There is nothing worse then being halfway through a 4 hour print and realising the print has started warping off of the build plate. This has happened many times before with ABS so instead of frustratingly hitting the kill button and restarting, I started thinking of solutions. Then I saw a roll of duct tape sitting on my desk - add this to it's very long list of capabilities. As long as you have a decent brim on your print, this little tip should work well. I haven't tried it on a print with no brim as I always print with one. (let me know if you try it in the comments)
Step 1: Print With a Small Brim.
I haven't tried this little tip without a brim so can't comment on it's success without one. I always print with a brim anyway as it lets the nozzle extrude a bit before getting to the actual print and gives me time to adjust the Z height (or calibration) by eye. This is easily done on a RepRap Mendel90. I tend to print with a brim of about 5-15mm depending on the object.
Step 2: Apply Duct Tape to Warping Area.
The sooner you notice an area warping the less of an effect it will have on the print. Simply cut the duct tape to fit (or use multiple pieces) and tape the brim to the build plate. Be very careful not to push to hard as you may pop the other side up! It's OK if there is still a small gap as the warping won't get any worse from now on. Smooth down (don't burn yourself) the tape so that it is nice and stuck. It lasted for the remainder of the print which was about two hours. I'm glad I figured this out as it saved me having to do a reprint of a very long print.
Step 3: Use It As a Normal Adhesion Method???
I see no reason why this cannot also be used to compliment your normal method of adhesion. On larger prints, once the brim is down it should help the print stick to the bed. Once an area has lifted even the slightest bit it will just keep getting worse so the tape should help stop it from lifting in the first place.
Thanks for reading my first instructable! Please leave any feedback or constructive criticism in the comments. If you enjoyed this 'ible or I saved a print from failing then please comment and favourite it. Happy printing! :)