked the loading point except when it is time to load a marble?

So far, I am liking this concept. It eliminates moving parts, so it is simpler.........and it solves the problem of the chain stopping at the load point and too many marbles try to load.

Since the load station is as close to the lower gear as I can get it, this should minimize issues with the chain flexing, that you see the worst flexing 1/2 way between the 2 gears.

Now, I need to design the unload station and see what issues there are with this concept.

Now is a good time to see what RPM the chain should operate, then the needed gear reduction ratio needed if max crank RPM is 100 for kids.  I set up an Excel Spreadsheet to roughly calculate everything.

5 RPM for chain does not surprise me. My marble lift using 3 big wood gears won't run above maybe 10 RPM.

As I suspected, a 20:1 speed ratio will require the use of a worm gear to be able to achieve that large of speed reduction.

You can use this link to download a copy of this spreadsheet.

The height of my 3 big wood gear marble lift model is 22" and I would like to keep this one below that.

It should come under 21" so the over-all height is fine.  I could maybe reduce the diameter of the  2 gears by 1 to help out, but I would have to redesign a lot of stuff, so I will stay with this design.

I need to move it in increments of 2-5/16 so I have an even number of links.  So 16 divided by 2-5/16 = 6.9 links. So move top gear up 7 links in sketchup.

On a real grain elevator, centrifugal force throws the grain into a collector to the right, which slopes into  a round pipe to go down to a bin.  The real grain elevator runs relatively fast, maybe over 100 RPM.  I am only running about 5 RPM on this marble model, so hardly any centrifugal force.

I'm thinking maybe the bucket holds the marble when it goes over the top of the gear, then there is an angled wood piece to direct it out the back into the unload chute?    This will challenge my mind, since I struggle thinking in 3D :)

The purple piece has a 6 degree slope to force the marble to exit the back. The marble is also constricted by the carrier ahead of it, to help force it out.  I need to build a prototype carrier and see if this idea works. I think I can build the carrier without the chain, and just rotate it by hand and see what happens.

In Retrospect, I should have designed the carrier for both load and unload at the same time, versus sequentially......oh well, live and learn :)   I could have 1 view at load and a 2nd view next to it at unload, make all pieces components so they are both updated at the same time.

On the bicycle chain model, the inner links tend to work inwards and they have to be shifted when they enter the gear..........also happens when transporting the model because of gravity. On this model, I should install a guide piece of wood inside the chain, between the sprocket to keep the inner links on the outside.  This is this easiest method I can think of to assure chain link alignment.

I thought the floor of the car before the one that dumps at the top would help contain the marble being unloaded.  When I laid it out, that proved to be wrong. There is a big opening for the marble to fall out, especially if the chain is going fast creating some centrifugal force.

May have to make a guide piece to keep it in the car until it exits.

It is turning out the carrier design is the key to the whole model !!

One the first chain model, the gear was not thick enough to make a good lead in chamfer or round-over for the chain.  If I increase the gear thickness, then I could use a larger round over bit and still have something in the center for it to guide on.  Food for thought.

I added a piece on the carrier to guide the marble out of the carrier versus falling down onto the previous carrier.  This is probably as good as I can get the carrier design until I build the sprockets and chain, then test it dynamically.

I need enough clearance on the lower sprocket for the carriers to clear the base board.

I checked my last model, the one with 3 big wood gears to lift the marbles, and the crank turns clockwise, and the first wood gear turns CCW..........this is what we want for the grain elevator concept model also.

The spur gear with 4" PD and 20 teeth looks ok, but I wonder about the worm gear.  I had roughly 1" between teeth on the 3 big wood gear model, and if I keep the 4" PD spur gear, the worm will only have .628 or about 5/8" at .625.  I don't want to go from 4 to 5" spur gear, because that lowers the crank  handle 1/2".  Maybe I should draw the worm and see what it looks like in Sketchup.

I can try making the 4" PD spur concept worm gear and see if I can make it ok.

The worm gear does not have to be 5-3/8" long, I could shorten it to about 3 inches and save a lot of time making the worm gear.

I had a chunk of 2.25" square white oak, so I used that to make the blank:

1. marked centers on both ends

2. chucked onto small faceplate, guided rear end on tailstock

3. turned from square to round

4. put 3 jaw chuck back on, turned other end round

5. drilled partially through on drill press with 3/4" Forstner bit, finished drilling with auger bit

6. drove on a short piece of 3/4" diameter red oak dowel, chucked with 3-jaw chuck on dowel, mounted live center on other end of dowel in tailstock

7. turned to 1.75" dia

8. marked teeth every 90 degrees using paper Sketchup print-out

I was able to use the 2 burr tools with the Dremel to hog out between the threads. I slit piece of 1/4" dowel on the bandsaw, then inserted a piece of my 220 grit roll that I use on my drum sander, to sand in between the teeth on the drill press.

I counted 21 links on the outside, after I raised the top by 1 link.  The  drop height was about 15" and I wanted 16", so I raised the top by 1 link.

So, 4 times 21 = 84 links needed for the chain.  The drop height is now about 17".

I can always lower it by 1 link, if I find out it is too high during the build process.  But, I can not easily raise it during the build process.

I am about to the point of starting to build the key components of the model, then of course try them out and adjust the design as needed.  Once the core load, unload, and elevator concept are working ok..........then I will start to build the descending paths for the marbles.

My process was:

1. Print out full scale image of gear

2. measure and mark center of red oak blank

3. drill 1/8" hole through center of blank

4. using compass and pencil, draw OD of gear on both sides

5. Drill pilot hole for screw on small lathe faceplate

6. screw blank onto faceplate

7. Band saw OD of gear blank a little bigger than finish size

8. Turn OD to size on lathe

9. remove from faceplate, place in 4-jaw chuck

10. With 3/4" Forstner bit in tailstock of lathe, drill 3/4" center shaft hole in lathe

11. Elmer's white glue on paper pattern

12. band saw sides of teeth

13. cut off teeth using scroll saw

14. mark and drill 6 decorative 5/8" dia holes in blank

15. wash off paper pattern, let dry in oven

16. put gear on stub 3/4" shaft on scrap piece of wood on drill press

17. Carefully rotate gear by hand and sand OD of teeth to give zero run-out to center shaft using 1/2" dia drum sander on drill press

18. gear completed

1. worm gear is made

2. spur gear is made

3. 3 inch wide vertical gear support piece is made with just hole in top, no hole drilled in bottom

4. blanks glued up to make base and big vertical piece

Strategy:

I remember it was tricky trying to get the right tension and spacing on the wood gear set I made before. The 2 gears were vertical, so the wood chain wanted to droop.

On this project, I am going to try to hand the top gear first using the 3/4" dowel in the 2 vertical pieces.

Then I will let the chain and 2nd gear hang down. I will make a dummy wood piece with a 3/4" hole and the same width as the vertical support, to increase the tension on the chain until I get the fit I want...........then mark where the shaft hole should be on the bottom.

My process was:

1. glue sketchup paper pattern onto 5/8" thick blank

2. bandsaw slightly larger than OD

3. use big 3" drum sander on drill press and sand exactly to OD lines

4. drill 3/4" axle hole in center

5. Round OD using special 5/16" round over bit I bought, Do both sides. Critical to guide chain links open as they enter the sprocket

6. drill 3/4" short hole in scrap wood and put in short dowel. Mount sprocket on dowel.

7. install 1/2" bit, line up where to drill 1/2 of a hole on sprocket, clamp scrap board to table, lock table on drill press

8. drill 1/2 holes with 1/2" dia bit

9. drill rest of decorative holes

10. scrub off paper pattern left and dry in oven

The only thing that did not work well, was that when I used the roundover bit, it wiped out about 5 of the outer 1/2 hole marks. Had to use another paper pattern to mark them.

On 2nd gear, I should make radial lines so I know where to drill if roundover bit removes 1/2 hole pattern.

After I made the 2 sprockets, I found that a 1/2" diameter dowel sliced with sandpaper fit ok for sanding the 1/2 circles on the drill press.

I usually save fixtures/jigs/patterns from past projects.  I found the router table fixture I used ok.  On the last project, I forgot to document that I used my smallest, or 1/8" round-over bit with it on the router table.

Note:  from the photo above, you can see the 1/8" round-over bit is not  a perfect set-up.  Works ok when doing 1st side, but when you flip it over, the bearing sort of rides against the top curved and routed service.  Not perfect, but good enough.

I did not find the jig I used to drill the 2nd hole in each link on the drill press, so I made another one.

As in the past project, I had to redrill the 2 holes in each link with 17/64" bit to give enough clearance for the 1/4" dowels to rotate freely.

I am going to try using a temporary 3 sided piece in the bottom, that I can push down on, and keep lined up with LH vertical piece..........then clamp when it is running right.   I will then mark center of axle and drill.  Should be interesting to see how it works :)

the temporary piece is shown in Purple below...............

I lost 1 at the drill press and 2 at the router.  Not a good idea to make the link at a 45 degree to the grain, more likely to blow up at router. Used white oak for links.

1. print out paper patterns for links from sketchup

2. stack 2 or 4 pieces each 1/4" thick and blue tape together.  Note that 4 gives you twice as many pieces as 2 thick, but your scroll sawing time is probably double for the 4 layers, so it is probably a wash of 2 versus 4 at a time.

3. put blue tape on top, not on bottom of stack

4. glue paper pattern onto top with White Elmer's glue

5. pilot drill 1 hole in each link, about 1/8" dia

6. drill 1/4" hole 1/2 way through and flip over to drill the other way. Avoids bad tearout you get if you drill through. Use Forstner bit.

7. Scroll saw

8. remove blue tape using sharpened 1" wide chisel

9. use fixture and drill 2nd hole 1/4" diameter in each link. Drill almost through, flip over and finish

10. drum sand in drill press and remove any transition points from scroll saw (start and finish points don't always overlap perfectly)

11. using fixture, put 2 links in fixture, roundover 1 side

12. flip 2 links over and route other side

13. drum sander to remove any grinder burn

14. put link in vise and drill 17/64".  Do not do in drill press, some will catch and really smack your hand hard!!

15. drum sander to remove burrs from last drilling

I made the 1/4" dowels 2-5/8" long, so they will eventually handle the carriers also.  I hammered each dowel through my piece of steel with a 1/4" hole, to make sure they are really 1/4" diameter and round.

Ran into problem, my temporary lower support piece was too thick and would not let the dowels pass through. I re-designed it and used 3/16 Luan sides instead of 3/4" thick stock.

I clamped the LH side of the lower support while I was pushing  down on the sprocket.  I started rotating the chain and notice the RH side was too high.

I held the RH lower block down while I rotated the chain.  The RH side wants to move up and down as the sprockets rotate??

I'm guessing I have some excessive run-out from the axle to the inside of the half-diameter 1/2" holes on the OD, and this is causing the motion.

I will take the sprockets off, put them on a dummy axle in a piece of scrap wood, then pencil mark the inner part of the 1/2" semicircle as I rotate........and see how much run-out I have. If I find the smallest distance, maybe I can Dremel the other holes deeper to match?

I had some trouble when drilling these holes on the drill press, with the bit wanting to slide off the curved OD of the gear.

I don't think run-out on the non-drilled portion of the OD of the sprocket matters, since the chain dowels only contact the half holes in the OD.

The good news is the 2 sprockets and the chain ran pretty nicely. Not a lot of friction, not a lot of slop in the chain moving around between gears, and the radiused OD kept the links separated as they entered each sprocket.

Here is the set-up I used...........a scrap board with a 3/4" hole for the axle and the sprocket to fit into.......

The first sprocket, which was on the bottom, had a difference about 1/8" from min to max pencil reading. I used the Dremel plus sandpaper on a slitted 1/2" dowel on the drill press to make them all the same run-out.

On the 2nd gear, the difference between max and min run-out was less than 1/16", so I took no action on that gear.

Time to re-assemble and see if everything improves.

I also glued up the dummy piece in the bottom so it wants to stay square.  Before, I just had some brad nails in it and the side pieces could flex some.

I made a short video and you can use this link to watch it.

It has been a few days since I worked on this model.  Today I:

1. marked the special spacer I used to locate the axle center at the bottom

2. dis-assembled and using the special spacer, I marked the axle hole in the thin vertical piece

3. drilled 3/8" axle hole on drill press

4. used thin vertical piece to mark the hole in the RH big vertical board

5. drilled big board in drill press

6. put it back together

It ran pretty smooth, actually better than the other day when  I was doing test work.

I went ahead and mounted the worm gear, spur gear, and crank handle.

WOW, it worked really nice as you see in the video I made. Use this link to watch the video.

Next will be trying out the first marble carrier !!!!!!!!!!!!!!!

I made the first carrier.

I checked it and the marble would not fall out when the carrier was at the top.  Turns out my design has a 1.0 inch gap, and the marbles vary a little over 1.  Easy fix, just Dremeled out some clearance and it worked fine. No big deal to check each carrier and dremel if required.

Next issue was carrier is hitting on the bottom.  My bottom axle must be a hair closer to the bottom plate than the Sketchup design.  Easiest fix is to just cut out a clearance rectangle in the base, like I have done for gear clearance on other projects.

Good news is marble seems to fall out at top ok.

Bad news is the carrier gets cocked maybe 10 degrees on the chain when it loads.  This angle gets a little worse when the carries is 3/4 the way to the top, and the marble falls out before it is supposed to.

Couple options to fix this:

1. Angle the carrier design

2. Make bottom piece angle higher than about 5 degrees it is now, so it will tolerate more tilting of the carrier

3. or a combination of  1 and 2 above.

I got my digital angle finder and with the carrier about 3/4 of the way up, the carrier was sloped at 11 degrees from horizontal.

If I redesign the floor piece, I can increase that angle from about 6 to 11 degrees. But that leaves no margin for error.

Go ahead and redesign the lower piece, and redesign the carrier to tip it about 10 degrees, and try that combination.

The new carrier was level at the loading position and the marble stays in the carrier all the way to the unload position !!

Now, I will install the 2nd carrier and see if the load position works ok or not.  

The carrier below the one that is being loaded, needs to be close to the carrier being loaded, otherwise there is too big of gap to keep the marble in waiting, from not being blocked by the 2nd carrier until it is time for it to be loaded.  This really sets the load height on the chute........which is close to what my sketchup drawing says.

There are 2 carriers done............and I need 21 total.....so 19 more carriers to go.

For the 3 rectangular pieces, I used this process:

-plane 3/4" stock to 1/4 thick

-rip to correct width on table saw

-make length mark on tan masking tape on chop saw, then saw pieces to length using pencil mark

For the 2 tapered pieces, I made 2 sketches of how to set up the table saw to rip them at the right angle, them used masking tape pencil mark on chop saw to cut to length.

took about 1.5 hours to make enough parts to build 19 carriers.

Scroll sawing is an  inherently slow operation, about the only thing I can do is gang saw 2 layers at a time.

You can use this link to watch a short video of 2 marbles loading.

Once you get the model moving and crank it full speed, you always find more problems!!

I did not cut the rectangle big enough in the base because one of the carriers hits the edge on the front.  Easy one to fix, just cut rectangle bigger.

One of the carriers as it comes into the load station, wants to catch on the edge of the load track.  I tried a 45 degree angle to guide it, but it stuck on that also.  I might need

to put a 3/4" dowel that can rotate just below the load chute. Should be a solvable problem.

Biggest problem is when you crank slow, the marbles unload fine at the top, but when you crank fast, there is not enough time for the marble to fall and hit the unload chute !!

Lots of good progress today.

-made longer curved unload chute, worked much better

-made mounting bracket for curved unload chute

-made 2 divider boxes

-mounted short unload track and #1 divider box

-tested and unload seems to work ok now through the divider box

Make the 3 round collector bowls and mount them similar to last game with 3 big wood gears.  Once I get location and height right on those, I can fill in the track to them.

NOTE:  Load station still needs some fine-tuning, but will save that for later.

I decided to try making different designed curves than I used on the Giant Marble Machine project that holds 26 marbles and runs automatically for 16 minutes. Those are small turns that take many pieces, then you have to angle them correctly, and mounting the angled pieces is tough.

Instead, I cut the 90 degree angle from 1x4 pine on the scroll saw. Then I take the piece that needs a drop in elevation to the band-saw, hold it with old fashion wood clamps, then band saw in the changing elevation.  Glue them up and they are ready to go. The nice thing is you don't have to use angle pieces to mount them.  I like them much better, although they do take more room than the compact ones used on the Giant marble machine.

I intentionally made the stairs long, so I could saw to proper length as required on the actual model.

I tried a very steep fall and sharp bend at the bottom, but it did not work.  I increased the angle of fall from about 15 to 30 degrees, then made a rounder bend at the bottom, and that design works.  The box at the end is to keep the marbles from going to fast and shooting out of the bowl.

It is about built. Remaining items:

1. install wiggle-waggle drop from 2nd divider to middle bowl

2. add handle on RH side

3. add reverse pawl on gear to keep from going backwards

4. debug and get loader working flawlessly

5. dis-assemble, stain, paint, re-assemble

The model is essentially done, except for debugging the loader.

I installed 4 carriers.  For about the rev of the sprocket, the thing is too hard to crank!!

with about 1/2 being ok torque to crank and the other half too tight, makes me think the issue is run-out:

-runout from sprocket axle center to each tooth

I also noticed the 1/4" dowels do not lay right on the half moon cut-outs as you go around the wheel?  In theory, they should lay right in the grooves?

===========

I laid out a piece of wood chain, it measured 22-5/16 inches long for 17 links = 1.3125 spacing for teeth.

In theory, each link is supposed to be 1-5/32 = 1.15625

so, my links are long by 1.3125 - 1.15625 = 0.15625 or 5/32" per link.  Boy, this is almost 4/32 or 1/8" long on each link??

===========

only engage 1/2 or about 8 teeth, so error across 8 teeth would be 8 times 0.15625 = 1.25", I don't have that much error !!

but, if this causes binding, then looseness or tightness should be the same as you rotate the sprocket?  and it is not.

so print out part of the sprocket teeth from sketchup and check the teeth spacing.

==============I had that dimension wrong above, re-measured, have 19 spaces between 1/4 dowels and it measured about 22.125 which gives 22.125/19 = 1.1645 actual between dowels.  Target is 1-5/32, = 1.15625.......so my links are 0.008" long, which is very believable.  Over 1/2 the links on a sprocket, this would be 8 teeth x 0.008 = .065 error.

Removed both sprockets and:

1. laid on top of Sketchup print-out of perfect sprocket, marked and Dremeled to get location and depth perfect

2. drilled a 3/4" hole in a piece of scrap plywood, put in short dowel, rotated each gear and marked min and max tooth depth with pencil,

            used Dremel to make each gear better

Now it cranks easier, but torque goes up when 4 carriers are in either gear.

I designed 0 clearance between the sprocket face and the inside of the carriers. Probably should make carrier like 1/16" wider, but 21 carriers already made.

So inside the carrier is 4 links at 1/4" thickness each, plus 5/8" wide sprocket.........so 1-5/8" total to fit inside the carrier, which is the nominal thickness inside the carrier.

At this point, easiest thing would be to remove both sprockets and try to belt sand about 1/16 off the 5/8" thickness to give a little clearance.

It still bugs me why the wood chain does not follow the sprocket holes exactly??  An idea, when I get the chain together, maybe I take a piece of scrap straight wood, saw out notches along the edge, and see if chain tracks the holes or not.

I got the torque on the crank about right, so I decided to tear down, stain, paint, and put it back together.  On some of other models, the friction got better, and lower torque, after the parts were finished.  Here is the condition of the model when I tore it down on the morning of March 13, 2023.

You can use this link to watch a video of how well it cranked before teardown.

I printed out the teeth from Sketchup laid in a straight line.  1-5/32 spacing, 1/4" deep, and 1/2" wide.  I scroll sawed the edge on a piece of scrap.

I then laid sections of the wood chain onto the straight gear, and they all fit relatively well.  I did not see the type of mis-alignment that I see on the top sprocket, so I think the links are designed ok per this exercise.  I can't explain why I see some mis-match on the top sprocket??

Once I got it tore down, I was able to lay the chain on the work bench, then see how well the sprocket fit in between the links.  On 3 carriers there was a little clearance, but on the 4th it was very tight.

So when I designed the carriers, particularly the inside dimension of the links which attach to the chain, I should have designed in 1/16 or 1/8" clearance above the 1-5/8" thickness of 4 links, each 1/4" thick, plus 5/8" sprocket.  DARN !!

I don't want to remake 21 carriers, so couple options at this point are:

1. belt sand each link to try to reduce the thickness

2. drum sand the 2 inside surfaces of the carrier that touch the chains

I already belt sanded the 2 sprockets to thin them up a little. I am afraid to try to plane them thinner in the power planer.

I made a scrap piece 1-5/8" thick and tried it on a couple of carriers. I had no clearance on those carriers, meaning the sprocket has to spread out the 2 sides of the carrier as the carrier goes around the sprocket.  I can use this piece as a gage when I drum sand down the ID of the carriers.

I also found that I allowed no clearance for the chain links to the carrier, especially on the one end where they are close to the carrier. Probably should have allowed 1/8" clearance in the design.

I belt sanded 6 links for testing. You carefully drop them on the moving horizontal belt sander, they move to the RH guard.  Press down with fingers to sand one side. I will have to do all the links eventually.

1. Drum sand with 60 grit spindle on both inside surfaces of carrier until a block 1-5/8" wide clears it ok

2. Use same drum sander on bottom of carrier to give more clearance for the links

3. Tough up inside of carrier with Dremel and deburr tool because drum sander will not go to very edge

4. Test fit by installing 2 dowel pins and 4 links, then insert one sprocket and make sure some clearance.

There is a lot of variation in the finished carriers geometry.  Almost need a fixture to assemble them to try to reduce the variation maybe.

Takes about 5 minutes per carrier to rework and test it. Better than making 21 new carriers.

I painted the base and 2 vertical pieces Fairbury Old City Hall Yellow.

The carrier 1/4" dowels are 2.75" long.  I made sure to drill them such they fit the variation in carrier thickness of 2-1/8 to 2-1/4" wide.

I tried 3/64" bit, but had to back down to ?? for the round dowels to fit.

Took quite a while to assemble up the 84 links on the chain and the 21 carriers !!

The carriers have 1 coat of paint on the side contact point, the links have 1 coat of cherry oil stain, then I rubbed Johnson Wax onto every link.  I also coated the worm gear with Johnson Wax.

I put the chain and carriers back on around the bottom sprocket without the top sprocket in place.  I then lifted the chain using the top sprocket and threaded in the 3/4" dowel axel on top.

I was pleasantly surprised the chain and carriers cranked nicely all the way around !!!  The carriers were also more consistent in that none hit the load chute, like one did when I only had 4 carriers on.  WOW, I thought I was going to have to rework the load assembly!!

The worm and spur gear also work a lot better with 1 coat of cherry oil stain, then with the Johnson Wax!!

I have had things get better and paint/stain and lubrication on other models.

One new bad thing, the marbles are not wanting to fall out at the top.  Looks like I will have to add some taper to get them to want to come out, using pieces of standard wedges.

You can use this link to watch a video I made of how easy the model was to crank.

I suspect I did not get the back of the carrier, the tapered piece, at a 90 degree angle to the sides of the carrier, and that is why the marbles don't want to come out.  It was very tough to tell by eye when gluing up the carrier whether you had a 90 degree angle or not.  I set up the table saw and made some short pieces with a 10 degree taper........then glued them to each carrier as shown below [the yellow piece].

The original back of the carrier had a 6 degree taper. On the ones I did install at 90 degrees to the carrier sides, I now have 6 + 10 = 16 degree taper !!

I then had to test each carrier, and usually had to Dremel in some more clearance using the round deburr tool.

Spent the  day on final assembly, including painting as I went.

I'm going to try to add a bell activated by the marble leaving the front curve and going into the air.  Model running ok, but more debug required, as usual with these models.

Finishing up the addition of a bell to the model.

Still have 1 carrier which is not releasing marble at the top to fix.

A few carriers are not loading because they are too far right or left of the load chute. May have to try adding a guide on each side of the carrier to better line them up.

Also, sometimes marbles get hung up on the few inches of track before the load point, need to fix that also.

Some touch up painting of the 6 dowels that hold the 2 blue bowls also.

I got the bell mechanism working, as shown in the sketchup drawing above.

Did a lot of touch up painting also.

Still had a couple of carriers that would not dump their marble at the top, so Dremel'd them until they worked ok.

Messed around with load mechanism, ended up putting in some small shims, to keep the marbles flowing, after the 2nd marble that is not supposed to load, is backed up temporarily.

Then had a few cases where carrier was not lined up, right or left, with the input chute.  Added vertical curved strip of wood on the LH side to keep them aligned.  Could add one on the RH side, but so far, not issues not loading, can always add later.

Had another problem where carrier loaded ok, then it lifted up the next marble instead of pushing it backwards.  Ended up putting  cover over the load area, which seems to work.

Wow, lots of debugging as I expected!.

I made 2 mistakes on my carrier design.

1. I did not allow any clearance for the mating chain links. I should have moved the carrier to the right of the links about 1/8" so the links do not rub against the carrier.

2. I don't think I assembled the carriers correctly, with respect to getting the back of the carrier at 90 degrees to the links.  When the assembled carriers got to the top, there was not enough slope angle to force the marbles out.

The first improved design image below adds the 1/8" clearance for the links and adds more slope to the back.

The 2nd improved design image has less pieces that the first one, but relies on proper 90 degree alignment at assembly. It also has a wider entry for the marbles.  A fixture or gage check would be needed to assure proper assembly.

I uploaded my model to the warehouse. You can download a copy using this link.

You can use this link to watch a video of the model in action.

This was a challenging project, primarily because the carrier design proved to be the toughest part of the model.

I had made 1 wood chain model before, so the chain was not too bad, but I had to add a vertical guide to align the carriers from right to left, at the loading position.  I also had to tip the carrier design about 10 degrees because the carriers sagged on the chain.

The grandkids should have fun with this one!