Giving up 2mm, back to N gauge?

[kingrail]

I bought the Bachmann Percy previously and it's a good little engine despite a few plastic parts on the valve gear

This was one of my failed conversions to 2mm but I maybe able to salvage and convert back to N gauge

I have a 2mm 3d printed Barclay body . Unfinished pic enclosed, its now more detailed!
Pretty sure an N scale version was also available

Only problem is last I  heard was that Shapeways (3d printer firm) had stopped trading so it may no longer be available

[Hendreladis]

3 hours ago, kingrail said:

I bought the Bachmann Percy previously and it's a good little engine despite a few plastic parts on the valve gear

This was one of my failed conversions to 2mm but I maybe able to salvage and convert back to N gauge

I have a 2mm 3d printed Barclay body . Unfinished pic enclosed, its now more detailed!
Pretty sure an N scale version was also available

Only problem is last I  heard was that Shapeways (3d printer firm) had stopped trading so it may no longer be available

 

I think you'll struggle to get the Percy mechanism into that body - if that is the idea. While the mechanism is very compact I think it needs some extra height around the firebox and some more width than the tank offers. A Hudswell Clarke or a Peckett with a bigger tank makes life easier while allowing for more lead to be added - managed to get a 3D print to weigh in at more than the Percy which would be essential for shuffling reasonable strings of wagons around a gasworks. The problem is the wheelbase on the Bachmann model which puts the rear axle bang in the middle of the fire. An LSWR B4 would work on it with a few minor compromises but, with no saddle tank, it won't weigh anything - suddenly the old Peco Wills casting looks attractive if you can carve 3mm from the width. 

[2mmMark]

2mm Magazine June/July 2004 has an article from me on adapting the Peco Peckett saddle tank.   I did indeed remove 3mm or 4mm from width of the cab, making it the same width as the saddle tank.  That makes the overall width acceptable for 2mm scale.

Frankly, I'd have returned that Shapeways print. It's awful, everything that's poor about 3d printing.  They could do much better than that.  Perhaps that's why they went out of business.

 

 

[tom s]

I am surprised it was printed at such a suboptimal angle to get the bad stepping on the front (and rear) faces.

 

When I got into printing, a smart friend of mine showed me how to choose an angle based on printer screen pixel size and layer height.

 

arctan(layer/pixel) will print a piece at the more or less the same stepping as printing flat. 

 

E.g. this was printed at 21.413 degrees : arctan(0.02mm/0.051mm)

 

Round topped profiles like saddle tanks or coach rooves might be better at the arctan angle * 1.5, need to do more test prints. It is the second best angle for the flat parts too.

 

I'd guess the shapeways staff just loaded the saddle tank in at 45 degrees and called it a day.

 

 

[Chris Higgs]

7 hours ago, tom s said:

I am surprised it was printed at such a suboptimal angle to get the bad stepping on the front (and rear) faces.

 

When I got into printing, a smart friend of mine showed me how to choose an angle based on printer screen pixel size and layer height.

 

arctan(layer/pixel) will print a piece at the more or less the same stepping as printing flat. 

 

E.g. this was printed at 21.413 degrees : arctan(0.02mm/0.051mm)

 

Round topped profiles like saddle tanks or coach rooves might be better at the arctan angle * 1.5, need to do more test prints. It is the second best angle for the flat parts too.

 

I'd guess the shapeways staff just loaded the saddle tank in at 45 degrees and called it a day.

 

 

 

With Shapeways, you could specify the orientation and angle you wanted it printed at. If you didn't, they would just put it at whatever orientation was most optimal for them given they would be printing many items all at once.

 

Chris

[Hendreladis]

On 22/08/2024 at 09:39, tom s said:

I am surprised it was printed at such a suboptimal angle to get the bad stepping on the front (and rear) faces.

 

When I got into printing, a smart friend of mine showed me how to choose an angle based on printer screen pixel size and layer height.

 

arctan(layer/pixel) will print a piece at the more or less the same stepping as printing flat. 

 

E.g. this was printed at 21.413 degrees : arctan(0.02mm/0.051mm)

 

Round topped profiles like saddle tanks or coach rooves might be better at the arctan angle * 1.5, need to do more test prints. It is the second best angle for the flat parts too.

 

I'd guess the shapeways staff just loaded the saddle tank in at 45 degrees and called it a day.

 

 

Hi Tom

 

Many thanks for the insight. 

 

I tried to work out the geometry of your explanation re print angles. Won't be doing that again in a hurry. 

 

Your example is fairly awesome in terms of detail, complexity and resolution. As a flattish example did you only need to apply your arctan multiplier in one plane? 

 

People often post examples of wagons etc tilted in multiple planes. Does one just apply your multiplier across all of them? 

 

I now need to find out the pixel size on my printer. More experimentation needed. 

 

Andrew 

[Izzy]

On 22/08/2024 at 09:39, tom s said:

I am surprised it was printed at such a suboptimal angle to get the bad stepping on the front (and rear) faces.

 

When I got into printing, a smart friend of mine showed me how to choose an angle based on printer screen pixel size and layer height.

 

arctan(layer/pixel) will print a piece at the more or less the same stepping as printing flat. 

 

E.g. this was printed at 21.413 degrees : arctan(0.02mm/0.051mm)

 

Round topped profiles like saddle tanks or coach rooves might be better at the arctan angle * 1.5, need to do more test prints. It is the second best angle for the flat parts too.

 

I'd guess the shapeways staff just loaded the saddle tank in at 45 degrees and called it a day.

 

 

 

That looks great. Is it to 2mm? Rather makes my class 16 detail look a bit wanting (slight understatement!) by comparison.  Wonderful what those of you capable of doing this kind of thing can produce.

 

Bob

 

 

[njee20]

20 minutes ago, Hendreladis said:

Hi Tom

 

Many thanks for the insight. 

 

I tried to work out the geometry of your explanation re print angles. Won't be doing that again in a hurry. 

 

Your example is fairly awesome in terms of detail, complexity and resolution. As a flattish example did you only need to apply your arctan multiplier in one plane? 

 

People often post examples of wagons etc tilted in multiple planes. Does one just apply your multiplier across all of them? 

 

I now need to find out the pixel size on my printer. More experimentation needed. 

 

Andrew 

I would say not to obsess over the angle. If you're printing a box (or arguably an open/box-wagon) then it has merit, but given most of the time you'll have detail on all faces it's more important to make sure you are supporting those properly. Increasingly printers have rectangular pixels too.

[tom s]

9 hours ago, Hendreladis said:

Hi Tom

 

Many thanks for the insight. 

 

I tried to work out the geometry of your explanation re print angles. Won't be doing that again in a hurry. 

 

Your example is fairly awesome in terms of detail, complexity and resolution. As a flattish example did you only need to apply your arctan multiplier in one plane? 

 

People often post examples of wagons etc tilted in multiple planes. Does one just apply your multiplier across all of them? 

 

I now need to find out the pixel size on my printer. More experimentation needed. 

 

Andrew 

Hi Andrew, I'll try and knock up a better explaination when I am back at my PC, have been meaning to settle on a subforum to start a workbench thread on for a while... I have seen the double tilting wagon prints, I think there is a way to use this technique but it will need some thinking. Currently the arctan angle works best in a single rotation as far as i know. As Njee says there is a lot of leeway in print angles, and non square pixels on newer printers adds a consideration. Surely there is still a best print angle for a square object covered in details though.

 

Cheers, Tom

[tom s]

9 hours ago, Izzy said:

 

That looks great. Is it to 2mm? Rather makes my class 16 detail look a bit wanting (slight understatement!) by comparison.  Wonderful what those of you capable of doing this kind of thing can produce.

 

Bob

 

 

Thanks! It is indeed 2mm, I have 15, 16 and 20 bodies ready in 3D, but wanted to confirm my chassis idea works before tackling the daunting underframe models. I measured D8110's bogies this week which should help. 

 

Your type 1s did renew my enthusiam for the prototypes in mini form! I admit feeling some imposter syndrome when posting these prints as my hand crafting skill is far below those of the scratchbuilders on this forum, but the printer can do some cool things. Lots of weaknesses to accomodate and work around too. 

 

Cheers, Tom

[Izzy]

1 hour ago, tom s said:

I admit feeling some imposter syndrome when posting these prints as my hand crafting skill is far below those of the scratchbuilders on this forum, but the printer can do some cool things. Lots of weaknesses to accomodate and work around too. 

 

There will always be things one person may be able to do better than another and I always think it's useful for an individual to try and play to their strengths whatever they may be. With particular regard to 3D printing I believe it's strength may lay in being used as part of a multi-media approach, say with such as the type 1's the main body where the detail lay being 3D with the cab and footplate in metal to give strength and weight as could the chassis and bogies. That is my main concern with 3D printed bodies, and most especially in 2mm, lack of weight for not only traction but also current collection.  I'm looking forward to seeing the finished models when they emerge. The prospect is really quite tantalising.

 

Bob

[tom s]

On 23/08/2024 at 10:33, Hendreladis said:

Your example is fairly awesome in terms of detail, complexity and resolution. As a flattish example did you only need to apply your arctan multiplier in one plane? 

 

People often post examples of wagons etc tilted in multiple planes. Does one just apply your multiplier across all of them? 

 

Having had another look at some of my test pieces, I think I misremembered the 1.5x and 0.5x thing, however this was my thinking.

On a grid of squares (left), a 45 degree angle will give the smoothest diagonal line, so it would make sense to tilt any flat profile prints to that. However the width of the squares being pixel width and the height being layer height means the line will be different between printers and settings. E.g my old Photon Mono has 0.051mm wide pixels, and I liked to print at 0.02mm layer height to make things look good, so my ideal line looks flatter (right)
The 2x1 lines also show up so I added them in teal and blue.

Orange line's angle to the x axis will be inverse tan/arctan/atan (width/height):
I also did double layer height and double pixel width to work out the angles of the blue and teal lines:
So whenever I print at 0.02mm and I don't have any aesthetic curves to worry about, I use 21.413 degrees.
The roof section ended up looking rubbish, and to sand all the stepping/staircasing lines away would mean damaging the bolt and roof details, so I made a test piece to try and visualise an angle that would look good.



I can't remember where it is, but this test piece functions the same, it is a 4.6 degree taper between two flat surfaces. It represents the bodyside of an NBL Type 2, which has the same problems as the roof. I have too many locomotive projects going on simultaneously. Every 0.5mm along it I rotated the profile by 1 degree, and placed a marker every 5 degrees. 

Result:

As expected, the stepping is really poor when printed flat, and at my arctan value 21.4 which emulates flat prints. Bad stepping also appears at the teal and blue line angles from earlier, which I forgot about the other day! However I can see there are options over which angles might give a decent result for these bodysides or a curved roof. Perhaps 15.5 or 31 degrees, where the contours are criss-crossing enough for a workably smooth surface. I feel like I have to set up another print to prove the theory before making instructions or recommendations to other 3d printer users on that subforum, but here was my thought process right now.

Cheers, Tom

Edited August 25 by tom s

[Hendreladis]

On 25/08/2024 at 07:16, tom s said:

Having had another look at some of my test pieces, I think I misremembered the 1.5x and 0.5x thing, however this was my thinking.

On a grid of squares (left), a 45 degree angle will give the smoothest diagonal line, so it would make sense to tilt any flat profile prints to that. However the width of the squares being pixel width and the height being layer height means the line will be different between printers and settings. E.g my old Photon Mono has 0.051mm wide pixels, and I liked to print at 0.02mm layer height to make things look good, so my ideal line looks flatter (right)
The 2x1 lines also show up so I added them in teal and blue.

Orange line's angle to the x axis will be inverse tan/arctan/atan (width/height):
I also did double layer height and double pixel width to work out the angles of the blue and teal lines:
So whenever I print at 0.02mm and I don't have any aesthetic curves to worry about, I use 21.413 degrees.
The roof section ended up looking rubbish, and to sand all the stepping/staircasing lines away would mean damaging the bolt and roof details, so I made a test piece to try and visualise an angle that would look good.



I can't remember where it is, but this test piece functions the same, it is a 4.6 degree taper between two flat surfaces. It represents the bodyside of an NBL Type 2, which has the same problems as the roof. I have too many locomotive projects going on simultaneously. Every 0.5mm along it I rotated the profile by 1 degree, and placed a marker every 5 degrees. 

Result:

As expected, the stepping is really poor when printed flat, and at my arctan value 21.4 which emulates flat prints. Bad stepping also appears at the teal and blue line angles from earlier, which I forgot about the other day! However I can see there are options over which angles might give a decent result for these bodysides or a curved roof. Perhaps 15.5 or 31 degrees, where the contours are criss-crossing enough for a workably smooth surface. I feel like I have to set up another print to prove the theory before making instructions or recommendations to other 3d printer users on that subforum, but here was my thought process right now.

Cheers, Tom

Many thanks for that Tom.

 

Your explanation clarifies what is actually some pretty elementary geometry. I couldn't see the wood for the trees in pursuit of that solution.

 

My mono S has a pixel size of 47 microns so the maths becomes easier now. My trial and error approach had ultimately led me to 20-25 degrees 'ish' but I'd have saved a lot of resin if I'd had access to your brain power earlier.

 

Clearly curves etc. demand a degree of trail and error still but you've certainly assisted my understanding of things.

 

Truly grateful (and apologies for hi-jacking the thread to a degree!)

 

Andrew

 

 

[Yorkshire Square]

On 01/08/2024 at 12:53, queensquare said:

Out of interest, what is era 2-3?

 

Jerry

 

That's when we have afternoon tea and biscuits and cake... 😉