Chris's Marion 91 Steam Shovel

[crueby]

I have not noticed this hint before.  Use a stamp pad to make an impression on the gasket.  Also one of the cheap leather punches from horrible freight is great to punch nice clean holes in the gasket.  The one with several punches on one handle.

Good tips!  In this case I had lots of holes that I wanted to line up very well, so drilling through the part into a wood block gave very accurate placements. Those punches would be handy in many other cases though!   

[Don1966]

Dog your like a hog at the trough you don’t stop till it’s done. Still with you Dog and waiting to see this baby running like a clock......did I say .........I.........like....... 



 
Don

[crueby]

Dog your like a hog at the trough you don’t stop till it’s done. Still with you Dog and waiting to see this baby running like a clock......did I say .........I.........like....... 



 
Don

You must have seen me at the resteraunt today, trough full of Haddock!   
Getting close now to first pressure on the engines!

[crueby]

Today I've been installing the studs for the cylinders and steam chests. They are threaded in at one end with a dab of Loctite blue medium strength to hold them. After some time to set up, started putting in the gaskets and the cylinder parts. Also have been going through all the bolts on the conrod, eccentric followers, and crank bearings, getting them installed with the same loctite to keep them from vibrating loose after the engines are on the model, they will not be easy to get at later so I want them to stay in place. First engine is all bolted up, been using a small drill chuck left over from my old Unimat to make it easier to spin the crankshaft by hand. It all feels proper so far. I'll get the other two up to this stage, then start installing the valve sliders and time them - going to be a couple of days before they are ready for compressed air (nearly a hundred studs, plus all the other bolts to do). Here is the first one, I am debating whether to go down one size on the nuts on the cylinder cover - these are small pattern steel nuts, I have some brass ones that have a slightly smaller dimension on the hex outside. The studs will be filed back a bit more too, some are sticking out a little too far.

[Don1966]

Yep I would go for the smaller nuts ........


 
Don

[crueby]

Yep I would go for the smaller nuts ........


 
Don

The more I look at it the more I agree. These are smaller pattern than standard ones but not small enough.


 




I have the other engines almost to the same point, just need a few o ring tweaks and will bolt on those cylinders too.

[Firebird]

Hi Chris

Here in the UK we have BA thread sizes which use bolt heads and nuts one size smaller than normal. I have even run a tap through BA nuts to get the 'LOOK' right

Great work

Cheers

Rich

[crueby]

Hi Chris

Here in the UK we have BA thread sizes which use bolt heads and nuts one size smaller than normal. I have even run a tap through BA nuts to get the 'LOOK' right

Great work

Cheers

Rich

That sounds right for models. I have a couple of brands of 2-56 'small pattern' nuts, each uses a different dimension - so much for standards!
 

[crueby]

Switching over from the steel small pattern nuts to the brass ones, here is a photo for comparison. The right is the brass, left is steel, in the center is one standard pattern nut for comparison:

[crueby]

And just noticed that Micro Fasteners has some longer 2-56 external hex head stainless screws back in stock finally, get em while they are there! Just put in my order for some.

[ddmckee54]

Definitely a wise choice to go with the brass small pattern nuts, they look to be more of a "scale" size.

My question, is there enough meat in the nut at size in brass, to hold against your steam pressure?  The elves might not appreciate having to dodge any brass Frisbees.

Don

[Dan Rowe]

Hi Chris, You are correct there is no set standard for small pattern nuts. The original US formula for the across flats  AF dimension was 1.5 times the diameter D of the bolt plus 1/8". In scale terms, this is 1.5D plus a bit or the next size larger hex. This is close to what J.I. Morris did and I still use the nut drivers made by them. American Model Engineers used the same standard. I see that J.I. Morris has added stainless steel to the brass line but WOW...... they are not cheep in SS.

The rule for BA is AF=1.75D which is why one size smaller hex looks good on a model.

I see a lot of stuff that claims to be small pattern nuts but if they do not list the AF I do not send them any money.

Cheers Dan

[crueby]

Definitely a wise choice to go with the brass small pattern nuts, they look to be more of a "scale" size.

My question, is there enough meat in the nut at size in brass, to hold against your steam pressure?  The elves might not appreciate having to dodge any brass Frisbees.

Don

It would keep them on thier toes!   




The brass nuts are .125" across the flats, and seem to be strong enough. I cranked down tight on some to test, and none stripped or slipped. There are 11 nuts on the front caps, 9 on the rear, so should be good. We will find out soon!

[crueby]

Hi Chris, You are correct there is no set standard for small pattern nuts. The original US formula for the across flats  AF dimension was 1.5 times the diameter D of the bolt plus 1/8". In scale terms, this is 1.5D plus a bit or the next size larger hex. This is close to what J.I. Morris did and I still use the nut drivers made by them. American Model Engineers used the same standard. I see that J.I. Morris has added stainless steel to the brass line but WOW...... they are not cheep in SS.

The rule for BA is AF=1.75D which is why one size smaller hex looks good on a model.

I see a lot of stuff that claims to be small pattern nuts but if they do not list the AF I do not send them any money.

Cheers Dan

Good info. Even from same maker, I have seen different dimensions for same thread size in different materials. You are right, if they don't show the size, better ask first.   

[crueby]

Better than usual, 10 steps forward, one step back. I need to remake the outside pairs of valve levers, they are just a bit (0.100") too short from the pivot rod to the top hole, would require bending the rod end down to use as is and I don't want to do that. So, will remake them. Fortunately these are simple parts, just need to redrill some flat bar and silver solder to new rods. I had made them to plan, but the valve rod holes in the steam chests are off spec, and its easier to fix the levers than to remake the chests! I cannot mill down the bottom of the chests, since the steam pipe holes would be cut through. No biggie - just go get another bowl of popcorn...!