If it is a hand reamer that you have you can make use of the tapered lead. Ream right through the bit you want a sliding fit, most off the shelf 6.0mm reamers will be H7 tollerance so you should get a sliding fit. On the part you want the pin to be a press fit don't ream in past the taper which will mean the hole is a bit smaller and the pin will be a press fit.

Edited By JasonB on 05/12/2016 20:42:44

I was surprised that a new h7 machine reamer made holes that were on the loose side for dowels, I took this up with a jig fitter who spends his life fitting dowels and he said they would stone a reamer to get the fit they wanted, as they don't buy them it was not a problem to adjust them, he even said the would run it in reverse in a drill and stone it. You may get a better fit with an old reamer than a new one.

Mike

The hole size can be influenced by a few factors. Obviously if the reamer is worn undersize, it will be difficult to make it cut big. The hole size can alter depending upon the type of material being cut, and also the amount of material you leave on for reaming and the speed and feed rate. I have mentioned in a previous post that the type of coolant used will also affect the hole size, neat cutting fluid(rocol etc.) will tend to cut a looser fit and I have used this to get a nice push fit. Also remember that hardened dowels are normally ground over nominal size. These are just practical tips learned through donkey's years of tool-making. Roy M.

You could simply loctite one half in. Part way through Dore Westbury development they decided that it tends to self centre things. Seems to be true.

I believe it's possible to buy dowels that are sized for a drive fit in reamed holes but it needs pretty good equipment to make sure that what ever is driving the reamer does so dead true. From what I have seen roll pins often doubled are usually driven into drilled holes now. Seems that they are sized so that another can be driven down the centre to negate the effect of the split in the pin.

John

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Get a hardened dowel pin and rub it up the front face, ie in the flutes of a reamer to increase the diameter.

To decrease, rub it on the top lands, only 3 or so swipes per flute.

Toolmakers have been doing this for decades.

Or you could just by extractable pins…. ready drilled & tapped!

Mark

I would look at possibility of doing a combination of John and Marks suggestions.

Source some self extracting ( tapped ) taper dowels and matching reamer.

Make your self a little slide hammer for extraction to take tapped studs for the dowel removal.

Result is likely to be a more positive and consistant repetitive fit.

What you want is some precision silver steel. I did have a source of it but they were taken over by some German company. It was 6mm dia as close as I could measure it. That is very likely to be a slide fit in a reamed hole and as I said the other half could be loctited. The clearance on a typical reamer will be about 1/2 the tolerance band.

Wish you luck rubbing but it is possible to reduce the size of a reamer by careful use of a stone. Not much though. All this pain is why sane companies switched to roll pins at least 20 years ago but it does depend on what is being located. The difficulties also explain the reason for taper pins which is what was at least recently being used to locate the parts of drop forge dies.

I was tempted to say that JS has been talking to the fairies but thought I had better not.

You could  of course turn up and polish what ever fit you want.

John

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Edited By Ajohnw on 06/12/2016 09:27:35

Yep, i'd concur there; I use a 6mm and 8mm reamer oftentimes and it always gives a press fit.

It is supposed to be bang on the number so it doesn't surprise me if it's slightly tight for a nominally sized bar, when you think about it this makes sense as theres no/ or little gap between the pieces so they seize slightly.(depending on the overall roundness, they wont be likely exact copies of each other in terms of form)

 If you keep moving them about they eventually wear into each other.

Michael W

Edited By Michael Walters on 06/12/2016 09:33:32