Polishing Inside of Hydraulic Cylinder

[Cooper]

I also use a wooden dowel with slit in end, wrap whatever sandpaper I’m using. I usually have cylinder chucked up in the lathe and just run wooden rod with sandpaper in and out by hand. I also leave a cross-hatched pattern like talked about above. Realistically for our purposes it’s no big deal how the finish is. (Still want to have it somewhat smooth) I think I use 600-800 grit hones for my final “polish”. And also keep in mind brass can sand down quick, so if tight tollarances are in need check often. I also do a quick polish with whatever metal polish compound I have around. (Any left over polish will turn your oil black quick. -I usually run the system for a bit then change oil. ).

[sparkycuda]

Thanks for all the responses. I worked on/taught 1:1 heavy equipment, but don't have experience with how the RC world is different for fit and finish of hydraulic pieces.

My Payhauler requires four stages to get retracted pin-to-pin centers at 3.9" and extended at 9", like the real one. Did learn about the differences between SAE hyd numbered o-rings and plumbing numbered o-rings: there are not the same dimensions. Plumbing #008 are 3/32" CS while hyd #008 are .070" CS. Makes a huge difference for groove and barrel fit.
Aw, the things you pick up while building stuff!

Ken