DJH 9F - my experience so far........

[Terry]

After well over a year I have recommenced work on my DJH 9F, having this weekend acquired an Avonside Works Chassis jig at last, along with a quartering jig and a few other essential tools to help me on my journey into kit building and P4 especially. The break was largely due to work and other life events getting in the way, as well as lack of some workshop space and some key tools to continue.

Although this is to be a P4 locomotive, I thought I'd practice using the jig by using the DJH frames and coupling rods as supplied as a sort of pilot at using the jig. I was planning to put together the basic OO gauge chassis etc, to get my hand in as it were. I have replacement Alan Gibson frames and coupling rods for the 9F proper.

I was amazed to find how inaccurate the supplied DJH OO gauge connecting rods and frames turned out to be in terms of connecting rod alignment with the frames. The Avonside Works instructions recommend setting the spacing using the connecting rods first for obvious reasons. When I had them all set up, I tried placing the frames over the spacing rods in the jig and it was obvious that this locomotive would never work if kit built with the axle holes in the frames in the position they had been etched. Maybe this is common for kits like this of that age?

The good news is I then made some good inroads into building the tender, and also soldered the Gibson supplied connecting rids (two parts each to go back to back) together, reamed out the wholes and aligned them on the jig for test fit. All looks good, and certainly eyeballing the Gibson frames against these on the jig, everything looks much better. I just have to take the plunge and start building the frames proper, using the Gibson Hornblocks ………. !

I will post some pictures shortly. The boiler and cab were assembled last year, and each went together pretty well, and I have test fitted boiler, cab and footplate together. It starts to look like a 9F! Yesterday’s effort on the Tender has also left me confident that I will find my way reasonably well, albeit quite slowly, but I do realise that the chassis is the big challenge! I do have some smaller, less complex kits that I could start with now, so may try a P4 chassis on something simpler first.

Any comments on the DJH chassis accuracy would be interesting, although not key to a proper P4 build!

Terry.

[Tim V]

Good luck!

I would suggest in these circumstances the first thing is to check if it is the frames that are right or the rods? Never assume, check the dimensions. Also with such a bad start are the rods the same size left to right? It has been known for there to be differences.

[grovenor-2685]

One problem with the 9F is that kits meant for 00 usually have a stretched wheelbase, otherwise the flanges don't fit, I don't know what the situation is with the AG frames but if they are still from the original Studiolith masters they should be OK.
Regards
Keith

[Terry]

Tim, Keith,

Driven by both your sets of advice, it seems that by checking, and double checking, I have found the issue ........... Richard Derry's book on the 9F (Irwell press) shows the centre distance between all five wheel sets as 5' 5". The Alan Gibson Frames measure at 21.75mm (as accurate as I can see!) which works out almost scale spot on (21.72mm). DJH do indeed seem to have stretched the wheel base as they measure front to back 22.75mm, 21.75mm, 21.75mm and 22.75mm, so an overall stretch of 2mm, or scaled up almost 6 inches too long! And yes, the stretch is done between the two sets of flanged wheels, each front and rear.

I also now realise also that my original issue, that DJH frames and connecting rods were out of line was simply down to me aligning the three rods per side on the DJH kit, incorrectly when test fitting, expecting the distance to be the same across all wheel sets. So I can build my "OO test chassis" and get my practice ready for the Alan Gibson frames and rods! win win, and thanks to you both, the life lesson re-learned, that one should check and double check everything!

Thanks!

Terry

[Horsetan]

Will you be spacing the frames at the correct 3'3" width?

[Dave Holt]

Hi Terry,

Because of the wheelbase issue, I used Gibson milled mainframes and the matching coupling rods for my P4 9F. The remainder of the valve gear was modified DJH/Comet. Quite a bit of work was required on the motion brackets, plus slide bar supports, etc.
As Horsetan has mentioned, the real locos had frames spaced closer than usual, so the axleboxes were central in the frame plates. I also replicated this but it does affect the way of mounting the horn guides in the frames - the usual backing plate arrangement allowing use of extended axle jigs to set the spacing using the rods is much more difficult. The use of a chassis assembly/alignment jig will greatly help - I didn't have one at the time and struggled a bit.

Good luck with the project.

Dave.