Andy, if you look at post #1280, I explained much of my preplanning for the tunnel. Although I see one thing I forgot to mention... the building & cement pad sits atop cement pilings 10 inch diameter - 10ft deep in the ground, so that will certainly help to anchor the dirt walls too. But I will add PWS sheet to the walls for added support, just like I did with the basement.
And the grinder, yes it's more for finishing vs continuous digging, get the sidewalls smooth & straight. And to clean the dirt off the cement ceiling.
Neil, fuel filters generally have a one way check valve in the them, correct? ...wouldn't be very effective for equilibrium.
It's been a long time since I had to split the JD850...
I had this "bright idea" yrs ago to install studs in two of the holes to make re-attaching house to u/c much easier, down in the basement is rather dark & hard to see, but using a locknut it eventually pulled the threads out of the nut. And then ofourse I couldn't then get the locknut to unscrew either.
So that was todays task... cleaned grime off with an electrical cleaner & then dripped crazy glue on the lock nuts to hopefully screw the studs out... but the studs were held in with blue locktite... one locknut actually screwed off the stud & the other one the stud twisted off flush... YAY more work to do.
Cut a slot with a die grinder - cutoff wheel, heat the snott out of it with a small torch... couldn't get it to budge, broke a few small flat tip screwdriver bits. Then decided to drill it out - only to break the 2,5 bit off 5mm inside the hole!
..eventually got the broken bit out, used a smaller 2mm bit to finish the pilot hole, then the correct size bit & finally tapped it again... all in all just 4hrs
but it's fixed
Amazing how those four little 3mm bolts can take so much torque!!!
Re-adjust the swing motor pinion for a tighter mesh to crown gear, give it an oil change, back to work for another winter.