Dougal 5 inch gauge

[dc309]

Hi all,

Has anybody built Dougal (www.ajreeves.com/dougal-111-c.asp) before? A friend of mine is getting the bits together to make one, but the drawings don't seem to add up! Are there any known drawing errors?

Is it intentional to have that much play between the axlebox and hornblock?




Cheers,
Dan

[Deleted]

Hi Dan

what play?...I see horn gap of 1" and axlebox width the same leaving the builder to decide where to reduce for running play or am I misunderstanding the question??

Pete

[Deleted]

Looking again...or are you referring to the 1/8th side play?

[dc309]

Hi Pete,

Yes, the horn is 7/16" wide, but the slot in the axle box is .562?

Dan

[Deleted]

well admittedly it seems a lot but not knowing the design perhaps this is intentional and other components work with this?

Pete

[Roger]

I think Dan's referring to the Axial clearance... ie Hornblock width 0.437" and axlebox 0.562"
The clearance on the inside is irrelevant, the overall movement in the axle is decided by the outside dimensions including the distance over the frames etc. You need a clearance on the horns in that direction else the axles can't lift on one side without binding.

[jma1009]

hi dan,

ive never seen one completed and in steam. it was a pretty rubbish design in fullsize and wont be any better in 5"g. the 1/8" slop mentioned above isnt a good start. you want say 14 thou on the driving wheelset, and a bit more say no more than 1/32" on the front wheelset.

i have a vague recollection there is a problem with the boiler design.

apologies for being so negative but there are much better designs and drawings!

cheers,
julian

[dc309]

Hi all,

I've just drawn it out on a piece of paper and I've now realised why the gap is so big! The Hornblock bolts onto the inside of the frame facing inwards, leaving the frameplate to take up 1/8" of the axlebox. Seams like a pretty odd design to me and I'm only a beginner! Presumably if the axleboxes are cast iron and the frames steel, it won't be too much of an issue?

Hope my explanation makes sense.

Cheers,
Dan

[runner42]

Yes I understand and agree. When I saw the side elevation of the hornblock I said to myself funny it doesn't have the flange for the hornblock to locate in the frame cutout. Your explanation that it bolts directly on the sideframe and that the outside of the frame provides the outer bearing surface for the axlebox makes sense, but the arrangement is unusual. Does the words and music require that the sideframes are bolted together and the hornblocks machined as a pair to ensure accurate positioning of the axleboxes for each wheelset? This design makes the hornblocks easier to machine but the downside is that the drilling the holes for fixing the hornblocks to the frame a little more tricky because there is not flange to locate it in the frame cutout.

Your concern that a cast iron axlebox is bearing on the steel sideframe is of little consequence, because the forces are mainly longitudinal and not lateral so the cast iron axlebox will bear mainly on the cast iron hornblock, given that there will be some cast iron to steel contact in the outer 1/8th" of the hornblock.

Brian

[Cro]

A Friend has built one and currently painting after a couple of years of running and it runs very well but I know they found mistakes. I will chat to him today and get him to give me a list if he can remember them!

[smallbrother]

I saw one at a rally a few years ago. Seemed to be running well too.

Pete.

[ejparrott]

I was going to say, 1/8" sounds like frame steel, but you already figured it!

As regards side play, on a 4-wheeled engine, I believe in literally running clearance only. My MW has a couple of thou only on each axle, no more is required, not like a big x-10-x

[mutley]

I have one ( well actually it was built as a 5th birthday present for my youngest 8 years ago), after a bit of tweaking runs very well. you need to be on the ball to keep it in steam but as a beginners engine its not bad. I fabricated most of mine and only used the smokebox casting. Boiler is a simple build as well.

[dc309]

Thanks for your replies guys.

Good to hear that you've got one that you've built Mutley, have you got any photos? Did you do it as slip eccentric or convert it to Stephensons?

Regards
Dan

[mutley]

[denford]

Some very neat silver-soldering there Graham

[dc309]

Thanks for those pictures Mutley, it looks like a great little model!

I've sent you a PM too!

Cheers,
Dan

[Nigel Bennett]

I recall a chap in the West Country built one with Stephenson's valve gear in place of slip eccentrics. My memory from a couple of decades ago is dim, but the name Edmonson from Taunton rings a dim bell. It seemed to run very well. There was another one at the Midlands Show last year.
I did think of building it - I got the Reeves drawings - but decided against it and built Tom Rolt instead.

[mutley]

Martin Evan designed a Stevenson valve gear modification for someone. I think the details are way back in the depths of this board somewhere but the person who had it wanted beer vouchers for the info.....

[dc309]

It's started! Spent a couple of evenings making and drilling the frames and bufferbeams, along with the associated angles.