Snowtrac sprockets

[MNoutdoors RIP]

So as the ATA is a new member here maybe you could help locate the mold from the foundry that closed in North Pole Alaska? Or do you have it already?
There are a number of members looking for new sprockets in the not to distant
Future.

Also be sure to ask member Bob about circus tents I'm sure he will smile.

 

[Sno-Surfer]

Count me in as one that's looking for two band sprockets. My current ones are made from steel it appears and wearing through the grousers.
Anyone one has a line on a set please let me know. Thanks.

 

[Snowcat Operations]

We have several members who also need sprockets. We also have one member who is making them out of a specialized plastic. We are also tracking down molds as well. I will pass on the info at this Wednesday Club meeting in Palmer AK. If anyone wants to drop in feel free to do so. Contact us here.

 

[Snowcat Operations]

So as the ATA is a new member here maybe you could help locate the mold from the foundry that closed in North Pole Alaska? Or do you have it already?
There are a number of members looking for new sprockets in the not to distant
Future.

Also be sure to ask member Bob about circus tents I'm sure he will smile.

I DONT HAVE ANY IDEA OF WHAT YOUR TALKING ABOUT BOGGIE?...... this is Bobcat smiling by the way.

 

[Snowtrac Nome]

guess who got that pic of the infamous bobcat, next to a cat that doesn't look like a bath tub

 

[Snowcat Operations]

I must say that I will not divulge my resource for that picture. I sir will go to the grave with that information. I wont mention that he lives in Nome, Alaska. I will also not divulge that he has a real snow cat (Snow Trac) either. His trust of me with such vital information and blackmailable information has humbled me. Thank you Snow Trac Nome for the picture.

 

[Snowcat Operations]

I must say. Bobcats lack of response is proof positive the he knows deep down inside that his Kristi truly is a Krusty.

 

[SnowTrac Hunter]

300 H&H had posted dimensions previously for sprockets. Niels sent me an STP file which I could open with Wedge, but without having a compatible version of AutoCAD I couldn't dimension.

The dimensions that were posted in another thread were slightly incorrect, so I am trying to correct per layout. I am going to try and make a weekend trip to verify. Three hour drive and couple mile hike in to cabin. The dimensions below are what I have come up with so far. Please feel free to correct me if I am off base.

Outer Tooth Diameter - 17-1/4" (17.25")
Outer Tooth Radius - 8-5/8" (8.625")

Base Diameter - 15-3/8" (15.375")
Base Radius - 7-11/16" (7.6875")

Tooth Degrees - 90*, 77.1428571*, 51.4285714*, 25.7142857

Circle Circumference - 54.19247"
Tooth Center to Tooth Center - 3-7/8" minus (3.8708")(14 Teeth)
Tooth Tip Width - 1" (Need to Verify)
Space at Base - 1-1/2" (Need to Verify, May need to be 2" for grouser which would take out slope)

Thickness - 1/2" to 1" UHMW depending on model.

Hope this is helpful. I have an older two band model. I would like to start out with 1/2" and see if it is durable enough before I modify my sprocket to fit thicker UHMW. Prices of UHMW vary depending on location. I purchased a piece of 18" x 10' for $350 in Anchorage, Alaska. You may be able to find cheaper in the Lower 48.

Thanks,
Joe

 

[300 H and H]

Keep us posted on your progress. My self and others are exploring UHMW cut on a water jet currently, as well as some Silicon Bronze foundry efforts. Snow Trac No. 268 has been running some UHMW with careful inspections, and some rotation of the sprockets for several years now. I like the quiet operation the offer, if they can be made to last well enough.

Regards, Kirk

 

[SnowTrac Hunter]

Will do. I need additional measurements from my track rig such as Center hole dimension, mounting bolt spacing and size, and actual grouser bar size to complete. I am hoping to make a template and cut 6 to 7 out of the piece of UHMW we bought. I was going to buy some premade from the local plastics shop, but the cost was prohibitive.

 

[SnowTrac Hunter]

I am tired of backing up steep hills. There may be some additional maintenance needed after I replace the sprockets. Will have to see. I would like to have it running good at least for one winter. Engine has run great since we rearranged the plug wires and went to an electronic ignition.

The pics of the layout do not show the center hole size or the seven mounting hole locations. Needs work. I will repost the pics with all the dimensions when finished.

 

[redsqwrl]

just to chime in, I work slow but never stop.... We have a scanner here that might be able to grab those points as well.

I am relying on others for help with the tooling but we will get there.

thanks for taking a lead.

 

[Snowtrac Nome]

I would think you have something else going on. I run my sprockets till the start breaking teeth usually some where between 1/4 and 5/16 of an inch, never had one slip ,if you have forward movement slippage I would look hard at chains and sprockets. mine got severely worn last winter from a rental I threw a new sprocket on and shortly after word threw a chain, after replacing chains I saw where the old chains hadn't been seating in the sprocket from the bad link bushings changing the pitch

 

[SnowTrac Hunter]

I would think you have something else going on. I run my sprockets till the start breaking teeth usually some where between 1/4 and 5/16 of an inch, never had one slip ,if you have forward movement slippage I would look hard at chains and sprockets. mine got severely worn last winter from a rental I threw a new sprocket on and shortly after word threw a chain, after replacing chains I saw where the old chains hadn't been seating in the sprocket from the bad link bushings changing the pitch

Don,
Quick look at inner drive sprockets and chain did not reveal any wear. Will take a pic of the bronze sprocket that I removed and post. Looks like they had tried to cover with a Black plastic that has worn off. It was worn down to nubs. I will check to see if I can adjust tension to help. Not sure of what it should be.

 

[SnowTrac Hunter]

Close-Up of bronze tooth with Black Plastic covering

 

[SnowTrac Hunter]

Trying again.

 

[Snowtrac Nome]

those are well worn I replaced a set that looked like that this winter

 

[SnowTrac Hunter]

Outer Tooth Diameter - 17-1/4" (17.25")
Outer Tooth Radius - 8-5/8" (8.625")

Base Diameter - 15-3/8" (15.375")
Base Radius - 7-11/16" (7.6875")

Tooth Center to Tooth Center - 3-7/8" minus (3.8708")(14 Teeth/Lug)
Tooth Tip Width - 3/4"
Space at Base - 2"

Tooth Degrees - 90*, 77.1428571*, 51.4285714*, 25.7142857

Mounting Hole Radius - 5-7/8"
Mounting Hole Size - 1/2"

Inner Hole Diameter - 10-1/4"
Inner Hole Radius - 5-1/8"


Circle Circumference - 54.19247"


Thickness - 1/2" to 1" UHMW depending on model.

Sorry it took forever to post finished dimensions. Snow Trac was low on my priority list this year.
Took about 3/4 day to router out seven sprockets when I finally got around to it.

 

[akmountaineer]

I have a couple of used ST4B sprockets that are in pretty good shape. Can anyone suggest a reasonable price for what I should list them for in the classifieds?

 

[JimVT]

to bad you can't rebuild them
i didn't realize i had so many.

 

[redsqwrl]

nay chance you want to make a pattern out of the one pretty unused 2 bander in the middle there.

wrap it in sheet wax from mcmaster carr. to build it up ect...

 

[JimVT]

that is my spare.i hade 5 casted when i changed mine.

 

[Bombi1]

Jim
Was your spare cast from the pattern that Lyndon/Warren had at one time?
Would you be able to post some pics of it?
Thanks

 

[JimVT]

it is from the alaska one that shut down

 

[Armbrust]

I have some almost perfect sprockets on my st4. They show no wear. I’m thinking of looking into reproducing them at a foundry. I wonder how much interest there is for this.
Paul