Re: LINN Model DD-15 "HafTrak" Dump (1/14)
 

Wow - lots of information on that link, thanks! Towards the bottom there was a link for 'More Pictures', on that second page there are a lot of plan views and detail drawings.

Re: LINN Model DD-15 "HafTrak" Dump (1/14)
 

Those are looking great, that's going to be a really impressive truck

Re: LINN Model DD-15 "HafTrak" Dump (1/14)
 

Wow, good catch I can not believe I missed that :p

Re: LINN Model DD-15 "HafTrak" Dump (1/14)
 

I'm back with a update on the Linn. I finally have some progress to show after a lot of research, I have a designed a prototype of the differential and final drives for the tractor. The trouble this entire build has been a lack of info, I quickly discovered that it is vary hard to find any technical or dimensional info about Linn tractors. I had a breakthrough when I found this post on the justoldtrucks forums by user 'Linntractornut' http://forums.justoldtrucks.com/2169...-Technical-etc in this post I found this image.

https://i.imgur.com/ycKgYNGh.jpg

Its a scan of a Linn parts book! And of the differential and final drives :drool: big thanks to 'Linntractornut' of shaing this info. So I finally had something to scale off.

Here is a photo of the differential in the real thing.

https://i.imgur.com/NxdBqQah.jpg

I this designed a model in CAD to allow me 3d print a prototype and hopefully CNC finished parts out of aluminum.

https://i.imgur.com/T4JevhGh.png


Lots of failed prints and designs later...

https://i.imgur.com/bSow66th.jpg

https://i.imgur.com/mxoLx89h.jpg



I have this.

https://i.imgur.com/hpbWh6Rh.jpg

https://i.imgur.com/MTJ9XuCh.jpg

https://i.imgur.com/UckdnWqh.jpg

https://i.imgur.com/Zr3TN2Eh.jpg


The differential is out of a 1/16 Traxxas E-revo and it is perfect size for this! I got the idea to use this differential from kerst's Liebherr LTM 1055 S-4 build. Thanks Kerst.

Now for the final drives gears I was going to cut my own as I now have a mill and indexing head but, I found that 48 Pitch gears which are commonly used in RC cars are perfect size. Using CAD I determined that a 12T pinion and 60t spur fits perfectly in the final drive case.

https://i.imgur.com/m4LHrhhh.jpg

So this how it sits. I will be working on machining the half shafts and a drive shaft, finishing the other track and hooking up a motor so it can finally move under its own power! :bounce:

https://i.imgur.com/Ce2bhHjh.jpg



-Shawn-

Re: LINN Model DD-15 "HafTrak" Dump (1/14)
 

Glad to see this project alive and well....looking forward to seeing this one....

Re: LINN Model DD-15 "HafTrak" Dump (1/14)
 

Really excellent design work! I love it. I usually end up with a pile of parts like that after a build also. Can't wait to see more.

Re: LINN Model DD-15 "HafTrak" Dump (1/14)
 

That's looking good! I'm looking at those phillips head screws, though. There's a site called microfasteners.com that sells small hex head nuts and bolts that would look real good on that case.

Re: LINN Model DD-15 "HafTrak" Dump (1/14)
 

I agree with you, the phillips heads do not look that good, but are good for quick and cheap fastening of prototype parts.

I'm going replace most of the 3d printed parts for cast aluminum or CNC'd parts as part designs are finalized. At that point I will replace all the fasteners with hex head nuts and bolts. I hope to post more about the aluminum casting as I get tools and work flow setup.


Thanks for the tip about microfasteners.com it looks like that is I will be purchasing my fasteners at.


-Shawn-

Re: LINN Model DD-15 "HafTrak" Dump (1/14)
 

Well that is a coincedence. On the Dutch forum someone is also building a Linn logging truck.

I believe it is an older model, but the fact that it is a Linn truck is rare enough.

For the text you need Translate, but you can check the pictures: https://www.modelbouwforum.nl/thread...-truck.278238/

Re: LINN Model DD-15 "HafTrak" Dump (1/14)
 

I'm still trying to wrap (pun intended) my head around the suspension. You're doing amazing work! I'm half-way (again, pun intended) doing a WWII half-track, and they pose a unique set of challenges.

I cheated and used a set of tracks from a robot kit (they're so cheap on Amazon/Fleabay it wasn't worth printing, and they're scaled pretty close), but otherwise not dissimilar to what you're doing. I think the track length is greater on those than on yours, so the suspension with its volute springs pushing on the bogies is simpler. Or at least better documented, lots of books about military stuff vs not so much for civvy.

The other pain I faced was that the front axle is driven, but the effective tire diameter of the track is much greater than the front tires (like 2.5x), so I couldn't use the same motor to drive the front axle as the tracks.

Oh, and it looks like you 3D printed the front leaf springs. Did you do them as one pack? I've done that for a coupla builds, with sufficient CAD work they *look* right, but I keep meaning to try printing individual leaves out of nylon and see if they are stronger / more accurate looking.

Anyway, wow, that's beautiful detail work, especially for parts that won't always be seen. I'll also be following with interest.

-- A

Re: LINN Model DD-15 "HafTrak" Dump (1/14)
 

Shawn:

Any progress on the Linn?

Don

Re: LINN Model DD-15 "HafTrak" Dump (1/14)
 

Not much I'm afraid. Unfortunately I have been on a hiatus from my projects due to having to move, All my tools are in storage (No room for them) I still have been doing CAD work and research for the Linn, my Gradall project and future projects :p (Hopto H-1900, Hopto H-700, Clark Michigan 175A, a tracked Gradall G-1000, Bucyrus-Erie 88-B) I have original manuals for them. I just need the time and space. Oh well maybe some day :thinking:

I'm still here, just in the background. Thank you for your interest I hope I can show some progress soon.

-Shawn-

Re: LINN Model DD-15 "HafTrak" Dump (1/14)
 

Understand about losing workshop space hope we get to see more of this one though....oh and this one Clark Michigan 175A... and this one..Bucyrus-Erie 88-B... LOL

Re: LINN Model DD-15 "HafTrak" Dump (1/14)
 

The 88-B would be quite a under taking for sure, the Michigan 175A should be pretty straight forward as it's quite simple in design.


-Shawn-

Re: LINN Model DD-15 "HafTrak" Dump (1/14)
 

Lol... simple for you maybe....

Re: LINN Model DD-15 "HafTrak" Dump (1/14)
 

Here is a small update on this project. It has been on the shelf for a while.

Some time back I was able to find a original parts book from a Linn tractor :drool:

https://i.imgur.com/Xxg53P4h.jpg

https://i.imgur.com/BwA8uxph.jpg

https://i.imgur.com/Pv1wn85h.jpg

https://i.imgur.com/8sIdZsoh.jpg







This inspired me to make a few parts for the drive line. From the parts book I learned that Linn used a splined universal joint, actually its more like a CV joint..

https://i.imgur.com/e3uJokKh.jpg

https://i.imgur.com/j3iBouAh.jpg

https://i.imgur.com/zgNHGHbh.jpg


Here you can see the scale of the parts.

https://i.imgur.com/m7vaUDDh.jpg


Rear hub and brake drum.

https://i.imgur.com/pA4pAJOh.jpg

https://i.imgur.com/wXnioOqh.jpg

https://i.imgur.com/EQT5MZ6h.jpg


I also machined a input housing for the differential to replace the 3d printed one.

https://i.imgur.com/MnezmuUh.jpeg


G-code test.

https://i.imgur.com/3EKE0obh.jpeg


Finished part.

https://i.imgur.com/OAtdd2Zh.jpg

https://i.imgur.com/hm95pNah.jpg

https://i.imgur.com/DBDwinOh.jpg

https://i.imgur.com/w5pFR6ph.jpg




-Shawn-

Re: LINN Model DD-15 "HafTrak" Dump (1/14)
 

https://i.imgur.com/28hSCwBh.jpg

https://i.imgur.com/YCEJ4UUh.jpg

https://i.imgur.com/gp2kO0th.jpg

https://i.imgur.com/I2V9y2th.jpg

https://i.imgur.com/YXarT6hh.jpg

https://i.imgur.com/JVEJTruh.jpg




-Shawn-

Re: LINN Model DD-15 "HafTrak" Dump (1/14)
 

Awesome to see this getting worked on again. The drivecup and pinion mount are beautiful. Do you plan on swapping all the printed parts for metal, or only high stress parts?

Re: LINN Model DD-15 "HafTrak" Dump (1/14)
 

I too am very glad to see this again. Some really great work you've done. Love the old manuals. I always look for them when I'm planning a build, they are a great reference to have. Often the only way to get dimensions if you don't actually have access to the real thing. What size milling bit did you have to use to cut out that input housing?

Re: LINN Model DD-15 "HafTrak" Dump (1/14)
 

Thank you.

I plan to replace all the 3d printed parts starting with the drive train. Planning the differential housing tool paths and work holding is proving to be difficult, but I will get there.

I used a 2 flute 1/8" (0.125) ball end mill 3 roughing passes 1 finishing pass.



-Shawn-