Constructing the Martin Lewis Little Engines Northern Tender

[Carrdo]

Some of the cross channels clamped in place.

Just be certain to check that everything is square and level in every direction before drilling and tapping as you only get one chance at this. To make things even more interesting, the channel sections themselves are neither square, straight or on size but since this is the devil I have come to know...

[Carrdo]

Endless drilling and tapping.

[JBodenmann]

Hi Carrdo
I have been greatly enjoying this thread on the 3/4" scale tender. Your workmanship and tenacity are both most admirable! Keep up the fine work!
Jack

[Carrdo]

Thank you all for your kind comments.

At times, one just has to keep slogging on.

I also have to mention that I have been helped out by so many fellow Chaski subscribers, I couldn't have come this far without all of the help given to me here.

Don

[Carrdo]

Aligning a cross channel as square as possible, then clamping it that way before drilling and tapping the channel angle bracket.

And if anything shifts during this procedure, start over again.

The small toolmakers clamps holding the angle bracket are just hanging on to the end corners of the bracket leg as there has to be room left for for the drilling and tapping tools.

Can be quite a frustrating process.

[Carrdo]

Further drilling and tapping.

[Carrdo]

A milestone reached, well sort of.

All of the outer angle brackets are now installed. All 36 of them.

But now there are still 36 inner angle brackets to install. They should be easier to do than the first lot as I can just drill through and bolt them together. No tapping involved and not as much fiddling with the holding/aligning.

Took stock of what still needs to be done to complete the lower half of the tender and I came up with 9 major operations still to perform including the tender hand pump. As slow as I am, I figure this is almost another year. I know, a lot of you could build the basics in a week but...

[Carrdo]

An example of some of the interesting problems one is faced with when installing some of the angle brackets.

See the first photo.

The problem is how to drill and tap through the inner legs of the two inner angle brackets which are to be bolted through into the end sill. One can't clamp anything here in the usual way due to the curvature of the end sill at this location.

After thinking about the problem for a bit (and after trying several things which didn't work), I had the idea of using the existing channel and angle piece assembly as an aligning guide/holding device.

The first thing to do was to make a short dummy channel piece and use the inner angle bracket itself as a drill guide to drill the through hole in the channel. This works only if the inner angle bracket is set central on the inside of the dummy channel piece and the end of the angle bracket and one end of the channel are square and flat to each other which is achieved by setting them against a square. See the second photo.

To align the drill, I also made up a short, solid stepped plug (not shown) to exactly fit the existing drilled hole in the insert angle bracket.

This two piece assembly was then fixed in place to the outer angle bracket as shown in the third photo. Actually, the photo shows the first dummy piece made (and discarded) as there was a problem which, fortunately, was observed before final drilling took place.

Note: the outer angle bracket was never removed from the end sill for the above operation as it is the locating aligning bracket. Make certain it is bolted tightly to the end sill (for if it moves then one has to start all over again).To begin with, the outer angle bracket is bolted in and the long channel seen in the first photo set in place after which the long channel is carefully removed.

Finally, unbolt the end sill from the rest of the tender underframe. One can now easily locate the previously scribed bolt hole location and drill and tap through the inner leg of the inner angle bracket as shown in the last photo. The height gauge was used to set the ends of the end sill level in the mill vise.

A seeming lot of work for very little but it did made for a perfect assembly.

And why didn't the first dummy channel piece work? The problem is, it is very easy to have the short dummy channel part reversed end for end and not to notice that each leg of the channel is not quite the same size or thickness (even though the dummy channel piece was cut from the same channel bar stock as were all of the other channels)!

The inset inner angle pieces were all machined to closely fit the inside of the various channel pieces and if the channel is reversed and this is not noticed, the drilled hole will end up in a slightly different location - enough to make assembly impossible without bending something.

The devil I have come to know.

[Carrdo]

It doesn't look much different than before but now sixty (60) angle brackets are fully bolted in (120 bolts).

Another 12 angle brackets to go, the innermost ones.

[Carrdo]

Finally closing in on attaching the last angle brackets.

The only issue with these last brackets is now one needs to remove about ten other angle brackets first to enable the long center channels/clamps to be removed.

Careful clamping and marking every bracket removed with their respective locations on the frame is required or nothing is going to go back together again.

And while one is doing this don't bump anything.

[Carrdo]

The completed tender underframe.

Seventy two brackets and 150 bolts later it is finally complete.

The last six bolts were daunting to install as one half of the tender underframe had to be completely disassembled to access each of the clamped brackets. The inner central corners all had 4 brackets each to give 144 plus 6 = 150 bolts in total.

Now each bracket in its exact frame location have to be permanently marked as if any of the brackets are ever removed...

[JBodenmann]

Hi Carrdo
Very fine bit of work.
Jack