Hymek Conversions

Right now I'm not sure which way up the cross bracings go, I had half an idea they go the other way up but I'd have to get my head round it to say for certain (I'm not actually at that stage yet). Now the issue about passing wire through the centres of the U frame is avoided if after soldering into place the wire on the inside section of the U frame (the two inner brake hangers only) are then cut off and stubs filed flat to the inside frame face, thus on the two inner brake hangers the chance of anything fouling up the chain is eradicated. The two outer brake hangers with the air cylinders don't need this treatment as the wires pass through the frame away from the Delron equipment... it also acts as additional strength for the U frame. Now I worked out that the hanger holes need to be drilled 15mm up from the botton edge of the U frame... this puts the brake blocks in alignment with the wheel / axle centres... not sure how correct this is on the real thing but to set the hangers much lower means the bottom of the castings will foul against the rails... maybe these castings are a little basic in design. That is not a criticism to PRMRP of course and more likely their advice against holding the hangers in place with through wires is because they want to avoid comebacks /complaints due to the very tight tolerances involved. The hole is drilled on mine as I say on the 15mm line at a point against each wheel and where the brake blocks allow free movement of the wheel without making contact on the wheel rims... on my U frame this was 2.5mm from the outer leading edge of the original etch... ends unfolded. Pics will show you what I mean Kimbo. I wondered if the problem with wiring as PRMRP suggest which is one bogie + and the other neg return (wired as they show in the download PDF) is that if the loco hits a "dead" spot then the Hymek stalls, I've decided to wire mine as follows:- the first bogie takes + current through the uninsulated wheelsets thus the frame is live via the post, neg is back from the motor to the insulated wheels. The second bogie is the opposite of this where Neg is returned through the uninsulated wheelsets but + current is collected through the insulated side (bogie wheelsets are at opposite sides here to the first bogie) ... eight slaters sprung pick ups are used, one for each wheel. The motors are connected through a terminal block located in the fuel tank castings for ease of seperating the bogies from the body frame. This way each wheel makes electrical contact and can ride over dead spots / rail side contact faults etc... a bit like the way DCC Concepts prove current flows in their Cobalt point motor wiring arrangements for a double ended pair of points. Sorry Kimbo if this reply has suddenly taken on massive rivet counting habits. cheers Paul

 

Steve that Hymek of yours is looking superb... in fact it looks better than a full size one heheyou could very much think you are looking at the real thing. Thanks again for all your help I'm not quite ready to dress the bogie detaill yet tho but this is excellent reference material. May I ask what is the paint code for the lime green colour? Mine will be D7044 in green as the last member from the first order batch.
Cheers PaulSteve Fay wrote:

 

Hi Kimbo,
Here are a few pics of the brake hanger arrangement I've used... please excuse my grubby fingers... had an afternoon in the garden oh dear.

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So the .7mm wire passes through the end section of the U frame the hole drilled is 2.5mm in from the end of the frame and 15mm up from the bottom edge of the frame... note that my frame may be constructed slightly differently, the overall length of the u frame is 114mm. The distance between the two inner brake hanger wires is 42mm across centre of holes. I realised that I had drilled this cross wire a little out of skew, so without making excuses the moral of the story is don't work late at night in dim conditions... I never learn To be fair it won't matter that much sisnce these items are not so visible when the bogie i dressed with its castings... anyway leason learnt as my effort here look rubbish.

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Now here is the inside of the frame, I drilled two holes through the centre bulkhead for the pick up wires to pass through, in the picture I have stripped the bogie components down so that a better shot can be made, the pick up wires pass down the inner side of the frame and are held away from the worm drive rotation by a little clip bracket I made from some scrap etch. At this stage I will touch out all the chipped paintwork before refitting the motor etc. Note also the inner brake hanger wires have been cut away after soldering into position, there is no confliction or snagging with the Delron.

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This is the hole drilled to take the Slaters plunger pick up body, the plunger goes on the outside of the wheel as this position keeps wires away from the Delron chain and worm drive. The hole is drilled at 3.5mm dia and is located 7mm up from the bottom edge of the U frame and 8mm in from the end at hole centre point. Sorry about busting in on your thread Kimbo with my build ... I'll start a build thread of my Hymec project and hopefully folk wishing to do a PRMRP conversion themselves can pick out the bits they want.cheers for now Paul

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Nice job Kim , looks like the real bogie.

Pete.

 

Great work there Kim, hats off to you dude for intuitive problem solving. Yes when I first came across your Hymek build thread I noticed that you had folded the etches in at the ends and wondered if you had a reason for this that would become apparent later on... so on my first bogie build (which turns out to be the one I'm working on currently) I did the same. I then realised there was nowhere for the brake hangers to attach to so my second bogie didn't get the folding treatment and I soldered a thin brass strip to the first bogie to re-lengthen it back to 114mm. Anyway all is good now and with advice and pictures from Steve I got round it, however PRMRP are very economical with their instructions and like I think the brake castings don't seem to sit aligned quite right to me, raising them a couple of millimeters sends the cast shoe out of true with the wheel radius as you say. Now the other issue I had when fitting the Delron chain was that suddenly a nice free flowing bogie jerked and stalled under power and only ran well in one direction... a bit like the Metro Vick Co-Bo that used to run up the Stoke Derby Line on it way back with a test train to the RCD at Derby all those years ago . So for now I'm leaving the Delron off since the way I fitted it was to slip the chain onto the cog on the wormed drive axle and then loop the chain onto the other cog by sliding the second axle assembly through the frame bearings... that way I was able eliminate too much slack in the chain. That's why my pictures showed the bogie stripped down as I was trying to find out what was causing the jerky running. Anyway at least I have a second BBT Hymek build to do after this one.
Cheers for now Paul