The miniature hex bolts holding the valve gear to drivers on my Sunset 4-6-0 are proving to be a challenge to loosen. First of all they only protrude about .032" so conventional hand tools don't want to get hold. Measuring the head in metric gives 2.9 mm and in inch .115" neither size shows up in wrench sets in my MicroMark catalog. I hesitate to buy a $50 set of wrenches only to find they won't fit my application. I also hesitate using anything that might mangle the heads of the six bolts I need to remove.  Note I also tried making a wrench using some 1/16" thick brass but the brass wants to bend instead and wouldn't break the nut lose.

Thanks

Bob

Last edited by flanger
Original Post

I would try the smallest crescent wrench you can find.  I have some that are very small, I mean very small.

 

Melvin

big train posted:

0.1 mm is a very small amount.  I suspect that a 3 mm hex driver would work for this task.  At least that's where I would start.

Me either....I’d think 3.0mm would do the trick, if not, stuff some paper in the socket and it’ll grab.....it aint like it’s torqued on like a head bolt ....no need for a 1/2 inch impact gun!...😝........Pat

The Water Level Route.......You Can Sleep

Just to add to the discussion. Here's the best closeup I was able to get. It shows how very slightly the Hex protrudes above the adjacent surface. I do have an assortment of small wrenches nothing works so far mostly because of how little edge there is available to put force on. But as "Big Train" suggested a 3.0 hex driver may grab this. I don't have one unfortunately.

Bob

 

IMG_7937

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flanger posted:

Just to add to the discussion. Here's the best closeup I was able to get. It shows how very slightly the Hex protrudes above the adjacent surface. I do have an assortment of small wrenches nothing works so far mostly because of how little edge there is available to put force on. But as "Big Train" suggested a 3.0 hex driver may grab this. I don't have one unfortunately.

Bob

 

IMG_7937

Sometimes the brass mfr’s put a nut driver(s) in the box ......might you have some other brands in your stuff? .....might be time to invest in a descent set of micro metric nut drivers.....you’ll need a thin wall for that bolt for sure......Pat

The Water Level Route.......You Can Sleep

As soon as I read Pat's nut driver comment I went digging UNDER the foam and low and behold...a nut driver...the right size...Like winning the lottery...almost .

Thanks Guys

Bob

Nut drivers, like sockets, have a little taper at the end of the hex to aid in getting it on the bolt head.  This can prevent them from engaging the thin hex heads used on some model trains. I had the end of all my nut drivers ground off so the full hex goes right to the end of the opening. This really helped with many side rod screws. A local auto machine shop did the grinding on their valve grinder. 

David Johnston posted:

Nut drivers, like sockets, have a little taper at the end of the hex to aid in getting it on the bolt head.  This can prevent them from engaging the thin hex heads used on some model trains. I had the end of all my nut drivers ground off so the full hex goes right to the end of the opening. This really helped with many side rod screws. A local auto machine shop did the grinding on their valve grinder. 

That’s a good idea, did you watch them do it? ......I’m guessing they swiped at the face with the stem trimmer?..........Pat

The Water Level Route.......You Can Sleep

I'm with David on grinding the head flat.  I was just working on a 3rd Rail steamer and I had to do that to the 3mm socket to get it to grip the head.  I also had to take it to the grinder and grind the sides down all around so it dropped into that recess.

Back in the bad old days, there used to be a thin-wall socket set for tight quarters, I don't know why the nutdrivers don't adopt that model.  It's not like you need all that metal for a 1/2" in diameter handle nutdriver, how much force are you really going to use?  So far I've had to grind down a few of my nutdrivers, I can imagine more will get the treatment when the need arises.

gunrunnerjohn posted:

I'm with David on grinding the head flat.  I was just working on a 3rd Rail steamer and I had to do that to the 3mm socket to get it to grip the head.  I also had to take it to the grinder and grind the sides down all around so it dropped into that recess.

Back in the bad old days, there used to be a thin-wall socket set for tight quarters, I don't know why the nutdrivers don't adopt that model.  It's not like you need all that metal for a 1/2" in diameter handle nutdriver, how much force are you really going to use?  So far I've had to grind down a few of my nutdrivers, I can imagine more will get the treatment when the need arises.

Yeah, I like the idea of a clean cut with the stem trimmer on my valve grinding machine.....I’ve just never thought of using it for that....I’ve always used that machine for well, .......valves ........😁...........Pat

The Water Level Route.......You Can Sleep

That's good you found the nut driver.

I was gonna suggest purchasing a pack of standard or metric ignition wrenches from Sears Craftman.  If the wrench doesn't fit flush, take the wrench and grind the  flat side on the side of a grinder wheel to make it flush surface. 

Pic below is a set of standard.

ign wrenches [1)

 

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harmonyards posted:
gunrunnerjohn posted:

I'm with David on grinding the head flat.  I was just working on a 3rd Rail steamer and I had to do that to the 3mm socket to get it to grip the head.  I also had to take it to the grinder and grind the sides down all around so it dropped into that recess.

Back in the bad old days, there used to be a thin-wall socket set for tight quarters, I don't know why the nutdrivers don't adopt that model.  It's not like you need all that metal for a 1/2" in diameter handle nutdriver, how much force are you really going to use?  So far I've had to grind down a few of my nutdrivers, I can imagine more will get the treatment when the need arises.

Yeah, I like the idea of a clean cut with the stem trimmer on my valve grinding machine.....I’ve just never thought of using it for that....I’ve always used that machine for well, .......valves ........😁...........Pat

I don't have a lot of valves to grind...

Weaver (Samhongsa) upscale brass models came with a tool.   The tool, similar to a pin vice, had the correct head/socket for the connecting rod nuts.  

 

Last edited by Mike CT
harmonyards posted:
David Johnston posted:

Nut drivers, like sockets, have a little taper at the end of the hex to aid in getting it on the bolt head.  This can prevent them from engaging the thin hex heads used on some model trains. I had the end of all my nut drivers ground off so the full hex goes right to the end of the opening. This really helped with many side rod screws. A local auto machine shop did the grinding on their valve grinder. 

That’s a good idea, did you watch them do it? ......I’m guessing they swiped at the face with the stem trimmer?..........Pat

I did not watch the grinding. I just dropped them off and picked them up a couple days later. 

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