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The Post Man Cometh.

James Coombes Engine

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Jerry Wray06/11/2014 07:40:41
84 forum posts
4 photos

While thinking about whiskey (whisky?)my mind went back over my own experience to recall when I was heavily involved in lining of steel drums. Our lab, probably the most expert in Europe discovered that resistance to gin and whiskey was the most difficult to achieve, more so than almost all other chemicals.

It's not the finish that's important but the characteristics of the polymer.

Jerry

Ian S C06/11/2014 11:01:33
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7468 forum posts
230 photos

Nick, on the flywheel casting there should be packing under the spokes, so that the clamp presses down on the spoke and the packing against the face plate. To get adequate clamping without the intervening packing risks breaking the spoke, or if like most of my flywheels the spokes will bend as they are made of hot rolled plate.

Ian S C

Nick_G14/11/2014 21:15:11
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1808 forum posts
744 photos

.

Bit of help please guy's. laugh

Whats the best machining process / order to turn this rascal :-

Into this :-

I presume the spigot in the bottom of the casting is to assist in holding during the process.

Many thanks, Nick

Paul Lousick14/11/2014 22:42:17
1652 forum posts
614 photos

Nick,

I would center it in the lathe chuck, face the back and turn the boss first which will give you a datum face and location diameter to machine the opposite sides and remove the location spiggot.

The drawing does not show any surface finish or tolerance for dimensions. Check it they are required before you start machining.

Paul.

Edited By Paul Lousick on 14/11/2014 22:43:55

Edited By Paul Lousick on 14/11/2014 22:47:25

Nick_G14/11/2014 22:52:29
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Posted by Paul Lousick on 14/11/2014 22:42:17:

The drawing does not show any surface finish or tolerance for dimensions. Check it they are required before you start machining.

Paul.

My understanding (possibly wrong) is that the drawings for Stuart engines are a 'guide' and parts should be made for 'fit'.

Thanks for the info on the sequence. It seems logical now.

Nick

JasonB15/11/2014 07:47:53
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Hold in 4-jaw , with spigot facing outwards and get it running as true as possible, use packing behind the flange to keep it at right angles to lathe axis. Remove packing and true up & face the spigot, you really only need the larger spigot dia so the small bit could be sawn off.

While still in the 4-jaw face the flange to leave the boss that goes into the cylinder, use the cylinder to gauge the size as you get close . Also drill and ream right through 3/16". This will keep the 1" dia and 3/16" hole concentric and at right angles to the top face of the cylinder.

Now hold the part by the spigot your Bison 3-jaw should be good enoght for this and face the gland boss so it is 7/16" from the machined flange face, counterbore 5/16" a drill will do for this. While held this way turn the top of the flange until it is cleaned up, leave the raised area around the gland boss as cast.

Finally hold it the other way around and turn off the chuck spigot and face the 1" dia, not critical if its a bit less than the 1/16" long

Finally mill the 4 edges square measuring off the 1" dia, then set the part true under the mill spindle and use co-ordinates to drill the 10 holes (zeuz tables will give you the calculation for the 6 holes)

lancelot15/11/2014 11:57:09
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63 forum posts
4 photos

Hi follks, Jason gave a very good run down on the machining sequence...I had to do the same only ''Different'' yesterday

reason being .when I started th build I worked to the first set of drawings...I found a problem 2 of them...the gland position was out of line with the cent of the 1'' spigit locator and the piston shaft a fair piece most of 2 mill....figured out how much to move spigot off centre and still retain working dimensions ...bored for shaft and found gland appr..40 thou. off ...stud positions ...nottoo happy ...a little off.........Three years later ''Parky''' I picked up on my build again...contacted Stuarts about the cover problem ...asked them if I should follow the first set of drawings ,as the latest showed 6 holes spaced against the first drg,,showed 4 spaced plus I had already fitted it to the cylinder It was agreed I should go with the original drg.......so that is exactly what I wasup to yesterday...following Jasons plan of attack 'less 2 holes'' one more thing ,,,height guage the centres of the gland stud positions and piston shaft centres front and bach of cover ....Good building.

Edited By lancelot on 15/11/2014 11:59:51

Nick_G15/11/2014 14:28:06
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1808 forum posts
744 photos

.

Cheers guy's

I shall attack this section at some point over the course of the weekend.

I may even use my newly delivered tools from Eccentric engineering. surprise

Nick

mechman4815/11/2014 16:49:46
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2828 forum posts
438 photos

The coloured packing's look like the backs of diamond hones, course, medium, fine, that I have, I don't see any wedge shapes, not that wedges would be very effective anyway.

George

Nick_G16/11/2014 17:18:42
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1808 forum posts
744 photos
Posted by mechman48 on 15/11/2014 16:49:46:

The coloured packing's look like the backs of diamond hones

George

Yup. That's what they are. yes

Nick

Nick_G16/11/2014 17:31:10
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1808 forum posts
744 photos

.

Some more progress made today. Although I did forget to photograph the cylinder end machining as described by Jason.

 

The piston was made.

 

And I could not resist stacking bits together to see how she was starting to look. (think I may need to 'fettle' the ports on the cylinder)

 

Nick smileywink

Edited By Nick_G on 16/11/2014 17:33:38

Nick_G17/11/2014 16:19:23
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1808 forum posts
744 photos

.

Are there any 'tricks', tips and general advice for drilling the PCD of holes.?

I know it's simple with a DRO fitted. But I have not.! sad

Cheers, Nick

JasonB17/11/2014 16:43:39
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19587 forum posts
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As I said in my instructions the formulas for various PCD numbers are in the Zeuz book so you just multiply your 1 5/16" by these to get the x & y co-ordinates. Or is you have a CAD package that will do it for you.

james coombes.jpg

To eliminate any backlash you may have it is worth then calculating these from one corner of the part rather than the centre point of the pcd, that way your handwheels will only be turning in one direction so you don't have to worry so much about backlash.

If you are going to spot through the covers to get the hole locations in the cylinder then a few thou error due to backlash is nor an issue

 

J

Edited By JasonB on 17/11/2014 20:49:33

Nick_G22/11/2014 21:30:08
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1808 forum posts
744 photos

.

Thanks once again Jason.

Today I made the crankshaft and it's associated casting. Fixing them together with locktight and a 3/32 silver steel pin pressed in through the side.

Then it seemed a good time to machine the bearings.

Have a good weekend everyone, Nick

Nick_G23/11/2014 12:08:55
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1808 forum posts
744 photos
Posted by JasonB on 17/11/2014 16:43:39:

To eliminate any backlash you may have it is worth then calculating these from one corner of the part rather than the centre point of the pcd, that way your handwheels will only be turning in one direction so you don't have to worry so much about backlash.

I have been thinking about the backlash and the fact that my machines are graduated in metric. To someone of my limited experience it's a recipe for disaster.! blush

The options I have are thus. (without taking the parts to my pro engineer friends workshop and using his DRO machines.)

1) Buy a DRO setup myself. - Nice, but I really have other calls on my money ATM so that is probably for the future.

2) I have a 2" travel dial guage. - Buy a second one (20 odd quidish) and configure them to record the X & Y thus eliminating any backlash and my feeble brain issues.

Nick

JasonB23/11/2014 12:32:02
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19587 forum posts
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3. use a claculator to convert to metric

4. Use your height guage to mark it out carefully, punch and drill. Use that part to spot positions onto teh second.

5. click a tab on the CAD to change dimensions to metricsmile p

jamescombesmetric.jpg

Edited By JasonB on 23/11/2014 12:54:39

Michael Gilligan23/11/2014 16:55:05
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17051 forum posts
757 photos

Of course, Nick ... Whilst you were machining the casting in the lathe, you could have just drilled the holes on a P.C.D. devil

MichaelG.

JasonB23/11/2014 16:57:59
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19587 forum posts
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Is that before or after Nick made some means to index the lathe spindle and a toolpost powered spindle to drill the holessmile p

Michael Gilligan23/11/2014 19:19:57
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17051 forum posts
757 photos
Posted by JasonB on 23/11/2014 16:57:59:

Is that before or after Nick made some means to index the lathe spindle and a toolpost powered spindle to drill the holessmile p

.

... or spent an hour knocking-up a bracket for his electric drill.

... and six is a pretty easy number to index.

MichaelG.

Nick_G23/11/2014 19:26:01
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1808 forum posts
744 photos

.

Don't make the sawdust in my bonce hurt any more than it does already guy's. - At this rate I will be fixing the cylinder ends together with wallpaper paste. wink

This evening I decided to machine the pedistal that supports the outer bearing.

Not the strongest of set ups so I took slow and light cuts.

It seemed to work out OK (except for the auto focus from the iphone wink)

Over to the mill to do the base side. Again not a major sturdy set up so I again went slow and light.

I gave quite a but of consideration to the mounting as I did not want to introduce even a small twist in the casting that would spring back once I took it out of the vice and leave me saying very rude words.! angry

It went thankfully OK - I deviated from the plan slightly by putting a recess into the center section of the casting.

Nick

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