I am working on a rise and fall indicator jig and drilled a hole for the pivot pin in 15mm thick A2. I am using a 3/32" drill bit for the pin, and I am wondering if the fit is too loose. When I put a dial indicator on the drill bit and push it around, I get almost one thou of motion. Is this normal or too much? I guess there will be some load on the pin always forcing it to the same side, so maybe the sloppiness does not matter?
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Rise and fall indicator question
- Thread starter Hubert S.
- Start date
I tried reaming to 3/32", but the drill bit would not fit. I then used a 0.0945" reamer, and now it wiggles a bit more than I would like.
I was using a drill bit as the pin. I will try to sand the drill bit shank/pin a bit and see if I can make it fit a hole reamed to 3/32". What sort of tolerance am I aiming for for this jig to work will? I guess a thou is too much, but how accurate does it have to be?
- Joined
- Feb 17, 2009
- Messages
- 7,310
Do the best you can. You can even put a drop of CA to hold the pin still. You do not want them to wiggle because it will give you various readings and drive you crazy trying to chase it.
When it comes to slipjoints consistency is key as well as not doing something until you have to.
When it comes to slipjoints consistency is key as well as not doing something until you have to.
Thank you, I will try to make a new set of inserts that do not wiggle at all. The jig itself is made from aluminum and I made insert from drill rod to reduce wear. Now I wish I had not pushed the inserts in. I hope I can get them out and still get a press fit on the new ones.
- Joined
- Nov 28, 2011
- Messages
- 288
I wouldn't worry too much about .001" of play in your rise and fall indicator measurements. In my experience with slip-joints, I find that at least that amount of correction is needed once the adjusted spring and blade are mated with the finished liner/scale/bolster sub-assembly and the exact pins used for final assembly. Even the orientation (rotation) of pins and bushings can have a .001" effect.
Saludos
J
Saludos
J
Now you tell me, I just pushed the loose inserts out!
Maybe that's what Adam meant when he said don't do anything until you have to?Jokes aside, I think tolerances stack up, and this is a pretty easy place for me to at least reduce one source of error. It will be a little while before I start on my first slipjoint anyway, as I am still waiting for materials to finish my SGA. In the meantime, I'll just putz around with an unnecessarily complex rise and fall indicator.
I made a new set of inserts with a 3/32" reamer and they have a lot less play. Curiously, the drill bit went into the reamed hole this time, which makes me think the first time I tried, I must have pushed the burr in on the back side of the hole instead of removing it, and that's why it did not fit. I pressed one of the inserts in, it took a bit less force than before but seems tight. I might add a drop of retaining compound for the remaining three. The picture shows what I've got so far. I plan to make a cam lever to push the spring up so I can insert the blade and test under tension. Everything still needs rounded corners and I also need to get a different contact point for the dial indicator.
