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O gauge Hymek extreme scratching.
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 Posted: 13 Nov 2017 16:56
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Is Line Clear
Paul


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At the risk of doing this subject to death particulaly since Kimbo and I have recenty had long convos on building up the replacement Hymek bogies I thought I'd start a new thread focused on the bodyshell and what to do with it. In essence the Triang Hymek bodyshell is proportionally accurate to within 2mm in length of true scale, however there are some quite significant and glaring errors which need to be addressed so this thread will attempt to deal with this ... or at least that is my current thinking :mutley2:.In the ideal world of course getting hold of a Heljan bodyshell is preferable but in the absence of dinosaurs roaming across Europe again the Triang Blue Flier Hymek is a good as any start point for scratching  a conversion from. Of course there is the muchly reveared JLTRT offering but then that isn't really extreme scratching.:thumbs: but it is a good source to purchase some of the more specialist detailing bits from. Basically i got my Hymeks from off of Ebay paying £16 and £25 for each one, my advice to anyone thinging of going down this road is get the older Triang version and not the Russian Novo equivalent as the earlier plastic is much more forgiving. The Novo version has a block losange shape cast onto the side, this was done to alter the mould and eradicate the Blue Flier logo of the earlier Triang ones.
Now I've added a picture so things don't get too boring, on the left is an unmodified Triang Hymek and on the right is one I did ealier :avatar:note the sticky back plastic tape still intact on the right :avatar:.

There are a few areas on the body that require attention, notably in the cab area as seen in the picture, the cab windscreen need altering and so does the cab roof profile. The swage ledge below the cab windscreens need reprofiling to around a 30degree downward slope and so does the lower edge of the route box aperture. These are areas of the model that isn't covered in the PRMRP detailing kit, more about this later though as Kimbo has already nicely covered the bogie build of these kits. one other quite important detail not covere in the PRMRP kit concerns one of the side ehgine compartment windows. On the Triang kit the two windows nearest the cab are cast as both smaller windows, in fact only one window is smaller and this is the one between the single access compartment door and the side louvre vent grill. the other small window on the other side has to be enlarged to the size of the middle windows. This means that one of the PRMRP window frame etches needs to be cut down in length. More about this later.
The picture above shows what I mean and also creates an instant Vic Berry stack... no I'm sorry its beyond me to convert these into Sulzer Type 2's and English Electric 20's.:scratchchin:
What the PRMRP kit does cover is the modifications that need to be done to the roof detailing, these include moving the circular roof fan grill sideways by 5mm, enlarging the exhaust outlet ports to a 5mm diameter and forming various other cubicle air intakes and vents. 


So this photo show some of the completed work done to date, some speedily knocked up lifting panel hooks have been made and temporarily fitted to see what it all looks like and if it is work going to make a set of 20 equally formed hooks. I think it does and so these crude wire hooks will be replaced with better ones as a next job before the body shell is primer sprayed.



The first modification i did was to change the shape of the front windows as they are nothing like on the Triang model, this involves removing the plastic gutter strip so that the roof line drew straight down onto the cab front where at this point a rather nasty "nose" on the front edge of the cab roof becomes apparent, gently file this down and also the front corners too. It doesn't matter if too much plastic is removed as long as nothing is filed off from the front and side window pillar surfaces as the cab shape has to have a new gutter fitted and this will follow the side profile directly above the window. I used 0.7mm wire but in hindsight OO scale square point rodding wire may have been a better choice. Anyway to fix I started at the centre of the cab and lowly working outwards to the corners the wire was gued in with cyano, the aim is to remove that pronounced upward central flair shape on the front windows and the wire will act as a guide in creating the new glazing shape. Once the cyano had set the corners can be bent round and the wire terminated behind the cab doors, now the next job is to filler in the gaps and I used a building product called Cuprinol Wood Fill, this is a two pack product and comes in white and natural colours, to me it has a much finer texture than car body filler or an Isopon type filler, P38 for example and it doesn't break away so easily during fine sqnding thin filler areas. Cuprinol products can be bought from Travis Perkins builders merchants or Google an equivalent product match if needed.


Filler all around the cab gutter area and then sand back until a gently curving front without the rise shape appears and also sand back the sides which have a less pronounced downward curving cab edge as on the Triang bodyshell. The above picture shows what i mean.
Now I dealt with the windows the top centres need to be lowered and the top outer corners need to be slightly raised, I used Green putty as a stopper but to get the right shape I used the Wood Fill which sticks superbly well to the Triang plastic and held the new wire guttering firmly in place. The lower edges of the front windows need to be reduceed too, they need to follow the bottom line of the side windows, again gently filing down will do the trick. the next job is to deal with the cab swage line which on the model is flat but should in fact follow the line of the side profile shape underneath the side windows and through the cab door.

Last edited on 13 Nov 2017 18:30 by Is Line Clear



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 Posted: 13 Nov 2017 17:15
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Is Line Clear
Paul


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Now there is plenty of plastic beef on the cab mould to file away, I was aiming for a 30 degree slope from below the windows, firstly the white plastic window moulds need to be glued to the main blue plastic body, the get a fine profile I held the edge of a new Stanley blade upright and shaved across the plastic  similar to the action of a carpenter planing wood, this is where that black line tape came in as seen on the earlier image, the tape is a guide for how far to shave using the Stanley blade.  It is a bit of a long winded process to undertake but I kept checking each side for an equal match and got there in the end. The planed ledge left from the shaving process can now be smoothed round with 600 grade wet and dry paper.

 
Once I was happy with the results of the shaving process which has to take out the forward top edge of the white plastic but not all the way back to the windows I then ran a fine filet of WoodFill over the back edge of the white plastic against just below the windows. After sanding and flatting back so the slope started and finished with the profile along the sides and the front windscreen line followed the same alignment as the side window I was happy.In my next post I will show how I made the roof detailing and then later discuss what I did to the bodysides which involved removing loads of plastic. Scary stuff I thought at the time.
Cheers for now Paul

Last edited on 13 Nov 2017 18:28 by Is Line Clear



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 Posted: 13 Nov 2017 17:45
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Rob Pulham
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Looking good Paul,
Proper modelling:thumbs:



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 Posted: 13 Nov 2017 18:22
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jakesdad13
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Rob Pulham wrote: Looking good Paul,
Proper modelling:thumbs:



Wot ee said :tophat::tophat:


Pete.



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 Posted: 13 Nov 2017 19:11
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Paul


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Thanks Pete... I like a challengehttp://www.click

Last edited on 13 Nov 2017 19:12 by Is Line Clear



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 Posted: 22 Dec 2017 01:42
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Paul


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Things have moved on a little on this build since the last picture upload, I have been concentrating on the bogies and devising a practical way to access the inner bogie if and when needed. Kimbo was a great inspiration when he came up with a fixing system so all credit here goes to his original idea. The way I build mine though is a bit different. Here is one bogie frame finished and dressed with detailing, the end cross braces have a small nut and bold fixing (I think it is a 2BA) 10mm long, the nut will be soldered onto a back plate permanently located on the end of the inner bogie U frame. The back plate is made from off cut brass etch, when coupled together both the outer and inner frame are held in allignment to the axle centres. I have set the spring castings slightly inset of the frame and these will sit inside a channel section soldered to the inner U frame and packed out with Plasticard to stop the outer frame rolling sideways on the brass bolts.


The channel pieces can be seen here on the painted and assembled bogie, the Plasticard packers fit behind the spring casting and cannot be seen. Also of interest is the Peter Harvey Designs bogie steps which are much more accurate than the white metal offerings that come with the PRMRP kit, you also get etched Timken bearing covers too. I have added additional detail such as air pipes made from 0.4mm wire and some thin brass strip over the frame casting next to the brake pistons as this gives a far more realistic look to the job.


Now this is the bit that Toto will like... a Delrin chain :avatar:, here is the end view showing the way I set the both cogs together on the drive axle. Also I opted for Slaters sprung pick ups as opposed to wipers.
And another sideways shot of the Delrin set up.


Now in the PRMRP conversion kit it says that one bogie collects the + whilst the other bogie returns power on the negative side, I decided there could be better way so the bogie pick ups will work on each bogie to collect power and return together. The A bogie will collect power from the un insulated side and return power via the insulated side of the wheel sets, the B bogie will collect power on the insulated side and return power via the uninsulated side. Both motors wired together so one bogies insulated wheel sets will contact the + rail with the other bogies insulated wheel sets contacting the return rail. Each bogie will be insulated at the pivot point of the sub chassis to prevent shorting out, but more on with pics that later. Project work for this build over Christmas will be to complete the sub chassis by soldering the bogie swivel stretchers in position, the critical bit here is to fit them at the correct depth so that when the body is mated to the frame the buffers are at the correct height and the loco sits squarely at each end. I'll add pictures as I go but for now that's all. 

Last edited on 22 Dec 2017 02:10 by Is Line Clear



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 Posted: 22 Dec 2017 01:54
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Toto
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Nice clear pictures. Not a lot of clearance between the Delrin chain and the motor worm. As you say, determining the height at which to set the biggie into the frame could be tricky. Very helpful post. Thanks for sticking it up. I'll be sure to be following the progress. Very useful. :thumbs:
Cheers
Toto.



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 Posted: 22 Dec 2017 02:04
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Paul


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Toto wrote: Nice clear pictures. Not a lot of clearance between the Delrin chain and the motor worm. As you say, determining the height at which to set the biggie into the frame could be tricky. Very helpful post. Thanks for sticking it up. I'll be sure to be following the progress. Very useful. :thumbs:
Cheers
Toto.
Thanks for the kind comments Toto, I have given this some considerable thought and have devised a way to do this, however before I explain  in another post I need to prove if it works but principally think of the Plasticard insulation packers that will fit under the bogie cross brace and the bogie swivel plate as shims. I have only about 2.5 mm to work with... I've already constructed the sub frame which bolts to brass angles fitted to the plastic bodyshell.



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 Posted: 22 Dec 2017 02:13
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I need to get my head round the plasticard element but I'm getting there. So far I understand it ..... which is good for me :avatar:
Cheers



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 Posted: 22 Dec 2017 02:40
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Paul


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Incidentally whilst on the subject of Hymek bogie kits I noticed recently on Ebay that a pair of Hymek bogies sold for just under £100, the powered bogie went for £62 and attracted some 22 bids whilst the non powered bogie went to the same bidder for £33. These were the earlier version and not the current PRMRP kit as supplied by Peter Bessant, the motor was the older can type and the worm had the brass insert, for another £95 the bidder could have gotten a complete kit containing updated items. Ah well folks never mind.cheers Paul



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 Posted: 22 Dec 2017 10:27
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ianvolvo46
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fascinating build to follow thanks

Ian vt



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 Posted: 22 Dec 2017 16:31
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Rob Pulham
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Hi Paul,
It's good to see how you have used the Delrin chain for the bogie.

At some point I have a Judith Edge ES1 kit to build and that has Delrin chain driven bogies with it. I also have a Sentinel shunter which I have delrin gears and chain for so its going to come in useful to me too.

Keep up the good work:thumbup:



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 Posted: 22 Dec 2017 21:37
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Paul


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Rob Pulham wrote: Hi Paul,
It's good to see how you have used the Delrin chain for the bogie.

At some point I have a Judith Edge ES1 kit to build and that has Delrin chain driven bogies with it. I also have a Sentinel shunter which I have delrin gears and chain for so its going to come in useful to me too.

Keep up the good work:thumbup:
Thanks Rob I really do appreciate your comments and support, by far the best tip I can offer over setting up the Delrin is firstly to make the chain up as a loop, then place it over one cog on its axle (it may be you then need to fit the wheelset together afterwards) and then offer the chain up onto  the other Delrin cog and slip the loop assembly onto the second axle. It is such a faff trying to connect a link and get good tension with both axles fixed in place, I know a chain tensioner can be made up in the run but to me it is lots easier to arrive at the correct chain length first then fit as described. The chain will slacken a little under testing but I found once set up everything is good. I also found it is important to avoid too tight a tension as this makes the motor labour and noisy and the running is quite jerky, also too slack and the bogie stalls badly when changing direction of travel. Hope this is a useful tip.
cheers for now Paul



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 Posted: 22 Dec 2017 23:54
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Paul


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And to conclude the great Delrin saga one final observation has to be mentioned in order to aid unhindered running of the chain on diesel loco bogie inner U frames. It may be necessary to file the inner faces on the axle bearings on the side where the chain runs because of space restrictions either on the wheelset axle or inside the frame itself. It is much better to file down the brass bearing a millimeter or so rather than file the machine plastic on the cog, the Delrin cog grips best if not having its surface contact reduced on the axle which otherwise might make the chain setup run poorly. 


Yesterday I mentioned about inserting Plasticard packing pieces on the inside between the outer and inner bogie frame to hold the unit stable, this overhead view shows the point where Plasticard packers will be fitted. The tiny wire cross runs are where the brake hanger gear will be fixed, these will be fitted once the bogie has been dressed with motor and gearing then the outer bogie frame can be offered up for final detailing and fitting of sanding pipes and wheel guards.


Now Christmas came early today... well three days early:avatar: as the postie handed me a nice jiffy-bag package from Laurie at JLTRT, containing some lost wax brass bits an etch and some resin cast cab desks. I took the opportunity to buy four of these desks because being a glutton for punishment I have another BBT Hymek to do at some point,:facepalm:  anyway the brass bits are cab desk controls, roof horns, windscreen wipers, jumper cables, brake pipes and such like.  Plus there are also four nicely cast white metal seats and a detailing etch which contains the lamp brackets. I felt these components are superior to the original white metal ones that came with the conversion kit. I'd also got a set of 82A shed plates from Fox and the etch numbers have arrived from Severn Mill.


So my Hymek will be finished in two tone green with small yellow panels, when new D7044 was allocated to Bristol Bath Road and was fitted with cast aluminium shed plates located on each driver side buffer valance. The shed plates were painted with a red background . The nice thing about the Severn Mill etch numbers is that you also get the builder plates as well. 

Last edited on 23 Dec 2017 11:05 by Is Line Clear



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 Posted: 23 Dec 2017 00:12
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Paul


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ianvolvo46 wrote: fascinating build to follow thanks

Ian vt
Thanks Ian glad you like and thanks for following too.cheers Paul



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