How to press fit a pin into a hole ?

You folk are making me evaluate whether or not I should invest in over-under reamer sets !
@homebrewed , @Winegrower , @BGHansen so far all seem to be fully loaded with reamer sets for ultimate hole-making!

So far, of the the 5 (or 6?) reamers I have, only three were bought, one at a time, as needed. Tis tightwad cheapskate I know, but I will sometimes alter a dimension to suit the tool sizes I happen to have.
 
graham-xrf said:
You folk are making me evaluate whether or not I should invest in over-under reamer sets !
@homebrewed , @Winegrower , @BGHansen so far all seem to be fully loaded with reamer sets for ultimate hole-making!

So far, of the the 5 (or 6?) reamers I have, only three were bought, one at a time, as needed. Tis tightwad cheapskate I know, but I will sometimes alter a dimension to suit the tool sizes I happen to have.
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Based on my experience buying used and new tooling off eBay, I'd recommend miking everything that is received. And then sending it back if it is not as advertised. I had terrible luck. I bought 3 individual reamers and they were all wrong sized. Two 0.2495" reamers at 0.251" and a 0.2490" reamer that ended up being 0.3760"! The package was mis-marked on the last one. My new over-under set, as mentioned, all the undersized reamers were nominal. I returned the set and was refunded. The three single reamers I got to keep, and got refunds. All I was trying to do was to press a pin in a hole, and wasted quite a bit of time with these horrid reamers. The very first reamer, I trusted it was onsize. This resulted in a slip fit of the pin. I was really glad I found this out on a test piece, rather than one of the pieces that was machined.

I ended up buying zillions of used reamers from one of our members here for a very good price. Nearly every single one was correct and on size. I measured them all. Not all of the markings were intact, so it was necessary to measure them. I marked the tubes I put them in. I am all set for imperial reamers and probably a lot of metric sizes now. (Didn't cross check the values to metric.) Got boxes of them...
 
WobblyHand said:
Based on my experience buying used and new tooling off eBay, I'd recommend miking everything that is received. And then sending it back if it is not as advertised. I had terrible luck. I bought 3 individual reamers and they were all wrong sized. Two 0.2495" reamers at 0.251" and a 0.2490" reamer that ended up being 0.3760"! The package was mis-marked on the last one. My new over-under set, as mentioned, all the undersized reamers were nominal. I returned the set and was refunded. The three single reamers I got to keep, and got refunds. All I was trying to do was to press a pin in a hole, and wasted quite a bit of time with these horrid reamers. The very first reamer, I trusted it was onsize. This resulted in a slip fit of the pin. I was really glad I found this out on a test piece, rather than one of the pieces that was machined.

I ended up buying zillions of used reamers from one of our members here for a very good price. Nearly every single one was correct and on size. I measured them all. Not all of the markings were intact, so it was necessary to measure them. I marked the tubes I put them in. I am all set for imperial reamers and probably a lot of metric sizes now. (Didn't cross check the values to metric.) Got boxes of them...
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Wow! I am envious.
I have to agree about eBay. I have also been burned.
I have bought milling cutters from Banggood, some HSS, and some carbide. They were at what I thought to be relative bargain prices, and pretty much exact when I measured them.

It brings me to the question about reamers. Mentioned here is heating the hole, and freezing the pin. When I have used reamers, I tend to go real slow, and keep trying to cool it down, because I suspected that cheerfully reaming out a hole would make it end up larger than intended. Then I reasoned that it should not matter, because if the reamer got fatter, because of getting hot, so would the hole, and they would both cool down together, staying the same size, in the end.

I have not had to make an interference fit often, and so far, done with a hammer. Taps, not very hard, on about 15 microns interference.
I had ambitions of making the Joe Pieczynski indexing plate --> LINK
 
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compact8 said:
I am looking to make a sine bar and the design I use requires a pin to be press-fitted onto a steel plate. The pin will not be subject to any stress but it need to stay in place securely. Assuming that I can drill a hole of diameter exactly the same as that of the pin, will it be possible to press the pin into the hole with a bench vice ? I believe the key is to ensure that the pin is perfectly perpendicular to the plate in the process and I cannot figure out a simple way to do it. Will appreciate some hints.
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You're making the hole...... You can make it as tight or as easy of a press fit as you would like. How strong is your vise? How large is the pin?

I don't fully understand how your sine bar will function, but the pin I assume is for measuring angles, and not bearing any large weight or cutting forces? If it's just measurinig, a light press is fine. Something you could tap in with a hammer or a block of wood. Do you have any left over or other similar material? Try some test holes, see how tight you want it. Making the hole 0.01mm to 0.05mm smaller than the pin would be a very practical range for an assortment of pin sizes that are appropriate for a small sine bar. I have no idea how large or powerful your vise is. Try a couple, you'll find a good number that makes as tight of a fit as you want, and when you find that you've left too much interference for your vise to confidently press it together... Then don't break the vise, just stop, and you'll know what your vise can handle. If you're pushing too hard on the vise, you need a bigger hole. If the pin pushes through with too little effort, you need a smaller hole.
 
I've always reamed holes on-size for press fit of +.0002 dowels.
 
When I got my set of over/under reamers I found that several had come out of their plastic shirt-protector style holder. That wouldn't have been a big deal, except that it had happened to a couple of +/- reamers with the same nominal size. I tried measuring their diameters but the results were all over the map. I had to resort to making some test holes and checking the fit with some known dowel pins.

So far all the ones I have used have proven to be OK as far as their specified diameters are concerned. Fingers crossed regarding the others.....
 
Ream the hole with whatever reamer you have, then make the pin to suit. I assume the pin is headed so keep the head the precise size required and make the shank too long. Polish a lead on the pin and press fit. Then remove the excess length.
 
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