Project "Snow Drift"

[Oldskool 6,643]

I'm almost to the point of ordering some sprockets. The original tire sizes on the donor zero turn are basically the same diameter as the finished screw units. My conundrum is should I gear up, gear down or go with 1:1? The weight of the screw units are definitely a factor. The weight of the entire rig vs the zero turn is a factor as well. Although that being said the zero turn is also capable of pulling a loaded cart behind it. Any input?

[ebinmaine 67,408]

One question that does come to mind for me is:

How difficult will it be to change the sprockets and drive if it doesn't work out quite the way you were hoping?

 

You stated earlier in the thread that you were going to try to install the paddles at one turn of barrel per length of paddle which in a perfect world would lead you to believe that the screws should turn at the same rate that the wheels would be that were installed on the original unit. 

 

 

Making the assumption that the screw is going to turn at the same rate that the wheel would have been turning because you are wrapping each paddle around exactly one time is going to be a little iffy because of a lack of traction in the snow. That said though I think I would gear down so as to slow the unit down as a whole and give yourself a better multiplication of torque.

 

[bds1984 1,429]

What transmission is in the zero turn or will you be using?  If it is from the zero turn, there are two ratings on a lot of them, one for maximum/intermittent and continuous.  With this being a screw drive, you will gain/lose gearing depending of the pitch of the threads/paddles.  That math has been lost on me through the annals of time after taking calculus nearly twenty years ago.  What do your screw units look like?

[Oldskool 6,643]

14 minutes ago, ebinmaine said:

One question that does come to mind for me is:

How difficult will it be to change the sprockets and drive if it doesn't work out quite the way you were hoping?

 

It should be pretty easy. They will be held on by a key and set screw.

[Oldskool 6,643]

17 minutes ago, ebinmaine said:

You stated earlier in the thread that you were going to try to install the paddles at one turn of barrel per length of paddle which in a perfect world would lead you to believe that the screws should turn at the same rate that the wheels would be that were installed on the original unit. 

 

 

Making the assumption that the screw is going to turn at the same rate that the wheel would have been turning because you are wrapping each paddle around exactly one time is going to be a little iffy because of a lack of traction in the snow. That said though I think I would gear down so as to slow the unit down as a whole and give yourself a better multiplication of torque.

 

Yes the paddles will be 1 turn for the length. I guess the other factor is distance of travel of the original tire vs the screw.

[Oldskool 6,643]

17 minutes ago, bds1984 said:

What transmission is in the zero turn or will you be using?  If it is from the zero turn, there are two ratings on a lot of them, one for maximum/intermittent and continuous.  With this being a screw drive, you will gain/lose gearing depending of the pitch of the threads/paddles.  That math has been lost on me through the annals of time after taking calculus nearly twenty years ago.  What do your screw units look like?

I wasn't aware of different ratings. Good to know. The drive unit is a left and right unit that are separate. They will be from a Toro Timecutter 16-42Z. Also taking into consideration that this isn't going to be used alot. Just around the property on occasion.  As far as what the screws look like I have not built them yet. At the moment approx  size is 17.75" x 65".

[wallfish 16,994]

On 11/6/2020 at 8:26 PM, Oldskool said:

Who wants to do some math? What is the length of 1 single spiral on a cylinder that is approx 14.75" x 66". I came up with 80.5" but I question that very much.

Back yard hammer mechanic math, wrap a rope around the pontoon in the spiral spacing you want, adjust spacing as necessary and measure the rope when your ready. Or use a cloth tape measure. Add 10% for adjustments and outside diameter difference for total length of material.  Not sure how to come up with the correct spacing for speed but bet there are some online calculators to help get it close depending upon circumference and the RPM of the pontoon. Figuring out the top speed you're comfortable with seems best because you can always slow the rotation speed with the controls. It would suck to find out it goes too slow at full forward afterwards. Fun to find out it goes faster and you go white knuckles on the controls.

 

What about cutting the bead section off tire rims? That's 2 circles per rim and using the same size rims would keep the dimension of the circles constant. One cut through the edge of the circle and they can easily be formed into a spiral. They're cheap or free and available. Or, find a huge slinky and your almost done! LoL  Motorcycle rims? Trailer rims? The steel from snowblower augers? Bicycle rims might be too thin but beefed up with round stock? Double up round stock? Just some more thinking out loud to see if anything sticks

 

 

[Oldskool 6,643]

53 minutes ago, wallfish said:

Back yard hammer mechanic math, wrap a rope around the pontoon in the spiral spacing you want, adjust spacing as necessary and measure the rope when your ready. Or use a cloth tape measure. Add 10% for adjustments and outside diameter difference for total length of material.  Not sure how to come up with the correct spacing for speed but bet there are some online calculators to help get it close depending upon circumference and the RPM of the pontoon. Figuring out the top speed you're comfortable with seems best because you can always slow the rotation speed with the controls. It would suck to find out it goes too slow at full forward afterwards. Fun to find out it goes faster and you go white knuckles on the controls.

 

What about cutting the bead section off tire rims? That's 2 circles per rim and using the same size rims would keep the dimension of the circles constant. One cut through the edge of the circle and they can easily be formed into a spiral. They're cheap or free and available. Or, find a huge slinky and your almost done! LoL  Motorcycle rims? Trailer rims? The steel from snowblower augers? Bicycle rims might be too thin but beefed up with round stock? Double up round stock? Just some more thinking out loud to see if anything sticks

 

 

When I get the material for the fins I will definitely get longer than I need. I just dont want to buy alot more than I need. If I stick with one full twist it should travel the length of the tube in one rotation. Which is basically the same length of travel as the original tire. Figuring that not the full length of the tube is in contact with the ground. I can easily change my gearing later if need be but once and done would be better. Your rim bead thought has my thinking. Maybe the lock rings from the ole " widow maker " rims would work

[Pullstart 62,834]

3 hours ago, Oldskool said:

I wasn't aware of different ratings. Good to know. The drive unit is a left and right unit that are separate. They will be from a Toro Timecutter 16-42Z. Also taking into consideration that this isn't going to be used alot. Just around the property on occasion.  As far as what the screws look like I have not built them yet. At the moment approx  size is 17.75" x 65".

Woah.  Not used a lot?  I’d be checking the mail 3 times or more an hour, running to the gas station for none more than... gas, skidding logs, skidding them back for time trials, you name it!

[Oldskool 6,643]

4 minutes ago, pullstart said:

Woah.  Not used a lot?  I’d be checking the mail 3 times or more an hour, running to the gas station for none more than... gas, skidding logs, skidding them back for time trials, you name it!

Lmao. Well when I said not alot i was thinking 1 or 2 seasons a year. Mainly snow, but I know what you mean. Why build it and not use it. I can bet if/when it breaks out in the field retrieval would be bit of a job. Heaven forbid I ever got it stuck

[Oldskool 6,643]

A bit of an update on the fins for the screws. Looks like I have a new option. There will be a plasma cutter sitting on my front steps tomorrow. I was wondering why the wife was asking how many cut-off wheels for the grinder I go through on a project. She told me if I was going to keep doing this,  it was more cost effective to just have the plasma cutter. Plus it being a time saver. Gottah luvah.

[8ntruck 6,998]

Assuming no slip, the screw drive would drive the tractor forward 66".   That is about the same as a tire with a 21" OD (66/3.14).

[ebinmaine 67,408]

9 hours ago, Oldskool said:

Gottah luvah

You probably oughta buy that one some flowahs. 

 

[Oldskool 6,643]

8 hours ago, 8ntruck said:

Assuming no slip, the screw drive would drive the tractor forward 66".   That is about the same as a tire with a 21" OD (66/3.14).

I was mulling that over as well. If I did about a 10in cone on the end it would have close to the same length of travel as the original tire of the zero turn.

[Oldskool 6,643]

1 hour ago, ebinmaine said:

You probably oughta buy that one some flowahs. 

 

You can bet I'm gonna

[ebinmaine 67,408]

3 minutes ago, Oldskool said:

I was mulling that over as well. If I did about a 10in cone on the end it would have close to the same length of travel as the original tire of the zero turn.

how's the power to weight ratio of what your building compared to the zero turn the pieces parts came out of?

[Oldskool 6,643]

12 minutes ago, ebinmaine said:

how's the power to weight ratio of what your building compared to the zero turn the pieces parts came out of?

I havent added anything up yet but the zero turn will weigh less. I'm thinking of using a 9.75 sprocket on the tank and maybe a 4ish  on the drive unit

[ebinmaine 67,408]

Is that slightly under driven compared to the zero turn?

[Oldskool 6,643]

5 minutes ago, ebinmaine said:

Is that slightly under driven compared to the zero turn?

Yes. Right now with the proposed  screw size and ground contact. The screw should travel the same distance as the original tire per 1 rotation. So the under drive is to compensate for the extra weight. I think lol

[ebinmaine 67,408]

50 minutes ago, Oldskool said:

Yes. Right now with the proposed  screw size and ground contact. The screw should travel the same distance as the original tire per 1 rotation. So the under drive is to compensate for the extra weight. I think lol

That seems reasonable to me. Do you know the rated top speed of the zero turn and is that the top speed that you're going for with your own vehicle?

 

[Pullstart 62,834]

13 hours ago, Oldskool said:

A bit of an update on the fins for the screws. Looks like I have a new option. There will be a plasma cutter sitting on my front steps tomorrow. I was wondering why the wife was asking how many cut-off wheels for the grinder I go through on a project. She told me if I was going to keep doing this,  it was more cost effective to just have the plasma cutter. Plus it being a time saver. Gottah luvah.

yep, that’s true love!

[Pullstart 62,834]

13 hours ago, Oldskool said:

Gottah luvah.

 

3 hours ago, ebinmaine said:

You probably oughta buy that one some flowahs. 

 

 

2 hours ago, Oldskool said:

You can bet I'm gonna

Does that come with lobstah and buttah?

[Oldskool 6,643]

16 minutes ago, ebinmaine said:

That seems reasonable to me. Do you know the rated top speed of the zero turn and is that the top speed that you're going for with your own vehicle?

 

I think the original top speed would be to fast for this build 

[Oldskool 6,643]

10 minutes ago, pullstart said:

 

 

Does that come with lobstah and buttah?

It may 

[Oldskool 6,643]

21 minutes ago, ebinmaine said:

That seems reasonable to me. Do you know the rated top speed of the zero turn and is that the top speed that you're going for with your own vehicle?

 

As you had asked before, I can always change sprockets later