Highland Railway Drummond 0-4-4T Passenger Tank

Thanks Rob

Although I think they will become even more popular, as the price for them is plummeting - Anycubic has the original Photon going for approx £123, I paid nearly 4 times that for my first one, 2.5 times that for my second Photon.

I didn't have any CAD experience before starting to use the 3D printer, but starting on a project, and learning by my mistakes (I know more things right first time - ish), I'm getting there, I'm a bit further down the learning curve on this side of it than the 2D and vector graphics side, which is waht is probably holding back the chassis side of things at the moment. I'll get there

Paul

 

Cheers Rob - I'll update the file name for the part.

Andy, 3D modelling the suduko puzzle thats keeps on giving

Paul

 

I'm only on easy level of suduko hence the issues with Fusion 360 and Solidworks

 

Hi Andy

I think Blender, Fusion 360 and Solidworks are all from the same type of modelling approach (each has thier own methods) but the approach appears similar, and the functionality is far more advanced than 123D especially when it comes to compound surfaces - just think of a Class 24/25/26/27 etc etc cab roof variable curves in all directions. Solidworks is the preferred option for me as I have someone who will help me out, however my small CNC m/c (a cheapo Banggood 3018) would prefer Fusion 360, and blender appears to be better at organic shapes. So something to keep me occupied in lockdown and retirement, judging by my progress so far the next life as well


Paul

 

A little progress today, and no not on the chassis

The Markits LSWR small Drummond buffers are a little too large at the base.

Now if I had a Lathe (the boss didn't think it counted as a Valentine present ) I could trim a couple of tenths off, but I don't and I didn't fancy putting it in my drill, so I'm going to file down part of the base. Actually it may be like this but in the drawing the buffer base is obscured by the buffer head or footplate.

These buffers are pre-drilled for wire to be added to represent the retaining bolts, so I used the holes to help align the base for filing. A piece of 0.7 wire was looped through a pair of holes and then used to keep the buffer shank flat. I then filed the shank parallel to the jaw.

Giving a flat on the buffer aligned with the bolt holes

A picec of 0.9mm brass wire was bent into a U approx 6mm apart and threaded through a pair of holes at a time and soldered from the rear to reduce the amount of cleanup.

Once cleaned up the buffers were glued in place with Rocket Max - thick super glue.

Just got the rear buffers to do now, and I think it's ready for paint - when it arrives

Paul

 

Well a bit o a lazy week so far, but after much procrastination I thought, well why not, as most of this loco is 3D printed why not the chassis

So here is the start of version 1 - Rigid Chassis



Based on Markits brass axle bushes - nominal 6.9mm dia (I measured 20 bearings all bar 2 at 6.9 the other two at 7.0). The printed hole should be 7.0mm but I'm expecting to have to enlage it slightly.
Only two frame spacers at the moment as I have to determine which motor/gearbox combination to use - I'm trying to avoid cutting the boiler, as the daylight between the splsaher and boiler looks good.

I will use a representation of the fire box & ash pan to form the central strengtheners.

I think I will try a test print as a test fit as I think I will need to adjust the length to suit the body, as the buffer area was built up for strength.

Paul

 

Test print completed

Frame thickness only 1mm thick, and printed horizontally to save time and resin.

I had placed some medium and heavy supports but looks like more are required at the right hand side.

as can be seen there is what looks like a layer shift towards the top, it's actually where the top spacers start and is where distance between the frames to the correct distance.

However the primary reason for the print was to see if it aligned with the body

The rear is fine but the front needs a little shaving off the front top corner for the chassis to the correct height.

As the boss on the wheel bearings is 3.1 mm I have plenty of scope to thicken up the frames, but may also use Union Jack shaped frame spacers that can be cut away once the chassis has been completed and cured.

Paul

 

Hi Gormo

Very valid points, the next test print will have thicker frames, measuring the bearing hole it varied from 6.6 to 6.8mm the 6.6 was always in the same place, so I'm hoping the thicker frame will help to correct the variation. I will increase the diameter of the hole to 7.2mm from 7.0 (looks like I loose 0.2mm during the print process).

One of the reasons for modelling the firebox and ashpan will allow me to fill the pan with either a speaker, dcc chip or lead - suppose if I fitted a speaker, it should get an mp3 player, with maybe a playlist from Motorhead, after all it is supposed to be a model of Heavy Metal .

This will allow additional weight to be fitted into the smokebox, tank sides and rear bunker, so I'm hoping it will be heavy enough.

Basic updates - frame now 2mm thick, slots for retaining screws moved forward 1.5 mm, bearing bush hole increased to 7.2mm and some additional temp supports for printing



I will test print a bit later, I need to take the dog to the vets for his booster shot - I think a protection against humans jag.

Paul

 

Well, we're making progress

As can be seen from the above picture the rear axle is distorted, and can be traced to the supports base lifting from the build plate. Next test will use all heavy supports.

The thicker frame and temp supports seems to have worked and the chassis feels rigid. I can twist the chassis but that will disappear when the the temp supports are replaced with the firebox and ashpan

The front axle holes are spot on

and both took the bearing well

The modifications to the front has worked, the chassis is flat to the underside, so I will do the same to the rear.

Having fun trying to pick the gearbox, all the ones I have tried so far will on the front axle involve removing part of the boiler, and on the rear axle the motor will end up in either the smokebox or cab interior.

However I have a plan, I could make two 13:1 gearboxes - 1 per axle, joined with a 2mm shaft. Between the two axles would be a spur gearbox giving somewhere in the the region of 4:1 to 6:1 ratio giving a overall ratio between 52:1 and 78:1 . I'd rather have the motor running at higher rpm, as I don't have the space to allow a loco to get to full speed.



The gearbox would rise up just after the start of the tanks, allowing the motor plenty of space to even have a flywheel fitted.

I could make the box with a single worm / wheel and drive either axle, but for the cost of another set of worm / wheel gears (approx a tenner) would be an interesting project.

The gearbox case would be resin printed (there is another way ) the worm shaft supported between two 2mm ID 5mm OD x 2.5mm thick roller bearings to avoid wear / stress on the resin print, the same would apply to the spur riser gearbox.

Boy this project keeps growing arms and legs.

Paul

 

Thanks guys

Playing around with bits of paper cut outs for motors and gearboxes, coupled with the attempt to try and print as much as possible, I thought I'd have a go at making my own gearbox (that and the price of some of these gearboxes are way more than the cost of the locomotive).

As this chassis is rigid, then it doesn't matter which axle is driven, so I have decided to drive the rear axle, with the worm gear shaft pointing forward. This will then have spurgear drive gear box rising up with the motor (a Mashima 1833 compatable) then sitting above the worm gearbox.

A search on ebay for bearings 2mm ID 5mm OD and 2.5mm deep bearings plus 0.19" (3/16) ID 3/8" OD 1/8" Deep bearings were ordered up, unfortunately they are on a slow boat from China - confirmation of being sent today, but estimated delivery dates of between 4 & 12 weeks.

But that gives me time to play - erm refine the design.

Also ordered up some gears from Ultrascale 30T, 15T (2mm bore) and a couple of sets of 30:1 worm / wheel sets. On Ultrascales site there are fully dimentioned drawings for each type of gear, and some calculator apps to give the correct center to center dimentions for different gear combinations.

Time to start and play with the software - I'm still using 123D, and have a Roxey Mouldings 40:1 gear set to play with.

First up to make up some of the components

2mm ID bearing



3/16"ID bearing



Roxey Mouldings 40:1 worm wheel set



Then start and assemble the bits together

There will be 3/16th bearings for each side of the worm, and the worm lay shaft will be supported by at least a 2mm ID bearing at each end, but may also have bearing between the worm and the 30T spur gear (I've still to create the spur gear 3D models)



There will be a 15T spur gear on the motor shaft, which will connect to the 30T spur gear on the worm layshaft. This will give a 80:1 overall reduction. I did order up two pairs of 30T and 15T gears, so if the space and urge took me I could try for 3 stage reduction and hit 160:1 - somehow I think this would be over kill, but maybe worth a try just to see if I can do it. Substituting the Ultrascale 30:1 worm wheel sets would give a 60:1 final reduction.

The motor mount section will be designed for me to be able to modify the gearbox easily before printing to suit each type of motor. Essentially anything with a 2mm shaft can be used, all I need to do is make a model of the front of each motor type (front bearing and mounting screw locations), the model is then aligned with the gearbox and the model deleted from the mounting plate giving the correct result. I will show this in a later post.

The chassis frames are 26mm apart, fitting the Markits wheel bearings I have a 19.6mm gap. Realistically 18mm max to allow the gearbox to be easily fitted and removed. Rough calculation of the bits so far 2 x bearings 1/8" wide = 6.35mm + Roxey 40:1 gear inc boss 6.2mm = 12.55mm so I have 5.45mm to play with. Now this is also showing a bit of kit building mentality, this is a 3D printed chassis, not a brass / nickel silver etched construction, so has more in common with a RTR model than an etched kit. So the gearbox can become part of the whole chassis ... mmmmmmm...

Time for bed I think to have further contemplation

Paul