mickoo
Western Thunderer
Handy tip for today, look forward to trying it out
Might be a bit of a handful on 0.45 mm frames mind 
W1 as rebuilt
- Thread starter Dikitriki
- Start date
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- 7mm djh finney7 kit design lner martin finney
Might be a bit of a handful on 0.45 mm frames mind 
Dog Star
Western Thunderer
I do hope that you do not mind me saying.... I feel quite full after such a feast.
Thank you for taking the time to explain about the methods of working... and how to get the required result.
regards, Graham
Scale7JB
Western Thunderer
Just mind your fingers...Handy tip for today, look forward to trying it out
JB.
Overseer
Western Thunderer
Mick,
The other thing to watch out for is the line thickness. Autocad can do strange things when printing with different plot styles so even if you set the line weight to 0 mm they can plot with a thickness. It is safer to switch all the line layers off after hatching and copy and save a file with the fill/hatched areas only for the etchers to use. They may do that at their end anyway.
The other thing to watch out for is the line thickness. Autocad can do strange things when printing with different plot styles so even if you set the line weight to 0 mm they can plot with a thickness. It is safer to switch all the line layers off after hatching and copy and save a file with the fill/hatched areas only for the etchers to use. They may do that at their end anyway.
mickoo
Western Thunderer
Hi,
Yes, quite correct, PPD only require the black fill, red front and blue back fill to work with, they do like you to keep the forth magenta outline layer so they can do a quick check for tabs that may be missing. Once that is done they turn off the magenta outline layer and convert the red and blue to white and produce the front and rear photo tools.
To save them time I do this at my end and make up the front and rear tools, then I print them out on A3 paper and look it over, despite all that I did miss a whole pile of rivets on the LH outer half etch skin
I'm hoping that any other errors are very minor and not affect the test build, not at the price just quoted for the first test run
Eastsidepilot
Western Thunderer
S-Club-7
Western Thunderer
Mick,
</eggsucking-mode on>
Selecting the hatch boundaries individually is a slow way of doing it.
</es-mode off>
mickoo
Western Thunderer
The Eagle has landed
Overall looks good
Couple of faults mind, nothing drastic, one is an own goal, the other a complete mystery.
The own goal is not adding the anti slip pips to one of the rear steps.
It should look like this
They are not very prominent and could do with beefing up but I'll not do a whole new sheet just for these two parts unless there are serious fit errors elsewhere.
The tarnish does not look so bad in real life as I've used an HDR function to sharpen the images and that has accentuated the staining. But they will need a wash with something before starting.
The other Issue is the rear pony pivot stay, it should be solid with a hole in the middle
Okaaayyy it's solid with a half hole, I can live with that, until you turn it over
It's half etched all of the rear and left a pip where the hole should be, I've checked the master art work and it's black both sides, I've checked the B&W art work for printing and it's black both sides and all three have a hole in the middle? This does confirm my worries about the hatching I had, it would seem that the art work is perhaps a little too big or too complex for the hatch fill to work correctly everytime.
I'll send the photos to PPD and ask their thoughts on how it might of happened as for it to be half etched underneath then that would have to be a big blue piece in the master art work or a big white piece on the rear photo tool, it is neither, just pure black both sides
It's not a big deal, i can fabricate a replacement from the spare etch around the work piece and then make a replacement on the cab etch art work.
Finally, the rear half etch frame work needs several bends and working them out would be difficult and impossible to add as a half etch guide line on the rear, perhaps you could do it with the more complex three or four layer system some people use, but for two layers you'll end up with slots.
The front
The rear
As an aid I've added some small triangles half etched on the rear, simply line top and bottom and scribe your guide bend line, better yet, use a skrawker to make a groove and you'll get a nice crisp bend on the other side
Ok time to break out the piercing saw and files
Overall looks good
Couple of faults mind, nothing drastic, one is an own goal, the other a complete mystery.
The own goal is not adding the anti slip pips to one of the rear steps.
It should look like this
They are not very prominent and could do with beefing up but I'll not do a whole new sheet just for these two parts unless there are serious fit errors elsewhere.
The tarnish does not look so bad in real life as I've used an HDR function to sharpen the images and that has accentuated the staining. But they will need a wash with something before starting.
The other Issue is the rear pony pivot stay, it should be solid with a hole in the middle
Okaaayyy it's solid with a half hole, I can live with that, until you turn it over
It's half etched all of the rear and left a pip where the hole should be, I've checked the master art work and it's black both sides, I've checked the B&W art work for printing and it's black both sides and all three have a hole in the middle? This does confirm my worries about the hatching I had, it would seem that the art work is perhaps a little too big or too complex for the hatch fill to work correctly everytime.
I'll send the photos to PPD and ask their thoughts on how it might of happened as for it to be half etched underneath then that would have to be a big blue piece in the master art work or a big white piece on the rear photo tool, it is neither, just pure black both sides
It's not a big deal, i can fabricate a replacement from the spare etch around the work piece and then make a replacement on the cab etch art work.Finally, the rear half etch frame work needs several bends and working them out would be difficult and impossible to add as a half etch guide line on the rear, perhaps you could do it with the more complex three or four layer system some people use, but for two layers you'll end up with slots.
The front
The rear
As an aid I've added some small triangles half etched on the rear, simply line top and bottom and scribe your guide bend line, better yet, use a skrawker to make a groove and you'll get a nice crisp bend on the other side
Ok time to break out the piercing saw and files
Nick Dunhill
Western Thunderer
I wanna go....I will be ready to begin my builds in a month or two and they look brilliant. Thanks very much Mick!!!
adrian
Flying Squad
Very nice - with such a complex sheet just to end up with the couple of errors is not bad going.
Another suggestion - I've been building up some chassis etches from the 2mmFS and what they have done is for things like the brake lever they have etched a slot into the framing around the side as a bending jig. So once you have cut out the brake lever you bend it up to fit into the etched slot. I'll see about getting a photo which should make it a bit clearer what I mean.
Another suggestion - I've been building up some chassis etches from the 2mmFS and what they have done is for things like the brake lever they have etched a slot into the framing around the side as a bending jig. So once you have cut out the brake lever you bend it up to fit into the etched slot. I'll see about getting a photo which should make it a bit clearer what I mean.
mickoo
Western Thunderer
Adrian, I did think about something like that for the bends at the rear, but never thought to make it a slot around the edge, I was looking to make it a piece you cut out and used as a edge sort of thing.
mickoo
Western Thunderer
You may have to wait a little longer, there's some issues with the slots and I don't know why, all the fold grooves and slots for tabs and such are useable, but all the slots in any half etched part are bleedin massive. The material is 0.45 mm and that's correct, the recommended slot is 1.2 x that thickness so that's be a slot of 0.54 mm, I made all mine 0.5 mm wide to allow for some cusp to bite the tab. However, every slot in a half etched part is damn near 0.7 mm wide, which means the tabs are flapping about all over the place and some of these parts that go through are stretchers so there's a gap either side and it looks shite.
This is magnified and not too clear but you can see the dark line caused by the gap.
I either re do this whole sheet or add the replacement parts onto the cab etch, the only problem is that sheet may not be 0.45 mm thick so will throw out all the spacing where ever these parts are used.
In fairness the gaps will probably be partially filled with paint and maybe some generous soldering, but it's the principle that's ticking me off and not knowing how on earth a slot at 0.5 mm on the art work can suddenly be 140% bigger....but only in the half etched areas ?
I'll push on and see what the rest looks like.
Richard Spoors
Western Thunderer
Mick, I hope you chase down the bugs that seem to have got into your first etch sheet without to much hassle. The whole project looks very exciting.
Cheers
Richard
Cheers
Richard
OzzyO
Western Thunderer
Mick,
I think that you would be better off dividing the slot size by 1.2 as you have to remember that any slot will be enlarged as it is etched through the metal from both sides. So if you start with a slot of 1mm and it's going through a sheet of 0.5mm it will end up at approx. 1.25mm at the outside edges and about 1mm at the middle, so if you reduce the size of the slots by 1.2 or 1.1 you should end up with the sort of size you require.
So that would be a a slot of approx. 0.5mm should be drawn at 0.42mm.
As if you increase the size by 1.2 the 0.5mm slot becomes 0.6mm approx.
IIRC increase for length by 1.2? depending on thickness but for slots dived by the same amount.
HTH.
OzzyO.
I think that you would be better off dividing the slot size by 1.2 as you have to remember that any slot will be enlarged as it is etched through the metal from both sides. So if you start with a slot of 1mm and it's going through a sheet of 0.5mm it will end up at approx. 1.25mm at the outside edges and about 1mm at the middle, so if you reduce the size of the slots by 1.2 or 1.1 you should end up with the sort of size you require.
So that would be a a slot of approx. 0.5mm should be drawn at 0.42mm.
As if you increase the size by 1.2 the 0.5mm slot becomes 0.6mm approx.
IIRC increase for length by 1.2? depending on thickness but for slots dived by the same amount.
HTH.
OzzyO.
mickoo
Western Thunderer
Ozzy,
That would certainly be the way to go in this case, however, the other slots that are in full thickness material are enlarged by 1.2 and they are fine, it's only slots in half etched material that is massively too big. Any bend half etches are also 1.2x material thickness and they are all fine too.
Anyway, onward with the bits that do fit perfectly, the rear drag box
Three layers in here and another small error, the top layer, that which will sit right under the cab has it's centre hole in the wrong place, too far forward by about 0.5 mm
It's a nothing issue as the two layers below line up and it is those two holes that will have the bolt passing through to secure the draw bar, none the less the master art work will be adjusted accordingly.
That would certainly be the way to go in this case, however, the other slots that are in full thickness material are enlarged by 1.2 and they are fine, it's only slots in half etched material that is massively too big. Any bend half etches are also 1.2x material thickness and they are all fine too.
Anyway, onward with the bits that do fit perfectly, the rear drag box
Three layers in here and another small error, the top layer, that which will sit right under the cab has it's centre hole in the wrong place, too far forward by about 0.5 mm
It's a nothing issue as the two layers below line up and it is those two holes that will have the bolt passing through to secure the draw bar, none the less the master art work will be adjusted accordingly.
JimG
Western Thunderer
Mick,
It might be argued that your 1.2 x metal gauge applies to slots in the full thickness but that it is too much for slots in half thickness metal. The instructions I have read regarding slot allowance recommends an increase of 15% of metal gauge to a slot to achieve a reasonable over cut such that the cusp remaining allows entry of the required width. Therefore, using this formula for half etched slots would mean using 15% of half the metal gauge.
The instructions I refer to are the Hollywood Foundry ones
http://www.hollywoodfoundry.com/Docs/Metal Etching Principles and Rules.pdf
...on pages 4 and 5.
But that etch is a great bit of work. I don't know if I would ever contemplate doing something as complex as that.
Jim.
Last edited:
mickoo
Western Thunderer
Jim,
I think your right, I've arrived from the other side and deduced that for slots in half etch areas then the slot needs to be reduced by about 15-20% of the 'original' material thickness.
I'd allowed for bend lines and slots a factor of 12% and even then with the cusp the interlocking parts fit very (almost too) easily, being as I'm drafting to a tolerance of 0.05 mm and using snap, I only have the option of 0.45 mm or 0.5 mm. Using material thickness slots wil reduce the slot in full thickness material just enough for the cusp to have a good bite on the part entering the slot.
Previously, all slots were 0.5 mm wide in full and half etch material, those in full have come out just over 0.5 mm wide and those in half etch are near to 0.7 mm.
So, the new measurements will be 0.45 mm for full thickness and 0.35 mm for half etch areas, even then 0.35 mm may be a little loose after the etching process. These may give a stronger bite but it's easy to push through the cusp, besides, it's easy to take material away but impossible to add it back.
I've not worked in material this thick before, so it's all a learning process, the EMD cab was 0.010" thick, the class 40 bogies I think were 0.015" and these are 0.018". I've had a quick look at both of those and neither had slots in half etched areas, well, none that required interlocking with other parts.
In the grand scheme of things we're only talking an error here of 0.1 - 0.2 mm and I maybe being a little too picky
I think your right, I've arrived from the other side and deduced that for slots in half etch areas then the slot needs to be reduced by about 15-20% of the 'original' material thickness.
I'd allowed for bend lines and slots a factor of 12% and even then with the cusp the interlocking parts fit very (almost too) easily, being as I'm drafting to a tolerance of 0.05 mm and using snap, I only have the option of 0.45 mm or 0.5 mm. Using material thickness slots wil reduce the slot in full thickness material just enough for the cusp to have a good bite on the part entering the slot.
Previously, all slots were 0.5 mm wide in full and half etch material, those in full have come out just over 0.5 mm wide and those in half etch are near to 0.7 mm.
So, the new measurements will be 0.45 mm for full thickness and 0.35 mm for half etch areas, even then 0.35 mm may be a little loose after the etching process. These may give a stronger bite but it's easy to push through the cusp, besides, it's easy to take material away but impossible to add it back.
I've not worked in material this thick before, so it's all a learning process, the EMD cab was 0.010" thick, the class 40 bogies I think were 0.015" and these are 0.018". I've had a quick look at both of those and neither had slots in half etched areas, well, none that required interlocking with other parts.
In the grand scheme of things we're only talking an error here of 0.1 - 0.2 mm and I maybe being a little too picky
Nick Dunhill
Western Thunderer
I think they look better than lots of etchings in commercial kits so don't beat yourself up too much. The errors could be down to the stop etch process, ie when the etcher stops the process. I've seen a lot of variation in identical commercial kits.. Well done they look super.