**This article is written under the assumption that you are familiar with the workings and operation of your marker. Read your manual and understand it's entirety before tinkering or adjusting your marker. I will not be responsible for any damages incurred to your marker, by you, if you use my articles for your own use.**
How to polish a delrin bolt:
This is a bolt that came out of a recently acquired Vice, how a bolt could get so out of shape is beyond me. I thought I might give my body shop skills a go and see what I could do to give this old bolt a second life. I have heard Delrin can be polished using a technique called flame polishing (which is about ten degrees of heat from success to needing a new bolt).
I was not about to try flame polishing, nor do I have the tools necessary to do so, however, I was not half bad at polishing metal and paint so here is my first try at Delrin.
Tools you will need:
Wet/dry sandpaper (I used 400 grit up to 2000)
Buffer wheel attachment for Dremel
Let's begin assuming you already have your old tired bolt out of your gun and ready to work on.
Remove the o-rings from the bolt using your pick tool. A jeweler's flathead would work too but nothing bigger than that. Remember we are trying to repair this bolt, not damage it more. You can remove the pin as well depending how extensive your bolt is worn. I left mine in as only the bottom side of the tail end was showing wear.
Beginning with your 400 grit, gently begin sanding the roughest edges down ( start with 800 grit if your bolt is not as bad as mine). Move your sanding operation to the faucet and soak the entire works sand paper and all, continue sanding with your lowest grit again as the water essentially doubles the grit value of your paper (400 becomes 800 when wet, 1200 becomes 2800, and your final 2000 grit becomes a glassy 4000). These values are strictly for example and do not dictate exact grit equivalence.
Run your finger tips over the bolt surface to feel for any inconsistencies and sand out until uniform. Your bolt should look like this when dried.
Repeat this process moving up through your grits of sandpaper. I did mine in 3 grits (400, 1200, 2000) as the added wet sand process in between equates to about 6 levels of roughness. Finally I finished up with a wet sand 2000 grit, ensuring my bolt surface was completely uniform and as smooth as I could get it.
Dry your bolt completely before the final step.
Using a Dremel tool with a buffer attachment, start at one end and slowly work your way around and across from end to the other. Ensure your Dremel is set to it's LOWEST speed as the buffer can heat up quickly and cause pitting and melting in the Delrin surface. I began at the "tail" end to make sure I had a good rhythm and speed before I got to the crucial area that lays in the breech of the marker.
You can see in my final result a few of the deepest scratches are visible but ultimately the surface is shiny and smooth. The bolt now travels with minimal resistance as compared to before the polishing when it would stick and cause a lot of shots to drop off. The entire process took me about 45 minutes and saved me almost $45 if I had just bought a new bolt!
Remember SLOW speed with your buffer and lots of patience. Happy polishing!