Southam

Neil, well done for writing a clear description of construction with the novice in mind and the three drawings of the frames for clarity (whoever she may be).

A couple of queries "The frames are the long members ......." How long does one have to be a member ?.

More seriously, what is the depth of the horn block slots in the frames, 1" or 11/4"

and the pitch of the horn block rivet holes 9/8" !!!

Neil, there is also a difference between your pfd drawing of the hornblock rivit positions and that on the mag drawing.

Edited By JasonB on 20/08/2016 10:19:37

My dimensions for the rivet positions in the bottom part of fig 5 have been mis-interpreted when redrawn and I seem to have missed it when checking them. It is all a bit crowded even when using three drawings for all the dimensions! The 1/4" is to the bottom pair of rivets and the 1" is to the top pair, both from the base of the frame.

Unfortunately I did the drawings in my pre-turbocad days and Corel Draw's auto-dimensioning seems to be optimised for architectural drawings of big buildings not tiny locos!

The hornblock cut-out is 1 1/4" high and 3/4" wide, I think i suggest using the hornblocks themselves as a gauge (the Reeves ones are hot pressed and very accurate, other suppliers may use sand castings).

As other suppliers hornblocks may have ribs in slightly different places, it's probably best to spot through from the blocks to the frames rather than the other way around.

I'll change the topic for this thread to drawing corrections.

Neil

On Fig 4 the dimensions for the two oblong apertures seem incorrect. The LH one is shown as 1/2" up from the recess and the RH one is shown as 3/16" up from the bottom of the frame.

Looks like a typo, should read 13/16" made up of the 5/16" cut out from the bottom plus the 1/2" that you mention.

These dimensions were added at a late date as I spotted that there were none showing the hight of either cutout on the original pdf. so that could explain the typo.

Edited By JasonB on 21/08/2016 13:29:08

Yes, my drawing shows the back one as 13/16 up.

These cutouts are cosmetic and the exact size/location or even leaving them out won't affect performance although I think they add to the appearance. Assuming you fit your speed control between the rear frames, then the rear hole provides a convenient place for a control-box socket.

Neil