Author Topic: Freelance mill engine from Stuart castings.  (Read 31682 times)

Offline steam guy willy

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Freelance mill engine from Stuart castings.
« on: October 19, 2017, 01:30:19 PM »
This is a new post and will be a mill type engine using the HP castings from the Stuart Triple . The engine will be designed as i go along using the engine block and a flywheel casting. The cylinders block was cut down first and then filed up by hand to get a true face on the porting part to work from.The block was then turned up to get the bore and end faces square and true.

Online crueby

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Re: Freelance mill engine from Stuart castings.
« Reply #1 on: October 19, 2017, 01:54:26 PM »
 :popcorn:

Offline steam guy willy

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Re: Freelance mill engine from Stuart castings.
« Reply #2 on: October 19, 2017, 02:28:59 PM »
The steam chest is then milled and filed up and there is a protosion/bump on the end for the valve rod to enter .to get this in line with the stuffing box drilled hole, an insert of perspex is temporarily fitted to stop the drill wandering about !!  The insert is then removed and the holes drilled to attach it to the cylinder block and the top plate is attached. The ports are cast into the block but are not quite square so these will have to be sorted out next !!

Offline steam guy willy

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Re: Freelance mill engine from Stuart castings.
« Reply #3 on: October 20, 2017, 01:47:29 AM »
The valve is made next, i have used a piece of scrap brass from a beer pump.... this is sawn out the and the transfer port milled. The buckle is filed up  and the next job is the valve spindle. The holes drilled through the parts is started off using an 1/8" drill as the end hole is i/8" to keep the spindle central . the spindle is however 5/32 " X40 TPI and the valve ,buckle and gland holes will be opend out to 5/32" next

Online crueby

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Re: Freelance mill engine from Stuart castings.
« Reply #4 on: October 20, 2017, 01:58:07 AM »
Willy, is it an optical delusion from the photo, or is the recess in the bottom of the valve slider too long? It looks like it will span all three ports at once.

Offline steam guy willy

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Re: Freelance mill engine from Stuart castings.
« Reply #5 on: October 20, 2017, 01:48:48 PM »
Hi Chris , you may be right however i did use the dimensions from the drawings,  they may be wrong ? will check it out when i get home !!!  The ports are a bit wonky and they are not dimensioned on the drawing so i am assuming you leave them " as cast " ............

Offline 10KPete

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Re: Freelance mill engine from Stuart castings.
« Reply #6 on: October 20, 2017, 05:14:59 PM »
Those ports should be machined out so the edges are square to the bore, straight, even and the two steam ports symetrically located about the exhaust. THEN you make the valve pocket to match/lap etc.

Pete
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Retired, finally!
SB 10K lathe, Benchmaster mill. And stuff.

Offline Jasonb

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Re: Freelance mill engine from Stuart castings.
« Reply #7 on: October 20, 2017, 05:33:20 PM »
Exhaust port should be 1/8" wide, 3/32" bars between and 3/32" inlets. They should all be 7/16" wide. recess in Valve should be 1/2" x 19/64" with the 1/2" in line with the 7/16" posts.

Knowing you a bit of work with a needle file will have the ports tidied up. Also poke a bit of wire down the passages as there is often core sand still in them.

J

Edited to 19/64"
« Last Edit: October 20, 2017, 06:25:05 PM by Jasonb »

Online Jo

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Re: Freelance mill engine from Stuart castings.
« Reply #8 on: October 20, 2017, 05:37:55 PM »
Willy turn the valve round by 90 degrees...  ::)

If you have the Triple drawings all the ports are dimensioned as is the valve.

Jo
Usus est optimum magister

Offline Jasonb

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Re: Freelance mill engine from Stuart castings.
« Reply #9 on: October 20, 2017, 06:26:05 PM »
Think the recess looks a bit too square so turning round may not work :(

Offline steam guy willy

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Re: Freelance mill engine from Stuart castings.
« Reply #10 on: October 20, 2017, 06:34:12 PM »
Thanks for these posts , and here are the original drawings......... the eccentric throws are 5/32" but set at 30 degrees ??? Jo, I thought i might have got the valve out by 90 degrees but i am a bit confused about the actually valve travel. The cavity is 1/2" which looks like the outside dimensions of the ports ? so will see what happens !!   also the Lomex exhibition poster, but i may not go as my neck is playing up...C2 toC6 joined together by plates ?!!!.....

Offline Gas_mantle

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Re: Freelance mill engine from Stuart castings.
« Reply #11 on: October 20, 2017, 06:37:10 PM »
Hi

Another member here, sent me this PDF file when I was asking for valve info  :)

Online Jo

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Re: Freelance mill engine from Stuart castings.
« Reply #12 on: October 20, 2017, 06:37:47 PM »
The cavity is shown in that drawing as 1/2" by 19/64ths... so 12.7mm by 7.54mm in real money.

the 5/32" throw gives an overlap of 0.4mm

Jo
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Offline Jasonb

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Re: Freelance mill engine from Stuart castings.
« Reply #13 on: October 20, 2017, 06:41:42 PM »
I doubt you need to have the eccentric leading the crank by 120deg (90+30) as you are making a single not triple. Something more like 100deg (90+10)should be a good starting point.

Offline steam guy willy

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Re: Freelance mill engine from Stuart castings.
« Reply #14 on: October 20, 2017, 08:50:34 PM »
Hi all thanks for the further info ...i have looked at the drawings and there are no dimensions shown for the porting ?? Also is there a write up on this engine in the ME magazine ??  Also this will be a single engine so will the throw be the same as the triple ?  Oh ,the joys of an undesigned  freelance !!!