Author Topic: The Dickson!  (Read 10158 times)

Online sco

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Re: The Dickson!
« Reply #75 on: June 03, 2018, 08:26:37 PM »
They look nice and crisp!

Simon.
Ars longa, vita brevis.

Offline maury

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Re: The Dickson!
« Reply #76 on: June 04, 2018, 04:11:31 PM »
Dennis, great looking castings! I know the columns were a particularly interesting challenge because of the cores and curved parting line. Great work. Can't wait to get some.

maury

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Offline Dennis

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Re: The Dickson!
« Reply #77 on: July 25, 2018, 08:18:38 PM »
Hello everyone, I can't believe how long it has been since I updated the Dickson build, but we have been working on it.

This afternoon I went to the foundry to pick up castings for the HP and IP cylinders.  There are photos below.

Photo 1. the pattern for one of the cylinders.  I only put one cylinder on each pattern board. I was concerned there would be a lot of bad castings at the foundry because of the small internal passages I tried to cast into the part.  However, that wasn't the case

Photo 2. the assembled core box for the internal piston valve steam passages and the cylinder bore.  The core sand is blown into the mold under pressure and I am told this makes a stronger one piece core. 

Photo 3. the core box opened up.  The cores are about 3/16 inch thick in the thinnest areas so I was trying to get the strongest core I could.  When I was walking through the casting area, most of the cores there could be measured in inches, not 1/16ths.  It takes more work to make the core box this way but the results are really good and there were no bad castings at the foundry.

Photo 4. Finally, the HP and IP cylinders as they came from the foundry.

One more pattern to go, the Low Pressure cylinder.  The LP cylinder core is even more complicated because there are two sets of piston valves to get the volume of steam needed for this large cylinder to operate.  The cylinder bore, and each of the piston valves are on separate planes so a simple two piece core box won't work.  The pattern is about 80% complete and I will post photos when it is done.

I have also been updating and making additional drawings for the project.  Up to 240 sheets so far.  Everything has been checked for clearance as far as I can with Solid Works assemblies which is quite a lot.  However I am sure there will be a lot of corrections to the drawings as we machine more parts. 

I'm looking forward to getting back to the metal side of the shop to machine some of these castings.

Dennis

Offline maury

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Re: The Dickson!
« Reply #78 on: September 07, 2018, 09:03:47 PM »
After setting the Dickson aside for a couple of months, it's time to get back to work on it. I was waiting
for Dennis to finish up the shop drawings for the columns and valve gear.There are over 200 pages of
drawings, so he has worked quite fevorishly on this task. I was working on the Tank cooled mogul during
this time, when I get some time I might post the progress on it.

So the work on the columns is an interesting challenge.These castings don't have any easy ways to hold in
the machine for work, so I thought I'd post what I did. Don't know if this is the best way, but it seemed
to work.

Step1: machine the flat surface for the cross slide. This will be a reference for all other machining
of the part. The height of the back of the foot is measured, and the height of the back of the top foot
is added. A spacer is made to raise the back of the top foot to the calculated height, and the cross
slide is machined to the calculated height.

Step2: The Feet are machined. With the part clamped parallel to the front plane, it must alsp be aligned
with the right plane.This is done by measuring and centering 2 sets of features, The insides of the feet,
and the width of the casting at marked points near the cross slide. This step is tricky and precrious and
care must be taken.The feet are then machined to thickness and trimmed to their proper size.

Step3: The easy part. The DRO is setup and the mounting holes are drilled.

Step4: After the feet are machined, the part is set up in the top plane and right plane using the 2 machined
surfaces.The cross slide for the valves is machined to height, the the DRO is set up again.

Step5,6: The holes for the cross slide caps are drilled and tapped.

Step7.8: Time to make the slots for the valve gear. Using the same setup, the slots are milled.

The tops of the feet will have to be cleaned up a bit for the bolts to fit down nice. After all the columns
are machined they will be assembled to the engine base for machining the tops and the pads which are at
angles on the fronts and backs. This will be for another day.

maury
"The trouble with socialism is that you eventually run out of other people's money."... Margaret Thatcher

Offline Dennis

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Re: The Dickson!
« Reply #79 on: September 08, 2018, 11:39:54 PM »
Big step forward Maury!

Thanks for posting the photos,  the best way to machine a part is the way that works for you and the resources you have. 

I like the way you machined the column and will be following your lead when I get to machining my columns.  Securing that casting to the milling machine table is a real challenge when the only flat cast surface is the first surface that needs to be machined.   I'm going to look at the drawing sequence and make sure the multiple drawings for each column follow the machining sequence you used. 

It is really good to see some more parts taking shape. 

Great work figuring out the column machining.

Dennis

Offline mechman48

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Re: The Dickson!
« Reply #80 on: September 09, 2018, 11:33:11 AM »
Very impressed with the progress so far; read through your write up so far, well thought out & presented, inc. pics...  :drinking-41: look forward to eventually seeing the completed model in operation :ThumbsUp:

George.
George.

Offline maury

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Re: The Dickson!
« Reply #81 on: September 14, 2018, 10:00:52 PM »
George, thanks for the nice comments.

Interesting week on the CNC. I have made tool paths for about half a dozen parts for the valve gear, and decided to start with the levers. I think these are the hardest and most precarious parts in the valve gear. Mostly because of their size. It took a few tries to get the tool paths tweaked in so I liked the results. Most of the work was done on the CNC, but I finished up on the Bridgeport.

Maury
"The trouble with socialism is that you eventually run out of other people's money."... Margaret Thatcher

Offline Ye-Ole Steam Dude

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Re: The Dickson!
« Reply #82 on: September 14, 2018, 10:14:57 PM »
Hi Maury,

Nice work and good looking parts.

Have a great day,
Thomas

Offline maury

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Re: The Dickson!
« Reply #83 on: September 16, 2018, 07:28:36 PM »
Thomas, thanks for the compliment.

Well, I worked up a CNC job to make a cross slide part for the Dickson. It is a 3D job with 2 setups. The first one turned out badly, due to excessive backlash on the Y axis. I adjusted it best I could this morning, and made the second part. it turned out usable, but not really what I would have liked. I think I will have to be replacing the ball screw and thrust bearings on the Y axis in the not too distant future, or just maybe ask Santa for a new machine for Christmas.

The part:

maury
"The trouble with socialism is that you eventually run out of other people's money."... Margaret Thatcher

Offline 90LX_Notch

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Re: The Dickson!
« Reply #84 on: September 16, 2018, 10:13:42 PM »
Following along Maury.

-Bob
Proud Member of MEM

My Engine Videos on YouTube-
http://www.youtube.com/user/Notch90usa/videos

Offline maury

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Re: The Dickson!
« Reply #85 on: September 17, 2018, 11:01:11 PM »
Folks, had a break from the CNC today and back to the lathe and mill.
I made some valve linkage parts, all from 303 stainless.
The linkage is the adjustable part in the linkage, and the screw is RT hand on
the lower end and LH thread on the upper.

maury
"The trouble with socialism is that you eventually run out of other people's money."... Margaret Thatcher

Offline Dennis

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Re: The Dickson!
« Reply #86 on: September 19, 2018, 08:19:40 PM »
Good progress Maury,
Dennis

Offline maury

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Re: The Dickson!
« Reply #87 on: September 20, 2018, 09:10:50 PM »
Dennis, thanks for the comment.

Back to the CNC, thought I'd work on the rockers. THis is a difficult part to hold, so As I posted earlier, I made a new fixture. I'm using 3/8 square 303 stock. Was planning to make the part out of 1/8 stock and use a screw to hold the post on. decided to 3D the whole part. This is the first time I used the tab feature in my BobCam. nice feature. Also, to avoid cutting the fixture, I put some .008 brass shim under the stock. Seems to have worked out nice.

maury
"The trouble with socialism is that you eventually run out of other people's money."... Margaret Thatcher