3/4" Scale J1e

[Greg_Lewis]

Just a caution to Jack's method with drawings. I once tried that with some dimensioned tender truck drawings from a loco cyclopedia and found that the drawings didn't scale out vis-a-vis the marked dimensions. In other words, by determining the scale based on one of the drawing's dimensions, that scale didn't work against some of the other marked dimensions. So the drawing wasn't really to scale all the way around, if you get what I'm feebly trying to say. What's that phrase, "Trust but verify."

[Harold_V]

Yep! Rule of thumb for the shop where I was trained was DO NOT SCALE DRAWING.
I'm not suggesting that it can't work---just use caution and follow Greg's advice. There's times when that's the only option at one's disposal.

H

[John Hasler]

Just a caution to Jack's method with drawings. I once tried that with some dimensioned tender truck drawings from a loco cyclopedia and found that the drawings didn't scale out vis-a-vis the marked dimensions. In other words, by determining the scale based on one of the drawing's dimensions, that scale didn't work against some of the other marked dimensions. So the drawing wasn't really to scale all the way around, if you get what I'm feebly trying to say. What's that phrase, "Trust but verify."

Might help to scale horizontal dimensions from a marked horizontal one and vertical dimensions from a marked vertical one.

There was a time when drawings always had DO NOT SCALE on them because previously doing so had been routine.

[Asteamhead]

John,
Paper is shrinking differently in vertical and horizobtal directions as time goes by, you're right!
Helps a lot to verify by using several different (long) dimensions for interpolation. Calculating a string of dimensions as f.e. with rivet-lines will yet be necessary sometimes. It's even more complicated when calculating in mm from US-dimensions for you are forced to interpolate odd dimensions to normed dimensions including tolerances. Think about bore diameters, bearings, radiuses and such.
Good news: A solid and proven HP 35 calulator or similar will help a lot
Jack,
awesome method regarding those parts for the cabin roof!

Asteamhead

[Fender]

I have found examples of Lima Locomotive drawings where (apparently) revisions were made to a drawing whereby a dimension was changed (or perhaps corrected) but the drawing itself wasn’t modified. Another common revision would show different dimensions for the same part, depending on the builder’s serial number, when several locomotives were built to the same set of drawings. I received a print from the California State RR museum of a Lima mikado trailing truck that was so out-of-scale that I’m convinced the draftsman distorted the drawing to allow it to fit on the starched linen medium used for the drawing!

[JBodenmann]

Hello My Friends
First off, thanks for contributing to the thread. I agree with you that dimensioning from drawings can have it's shortcomings. If I were making something with critical dimensions like valve gear parts this method would definitely not do. But here I'm just making a little bit of baloney, a dummy stoker engine to fit under the cab. I have made things like this in the past with only grainy shadowy old photos to work from, so this drawing dimensioned with my crude paper scale was bit of a luxury. Different methods can work in different situations. Soon I will be making a dummy trailing truck booster and fortunately I have fairly complete fully dimensioned drawings for that. Go with what you got! This weekend was spent fiddling with the cab. So here are some snappies of progress. In our first photo a drilling fixture is being used to drill one of the cab sides. The fixture was made using the milling machine and the digital read out. The holes are #55 for some small brass esutchion pins that will be used as rivets. The second photo shows the cab temporarily stuck together with some #00-90 brass screws. You can also see some cards stock mock ups of the cab side windows and the Prime ventilator cab front doors that were made just to have a look. Also visible are the rounded cab corners. The temporary cab floor is 1/8" plywood. It's always a good idea to mock things up and set back and look at things for a while. I will often stick my thumb out and fudge things a bit when scale doesn't quite look right. A couple examples of this are the turret casing on a nickel Plate Berkshire, and the pilot steps on a Southern Pacific Atlantic. If made like the prototype, to me they just don't look right. So I made some very minor changes...ahh much better. Now I'll not divulge what I did, nobody has ever noticed, and I have been waiting to see if anyone does. And our last photo for today is just a general view. I have been wanting to get the cab plunked down on the engine so I could get this photo. It's going to be a big engine, big being a relative term. Starting to look like a J1e, too much fun.
Happy Model Building
Jack

[kcameron]

Updating dimensions on a print was quite standard 'in the old days'. If you consider the man hours it would take to reproduce a new drawing with those changes (BC - before CAD) you can understand why the whole drawing wasn't redone many times. While today, you edit a few numbers, hit print, you have a new scaled drawing. But they still carry the mark "do not scale from drawing" as the trust in printers holding to dimensions is not that high. Even the oldtime plotters from one side of an E print to the other the error could add up.

[JBodenmann]

Hello My Friends
Had a great time playing in the shop today. Spent the day on the cab, and I didn't break anything or hurt myself. Life is good! In our first snappy the front sheet has been marked out and center punched for the rivets that will join the front to the curved angle that the roof will rivet to. It has been clamped to the rear sheet and now they will be drilled together. In the second photo the curved angle has been clamped to the front sheet. The little black circles are where it will get drilled and tapped for #00-90 brass screws to hold things together, and in alignment when the rest of the holes get spotted through. Photo number three shows the back side of front sheet and the angle held on only with the #00-90 screws ready to have the remaining holes spotted through. Number four shows the whole mess drilled and ready for rivets. Also the side windows have been hacked out. Things won't start getting riveted in place for some time. There are a number of things to make and fit up first. Our last photo shows the roof crudely mocked up in card stock. There are three roof panels, a center one, and the side roof panels have an interesting feature on the J1e's. The roof panels wrap down around the cab sides and forms the top of the window openings. I just think this is cool. The New York Central had pretty tight clearances and this was probably a result of scrunching the cab down as low as possible. I have been thinking about the treatment of the cab roof, weather or not to make a removable panel in the roof for operation. A removable panel has some benefits, easier access to the controls, better view of the pressure gauge and water glass. But it makes the roof much more complicated, as it still must have the three ventilators that her big sister did, and it greatly weakens the cab. So I think I will make the cab roof without the removable panel. The fact that there are three roof ventilators will make viewing the water glass and such not to much of a problem. And I may fudge a little and make the roof hatches just a bit oversize. Decisions, decisions...all great fun.

[Greg_Lewis]

... I didn't break anything or hurt myself....

Lucky man....

[JBodenmann]

Hello My Friends
Got a bit more done on the Hudson cab today. The cab sides had some more rivet holes located and drilled. Then the cab roof got some attention. As stated earlier the cab roof has three sheets. The center sheet and two outer sheets. The outer sheets have a large radius over the top of the roof and then a tighter radius at the edge where it curves down to meet the side and form the top of the window opening. The large radius was easy as it was just squirted through the slip roll. The tighter radius was a bit of a fiddle and required rigging up some sort of form tool. So a bit of round stock was found that was the right diameter and plunked down in the milling machine vise. It was set on some parallels to get the correct height as seen in the top photo. A line was made with a Sharpie on the roof sheet to show where the curve should begin, and it was clamped in the vise. Then it was bent around the round stock by hand as seen in the second photo. On a small piece of material like this hand forming will do. One of the advantages of 3/4" scale It was bent a little and then the fit was tested. Bent a bit more and tested again until the fit was just right. All the cut outs and radiuses were made before rolling and bending. It was not annealed. Next the middle roof sheet will get cut and formed. You can see how the window opening projects into the roof sheet. I don't know if this was done on other engines. Once all the roof pieces are made they will be drilled for the rivets that hold it to the side sheets and also the curved angles. The cab will be made so that it can be removed from the engine while leaving the cab front in place. The throttle linkage for the front end throttle, the operating rod for the power reverse, electrical connections to the headlamp, number boards, marker lamps and various piping fit through the cab front. So this will make cab removal for repairs and servicing much easier. I built quite a few engines before the little light bulb went on and I figured this one out. Even blind squirrel...well you know. More to come.
See you later alligator.
Jack

[Asteamhead]

Hello Jack,
It's impressing to watch your artfull brass work! There's always something to learn by watching how things are done efficiently by means of good ideas, a sure hand and just a minimum of tools
Keep on posting your progress, please!

All the best by Asteamhead

[makinsmoke]

Jack,
I love the idea of a front cab wall that stays put. What a great idea! Can't wait to see how you do it.
Brian