SP-15 Questions

Hey All, I have a Challenge 15MP which is the knock off of the SP-15 and am having two issues that I would love some help figuring out.

Question #1: Oscillating Roller
Recent home construction resulted my contractor accidentally flooding the room where I keep my press with very fine concrete dust. I cleaned off my press till it was shiney as possible, oiled it up and started printing.

Everything was going fine till my roller locked up. The newly applied vaseline was thick as mud. I cleaned, vasoline and cleaned the worm multiple times and now it’s looking much better and thinner after running for 1/2 an hour. Still, I can hear a few bits of debris rolling around in the core of the roller.

Would love to take the roller apart and give it a more thorough cleaning. Not sure if the Challenge roller is the same as the SP-15 roller but there are no set screws or apparent ways to take the roller off of the worm. Does Anyone have any thoughts?

Question #2: Switching Itself Into Trip
About every 15th run my press switches itself from print into trip. This happens when the carriage is 2/3rds of the way back to the starting position and I can’t seem to figure out why and what to adjust.

Thanks in advance!

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6 years ago

Issue #1: Oscillating Roller
Went to put the oscillating roller back together and then testing the rotation while it’s still off of the press, it continues to “hang” on both ends of the rod. Visited Jeff, (the owner of the only other Challenge 15-MP in Oregon) and showed him the picture of my pawl (see here). He said that mine looks damaged and that the two ends should be more pointed. Also under closer inspection, the diamond rod looks like there are slight burnishes to the end points on both sides.

Planning on taking the diamond rod to a machinist to have those burrs filed off and sharpened but looks like the pawl is actually the problem and will need to fix or replace.

Issue #2: Switching Itself Into Trip
Springs , roller trip and washer std are all accounted for and functioning. There is a bit of dust around the trip mechanism and so I plan on getting some pipe cleaners and canned air to clean them up a bit to see if that helps.

Paul Moxon, Moderator
6 years ago

Lightly coat the pawl and circumference of the end disc with Vaseline then assemble. Coat the diamond shaft after assembly. Add SAE 20 to the screws.

Paul Moxon, Moderator
6 years ago

Regarding question 2: Check that there are four white trip rollers on the side of the press bed. These contact the trip arm (inside the carriage side plate) that shifts the cylinder eccentric between print mode and trip mode. A spring (#122) in this assembly prevent the trip arm from slipping. It may be that one or both springs (#122) may be broken. This would allow the trip arm to slip. The only way to access them is to disassemble the carriage. See 15 MA/MP manual page 6. This requires removing the inking assembly, tie rods and the side plate. I have done this on SP Vandercooks which one the operator’s side requires a bearing extractor (wheel puller). These can be rented from an auto parts store.

Paul Moxon, Moderator
6 years ago

Regarding question 1: On the end of the oscillator tube you’ll find three 10-24 set screws near the circumference. Use a 3/32 hex key. You will likely need a pick to clean out the edges. Once the screws are removed, tap the opposite end of the shaft with a mallet. This will force the end disc out of the tube. You can then remove the pawl and shaft from the end disc. The pawl is comparable to the Vandercook worm crescent. The shaft, called a diamond shaft, is a single rod of steel with the worm gear cut into it.

After cleaning, check both the pawl and diamond shaft for broken points. If interested, have had new pawls and diamond shafts fabricated and now have a pawl and diamond shaft.

Regarding question 2: I’m not certain of what you mean. The impression cylinder should automatically be in trip during the return carriage travel. Perhaps you can post a video.

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