I Don't Know Why I Ever Got Involved...
Moderator: Harold_V
Re: I Don't Know Why I Ever Got Involved...
It is starting to look like a reverser assembly.
Re: I Don't Know Why I Ever Got Involved...
Further machining operations including end rounding on the reverser lever and plunge milling the quadrant plate to accept the reverse lever. I had hoped that simple plunge milling would give the reverse lever enough side to side travel but it didn't so I had to setup the rotary table again to rotary mill out a much wider sector. That final operation required a lot of concentration and nerves.
Re: I Don't Know Why I Ever Got Involved...
The basic reverser parts are now finished with more end rounding, shaping of the quadrant plate and the locating and drilling the sector piece. Half of this I had to guess at (which is never good) as there were no real details given and only a few basic overall dimensions.
All of the latch mechanism still has to be made but before that can commence, I have to find some space somewhere to locate the reverser in the cab, mount the reverser and the reach rod, then determine the full extent of the valve travel and mark it on the quadrant plate, then determine where the reach rod will sit on reverser lever so one can fully traverse the valve. So many things to juggle but fortunately LBSC does describe how to do this so I may be lucky. We shall see.
All of the latch mechanism still has to be made but before that can commence, I have to find some space somewhere to locate the reverser in the cab, mount the reverser and the reach rod, then determine the full extent of the valve travel and mark it on the quadrant plate, then determine where the reach rod will sit on reverser lever so one can fully traverse the valve. So many things to juggle but fortunately LBSC does describe how to do this so I may be lucky. We shall see.
Re: I Don't Know Why I Ever Got Involved...
A start on all of the trigger parts. After reading a bit more, it does seem that these parts need to be partially or completely made before installing the reverser. Just don't drill any of the locating or mounting holes.
LBSC says these parts are so easy to make no detailed description is required. Well, maybe for him but I had my fair share of problems so far. On the first buckle, I slotted the 1/16" by 3/32" deep cross slot at the wrong end of the larger slot and there are major holding problems with all of these parts being so small and fiddly. And they all have very exacting geometry or nothing is going to work as drawn.
One thing I have become good at is making miniature band sawed slots. There are lots of those here.
Note all of the scribbled dimensions (some of which are still to be determined) which I had to add and revise and revise...
LBSC says these parts are so easy to make no detailed description is required. Well, maybe for him but I had my fair share of problems so far. On the first buckle, I slotted the 1/16" by 3/32" deep cross slot at the wrong end of the larger slot and there are major holding problems with all of these parts being so small and fiddly. And they all have very exacting geometry or nothing is going to work as drawn.
One thing I have become good at is making miniature band sawed slots. There are lots of those here.
Note all of the scribbled dimensions (some of which are still to be determined) which I had to add and revise and revise...
Re: I Don't Know Why I Ever Got Involved...
Further milling operations on the trigger.
So far there are over 15 different operations to get the trigger part this far and probably another half dozen to finish it. And the more you work on it, the more difficult it becomes to position and to hold it.
So far there are over 15 different operations to get the trigger part this far and probably another half dozen to finish it. And the more you work on it, the more difficult it becomes to position and to hold it.
Re: I Don't Know Why I Ever Got Involved...
Working on the latch.
This is a very difficult part to machine correctly due to its rigid geometry and how to hold it securely. As it is being formed, it gets weaker and weaker structurally and yet it has to be held very securely for every operation.
Particularly taxing was milling it down to its finished thickness of 1/16" thick at one end. I used the setup shown in the third photo. I was using a freshly sharpened end mill and a DOC of only .001" -.002" per pass at a truly minuscule feed rate and on every pass I was terrified that the part would collapse.
From a starting thickness of 1/8", I end milled down the one end to 5/64" (.078") and then gave up.
To finish, I used the surface grinder blocking in the part in as shown in the fourth photo. I don't know how I would have done it any other way. The SG has saved my bacon so many times by now...
The last photo shows the buckle, the latch and the trigger in their correct geometric positions. It looks like I will have to make the quadrant plate over again as the lower pivot point on the first quadrant plate needs to be raised by about 5/16" to achieve the above ideal relationship. But when you are guessing on a lot of things, sometimes you guess wrong.
Still more work to be done to finish this assembly.
This is a very difficult part to machine correctly due to its rigid geometry and how to hold it securely. As it is being formed, it gets weaker and weaker structurally and yet it has to be held very securely for every operation.
Particularly taxing was milling it down to its finished thickness of 1/16" thick at one end. I used the setup shown in the third photo. I was using a freshly sharpened end mill and a DOC of only .001" -.002" per pass at a truly minuscule feed rate and on every pass I was terrified that the part would collapse.
From a starting thickness of 1/8", I end milled down the one end to 5/64" (.078") and then gave up.
To finish, I used the surface grinder blocking in the part in as shown in the fourth photo. I don't know how I would have done it any other way. The SG has saved my bacon so many times by now...
The last photo shows the buckle, the latch and the trigger in their correct geometric positions. It looks like I will have to make the quadrant plate over again as the lower pivot point on the first quadrant plate needs to be raised by about 5/16" to achieve the above ideal relationship. But when you are guessing on a lot of things, sometimes you guess wrong.
Still more work to be done to finish this assembly.
Re: I Don't Know Why I Ever Got Involved...
End rounding on the latch.
This operation required every trick I knew.
At this point, one could not clamp the latch in any conventional way.
The latch was first set on the 1/16" dia. centre plug peg of the rotary table as seen in the first photo.
The 1/16" thick "weak" end of the latch (in reality the entire latch was now very weak) was then tightly clamped between a small toolmakers clamp as seen in the second photo.
This assembly was then transferred to the rotary table where the rotary table clamps clamped only the toolmakers clamp which sandwiched the latch and the centre plug to hold it down in place.
The overall setup is seen in the third photo. As you can see, there was now so little room for the cutter to cut (it virtually required nearly a 270 degree rotation), the operation had to be carried out in two steps by altering the clamping positions between steps to allow visual observation of the end rounding operation and to have the spindle of the mill clear all of the clamping obstructions.
LBSC states this can all be done by filing. Well, no comment.
This operation required every trick I knew.
At this point, one could not clamp the latch in any conventional way.
The latch was first set on the 1/16" dia. centre plug peg of the rotary table as seen in the first photo.
The 1/16" thick "weak" end of the latch (in reality the entire latch was now very weak) was then tightly clamped between a small toolmakers clamp as seen in the second photo.
This assembly was then transferred to the rotary table where the rotary table clamps clamped only the toolmakers clamp which sandwiched the latch and the centre plug to hold it down in place.
The overall setup is seen in the third photo. As you can see, there was now so little room for the cutter to cut (it virtually required nearly a 270 degree rotation), the operation had to be carried out in two steps by altering the clamping positions between steps to allow visual observation of the end rounding operation and to have the spindle of the mill clear all of the clamping obstructions.
LBSC states this can all be done by filing. Well, no comment.
-
- Posts: 1573
- Joined: Thu Apr 26, 2012 10:15 am
- Location: Tennessee, USA
Re: I Don't Know Why I Ever Got Involved...
Lots of work for such a small part! The quadrant looks great, though. I'm sure it will be a lot more user friendly than a screw reverser. I haven't ever driven a locomotive with a screw reverser, but I'm told that they work great until you have to start changing directions frequently, then they get old quick.
Re: I Don't Know Why I Ever Got Involved...
One of my 3/4” scale locomotives has a screw reverse and I love it. Yes…..not great for switching, but how much switching do you actually do?Pontiacguy1 wrote: ↑Fri Dec 17, 2021 8:02 am Lots of work for such a small part! The quadrant looks great, though. I'm sure it will be a lot more user friendly than a screw reverser. I haven't ever driven a locomotive with a screw reverser, but I'm told that they work great until you have to start changing directions frequently, then they get old quick.
The real advantage of screw reverse is having infinitely adjustable cut off. With a pole reverse you are limited to the notches on the quadrant. With screw reverse you can hook the valve gear up with absolute precision. Some British designs have the ability to operate as a screw reverse, and with lifting a latch….the same as a pole reverser for switching.
Keith
Re: I Don't Know Why I Ever Got Involved...
More rotary milling, this time to finish the trigger handle. Followed by some careful belt sanding to finish the handle top profile.
Screw reverser vs latch type reverser. Yes, many decades ago I did make a screw reverser for the 3/4" scale Hoffman Hudson. See the second photo. Making the multi start thread can be a challenge but I have a neat trick for that.
Also, take a look at the reverser trigger drawing (photo #2) for the 2.5" Gauge Ayesha vs the later detailed reverser trigger drawing on LBSC's 5 " Gauge Speedy (the last photo). Maybe it is a drafting error but the Ayesha trigger doesn't make any sense to me as drawn when you look at the Ayesha drawing closely. Not exactly the right time to be saying this as, so far, I have used the Ayesha drawing as a guide.
Finally, locomotive construction requires a lot of fixturing with manual machining. The third photo shows all the rotary table centreing plugs needed for various locomotive machining operations carried out over the decades (mostly end rounding).
Screw reverser vs latch type reverser. Yes, many decades ago I did make a screw reverser for the 3/4" scale Hoffman Hudson. See the second photo. Making the multi start thread can be a challenge but I have a neat trick for that.
Also, take a look at the reverser trigger drawing (photo #2) for the 2.5" Gauge Ayesha vs the later detailed reverser trigger drawing on LBSC's 5 " Gauge Speedy (the last photo). Maybe it is a drafting error but the Ayesha trigger doesn't make any sense to me as drawn when you look at the Ayesha drawing closely. Not exactly the right time to be saying this as, so far, I have used the Ayesha drawing as a guide.
Finally, locomotive construction requires a lot of fixturing with manual machining. The third photo shows all the rotary table centreing plugs needed for various locomotive machining operations carried out over the decades (mostly end rounding).
Last edited by Carrdo on Fri Dec 17, 2021 6:46 pm, edited 2 times in total.
Re: I Don't Know Why I Ever Got Involved...
PS: The Ayesha trigger drawing, upon closer Inspection, is OK. I am losing it.
Last edited by Carrdo on Fri Dec 17, 2021 6:47 pm, edited 2 times in total.
-
- Posts: 1573
- Joined: Thu Apr 26, 2012 10:15 am
- Location: Tennessee, USA
Re: I Don't Know Why I Ever Got Involved...
Actually, a lot more than you would think. I like to run operations sometimes, and if you're running a local, you'll end up doing a ton of switching. Of course this is in 7 1/2" gauge. I've been the person operating the yard switcher before and ended up switching out cars all day. You'd be surprised at what an 0-4-0 can do switching.Yes…..not great for switching, but how much switching do you actually do?
Don't know that I've ever heard of anyone running operations in 3/4" scale.