Constructing the Josslin Hudson

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Carrdo
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Joined: Thu Mar 06, 2003 2:20 pm
Location: Toronto, Canada

Re: Constructing the Josslin Hudson Part 58

Post by Carrdo » Sat Oct 17, 2015 4:36 pm

More work on the basic frame assembly, specifically, the cradle casting.

I am jumping around wildly from one part to another but that is the way I do things.

This project has been sitting around waiting for me to do something about it since 2010 when I first sketched out the pattern drawing needed to produce the part. I could have produced the part from the solid as it is not difficult to make but I wanted to try my hand at pattern making.

First it is a two part pattern which is new to me. One has to start somewhere.

Second, I have a mentor who is assisting me.

Third, it is the drawbar pocket on the engine cradle. Most cradle castings have the drawbar pocket cast in as part of the cradle but the Josslin Hudson cradle does not. It is made as a separate piece which attaches to the rear of the cradle.

More machining....

The first photo shows the setup used to produce the 3 degree draft on all sides on one of the parts. Not my first choice on the way to do it but when conditions become pressing and you have to finish the job fast...

Just make sure everything remains square, you are firmly clamped and take light cuts with a sharp cutter.
Attachments
544 Setup to Achieve 3 Degree Draft for a Two Part Pattern (cradle drawbar pocket).jpg
545 Finish Machining the First Part of the Two Part Pattern.jpg

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Carrdo
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Re: Constructing the Josslin Hudson

Post by Carrdo » Sun Nov 01, 2015 6:14 pm

I was stopped for a while on the second piece of the pattern due to not having the needed cutter. Poor planning on my part.

Had to purchase a rather expensive 3 degree tapered carbide 1/8" ball end mill as shown in the photos.

Ran the end mill(s) as fast as I dared using aluminum cutting fluid. What a mess. The chips made a glue like paste which sticks to everything.

On work like this the rule is to do the internal machining first; so roughed away most of the cut with a 5/8" two flute HSS end mill and only used the special tapered carbide cutter to finish the tapered side walls of the cutout. The two pattern pieces should fit closely together when finished.

Just slow careful work.

The pattern person says one piece of the pattern will be the cope the other piece the drag.
Attachments
546 Internal Machining on Second Part of Pattern.jpg
547 The Two Part Pattern Pieces.jpg

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Carrdo
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Re: Constructing the Josslin Hudson

Post by Carrdo » Mon Nov 02, 2015 7:06 pm

The second part of the pattern roughed out with all of the cutters employed to get it to this stage and for final finishing. Every surface on this part, except for the top, bottom and flange underside surfaces, will be tapered 3 degrees.

I don't particularly like roughing out and I don't like machining aluminum so am happy this fun job is coming to an end.
Attachments
548 The Second Part of the Pattern Roughed Out.jpg

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Carrdo
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Re: Constructing the Josslin Hudson

Post by Carrdo » Tue Nov 03, 2015 6:48 pm

A couple of finish machining shots.
Attachments
549 Finish Machining.jpg
551 Finish Machining.jpg

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Carrdo
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Re: Constructing the Josslin Hudson

Post by Carrdo » Wed Nov 04, 2015 4:54 pm

Some additional finishing shots and the finished pattern piece.

Will see what the pattern person has to say.
Attachments
553 Finish Machining.jpg
554 Finish Machining.jpg
555 Finished Pattern Piece Located on Cradle.jpg

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Carrdo
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Re: Constructing the Josslin Hudson

Post by Carrdo » Thu Nov 05, 2015 2:55 pm

The pattern pieces will be put in the mail as the pattern person said they looked good and he would be willing do the bronze castings. I will have 7 pieces cast.

In the meantime, onto other adventures.

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Carrdo
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Re: Constructing the Josslin Hudson

Post by Carrdo » Thu Dec 17, 2015 11:23 am

I picked up the drawbar pocket castings yesterday and they look excellent. See photo.

On one casting you can see the gates and runners which have been left on while the two little spikes on the same casting are the air vents.

There is a lot more to this casting business than meets the eye. It is quite a procedure. I took some photos of how the pattern was placed in the cope and drag box and then how the pieces were manipulated and of the moulding sand used but the home shop caster took shots of the entire procedure.

Some of the other patterns produced by the castor for his own projects are incredible.
Attachments
558 Bronze Castings Produced from Pattern.jpg

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Carrdo
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Re: Constructing the Josslin Hudson Part 57

Post by Carrdo » Sat May 21, 2016 6:42 pm

I finally succumbed to digital machining.

For locating, drilling and boring of the various side rod crankpin openings, I took the partially machined side rod blanks over to Richard's place and his digitally equipped Bridgeport.

But first, we had to determine how good my machining was up to this point.

As described in Chaski recently and elsewhere, we used the push/pull method to measure the actual axle distance between the first and third axle and then the actual distance between the third and second axle. Vernier caliper readings were also made over the axles on the RH and LH frames to determine if there was any side to side variation.

Compared to the print spacing, the actual vernier caliper measurements indicated a reading of 0.003" greater than the print dimension over the first and third axle (11" plus) and 0.002" greater than the print dimension between the third and center axle. Not bad for purely mechanical non digital layout work, using only a good graduated scale, an eye loupe, good lighting and a fine point scriber. But what was more important, the vernier could not detect any variation side to side (when a measurement was taken at either the RH or LH frame). So all of the axleboxes were truly square in the main frames and in a straight line. I was really happy.

The photos show the setup used and the final boring of a front side rod. The partially machined blank was first indicated along the leading front edge (the reference edge) to ensure the side rod blank was dead parallel. Richard routinely sets the digital readout to 0.0002" (as it can discriminate down to 1 micron which is 0.001 of a millimetre!). I doubt the machine can do this and my boring head and telescoping gauges certainly can't, but I can do better than 0.001" by "feel".

One final note, I used both a new carbide and HSS boring bar (which had been freshly sharpened by me) and the Bridgeport's finest (automatic) quill down feed. No contest. The finish with the HSS boring bar was by far the better of the two. For home shop work, properly sharpened HSS can't be bettered (my experience).
Attachments
370 Boring the Main Crankpin Opening on a Front Side Rod.jpg
371 Boring the Leading Driver Crankpin Opening on a Front Side Rod.jpg

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Carrdo
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Re: Constructing the Josslin Hudson

Post by Carrdo » Sat Jul 09, 2016 10:22 pm

Had another session at Richard's today on his mill and completed the boring and reaming on both front side rods.

I had a small center drill shatter when drilling the third and final hole on the second front side rod. As always the worst thing that could happen did at the worst possible place and time. Of course the shattered HSS bits were thoroughly cemented in to the center hole.

After struggling to grind the pieces out I thought that the work may have shifted which would have been a start over again situation but fortunately nothing had moved.

The digital readout x, y, z axes on Richard's mill are routinely set to 0.0002" so I don't think I need to worry about the hole spacing not being correct.
Attachments
372 Completed Boring and Reaming of the Front Side Rods.jpg

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Carrdo
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Re: Constructing the Josslin Hudson

Post by Carrdo » Fri Jul 07, 2017 2:19 pm

Pushing on with the Josslin Hudson side rods. This time with the rear side rods.

These Hudson side rods are more tricky to make than one can imagine. One has to study the Josslin drawings very carefully to appreciate this.

Firstly, the side rods are not symmetrical about the rods longitudinal center line i.e. they are cut deeper at the front than at the rear.

Second, there is a LH and a RH to these rods as well as a front face and a rear face. Both have to be marked and machined in relation to their final position on the engine.

Thirdly on the rear side rods, there is a stepped pin hole in the forked end of each rod and the stepped pin is inserted from the back of the rod making the largest hole size on the rear face/fork of the rod and the smaller hole size on the front face/fork of the side rod. This means that the partially machined rear side rod blanks have to be laid out on their rear face (with the rear face facing upwards), unlike the front side rods which all have straight through holes, to machine the stepped pin hole all at the same setting and to have the two fork hole sizes machined totally concentric. And this means that the partially machined rear side rod blank has to set up reversed to that of the front side rod blank. Don't ask me how I came to all of this.
Attachments
373 End Mill Drilling a Rear Side Rod Partially Machined Blank.jpg
374 Finish Reamed Forked End of the Same Rear Side Rod.jpg

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