Constructing the Josslin Hudson

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Carrdo
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Location: Toronto, Canada

Re: Constructing the Josslin Hudson

Post by Carrdo »

Finish profiling the bottom section of the front side rods. The setup looks to be a bit of a hash but it worked fine when used with light cuts and a sharp cutter.

One has to support the rods as shown in several places in order to avoid bending or distorting them when the table clamps are fully tightened. I also wondered how well the bottom of the tee slot had been machined as, with this setup, the bottom of the slot was used as the final reference surface upon which everything rested but in the end the centre portion of the rods came out dead parallel and on size.

Still have at least six more operations to go.
Attachments
889 The Setup and Machining of the Bottom Middle Section of the Front Side Rods.jpg
890 The Fully Profiled Front Side Rods.jpg
Carrdo
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Joined: Thu Mar 06, 2003 2:20 pm
Location: Toronto, Canada

Re: Constructing the Josslin Hudson

Post by Carrdo »

The finished front side rod fluting. This was not without a few issues.

The Josslin prints call for a 5/16" wide inner fluting leaving a 1/16" wide rib on the top and bottom.

One has to remember that the diameter of the cutter on the inner fluting has to be the same size or a size smaller than the diameter of the cutter of the primary or the outer fluting as, if it is not, the larger diameter cutter will cut past the end vertical line of the primary fluting before the inner fluting is complete.

As the Josslin prints don't specify these diameters, I just measured the prints and found the outer fluting could be cut with a 7/8" diameter end mill. So, the inner diameter fluting cutter, ideally, could be 3/4" diameter or 7/8" diameter maximum.

I planned to use a Woodruff cutter to do the inner fluting but guess what no manufacturer makes a 5/16" wide cutter having a 3/4" or 7/8" diameter. The widest one can get in these diameters is 1/4" as Woodruff cutters are made for other purposes.

I could have gone to a tee slot cutter as these are made in greater widths and diameters but they are not made on size, for example a 5/16" nominal tee slot cutter is actually 21/64" wide to give clearance in the slot. A 1/4" nominal tee slot cutter has a 17/64" wide face, very close to what was needed but I couldn't find one.

So, in the end, I went with a 1/4" wide Woodruff giving slightly thicker top and bottom rib widths.

The setup shows how this was done as described previously. The mill's table stops have to be carefully set to limit the length of the cut by taking careful trial passes initially. And as one cuts the slot deeper, the table stops will likely have to be adjusted slightly inwards as the slot length increases the deeper the slot becomes. The actual slot depth was measured with a vernier depth gauge as seen in the second photo.

Next will be to machine the rods to their finished thickness.
Attachments
892 Checking that Everything is Level.jpg
893 Inner Fluting a Front Side Rod.jpg
896 The Finished Front Side Rod Fluting.jpg
djjh87
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Re: Constructing the Josslin Hudson

Post by djjh87 »

Nice work on those rods. My little narrow gauge engine will not get quite the detail you and Odyknuck are turning out. Jim
No problems just solutions.
Odyknuck
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Re: Constructing the Josslin Hudson

Post by Odyknuck »

Really nice work on the rods
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NP317
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Re: Constructing the Josslin Hudson

Post by NP317 »

Looks great!
Brings back memories of machining the rods for my locos.
RussN
Carrdo
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Location: Toronto, Canada

Re: Constructing the Josslin Hudson

Post by Carrdo »

The next operation was to grind down both ends of the front side rods to their final thickness. This seems to be a straight forward operation although it is anything but that.

As with the rear side rods, the front side rods have 1/32" offset centrelines at each end. This is done so that the inner finished faces of all of the rods end up being in a straight line as the thickness of the finished big end of the front side rod is 5/16" while the small end is only 1/4" thick.

To ensure everything is as per the Josslin print, a detailed layout sketch was produced which gives the height of the two offset centre lines from a flat reference surface and then one has to work backwards from there to establish the amount of material one has to remove from each side of both end faces. And since both rod blanks were not of equal thickness to start with, the amount of material to be removed varies between rod 'A' and rod 'B'.

One needs to take accurate measurements, to check and check again that they are correct, as well as to orient each rod correctly when taking these measurements also ensuring ones markings and nomenclature are correct as it is all too easy to get things very wrong.

After that it was off to the surface grinder to remove metal on the inner rod end faces first as these faces are the ones which end up in line. Then a rod was flipped over and the front end faces ground down, this operation involving different thickness of metal to be removed as the front rod end faces are not in line. Do one rod this way and then repeat the same procedure with the remaining rod. I added a little metal blocking to ensure nothing moved.

I elected to do a little rod slimming at this point as shown in the third photo. With the rods oriented the way they are on the rod fixture, as seen in the third photo, shimming was now needed to bring the two rod ends back into line for slimming the centre portion of the rod. With the rods reversed, no shimming was necessary as the rear end faces of the rods are in line but not the front faces.

Hours and hours of careful work later, the rods are nearing completion.
Attachments
897 Layout Sketch Detailing What Material Still Has to be Removed at Each End of the Rod.jpg
898 Grinding Both Ends of One Side of a Front Rod to the Finished Thickness.jpg
900 Slimming Down a Rod.jpg
902 The Front Side Rods After Slimming and Grinding Both Ends to Final Thickness.jpg
Odyknuck
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Re: Constructing the Josslin Hudson

Post by Odyknuck »

Nice work. Having a surface grinder is really handy. Been wanting to buy one for years, just do not have a place for it.
Carrdo
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Joined: Thu Mar 06, 2003 2:20 pm
Location: Toronto, Canada

Re: Constructing the Josslin Hudson

Post by Carrdo »

Proceeding to finish machine the front side rods. This involves finishing the front side rod's tongue extensions to finished thickness.

The setup and description is much the same as described previously. From the centre line of the rod on the big end, it was determined how much metal was to be removed from one face of the tongue extension and the depth of material to be removed was measured with my vernier depth gauge set against the surface ground big end face.

Once one face had been machined, the rod was flipped over and the remaining tongue face was milled down until the tongue was a nice shake less slide fit in the fork of the matching rear side rod. Of course on one of the setups, the levelling shims had to be used as shown previously. The rod could also be removed and replaced on the rod holding fixture and thickness measurements taken without fear of losing the setting as I used the mill's table stops to set the end mill travel and the rod's position on the fixture was maintained by the fixture locating pins which were firmly tightened at all times.

After removing all machining burrs, the front and rear side rods could now be assembled as a unit.

Still need to drill and chamfer all of the side rod oiling holes once all of the bronze bushings have been pressed in.
Attachments
903 Milling a Front Side Rod Tongue to Finished Thickness.jpg
905 Milling a Front Side Rod Tongue to Finished Thickness.jpg
907 The Finished Side Rods Assembled.jpg
Carrdo
Posts: 1444
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Location: Toronto, Canada

Re: Constructing the Josslin Hudson

Post by Carrdo »

The side rods coupled to the main drive wheels.

As expected, everything is very tight so some "quantitative easing" is in order.

Josslin was an excellent draftsperson but not a locomotive builder so in some areas he left hardly enough room for any movement. There are a few binds where some of the suspension bits interfere with the full rotation of the main drivers so now I have to tear everything down to the main frames and substitute some counter sunk miniature flat head cap screws where bolt heads now exist. This will give the necessary axle side to side end float of greater than 1/32" where none now exists due to the bolt head interference.

Always something more to do.
Attachments
908 The Side Rods Coupled to the Main Drive Wheels.jpg
Carrdo
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Joined: Thu Mar 06, 2003 2:20 pm
Location: Toronto, Canada

Re: Constructing the Josslin Hudson

Post by Carrdo »

Finishing the side rods by drilling all of the oil holes, eight in total having two different sizes using a #43 and an # 50 drill. The reason for the drill sizes is they are tap drill sizes and, if one wishes, one can tap these holes for a sealing plug or a miniature oil fitting in the future.

The machining operations were to set the rod level in the mill's vise using the flat ground block seen in some of the photos to the top of the vise jaws (as mine have been ground dead flat and to the same height in the SG) and, if needed, support the free end of a rod, then spot, drill and chamfer each oil hole.

Finally, deburr and clean everything.

I actually finished something which is amazing.
Attachments
910 Drilling a Small Oil Hole in a Front Side Rod Tongue.jpg
911 Spotting an Oil Hole in the Big End of a Front Side Rod.jpg
912 Spotting an Oil Hole in the Small End of a Front Side Rod.jpg
913 Chamfering an Oil Hole in the Small End of a Front Side Rod.jpg
914 Drilling an Oil Hole in a Rear Side Rod.jpg
915 The Finished Side Rod Assemblies.jpg
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Bill Shields
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Re: Constructing the Josslin Hudson

Post by Bill Shields »

Very nice
Too many things going on to bother listing them.
Carrdo
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Joined: Thu Mar 06, 2003 2:20 pm
Location: Toronto, Canada

Re: Constructing the Josslin Hudson

Post by Carrdo »

Whats coming up next. Fix an issue which I need to deal with now before proceeding further.

As I mentioned previously, as seen from the attached photos, the axlebox extended ear 2-56 NC hex head bolts need to be replaced with the same size flat head cap screws as with things as they now exist, these bolt heads interfere with the driver side to side end float. This became much more obvious after I trial fitted the side rod assemblies.

I will mark things in place as they have all been custom fitted but 12 of these bolts need to be replaced. Unfortunately, everything has to come apart again to effect this fix. The fix is definitely not prototype but as I want a detailed working model (with the emphasis on working) sometimes one has to deviate for very obvious and practical reasons. Anyway, one will never see the change.
Attachments
916 The Axlebox Ear Bolts which Stick Out from the Main Frames.jpg
917 Driver Side to Side Float Interferes with These Bolt Heads.jpg
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