Press fit woes

[WobblyHand]

So I attempted to make this spanner wrench, based on @darkzero's thread.

Everything went relatively well... Except at the end. It's ok for a first tool, save for the pin. There's plenty of little things wrong with it, but it would be serviceable.

The hole for the pin ended up too large, so the 0.1875" pin falls out. Now, I drilled the hole with a #14 drill, followed by a #13 drill, followed by a 0.1870" reamer. The idea was to have 0.0005" interference fit. What I didn't account for was the runout of my old drill press. I miked the drills and the reamer, and they check out ok. Then I measured the chuck runout using the reamer as the reference. It was a little larger than 0.005". Yeah, more than 10x greater than what I was trying to hit. That's not going to work.

So I need a long and short term solution. Short term: What tool is used to measure the ID of the hole accurately? (0.1800 -0.2000) I can turn a pin to the right size, but knowing the diameter might help! Might take a few goes at it, but that's ok. Or, I could drill the hole out, and machine a screw. The screw would thread in from the back. I could machine off the threads that protrude to form the pin. Longer term: Is upgrading my drill press with good bearings worth the effort, or should that money (plus extra I'd presume) be better spent on a real mill? Doing anything precision on this current setup right now is a waste of effort. So what to do? Seeking some practical advice. Temporarily have lost the wind in my sails.

 

[Ulma Doctor]

ball style hole gauges work wonderfully, like these below


another possibility to repair the oversize pin is to add a bit of locktite 609 to retain the pin
OR

make an oversize pin and try again

 

[Nutfarmer]

If the pin is being pressed into steel ,I would just silver solder in in an not worry about it. If in aluminum and it's a slip fit locktite might work. To accurately measure that size of hole for a press fit gauge pins would be the best way to go ,but few of us have full sets of gauge pins. Small hole gauges can be used to measure a hole that size. I can't do better than half a thou. with them

 

[WobblyHand]

For the ball style hole gauge, is there something reputable that isn't Starrett priced? I own a few Starrett tools, but, their pricing for that set is higher than I'd like to pay. Is there a decent set that's less expensive?

Never used 609. It seems it might work. My Starrett dial caliper measured the hole around 0.191 or so, the pin is 0.1875, which is a gap of 0.0035". That is 0.09 mm. 0.15mm cures to 100% in 24 hours. 0.2mm never gets to 100%, only 50% strength.

 

[middle.road]

Next time instead of using the reamer under power try it by hand. Especially with smaller diameters.
If it is currently a decent 'slip-fit/no shake' JB-Weld might do the trick.
I've done that before on Ø.25 and less.

 

[vocatexas]

I've bought lots of micrometers and other machinist tools at pawn shops and estate sales for anywhere from pennies to dimes on the dollar. If you keep your eyes open there ARE deals out there. I've got a feeling that the next six months will be a buyer's market with people selling things they can part with to put money back in the bank.

 

[WobblyHand]

The pin would be pressed into steel. Silver solder is a good idea. The 0.0035" gap would be filled right up.

 

[Janderso]

I have a full set of gauge pins up to .500”.
I use them quite often to measure/verify inside dimensions. Easy-peasy

 

[WobblyHand]

Next time instead of using the reamer under power try it by hand. Especially with smaller diameters.
If it is currently a decent 'slip-fit/no shake' JB-Weld might do the trick.
I've done that before on Ø.25 and less.

What do you hold the reamer with? Some sort of pin vise?

Pretty sure the damage was done by the drills, long before I got to the reamer. If the drill has big runout, not much for the reamer to d ream. Real problem is the drill press bearings.

The pin wobbles in the hole. Silver solder seems to be a good idea. I have a Prestolite torch. No idea if there is any silver solder on the premises. Have to go poking about the garage to see if there is some hidden.

 

[middle.road]

A decent stout tap handle, put a piece of emery cloth on it perhaps.
I also have a 3/8" drill chuck with a 'T' handle mounted to it.
You've got nothing to lose by trying some JB on it, unless of course you have a torch and some silver solder.