Best way to figure out motors and gear reductions

[TylerDSAudi]

I'm working on a few projects where I'm going to be using electric motors to run spools to bring in and out cables. What's the best way to figure out what rpm of motor you need and reductions ect.

I'm guessing you'll need to know the weight you will be bring in to make sure the motor can handle it as well how fast you want to bring it in.

Anyone got tips or websites for conversions?

[modelman]

I like the shovel you have started (inherited). Shovels are one of my main interest. You just have to do a little math and use common sense when figuring speed. I would start by dragging a pc. of string along a surface and decide how fast you need it to move. Then with a tape measure and a stop watch see how long it takes to move the string-say 1', then do the math-moving at the speed you want see how far it will move in 10 sec., 20sec. and 30 sec. etc. and that will give you an idea of the speed you need. Then measure the circumference of you drums and figure how much rope it takes to do one revolution and convert this to the rpm you need to move the rope. I hope this makes sense b/c it is hard for me to explain this stuff trying to type wit h one finger . maybe this will give you a way to get started and it should become clear after a bit. If you have questions that's fine-me or someone on hear will try to answer them. I look forward to watching the shovel build progress.

[TylerDSAudi]

Originally Posted by modelman

I like the shovel you have started (inherited). Shovels are one of my main interest. You just have to do a little math and use common sense when figuring speed. I would start by dragging a pc. of string along a surface and decide how fast you need it to move. Then with a tape measure and a stop watch see how long it takes to move the string-say 1', then do the math-moving at the speed you want see how far it will move in 10 sec., 20sec. and 30 sec. etc. and that will give you an idea of the speed you need. Then measure the circumference of you drums and figure how much rope it takes to do one revolution and convert this to the rpm you need to move the rope. I hope this makes sense b/c it is hard for me to explain this stuff trying to type wit h one finger . maybe this will give you a way to get started and it should become clear after a bit. If you have questions that's fine-me or someone on hear will try to answer them. I look forward to watching the shovel build progress.

This makes total sense for sure! Good ideas ill have to sit down and start that to get an idea of what i need, Thanks!

[9W Monighan]

Tom is correct and I'll try to add some more to this. Something I noticed on your shovel is, The hoist drum will need to be larger in diameter because the rope diameter you will be using has to have a minimum diameter it can flex around to keep it on when there's no tension and not damaging it if it wraps on top of another wrap because of too much crowding the dipper handle. There only needs to be enough rope on the drum for the dipper to make one complete cycle plus one or two extra wraps to keep the rope from pulling out of the clamp holding it on.
On shovels the hoist drum is tapered also. This taper speeds up the feet per minute through the hoist cycle because the circumference is constantly changing and gives more power where the most digging is taking place. Once you have the diameter figured out,figure out the gearing.

[TylerDSAudi]

Originally Posted by 9W Monighan

Tom is correct and I'll try to add some more to this. Something I noticed on your shovel is, The hoist drum will need to be larger in diameter because the rope diameter you will be using has to have a minimum diameter it can flex around to keep it on when there's no tension and not damaging it if it wraps on top of another wrap because of too much crowding the dipper handle. There only needs to be enough rope on the drum for the dipper to make one complete cycle plus one or two extra wraps to keep the rope from pulling out of the clamp holding it on.
On shovels the hoist drum is tapered also. This taper speeds up the feet per minute through the hoist cycle because the circumference is constantly changing and gives more power where the most digging is taking place. Once you have the diameter figured out,figure out the gearing.

I agree the drum could have been bigger for sure, but its something I won't be able to change or I will have to rework most of the model. There is maybe a quarter of an inch from the drum ends and the motor side. Then there isn't room to move the drum/motor gear system further back either. I plan on making my rope tie in's on the ends and then hopefully, the rope will follow the grooves towards the center of the drum. I might just have to up the speed to overcome the smaller drum.

( Side note ) I know how big the drums are on these shovels and draglines in real life, one thing I'm going to make sure to do on my dragline build is to have big drums to take out the need of a lot of gearing.

[modelman]

9w is correct but he is a professional machinist and doing things like tapered drums was way above my skill level. My shovel model was small so I too had small drums but I used 3/32" black nylon rope and it would wrap good and stay in the grooves on the drums even with no load. Depending on how accurate you want to stay to scale you might want to consider this. I tried wire rope on my shovel and it would not work. If you click on my user name and get my public profile there are build pictures of my Marion 182M shovel. May be some things that will help-not sure. Good luck

[TylerDSAudi]

I do agree that it would definitely be the correct way to do it, but like I said there would be a lot of reworking the model. From what I've been researching and comparing online most of his specs on this shovel are 1:1 as that's how intended to build it, I'm not sure why he went with such a small drum though. It will just be something I'll have to live with though.

This thread was more or less for me starting on building/buying the parts I need to get my dragline to build going again. I'm going to start looking for electronics to drive the spools and build the spools.

My plan with the spools would go something like this: Get aluminum stock the size I figure out will be the diameter of my spool. I don't think i have the skill on my lathe to taper it, but I will be able to put the grooves on it. A rod will go through end to end and brazed into place. I will make a mount to hold the spool on out of wood, which will also be my motor mount. For my gear ratio, I think I'm going to pick the right RPM motor that is close to the speed I need, then with a gear mounted to the rod, the motor gear will contact it from there driving the spool. I'll have to figure out how those 2 gears will affect my rpm on the motor that I start with.

My plan is to use smaller metal wire rope I found for my build and set up a grid on the floor and pull it in and time it to figure out what I'm looking at for speed and do the calculations for RPM.

** On a side note Modelman I was looking over your shovel build and its very impressive. We had 4 190 B Electric rope shovels at our mine I would run, they were quite old machines but they paid for themselves time after time for how long they had them for haha Your servo wire latch bar release gave me some ideas for my shovel I will private message you with some questions.

[frizzen]

I'm just a hack who had to have someone else make my conversion parts.

If you didn't already have drums made, I'd suggest finding a series of suitable gearmotors first just to make sure it can fit the form factors, then you can kinda fine tune speeds with the drums and esc endpoints. So like a 1" diameter cable bed on a drum pulls 3.14" of line per rev, 100 rpm motor at full speed pulls 314" of line a min. Smaller drum more torque, larger drum more speed.

Might want to pick up a Fish or Luggage scale to see what kind of line forces are involved with digging in the surfaces you want. If you run a line from the control through all pulleys, around the drum, then tie a loop and hook to the scale. 'X' pounds of force on the line x 'radius of drum' = inch pounds torque.
So like a 15 lb pull on a 1" drum is 7.5 inch pounds or 0.625 ft/lb. Then add in some working and safety margins.

I know on some of the smaller machines some are running nylon cord from blinds. I like the inner strands of 550 paracord, (mil-c-5040 type 3). Just make sure whatever you use is able to lay without birdnesting on your drums. Wire ropes have a lot of spine at this scale, unless you build something big enough to walk itself to work. Keep your first wrap tight and perfect, use enough cable that full extend won't touch that wrap.

https://emce.com/about-winches/winch calculation

[TylerDSAudi]

Thanks for the reply and lots of great advice. I’ve been watching videos on different speeds of gear motors and I’m looking at around 50-80 rpm looks like a good speed at full speed, than factor in the drag of slowing the motor down in digging sequence as well you won’t be full speed most of the time more or less 60-80% ratio.

I forgot the size of my wire rope I bought and I have read on forums that some have luck with it and other haven’t, I might try it to see how it goes, but I have used paracord like you said in my tonka dragline build and other models and it works great too. It’s very strong, has a good thick look to it and doesn’t have memory to it so it goes where it has too.

Plan is to order in some motors in the next few days some 50ish and 60ish rpm motors that are the same so when I do build the spoils and mounts I can change between the 2 to get the best fit and speed.