Constructing The Josslin NYC Hudson Lead Truck

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Carrdo
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Re: Constructing The Josslin NYC Hudson Lead Truck

Post by Carrdo » Tue May 07, 2019 3:23 pm

All of the four axleboxes are now matched and ready to be drilled, bored and reamed for the axles. Just some slow careful work to get to this point.
Attachments
560 The Matched Axlebox Pairs.jpg

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Carrdo
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Re: Constructing The Josslin NYC Hudson Lead Truck

Post by Carrdo » Wed May 08, 2019 4:40 pm

Drilling, boring and reaming for the axle openings in each axlebox.

This is where having a matched set of axleboxes pays dividends. Actually, I made all four axleboxes to exactly the same external dimensions but one can make a double pair matched set also.

Set an axlebox up in the mill vise on parallels as per the first photo for center drilling-drilling. I used a custom made drill bushing (the drill bushing was turned to the same diameter as an axlebox was long) to set the center drill exactly on center lengthwise between the vise jaws. Then, I used an eye loupe to set the center drill in the cross direction to split the "line" between the axlebox body and the top edge of the celler insert. As seen in the last photo, this line shows very distinctly when part of the axlebox is surface ground and the other part is milled. After drilling, I made further (mechanical) checks to confirm that the the hole position was correct.

Each axlebox is set up the same way and as a result all of the axle openings in each axlebox will be exactly in the same position.

Drill, bore and ream as shown in the photos.

The result, a perfect centered running fit on an axle.
Attachments
561 The Initial Drilling.jpg
562 Intermediate Boring.jpg
563 Final Reaming.jpg
564 A Perfect Running Fit.jpg

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Carrdo
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Re: Constructing The Josslin NYC Hudson Lead Truck

Post by Carrdo » Fri May 10, 2019 11:13 pm

After machining the axle holes in the axleboxes, the twin axles which had been roughed out previously were finished. For these axles, cold rolled steel round bar was used.

The axle (running fit) bearing surfaces were 7/16" diameter with the wheel (press fit) surfaces 5/16" diameter. I use the standard rule for press fits of 0.001" per inch diameter of shaft size. Therefore, machine the axle ends where a wheel is to be pressed on 0.0003" over 5/16". I consider a running fit to have only 0.001" clearance for this size of axle assuming that the axlebox has been machined correctly.

To machine an axle, a 1/2" dia bar was held in a 1/2" collet in the lathe, one end of the bar faced square and then lightly center drilled. Reverse the bar end for end and face the axle to its overall print length. Then lightly center drill the remaining end.

Set the bar between centers in the lathe and rough down one wheel end and the center section to 0.005" over finished size. Reverse the bar and turn down the remaining wheel end section also 0.005" over finished size. For plain back wheels, ensure that the length of the roughed down center section is gauge +0.010" ( i.e. 3-9/32" +0.010"). But the Josslin wheels are not plain back for each rear face center hub stands 1/16" proud of the wheel rim. So, in this case, the length of the roughed down center section would be 3-9/32" -1/8" +0.010".

The above operation is also a good test of any twist in your lathe bed, how good your lathe centers are and how sharp is your cutting tool. With any of the aforementioned problems present, you will not turn parallel but taper with an unsatisfactory surface finish. Correct these problems before proceeding further. I do not intend to tell anyone how to do this here other than to say I had to slightly adjust my tailstock alignment.

Then proceed to finish an axle to the finished print sizes modified as necessary by the above requirements.
Attachments
565 Machining an Axle Between Centers.jpg
567 The Axles Installed as a Running Fit in the Axleboxes.jpg

gamh44
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Re: Constructing The Josslin NYC Hudson Lead Truck

Post by gamh44 » Sat May 11, 2019 5:16 am

Carrdo

Following along with your truck build - thanks for posting.
Carrdo wrote:
Fri May 10, 2019 11:13 pm
For these axles, cold rolled steel round bar was used.
So will you just have steel axles in steel axle boxes - or something between?

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Carrdo
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Re: Constructing The Josslin NYC Hudson Lead Truck

Post by Carrdo » Sat May 11, 2019 8:25 am

The axleboxes themselves are made from Meehanite cast iron which works just fine with the steel axles. I got this from no other than C. Purinton when I was in correspondence with him decades ago.

gamh44
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Re: Constructing The Josslin NYC Hudson Lead Truck

Post by gamh44 » Sat May 11, 2019 4:00 pm

Thanks.

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Carrdo
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Re: Constructing The Josslin NYC Hudson Lead Truck

Post by Carrdo » Mon May 13, 2019 11:17 am

Further work on the axleboxes, this time machining the top surfaces for the equalizers and then drilling the axlebox oil holes.

The round plug piece seen in the second photo was held in the drill chuck and used to center it over the top slot in an axlebox for the oil hole drilling.

The top portion of the oil holes were drilled vertical 1/8" dia. by 1/8" deep and then an axlebox was angled 30 degrees from horizontal and a #50 drill was used to drill through the bottom of the 1/8" section into the axle opening.
Attachments
569 Machining the Top of the Axleboxes for the Equalizers.jpg
571 Oil Hole Drilling.jpg
572 Angled Oil Hole Drilling.jpg
573 The Finished Oil Holes.jpg

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Carrdo
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Re: Constructing The Josslin NYC Hudson Lead Truck

Post by Carrdo » Tue May 14, 2019 2:40 pm

Finishing the axleboxes curved top.

After laying out the center top curve, the curve was generated by initially carefully belt sanding away the corner edges, followed by hand filing and finally to the finished profile by die filing.

Just a bit of slow careful work.
Attachments
574 Axlebox Curved Top Finished by Die Filing.jpg

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Carrdo
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Re: Constructing The Josslin NYC Hudson Lead Truck

Post by Carrdo » Thu May 16, 2019 7:34 pm

The start of machining the lead truck steel wheels. Basically, I follow Kozo's method (see Sept./Oct. 1992 Live Steam) with some minor variations.

The Josslin lead truck wheels have both a front and rear wheel profile. In the long distant past I made up some cardboard templates which, to date, have been used over and over again. See the first photo. The templates are marked as being an inner wheel face profile and and an outer wheel face profile and as well they have an arrow which points in the direction of the the wheel rim. You don't know how easy it is to get things mixed up here.

To machine the wheel face profile use a couple of different size nose radius turning tools and slew the lathe's compound around to rough out the profile, taking lighter cuts and checking more often with the cardboard template as the face profile is near fully formed. Then, I smoothed things out a bit with a riffler file.

I have shown this before but for "parting off" a wheel blank from a short piece of large diameter bar stock, I set up the bandsaw as shown in the second photo. Some comments and precautions on this.

Use only a very fine 32 tpi tooth bandsaw blade to avoid the blade snatching, rotating or even worse lifting the work. Do not use a blade with teeth as coarse as what is seen in the photo!! Use a wood block set at approx. the centerline of the work to "tap" the work gently against the bandsaw blade. Let the bade do the cutting and do not force it heavily into the work as light tapping will produce a straight cut. One will soon determine what pinch pressure and tapping force work best together.

The method works but it is very slow so if you don't have patience, don't go this route.
Attachments
575 The First Operation on a Lead Truck Wheel (outer face).jpg
576 The Bandsaw Setup to Part Off a Wheel Blank from a Short Piece of Bar Stock.jpg

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Carrdo
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Re: Constructing The Josslin NYC Hudson Lead Truck

Post by Carrdo » Tue May 21, 2019 7:18 pm

The first stage of wheel turning completed.

And if you think I machine in showroom conditions, I don't. See the first two photos. And that was after the second cleanup.
Attachments
577 Facing a Wheel Blank.jpg
578 Wheel Turning Chips.jpg
579 First Stage of Wheel Turning.jpg

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Carrdo
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Re: Constructing The Josslin NYC Hudson Lead Truck

Post by Carrdo » Thu May 23, 2019 11:12 am

The second stage of wheel turning.
Attachments
580 Second Stage of Wheel Turning.jpg

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Carrdo
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Re: Constructing The Josslin NYC Hudson Lead Truck

Post by Carrdo » Thu May 23, 2019 8:06 pm

Turning on the backside of a wheel with the toolbit set upside down in the toolholder.
Attachments
581 Turning on the Backside of the Wheel with the Toolbit Upside Down.jpg
Last edited by Carrdo on Thu May 23, 2019 8:08 pm, edited 1 time in total.

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