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Turning the Piston ram on a 71/4 Hunslet

Viceroy

Joined: 14-10-14

Topics: 29

Replies: 39

Posted: Wed 28th Nov 2018, 11:39am
Turning the Piston ram on a 71/4 Hunslet

Could anyone give me a little advice on how to turn the piston ram for the brakes on my Hunslet, the casting from Reevs has no spigot just a small hole in the back of the casting, any advise would be most welcome.
 

Replies To This Post

Xz

Joined: 1-01-92

Topics: 25

Replies: 300

Posted: Wed 28th Nov 2018, 7:03pm

I'm not sure of what the finished article should look like, but could it be drilled in the lathe chuck and mounted on a mandrel?

 

Viceroy

Joined: 14-10-14

Topics: 29

Replies: 39

Posted: Thu 29th Nov 2018, 1:44pm

Hi Xz Please see the attached jpg file, thanks for the advice perhaps this makes things clearer
Hi Xz Please see the attached jpg file, thanks for the advice perhaps this makes things clearer
 

Xz

Joined: 1-01-92

Topics: 25

Replies: 300

Posted: Fri 30th Nov 2018, 11:14am

Yes, seems much as I suspected. The drawing doesn't show a drilling for a piston rod (perhaps there is another view, no matter). I would mount as close to centred as pos and drill for the rod and face the flat side, and then mount on a purpose made mandrel, and even if the hole is quite small as long as the flat face is butted onto the larger diameter of the mandrel you will be able to turn to size (there's probably plenty of meat on it anyway). Be gentle when cutting the ring grooves it may be prone to chatter.

If there is no rod hole then drill one anyway, if not needed, it can always be filled afterwards.

Bob G.
 

Viceroy

Joined: 14-10-14

Topics: 29

Replies: 39

Posted: Fri 30th Nov 2018, 5:49pm

Thanks again Bob G. No piston rod is required, the ram for the steam break works on a free none fixed activator arm, I will drill a hole and thread for a mandrel and then make good after machining. will be carefull

Thanks again, your advice is always supportive and very helpful. Kevin
 

Mick

Joined: 1-01-89

Topics: 9

Replies: 167

Posted: Fri 30th Nov 2018, 7:45pm

I only just got to see your question and I agree fully with Bob's comment. As you say these types of steam brake valve pistons don't have a crank and are effectively free in the cylinder. May I add one word of caution, this is an appalling looking pattern, the rough surface with its lumps and bumps will play havoc when you try to turn it, particularly on a small diameter mandrel. If you have recently bought it from Reeves I would return it and ask for a better one! If not, then try to remove as much of the rough outer layer as you can either by filing or on a linisher if you have one, otherwise the tool will snag and pull the job apart. Good luck.
 

Viceroy

Joined: 14-10-14

Topics: 29

Replies: 39

Posted: Fri 30th Nov 2018, 8:10pm

Thanks Mick,

Unfortunately the item " was " a Reev's casting brought about three years ago, I think filing and linishing will be the way forward and taking my time when turning

Thanks again.
 

EJParrott

Joined: 30-07-13

Topics: 2

Replies: 21

Posted: Mon 3rd Dec 2018, 9:59pm

Hold ins soft jaws, turn into one of the ring grooves, flip in soft jaws, finish turn. Don't know how much is left on the length, but if you turn from the right side on the drawing into the second groove, then when you flip it you can clock on the land between the rings to confirm it's true.
 

Viceroy

Joined: 14-10-14

Topics: 29

Replies: 39

Posted: Tue 4th Dec 2018, 1:18pm

My thanks again to Bob, Mick and EJ Parrot, After reading the initial advice from friends from 7 ¼ society, I filed and linished the surface of my casting, I then put the casting in a four jawed chuck cantered as best I could and then finished the back face of the casting, I then drilled a 5/16 dia hole in the reverse of the casting.
I then put a small piece of 1 ½ steel bar in my three jaw chuck and finished the protruding fact, then cantered the face and drilled and then drilled and taped and 5/16 BSF thread in the hole.
I then put the casting up to the face of the 1 ½ steel bar and using two steel washers on a 5/16 BSF bolt tightened the bolt until totally tight, I then centre drilled the bolt and using the tailstock locked the hole lot up for machining.
Please see the attached photo, I can confirm all is going well, and I have been taking my time when machining, today the outside diameter is complete, next will be the two seating’s for the two piston rings, I will then take down this structure and reverse the casting in my three awed chuck and finish the reverse face and finish the hole by welding or brazing etc. 
Any comments would be appreciated.
My thanks again to Bob, Mick and EJ Parrot, After reading the initial advice from friends from 7 ¼ society, I filed and linished the surface of my casting, I then put the casting in a four jawed chuck cantered as best I could and then finished the back face of the casting, I then drilled a 5/16 dia hole in the reverse of the casting.
I then put a small piece of 1 ½ steel bar in my three jaw chuck and finished the protruding fact, then cantered the face and drilled and then drilled and taped and 5/16 BSF thread in the hole.
I then put the casting up to the face of the 1 ½ steel bar and using two steel washers on a 5/16 BSF bolt tightened the bolt until totally tight, I then centre drilled the bolt and using the tailstock locked the hole lot up for machining.
Please see the attached photo, I can confirm all is going well, and I have been taking my time when machining, today the outside diameter is complete, next will be the two seating’s for the two piston rings, I will then take down this structure and reverse the casting in my three awed chuck and finish the reverse face and finish the hole by welding or brazing etc.
Any comments would be appreciated.

 

Mick

Joined: 1-01-89

Topics: 9

Replies: 167

Posted: Tue 4th Dec 2018, 1:36pm

Well done, you've made an excellent job, and I'm sure I speak for us all in saying we are happy to have helped. As far as the hole is concerned, I suggest filling it with a threaded piece of brass Loctited in.
 

Xz

Joined: 1-01-92

Topics: 25

Replies: 300

Posted: Tue 4th Dec 2018, 7:14pm

Seconded Mick. Glad it's gone well. I'm not sure the tail-stock was necessary, but nowt wrong with belt and braces.
 
 
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