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Straightening MPS's Tracks





This past Saturday we spent some time at Great Lakes Pressed Steel straightening the tracks to Medieval Postal Service. Both tracks had a bow in them from the original welding process last fall, and so we had to be very careful when clamping the carriages to the main axle. The tracks both bowed inward along their length such that the center of the tracks was about 1.5" tighter than at the ends. We had to adjust the carriage spacing so that the wheels were not too tight in the center, but still were not in danger of falling off the tracks. This took quite a bit of time to get right, and was an issue we were not happy about. We lived with it for 2008, luckily without too much trouble, but this issue did not help matters when we misfired our last shot at Delaware.

Straightening these tracks was one of our priorities, especially since we are going to be extending the tracks this year. The bow would only be exaggerated with more length. Using a few 4x4's and an overhead crane, we gently lowered approximately 3500 pounds of steel onto the tracks so as to remove the bow. The straightness check was done on a 10-foot long press bench, and both tracks are now within +/- 1/16" of straight, and in most places this is even less of a deviation. We should be all set to proceed now.

straightening tracks thumbnail checking track straightness thumbnail done checking tracks thumbnail

In other news, the frame redesign for the 2009 Medieval Postal Service is almost complete. In addition to a longer frame to accommodate longer tracks (the length of which has been played with on Working Model 2D extensively), a new method of fastening the base together is being devised. The angle bracket and bolt method that we used in 2008 worked, but wasn't the most space-efficient method (especially when packing), and was a little brittle. We think we have a way to deal with both issues at once, without making assembly any more difficult.

More designing work is underway, with most of the issues previously identified on the list. Hopefully reconstruction of the frame will start soon, but first the workshop needs to be set back up. The workshop was moved to a new building in February, and renovations on the upper floor took priority over rebuilding the benches and such we used for the workshop. This week we are hoping to start rebuilding the benches, and construction of the new pieces for Medieval Postal Service's frame can then be built. We need to find a new range to test fire at, and hopefully by the end of the summer we will be ready to begin testing.




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Use "common sense" when operating trebuchets and catapults. Even little ones can be dangerous. Do not place anything you are not willing to lose in the plane of the arm rotation (this includes yourself, body parts, car windshields, cameras, etc). These catapults and trebuchets are capable of throwing just as far backwards as forwards, and the use of a backstop of some sort is recommended, though the use of one does not make the region behind it safe.

Also, just because the throw got away safely downrange does not mean the end of the danger. The arm is likely still swinging wildly along with the counterweight, and there is a sling whipping around. One thing many people fail to take into account is this sling; some people put a metal ring on the slip end of the sling and this ring can HURT when whipping around!

Have fun hurling, but please KEEP IT SAFE!!!