Constructing The Josslin NYC Hudson Lead Truck
Moderator: Harold_V
Re: Constructing The Josslin NYC Hudson Lead Truck
A not too good photo of couple of leaf spring drilled holes. You can judge the result for yourself.
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Re: Constructing The Josslin NYC Hudson Lead Truck
I must have done something right for a change as all of the leaf springs are now installed in the leaf spring centre hangers.
Thirty four (34) holes drilled in the spring steel with all of the drills surviving and in excellent condition.
I still had to undertake some further dog work to final fit all of the leaves.
What was supposed to happen and nearly did but not quite.
The leaf spring roll miked 0.0315" - 6" which is very slightly oversize. The centre hanger centre post has to be drilled exactly in the centre of the centre hanger inner rectangle (width wise), be totally square to it and as well, be straight/on size. I also made the centre post a tap fit in the drilled holes. As far as I could tell, they all were.
The centre hanger inner rectangle has to be truly that and here there was a problem. Mine, after machining, turned out to be very slightly barrel shaped.
As a result of the above, some of the spring leaves would hang up on one side or on the other of the inner rectangle side walls.
The solution, more dog work.
The edges of the offending leaf springs were stoned down a bit with an oilstone, the centre hanger inner rectangle was carefully re-worked near each end and in the corners with a square file, and each 1/16" dia. centre post was given a lick with a fine needle file in the lathe and a slight taper filed on one end.
After that, final assembly with no problems.
End of story.
Thirty four (34) holes drilled in the spring steel with all of the drills surviving and in excellent condition.
I still had to undertake some further dog work to final fit all of the leaves.
What was supposed to happen and nearly did but not quite.
The leaf spring roll miked 0.0315" - 6" which is very slightly oversize. The centre hanger centre post has to be drilled exactly in the centre of the centre hanger inner rectangle (width wise), be totally square to it and as well, be straight/on size. I also made the centre post a tap fit in the drilled holes. As far as I could tell, they all were.
The centre hanger inner rectangle has to be truly that and here there was a problem. Mine, after machining, turned out to be very slightly barrel shaped.
As a result of the above, some of the spring leaves would hang up on one side or on the other of the inner rectangle side walls.
The solution, more dog work.
The edges of the offending leaf springs were stoned down a bit with an oilstone, the centre hanger inner rectangle was carefully re-worked near each end and in the corners with a square file, and each 1/16" dia. centre post was given a lick with a fine needle file in the lathe and a slight taper filed on one end.
After that, final assembly with no problems.
End of story.
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Re: Constructing The Josslin NYC Hudson Lead Truck
The next and last operation is to drill both ends of each leaf spring bundle for the leaf spring end hanger pins, a total of 4, 3/32" diameter holes.
It is one of those operations which looks easy until one actually has to do it and then it isn't.
The drilled holes have to be equidistant from the centre of the longest leaves (1-3/16" as per the Josslin drawing), they have to be exactly centred on the leaf springs width wise and also be truly radial (i.e. at right angles to a point on a curve). This last requirement left me scratching my head for quite some time.
See the first photo for how the equidistant requirement was met. One could also use a close fitting pointed rod. If the ends of the leaf springs have layout dye, and one rotates the drill carefully, this will result in a small visible dot. Then check with an engraved scale under magnification and good lighting.
A practical method of achieving the radial requirement (and it has to be practical) was to first draft a circle sector cutout in stiff cardboard having a bottom curvature of 6" ( the rolled in curvature of the top leaf spring) as described previously. It is important that the sector have a clear visible centreline as shown. See the second photo (729).
The sector template cutout was carefully cut as shown in the third photo (730), the bottom radius made to match the top leaf curvature as seen in the photo.The sector template curve was rough cut and then carefully belt sanded down to the layout line with final hand sanding to remove any raised burrs.
The basic setup in the mill for locating the leaf spring end hanger drilled holes is shown in the last photo (731). It is rather tricky and tight. One needs to use the drill bushing to have centre width wise, one needs to have the small toolmakers clamp hold the ends of the spring steel leaves tight together for the drilling operation, the backing spacer block needs to be exactly as shown to give vise jaw clearance to the toolmakers clamp, to locate the drill bushing (both on width and distance) from the leaf spring centre and to allow positioning of the drill.
To be continued.
It is one of those operations which looks easy until one actually has to do it and then it isn't.
The drilled holes have to be equidistant from the centre of the longest leaves (1-3/16" as per the Josslin drawing), they have to be exactly centred on the leaf springs width wise and also be truly radial (i.e. at right angles to a point on a curve). This last requirement left me scratching my head for quite some time.
See the first photo for how the equidistant requirement was met. One could also use a close fitting pointed rod. If the ends of the leaf springs have layout dye, and one rotates the drill carefully, this will result in a small visible dot. Then check with an engraved scale under magnification and good lighting.
A practical method of achieving the radial requirement (and it has to be practical) was to first draft a circle sector cutout in stiff cardboard having a bottom curvature of 6" ( the rolled in curvature of the top leaf spring) as described previously. It is important that the sector have a clear visible centreline as shown. See the second photo (729).
The sector template cutout was carefully cut as shown in the third photo (730), the bottom radius made to match the top leaf curvature as seen in the photo.The sector template curve was rough cut and then carefully belt sanded down to the layout line with final hand sanding to remove any raised burrs.
The basic setup in the mill for locating the leaf spring end hanger drilled holes is shown in the last photo (731). It is rather tricky and tight. One needs to use the drill bushing to have centre width wise, one needs to have the small toolmakers clamp hold the ends of the spring steel leaves tight together for the drilling operation, the backing spacer block needs to be exactly as shown to give vise jaw clearance to the toolmakers clamp, to locate the drill bushing (both on width and distance) from the leaf spring centre and to allow positioning of the drill.
To be continued.
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Re: Constructing The Josslin NYC Hudson Lead Truck
To use the circle sector template to set the spring bundle radial, see the first photo (732). The bottom of the centreline on the pie shaped sector template is set on the layout "dot" on the top leaf spring and the template centreline is aligned to a machinist's square set on the top of the milling machine vise jaws. My vise jaws have been ground square and parallel to the base of the milling machine vise so this aligns the circle sector template centreline parallel and radial to the spindle of the milling machine.
This is a truly fiddly operation as one really needs 3 or 4 hands to do this (to tap the entire assembly around into position without losing the overall alignment). One has to partially release the vise jaw pressure and with this vise, the vise jaws are either locked or are loose so... but in the end I managed through patience and determination. The vise also has openings in its base into which things disappear regularly so in the end I got fed up with this and closed them off with some masking tape.
To do the actual drilling after aligning all parts I used the cutting tools shown in photo 734. I did not have a 3/32" dia. carbide spade drill on hand to do the drilling this time, it being destroyed by a spring steel cutting operation previously so I used what was available. A carbide spade drill is not really suitable for this operation as it is only designed for thin sheet metal drilling and having to drill down through several spring leaves, this is regular or even deep hole drilling. So one should use a regular carbide stub drill for this operation (which I didn't have either). So the sequence was drill bushing/ 1/16" HSS drill for alignment, followed by the 1/16" dia. spade drill to produce a very shallow hole, followed by a 3/32" dia. (short length of cut) carbide end mill (slight plunge milling) to deepen the hole and finally a 3/32" dia.(long length of cut) carbide end mill to plunge cut right through all of the leaves.
This worked but the spring steel got back at me for on the second hole the long carbide end mill jammed and snapped off! The reason for this was the outer ends of the spring leaves were clamped together tightly with the toolmakers clamp but the inner shorter leaves where the carbide end mill cuts through leaving only a half or partial circle were still free to flex under the cutting action and they did jamming the cutter. I could have made a second custom support block to prevent their movement, but it would have made the basic setup even more complicated and fiddly than it was. In the end the holes cleaned up nicely (photo 733) but lesson learned, as I have said before spring steel will show its nasty side whenever and wherever it can.
The last photo (735) shows how it all went together in the end and yes, I have to say the above method worked very nicely.
This is a truly fiddly operation as one really needs 3 or 4 hands to do this (to tap the entire assembly around into position without losing the overall alignment). One has to partially release the vise jaw pressure and with this vise, the vise jaws are either locked or are loose so... but in the end I managed through patience and determination. The vise also has openings in its base into which things disappear regularly so in the end I got fed up with this and closed them off with some masking tape.
To do the actual drilling after aligning all parts I used the cutting tools shown in photo 734. I did not have a 3/32" dia. carbide spade drill on hand to do the drilling this time, it being destroyed by a spring steel cutting operation previously so I used what was available. A carbide spade drill is not really suitable for this operation as it is only designed for thin sheet metal drilling and having to drill down through several spring leaves, this is regular or even deep hole drilling. So one should use a regular carbide stub drill for this operation (which I didn't have either). So the sequence was drill bushing/ 1/16" HSS drill for alignment, followed by the 1/16" dia. spade drill to produce a very shallow hole, followed by a 3/32" dia. (short length of cut) carbide end mill (slight plunge milling) to deepen the hole and finally a 3/32" dia.(long length of cut) carbide end mill to plunge cut right through all of the leaves.
This worked but the spring steel got back at me for on the second hole the long carbide end mill jammed and snapped off! The reason for this was the outer ends of the spring leaves were clamped together tightly with the toolmakers clamp but the inner shorter leaves where the carbide end mill cuts through leaving only a half or partial circle were still free to flex under the cutting action and they did jamming the cutter. I could have made a second custom support block to prevent their movement, but it would have made the basic setup even more complicated and fiddly than it was. In the end the holes cleaned up nicely (photo 733) but lesson learned, as I have said before spring steel will show its nasty side whenever and wherever it can.
The last photo (735) shows how it all went together in the end and yes, I have to say the above method worked very nicely.
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Last edited by Carrdo on Sun Apr 12, 2020 11:10 am, edited 1 time in total.
Re: Constructing The Josslin NYC Hudson Lead Truck
A couple of additional photos.
Two more holes to drill and I am finally, completely, finished. Only I now have to go out and purchase all of the carbide cutters which I should have used but didn't have.
Two more holes to drill and I am finally, completely, finished. Only I now have to go out and purchase all of the carbide cutters which I should have used but didn't have.
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Re: Constructing The Josslin NYC Hudson Lead Truck
Finished at last but again it fought me to the bitter end. No broken carbide cutters this time but you had better clamp all of the leaf spring free ends when drilling the ends of the leaf springs for the end hanger pins.
This is the third completed Josslin Hudson lead truck together with the rebuilt Langworthy Hudson lead truck - enough for a lifetime. The truck is a bit stiff but it all moves and rocks as it should.
This is the third completed Josslin Hudson lead truck together with the rebuilt Langworthy Hudson lead truck - enough for a lifetime. The truck is a bit stiff but it all moves and rocks as it should.
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