Search the Community
Showing results for tags 'pins'.
-
A while back we had a discussion on here somewhere about putting alignment pins in slightly larger than average holes. I was a big proponent of knurled pins. I've knurled lots of stuff in the past. Tool handles, injector nozzles, lock and adjuster nuts on optical mounts, and on my home made carbide scribes. Well, I accidentally drilled some press fit pin holes with the clearance size drill bit the other day. Oops. I decided to prove my point. Unfortunately the stainless that my stock pins is made of would not take a big enough knurl to do the job. I studied it on it a bit, and then decided to do some experiments. If the hole was only a thou or two I could get enough, but at 4 thousandths over size it was tough. Now I could have delved into my sealants and adhesives cabinet and dug out some of the exotic Loctites I have in there, but I wanted to see what the mechanical answers were. You can shim a hole of course, but its hard to do so it looks good. Maybe for my own mold, but not for a customer. Finally I just did it the easy way. I turned custom pins. No kidding. I keep 416L and 303 stainless rod (in a pinch my local metal vendors stocks 304) on hand for various other projects in a few sizes, so I just picked up a piece of 416 that was larger and turned it two about 3 thousands larger than the over sized hole. Then I turned the part that would stick out of the hole to the standard size to fit the clearance hole on the other plate, and radiused the end the way I normally do. Works perfectly. Now I wouldn't want to have to do hundreds of them, but the 5-10 minutes it took me to do one set was certainly more efficient than recutting the mold from scratch. Now that I've done a set could probably do it 2-3 minutes in the future. especially if I move the small lathe into the machine room with the big lathe so I don't have to walk back and forth. Making custom pins was the fastest and easiest way to do it. Now I want to be clear. I have knurled a pin to over size it to have an interference fit in a hole many times, but I've never done it before with such a small pin with that alloy. My vendor just says 18-8 which encompasses a whole range of stainless alloys. I hesitated to post this for a few days, because I know some guys who never make a mistake at anything might take it as an opportunity to be negative, but then I thought. So what. By posting this I might help somebody.