Mk2 Lever frame musings
Posted: Sun Aug 19, 2018 7:24 pm
Having completed the first stage which is 15 levers of 50 ( the points levers, these will be rearranged in the 50 frame ) , I feel I can comment on the process and the etch
Firstly its a very enjoyable process , building as it does into very robust and surprising heavy unit
First forming the quadrant . I tried the " rolling method " , but I found that problematic , I finally settled on a method of tack soldering the quadrant plate , onto its former and by pressing down as I proceeded around it formed the necessary curve. However Im not entirely satisfied, personally I think proper rolling bars are the only solution ( I hope to pick up a set at telford )
I didnt follow the instructions in relation to the rubbing strip , I merely tack soldered at one extreme , pressed them home and tack soldered them , worked well
I used 0.5 wire for the catch handle pivot , as this was more readily available and drilled the clearance to 0.6. Where The catch box was located onto the lever , I merely used my 0.5mm drill as a dowel, soldered it up and withdrew the drill, which was held in a pin vice
As can be seen , the 2.5mm rod was tapped and secured with m2.5 nuts , the centres of the design just allow the nut to be on the end
Since Ive converted al my BA stuff into bitcoins !, I used m2.5 steel /nickel plated nuts and bolts in replacement , these are a dime a dozen , with Carrs yellow flux they solder very well onto the nickel
IN a similar vein , instead of 8BA threaded rod, I used m2.5 ( 2.5 rod is available from Albion, as is 0.5mm wire and 1.2mm tube ) I used the same M2.5 rod tapped and fitted with nuts
Now the comments
(a) Of all the folds that can go wrong the catch box is irretrievable when it does , whereas the catch handle can be rescued . Please on a revision of the etch , add one or two spare catch boxes, its not like there isnt space ( I have more 8Ba etched washers then I can throw a stick at ) , add a spare catch handle , an extra rubbing strip as well. Having to fork out ( as I did ) for a complete 5 lever etch to ensure I had a backup isnt pleasant !!
(b) Consider adding a little more clearance between the catch box, and the rubbing strip, The catch box is cosmetic and adding a little more clearance, means that errors in the rolling of the quadrant dont end up fouling the catch box, I found I had to file the rubbing strips quite extensively to ensure free movement , 0.5mm extra clearance would go along way here
(c) Would it kill the economics to include a spare spring , see the point in (a)
(d) The typical hole in a " standard microswitch " , mine where Omron from Farnell is about 2.4mm , eased out to a clearance for m2,5 bar means the 8BA threaded rod can be kept in your bank vault gaining value
(e) I may be wrong , but it looks to me that the hole centres of the microswitch support rods are a tiny bit off, my switches ( as are most ) are specified with centre of 9,5mm +-0.1mm but the fret looks slightly less, This may be less apparent with 8BA rod , but with M2.5 you have to elongate the holes
(f) The resting position of the catch handle is largely determined by the position of the catch rod pivot , small position differences in the pivot , can cause the catch handle to " rest " in quite noticeable different resting positions, It would be useful to have a defined | stop " or land for the catch handle , so when released it returns to a consistent position not determined by the exact pivot construction
(g) with the standard microswitches I have , I most definitely have to bend the roller arm to bring the roller both closer to lever and its pivot point, I cant say thats needed on all of them , but it is on this . Had I a preference, I would have integrated a microswitch into the frame itself , rather then a seperate etch , as this constrains the mounting requirement to placing the whole frame on a " sub=floor "
(h) Im sure theres a good reason , but why was the orientation of of the frame done the way it was ,surely it should fit into a " signal box floor" , whereas this frame has the rear considerably higher then the front , I have to put cosmetic pieces around the back and side to hide the rear from view
Having said all that , its a great product , well done
Dave
Firstly its a very enjoyable process , building as it does into very robust and surprising heavy unit
First forming the quadrant . I tried the " rolling method " , but I found that problematic , I finally settled on a method of tack soldering the quadrant plate , onto its former and by pressing down as I proceeded around it formed the necessary curve. However Im not entirely satisfied, personally I think proper rolling bars are the only solution ( I hope to pick up a set at telford )
I didnt follow the instructions in relation to the rubbing strip , I merely tack soldered at one extreme , pressed them home and tack soldered them , worked well
I used 0.5 wire for the catch handle pivot , as this was more readily available and drilled the clearance to 0.6. Where The catch box was located onto the lever , I merely used my 0.5mm drill as a dowel, soldered it up and withdrew the drill, which was held in a pin vice
As can be seen , the 2.5mm rod was tapped and secured with m2.5 nuts , the centres of the design just allow the nut to be on the end
Since Ive converted al my BA stuff into bitcoins !, I used m2.5 steel /nickel plated nuts and bolts in replacement , these are a dime a dozen , with Carrs yellow flux they solder very well onto the nickel
IN a similar vein , instead of 8BA threaded rod, I used m2.5 ( 2.5 rod is available from Albion, as is 0.5mm wire and 1.2mm tube ) I used the same M2.5 rod tapped and fitted with nuts
Now the comments
(a) Of all the folds that can go wrong the catch box is irretrievable when it does , whereas the catch handle can be rescued . Please on a revision of the etch , add one or two spare catch boxes, its not like there isnt space ( I have more 8Ba etched washers then I can throw a stick at ) , add a spare catch handle , an extra rubbing strip as well. Having to fork out ( as I did ) for a complete 5 lever etch to ensure I had a backup isnt pleasant !!
(b) Consider adding a little more clearance between the catch box, and the rubbing strip, The catch box is cosmetic and adding a little more clearance, means that errors in the rolling of the quadrant dont end up fouling the catch box, I found I had to file the rubbing strips quite extensively to ensure free movement , 0.5mm extra clearance would go along way here
(c) Would it kill the economics to include a spare spring , see the point in (a)
(d) The typical hole in a " standard microswitch " , mine where Omron from Farnell is about 2.4mm , eased out to a clearance for m2,5 bar means the 8BA threaded rod can be kept in your bank vault gaining value
(e) I may be wrong , but it looks to me that the hole centres of the microswitch support rods are a tiny bit off, my switches ( as are most ) are specified with centre of 9,5mm +-0.1mm but the fret looks slightly less, This may be less apparent with 8BA rod , but with M2.5 you have to elongate the holes
(f) The resting position of the catch handle is largely determined by the position of the catch rod pivot , small position differences in the pivot , can cause the catch handle to " rest " in quite noticeable different resting positions, It would be useful to have a defined | stop " or land for the catch handle , so when released it returns to a consistent position not determined by the exact pivot construction
(g) with the standard microswitches I have , I most definitely have to bend the roller arm to bring the roller both closer to lever and its pivot point, I cant say thats needed on all of them , but it is on this . Had I a preference, I would have integrated a microswitch into the frame itself , rather then a seperate etch , as this constrains the mounting requirement to placing the whole frame on a " sub=floor "
(h) Im sure theres a good reason , but why was the orientation of of the frame done the way it was ,surely it should fit into a " signal box floor" , whereas this frame has the rear considerably higher then the front , I have to put cosmetic pieces around the back and side to hide the rear from view
Having said all that , its a great product , well done
Dave