in Fatbike Forum

The machine I've been building is finally complete and I'm now testing the groomer. The project was delayed by about 2 months due to unrelated events, but I finally had a chance to get it running last weekend and build the prototype drag just this morning.


Here are some specs:

• Built from scratch using a standard snowmobile track
• 6.5 hp
• Speed range of 1.5 to 10 mph
• Tractive effort of 200 to 600 lbs depending on speed (it will push a truck if it gets enough traction!)
• Grooms (and packs!) a 22" wide trail with the prototype groomer
• Will fit through any CORP trail
• Has a modified SRAM X7 shifter for a thumb throttle (possibly my favorite feature!)
• Does not require snow to operate (unlike a snowmobile). It can operate on dry ground in the summer and pull earth-engaging attachments. I have several planned, but the main one is a packer to wear-in new trails much faster

Attached is a teaser shot of how it can pack and smooth loose snow. This snow was uneven and 3 to 12 inches deep in drifts. One pass flattened everything. The groomer is in the background...more details later.


I've never built a tracked machine like this before or tackled such a project all at once. Usually, I buy something similar and incrementally modify it. This project involved starting from scratch with a track and some snowmobile parts and welding up a track frame, power unit frame, aligning everything, building an engine mount, building shafts with brake and sprocket attachments, building the handlebar, setting up controls, and all those other little things that take twice as long as you expect. There was never a moment to test sub-components until the end when I started up the new engine. There was a lot of engineering going on in the background before I started buying parts! The first drive was pretty rewarding. Unfortunately, with winter over, most testing will happen next season.

Awesome! lets see detailed pictures of your work!.... no reason to keep it a secret. How do you plan on getting it to the trail? Does it use a normal centrifugal clutch? 6.5 HF clone motor?

This video sums it up:


https://www.youtube.com/watch?v=VHFYmehzE3o

That Rig looks SWEET.

Hey Jeff. Do you have more pictures of the actual rig? I would love to chat with you about it some time.

I need to take a few. I just got it out for the last snow and groomed a few passes around my yard, but the snow didn't need it so I didn't bother to take it to the trail. I drove it a few laps in the grass today just for fun and to show it to some friends.

I'm swapping out a few parts on it for the season. I'm switching to a twist throttle like a mini bike so my hands stay warmer with mittens and to reduce fatigue. Then I'm welding up the drag out of steel (the prototype worked so well I'm not changing much). I've got a few other projects going on right now, mainly building a cargo bike and some cabinetry, but I should get back to the groomer soon. Although it is ready to go as-is if we get a snow today.

The machine is officially called the Groominator!

This snowstorm surprised me; I didn't think we would get snow for a while, and especially not this much. So Monday night I finally got around to rebuilding/upgrading the drivetrain and rewiring the electrical to a permanent configuration, plus adding a twist grip throttle.

I found that a single type of drag doesn't work in all conditions. The drag I built last year works great for busting up potholes to smooth an existing trail or to pack powdery snow, but on deeper wet snow it loaded up faster than it could disperse it and would become too difficult to pull. So last night I rigged up a simple sled for fresh snow. This worked very well this morning at Quarry Ridge. I had no problem driving the entire trail, although this recent snow is very slick and I ended up sliding sideways a little on trails with a lot of sideslope. On the other hand, berms were fun!

I think the plan will be to use this sled to knock the trail down right after a storm, taking most of the air out. Then after a few days of hardening I can return and smooth the trail with the other drag if it needs it.

Excellent work!

That project has turned out great!

Is there anything in there that churns up the snow before compacting it?  My understanding (armchair groomer here) is that getting the air out of the snow helps to compact it better. 

For the side slip, you might be able to address that by adding more runners across the grooming area rather than just on the side, it would give some lateral traction and leave a corduroy print which could also be helpful if the surface gets icy before tires add some texture to it.

Once you're happy with the design do you want to train a grooming crew on how to use it?

we're meeting around 7pm tonight to test the groomed trails. c u there.

The track significantly churns and packs the snow before the sled/drag rides over it for smoothing. Tracked machines always have a little bit of slip with the ground as the track passes over the idlers, causing it to flex and settle in. This works really well and the majority of the compaction is from the track. On the original drag for the packed trails, I do have additional churning after the track to help knock off high spots, but I found that to be unnecessary and detrimental on the fresh snow.

The drag doesn't slip sideways, it's the track. There's not much crosstread on a track. This was only a problem for a few hundred feet in a few areas due to drifting, so no big problem. I did design the frame for a 1.5" paddle track, so I may have to keep a lookout for a used one.

I do plan to add additional tread on the bottom of the sled anyway. I just built that sled quickly as a proof of concept. I'll probably put steel wear bars on the bottom at some point.

I'll probably do all of the grooming. If I can groom the whole place in an hour, that's quicker and less hassle than meeting someone to pick it up/drop it off, etc. And it's fun.

Awesome.