Toto's Traversers

Now this thread will be a slow burner, especially over the next few weeks, however as a teaser here goes.

As many may have noticed Toto's Luib Bridge layout is progressing, and he has promised it to the Elgin Exhibition as a work in progress, and part of that progress involves a fiddle yard (or two), and guess who has been tasked with that job .

These will be the standard 54" x 21" size board Toto has settled on, and be double ended, so can be used on many layouts even as a through fiddle yard.
They will be traversers with a 48" tray with a 3" lead in at each end.
Board alignment will be by pattern makers dowels, and will make a jig to allow the dowels to be correctly fitted to multiple boards.

http://www.stationroadbaseboards.co.uk/cart_dowels.htm

The traversers will be motorised using Nema 17 stepper motor and Arduino based controller, positions being controlled via DCC - in a similar vein to Viccy Road.

Putting some the lessons learned from Viccy Road in to action, we will be using 8mm Lead screws now readily available from Ebay etc

http://www.ebay.co.uk/itm/T8-500mm-...301?hash=item2383766eed:g:eek:-UAAOSwt0FZBFCc

And heavy duty drawer runners as slides.

The tray will be able to go beyond the front and rear edges of the boards to allow for greater movement, but will need to be within the 21" board for transport.

Better motor mounts and belt tensioner

So that's the brief.

Prototype for the motor mount - to see if I'm up to making it.







This was based on a drawing on line to see if I could get the accuracy - the final design will have webs either side of the motor, but happy with the result so far.

Paul

 

Don't know about time - I was tucked up in my bed, while it beavered away.

Just did a quick calculation, the test print roughly two 55x55x5 pieces weighed in at 19.5 grams, lets be generous and call it 20g, used approx 24p worth of plastic - think I can afford a few more test pieces .

The big time saver will be once I have the pieces finalised, I just print up enough to make two.

And some of the bits may find there way on to Viccy road.

Paul

 

Anyone who's used CAD and 3D modelling software would find these easy to use, for me like Toto my 3D modelling normally requires, hammer, chisel, files and saws , ludite I know, so the learning curve has been a bit steep, but I'm starting to get into the mind set.

But quickly becoming a weapon of choice, especially with the different choices of materials, PLA (Brittle, Hard, but susceptible to heat), ABS, PLE, Wood filler based materials, Carbon Fibre, Nylon etc, etc. I'm still on my first 1Kg reel of PLA that came with the printer.

Have as look at

http://thingiverse.com/

to get an idea of what you can do - and they're free to download and use, just read the users terms and conditions - majority is not for comercial use, and let them see your finished print.

back to the chores

Paul

 

Version two ready to print

Settings used extruder temp 200c, no bed heating, layer height 0.2mm, Infill 15% with 3 surface layers

The print isn't solid But actually 15% (the infill setting), to achieve this the slicer software MakerWare in my case generates a honey comb pattern to infill.




and just keeps building the layers up



And the two versions side by side


And with the Nema 17 motor fitted - this motor is a 0.4A version





It took 2h17m to print, and used 29g of material.

Paul

 

I reckon the lower half of the boiler for the Lima O gauge 4F could be up soon, then maybe the wagon tippler for the Gas works

But the flounder will be on my back if I procrastinate too much

Paul

 

This may be of interest to our antipodean members

https://youtu.be/77rGwN9PQ9I

and it seems to work even though its upside down

May be too late of course - and not available in the UK, but if enough people badger them you never know.

Paul

 

Two goody bags arrived from China or was it Hong Kong, never mind - here's a piccy of one.



2 x 8mm smooth rails and support brackets (two per rail)
4 x 8mm ID linear bearing blocks
1 x 8mm lead screw (giving approx 7 to 8 mm movt per rev) and T nut
2 x Pillow block mounted bearings (22x8x7)
2 x flexible couplings (5mm dia for the motor - 8mm for the lead screw.

Rails and lead screw are all 500mm long.

Each set will form the basis of the traverser mechanicals, for these traversers I'm using rails rather than drawer slides. With the popularity of 3D printers, these parts are becoming quite cheap the above lot inc postage was less than £25.

Now just have to start the builds.

Control system will be as the Viccy Road traverser - Sparkfun Big Easy Driver for the stepper controller, and an Arduino Nano for the controller.

Paul

 

Well, when the big yun (I use the term figuratively, rather than factually), offers to come up and give me a hand with getting the traversers started, I'll take it for the preverbrial kick up the but and get on with it.

Step 1,

As these traversers are intended to be used for modular layouts, I need to make a jig that will allow me to fit them to many baseboards.


So I've used a piece of 18mm Mdf, with 30mm holes drilled a 7" and 14" from the front face for dowels, and 3.3", 10.5" & 17.5" for the securing bolts.
The holes were drilled with a forstner bit, and are the correct size for the router 30mm diameter guide bush.
Piece of ply were added to help locate the jig, which is clamped on to the baseboard end and the holes and rebates cut with the router.


Now onto the traverser boards

Toto has set the size too 54" long, 21" wide and 5" deep.
As these are to be double ended, it was decided to have a 3" lead in at both ends and a 48" (4ft) traverser.

An extra foible was added to the mix when Toto decided he needed extra tracks to be able to access the traverser from the last board on Luib Bridge, so I decided to make the 3" lead in removable so it could be swapped for a standard single road entry or a custom one.

12mm ply has been used, and to help strengthen the corners I routed a 12mm slot in the sides and end, positioned at the correct height to support the removable 3" lead in.


The webs were created from off cuts from the sheet.


Joints were glued, pinned and clamped.


Now just waiting for the glue to dry.

Paul

 

Quick(ish) trip to wikes for 4 x 2 sheets of ply two 12mm for the traverser tables and one 6mm to act as spacers between the tracks - crazy the 6mm sheet was a pound cheaper than the 3 mm sheet of ply

Shed time to see if I can get the first one up and running.

Later

Paul