Sand pipes for removeable wheelsets

User avatar
BryanJohnson
Posts: 131
Joined: Wed Jul 23, 2008 7:45 pm

Sand pipes for removeable wheelsets

Postby BryanJohnson » Wed Oct 14, 2020 7:32 pm

I'm on my second CSB chassis (a much modified Comet Crab) and trying to learn from my first.

I'm finding that having the removeable wheelsets from having CSB's is a benefit during construction, and will also be when I get round to painting and weathering. I've successfully got removeable wheelsets & brake gear and as it's split chassis I don't have pickups to worry about.

However, fixed sandpipes get in the way of dropping the wheels, especially the centre driver which has pipes coming in on each side. I need to include the small support bracket fitted to the inside of the frames and steam supply pipe as well as the actual sand pipe. The sandpipes don't go near enough to the brake components to be attached to them. I fixed them solid on my first chassis so need to bend them in and out of the way which isn't ideal.

Are there any suggestions for having these as removeable / adjustable items to allow the wheels to be dropped?
My first thoughts are:
1) Allow them to pivot where fitted to the sand box and so swing out of the way. This would need to have the bracket and steam pipe no higher than the bottom of the frame, or
2) Have the pipes and bracket as one unit, then fit from below with the sandpipe slotting up into the sand box and the bracket going behind the frame. I considered having a wider section above the bracket that could have a slot going over a bolt inside the frame, then fix all in place with a nut over it. There would be much more room for this if there weren't the CSB components which is where we started....

Does anyone have any suggestions for an elegant but simple solution?

Bryan

Philip Hall
Posts: 1582
Joined: Mon Aug 10, 2009 7:49 pm

Re: Sand pipes for removeable wheelsets

Postby Philip Hall » Wed Oct 14, 2020 11:11 pm

These days I often make sandpipes (and other pipes on a chassis) from soft iron wire. It’s usually black, available in various sizes from Eileen’s, easy to bend but holds its shape well. It can be bent back and forth quite a few times without fracturing, so removal of wheel sets occasionally should do no harm.

Philip

Dave Holt
Posts: 346
Joined: Thu May 28, 2009 9:44 pm

Re: Sand pipes for removeable wheelsets

Postby Dave Holt » Wed Oct 14, 2020 11:17 pm

Hello Bryan.
If your wheel sets are removable, then I assume you have a keeper plate of some sort to retain them in the frames? Perhaps you could attach the sand pipes and their brackets to the keeper and have the upper end/sand traps a loose fit into holes in the bottom of the sand boxes? These shots of the keepers for a Stanier Caprotti Black 5 and an Ivatt Class 2 tank show how I attached the sand pipes (I don't bother with the steam pipes).
Cap_Blk5_016.JPG

Ivatt_2T_012.JPG

Dave.

Dave Holt
Posts: 346
Joined: Thu May 28, 2009 9:44 pm

Re: Sand pipes for removeable wheelsets

Postby Dave Holt » Wed Oct 14, 2020 11:20 pm

Here's a better shot of the Black 5 keeper.
Caprotti_Blk5_keeper_001.JPG

At the time of the photo, I thought the brake rigging was inexorably entangled with the keeper due to the stretchers passing between the sand pipes and their support brackets. I later found it was possible to wiggle them apart and, more importantly, back together again.
Dave.

User avatar
Tim V
Posts: 2479
Joined: Tue Jul 29, 2008 4:40 pm

Re: Sand pipes for removeable wheelsets

Postby Tim V » Thu Oct 15, 2020 8:26 am

I've used copper wire in the past. Removing the wheels isn't done that often.

And don't forget that those who build fixed wheelsets don't have the option to remove them!
Tim V
Scalefour News Editor

davebradwell
Posts: 415
Joined: Fri Jan 18, 2019 3:48 pm

Re: Sand pipes for removeable wheelsets

Postby davebradwell » Thu Oct 15, 2020 8:47 am

A further advantage of Dave Holt's plate is that the brakes are well secured against drifting or being knocked out of alignment and so causing shorts. Being able to easily dismantle a model is important when getting the chassis to run properly - if it's difficult, this will discourage you from making that final tweak.

DaveB

User avatar
BryanJohnson
Posts: 131
Joined: Wed Jul 23, 2008 7:45 pm

Re: Sand pipes for removeable wheelsets

Postby BryanJohnson » Thu Oct 15, 2020 12:33 pm

Thank you for your quick and interesting responses.

1) I like the suggestion of using a different material to give more flexibility. The sandpipes scale to 0.45mm, which is still quite stiff in brass. Either material should allow soldering of the bracket and steam pipe to the main sandpipe. I think I would prefer to use copper over soft iron as the chassis will still get a few dunks in the ultrasonic bath so I try to use non-ferrous metals throughout to avoid any rusting before it’s even finished.
2) Hanging the axleboxes from the CSB wire for the suspension automatically keeps the wheelsets in the chassis, so there is no requirement for any separate keeper plate. I have already got the brakes as separate units so these do not need any further structure either for this loco.

For my earlier non-CSB chassis, the wheelsets, brakes and sandpipes are all fixed in place. Moving to a system which inherently makes the wheelsets removable has encouraged me to make the other chassis elements work in conjunction with this. I fully agree with the points raised that a) construction is a step by step process and having separate sub-assemblies simplifies checking and adjustment as this progresses and b) once all is completed it shouldn’t need to come apart again.

I think I’ll go for the copper wire approach as it seems to meet all my criteria:- effective, non-corroding, simple and elegant.

Thanks again for your input

Bryan

Enigma
Posts: 364
Joined: Tue Aug 13, 2013 2:49 pm

Re: Sand pipes for removeable wheelsets

Postby Enigma » Thu Oct 15, 2020 3:20 pm

Sand pipes are generally the last thing I fit and I try to have a reasonable interference fit so that they can swivel if necessary. Very rarely need to remove wheels once the chassis is up and running satisfactorily.

Philip Hall
Posts: 1582
Joined: Mon Aug 10, 2009 7:49 pm

Re: Sand pipes for removeable wheelsets

Postby Philip Hall » Thu Oct 15, 2020 4:02 pm

I might add that I don’t like to dismantle a chassis once it’s running nicely, so I always paint or blacken the frames and various bits before assembly. As some have said, often the thing never runs as well if it’s been taken apart again and I try not to do it. So for me details like sandpipes can go on last and stay there.

However, I have yet to build a CSB or any other kind of sprung chassis...

Philip

User avatar
BryanJohnson
Posts: 131
Joined: Wed Jul 23, 2008 7:45 pm

Re: Sand pipes for removeable wheelsets

Postby BryanJohnson » Thu Oct 15, 2020 6:29 pm

I've discovered as I've gone along that the Crab isn't an easy prototype, so I think all aspects of it need to be considered together.

As an example, this photo of the one at the NRM shows the position of the front sandbox, so I wouldn't want to leave it until the end. I'm also making the cylinders and valve gear as a separate unit, as per Julian's and Mark's earlier versions shown in the https://www.scalefour.org/forum/viewtopic.php?f=20&t=5538&hilit=crab thread.
Attachments
Crab LHS cylinder & front sandbox.jpg


Return to “Chassis and Suspensions”

Who is online

Users browsing this forum: No registered users and 4 guests