Author Topic: Bernay Build - MZT  (Read 27509 times)

Offline mzt

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Re: Bernay Build - MZT
« Reply #30 on: July 25, 2012, 01:31:10 PM »


Alum. Bernay Taking shape


Had to solve a slight binding into the piston rods inserts, due to not enough side clearance into the rectangular slots : now I think of it,
I never cared checking their dimensions with the drawings while making them (?)  ::)

A few strokes with a round file (green circles in the photo) and so much for my previous efforts into having them nicely finished.  :big: :big:

A bit of work into cutting the rods to length, fitting the pistons, threading for the nuts, etc and here it is.





Marcello
This is a fitting job,
not a production job that can be measured in.

Offline mzt

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Re: Bernay Build - MZT
« Reply #31 on: July 25, 2012, 01:31:40 PM »

Steam Chests


Yesterday I finally got around drilling and tapping the holes for the valve stems and steam intakes into the steam chests, wonder why I postponed this simple task so long.

Here?s a picture of the two of them, patiently (not sure about that!) waiting for me to make and fit the valves and linkages.

Quite a pleasant view on my lathe bench, You know the feeling I?m talking about.




Now I think of the missing parts, the pipe fittings and steam covers are also still hidden somewhere  into the metals pile. Then the wooden bases,
one eccentric strap, a hundred studs (if I decide to go for them in place of screws), some castle nuts, gaskets, ?

Still enough work to do not to feel hastened into having it done.  ;D



Marcello


This is a fitting job,
not a production job that can be measured in.

Offline mzt

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Re: Bernay Build - MZT
« Reply #32 on: July 25, 2012, 01:33:09 PM »

Another eccentric strap

Here?s the plates, already cut (and fastened) to the central line. I?ve centered the RT under the spindle, then fitted the support
plate and drilled four holes in it for the holding screws. Now, I will mill the bearing area to size,  then cut the external shape
adding new clamps when the lower screws will cease supporting the workpiece.
 





The task was completed successfully, the bearing having come out of the machine to a light  fit with the eccentric. 
In a few minutes of handwork, I got the sliding fit I was looking for.
 
Valve gear

Quite a few parts in it!
Started with cutting all the rods for the two engines to the length specified on the drawings and the diameter I had chosen when
making the parts. I?ve not been too consistent when converting the 0.185? measure to metric: sometimes it came out to 4mm and in
some other occasion it came to 5.
Bright side is IF I manage to make them correctly, then there will be little chances to mount the improperly.

Just to make myself sure about what I was going to do, I cut all the arms from a strip of plastics, drilled the holes at the
specified distances and press fitted (some light hammer blows) the rods into them.

Both engines accepted them without complains: the only item I had to make different is the one I could not find a drawing for,
though I?ve gone through the set a few times: that?s #1 arm, the direct link from the bearing to the support bracket. There?s a
slight difference of a few tenths of millimeter between them in the measurements I?ve taken on each engine, for aesthetical reasons.




Though I has intentions of making them into metal as the next operation, I realized the press fitted arms on the brackets would have
got into the way bringing them to the desired level of completion. Rather do that job first and make the links later.

A quick look into the scrap box showed a few filing buttons of the shape I needed




But not of the correct diameter.

In fact?




I had to make them, but took no pictures neither of the buttons not the finished brackets.


Valve Rod gland nuts

Had ideas about making them through a form tool, here?s the results of my efforts with a Dremel on the second end of a 8mm lathe tool:
it cuts on the front and on the curved portion (the second notch being a relief for the end of the curve)
 



Here?s how it cuts, a ?facing? cut on a test piece from the odds and ends. Of course, had I chosen the second end of a longer tool,
the setup would have been easier, but so it goes?
Not perfect, but the idea is not bad. Gotta work on it a little more.



Not having enough length of 14mm hex bar to make the four nuts I needed, I made only two out of it, and got the other two by knurling
and doming some 13mm brass rod. Not that I had not thought about filing them from larger stock, but shop temperatures over 30C put
little interest into doing that. Rather drill and hacksaw the valve arms, instead.

Marcello

This is a fitting job,
not a production job that can be measured in.

Offline mzt

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Re: Bernay Build - MZT
« Reply #33 on: July 25, 2012, 01:33:46 PM »

Valve Arms

Step 1, drilling the holes.



 
Step 2, thinning the arms.



 
Step 3, rounding the ends.



 
Aint much happy with them.
I hold them through a single screw on the mandrel protruding from the chuck, had some slips, even turned the wheels in the wrong
direction a coupla times, maybe three. That?s working in haste.
Now I know how NOT to make them, will do the next set in a different way; better results are not guaranteed.


 
Good news are picture 1 unexpectedly revealed the place shop gremlins have hidden the valve pin that set me on the floor with a
led torch for over an hour (got back into possession of 3  long time missing M6 machine taps and a 5.10mm stub drill, tho). 
Still no news of the big red box of assorted O-rings, and that?s over a year now. An amazing mystery.


Marcello
This is a fitting job,
not a production job that can be measured in.

Offline mzt

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Re: Bernay Build - MZT
« Reply #34 on: July 25, 2012, 01:34:16 PM »

Valve Arms - try 2

Step 1, material cut overlength from a 20x20 bar and brought to thickness.
The plate they?re sitting on is a temporary iron sub-plate for the RT.





Step 2, holes drilled: this time I decided to drill and ream them 3mm dia (finished sizes will be 4 and 5mm depending
on the shafts dia. and required fit).




Step 3: having centered the RT with the spindle (ruler trick again) I fastened the sub-plate and drilled a 2.5mm hole for an M3 screw
in line with the spindle. Next, I drilled various 3mm holes at convenient distances and angles for a 3mm pin that should prevent unwanted
rotations of the workpieces. I had planned for another M3 screw, but that gummy iron base does not tap very nicely, and I have no
replacement machine taps in that size, should it break. Did not want to take unnecessary risks with it: the pin should do.




Marcello

This is a fitting job,
not a production job that can be measured in.

Offline mzt

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Re: Bernay Build - MZT
« Reply #35 on: July 25, 2012, 01:34:46 PM »


Valve Arms ? continued


What I did was rounding each of them between screw and pin, rounding each end to the depth of the arm (about 1.6mm)  then again on the second end.
A good clean and deburr of the now finished side and again to the other face.

Next, some blue and scriber, and again on the RT: this time to full depth, taking care of the imparted rotations (chose to make the +/- 140deg. from
the line passing through the screw and pin centers.

That meant mounting each of them 6 times.

When I realized I had forgot making two of them, I quickly mounted one, made a 360deg passage 1.6deep, reversed the item for a -140 to +140 deg full
depth cut and then cut the 80deg. I had left on the arm 1.6mm deep.
That?s 4 four setups instead of six, and they came out better finished.




Had I followed the ?original? plan I had, about mounting them between pin and STUD (3mm dia) they would have come out of the machine in better shape:
the tiny difference in diameter from the screw I used and the reamed hole can be spotted. Was too eager to put the word ?DONE? on them.
They will clean, but I will have to make a few studs like that in any case, so that would have been time well spent.



I want to see whether and how this thingy runs, simply cannot wait anymore. Gotta find another cure for that.



Marcello
This is a fitting job,
not a production job that can be measured in.

Offline mzt

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Re: Bernay Build - MZT
« Reply #36 on: July 25, 2012, 01:38:31 PM »
Something "new", finally.  :)
----


Valve Arms ? its taking forever?

Milling the arms, having set them parallel (at an angle, in the picture below) to the vise through a couple of pins into the holes.
 



A repetitive job, but the worst is yet to come.



 
Being too late to pay a visit to the pub (and not too early to go to bed) I spent a little time toying myself with some small dia. rods,
scissors, double sided tape, glue, paper, ad paper tape.
The idea being making some small, finely grained, sandpaper drums to be used on the Dremel: cut a strip of sandpaper the size of the double
sided adhesive tape I had, then cut an equal length from the roll and made myself a strip of adhesive sandpaper. (Not such a good idea, in hindsight)
Wrapped enough of it around the rod to make a full turn (in the correct direction) and cut it 5mm overlength for overlap; peeled off the
sandpaper from the tape (You see why making that strip was not so clever)  and put a drop of glue on the back of the overlap.  A second wrap
into plain paper, then some adhesive tape to keep it tightly wrapped till the glue cures, with the idea of putting them to the test on next
shop session.

?Valve Arms ? hunting for a decent finish

Completely forgot about them drums! Spent about three hours working with files, tool blanks of square and round sections wrapped into
various grades of sandpaper, to improve the finish of three and half of them arms. Then, they came to mind, and I could get to the end
of the first set in another hour.




PS. If You go this way, take care to use rods small enough to fit the rotary tool You?re gonna use: my brass one, didn?t!
 
Before




Five minutes later (same position, the blue ink mark on the link was purposely added after taking the first picture).



 
Didn?t get the decent finish I was looking for, ended with some half decent finish, though better than what can be seen here.
Gotta put them in place on the engine, to judge whether it would be enough.



Marcello
This is a fitting job,
not a production job that can be measured in.

Offline smfr

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Re: Bernay Build - MZT
« Reply #37 on: July 25, 2012, 04:44:05 PM »
It's great to see this build here. Lots of good stuff in it!

Simon

Offline mzt

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Re: Bernay Build - MZT
« Reply #38 on: July 26, 2012, 10:26:56 AM »

Press Jigs

After soOOO many years, I finally got around making a few reamed jigs to help keeping shafts square when pressing them.
Even put a label on a plastics box to store them in!




They worked so well I could assemble the valve links and rotate the crankshaft without sensing binding points.


 
Now, for the valves, covers, and retainers.


Marcello
This is a fitting job,
not a production job that can be measured in.

Offline mzt

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Re: Bernay Build - MZT
« Reply #39 on: July 27, 2012, 11:10:32 AM »
The Alu. Bernay

The Alu. Bernay
Yesterday night, I got the second set of links pressed. Some light knurling on one end of a 5mm shaft was in order as the not all the drills
had come out to a press fitting size (*).  They hold well. (On the previous set I had to knurl the 3mm pins only, but that was by choice).
Some light bindings here, but they were not in the valve links: they?re again as square as they need to be.
The problem is in the bearing: I would have sworn I had already brought it to completion, still it needs some work with filing buttons,
hacksaw  and some smoothing on the faces.
I have ideas that making the two halves into different grades of alu. wasn?t smart.  Aluminium itself for bearing use isn?t, but there?s not
much brass left on the shelf.
Got ideas about some simple mods to the press, too.  Should make the thing more usable.

 


As for rounding the bottoms into the valve brackets, I see that it went forgotten.
Other unfinished parts, I can dismount and polish later.


Marcello


---

(*) Got a set or ?unpredictable? tin-coated drills. Some cut larger, some cut less than the nominal size.
As I was looking for a less than 5mm hole, I pre drilled 3.5 than 4.7, tested,  4.8, tested again, 4.9 was what I wanted!

The second drill, I made 3.5, saved a little time on 4.7 and 4.8 going straight to  4.9 
Sliding fit.
Lesson learnt.




This is a fitting job,
not a production job that can be measured in.

Offline smfr

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Re: Bernay Build - MZT
« Reply #40 on: July 27, 2012, 07:07:52 PM »
It's great to see these two engines coming along. Following with interest!

Simon

Offline ref1ection

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Re: Bernay Build - MZT
« Reply #41 on: July 30, 2012, 04:56:57 AM »
Marcello,

It's great to see these engines coming to life. I wondered who would be the one to build this. Following along for the rest of the build with interest.

Ray
Indecision... the key to flexibility!

Offline mzt

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Re: Bernay Build - MZT
« Reply #42 on: July 30, 2012, 08:04:12 AM »

   She runs.


Marcello
This is a fitting job,
not a production job that can be measured in.

Offline swilliams

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Re: Bernay Build - MZT
« Reply #43 on: July 30, 2012, 08:48:29 AM »
"She runs."
That's great Marcello. A real nice pair of engines you're building here

Steve

Offline mzt

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Re: Bernay Build - MZT
« Reply #44 on: July 30, 2012, 01:10:58 PM »


Small fittings, valves and steam chest covers.

Cut two covers from 4mm brass sheet, and another couple from some black anodized alu.: just drilled the holes for the screws,
will bring them to dimensions after the ?test?.  I?m in haste, now.

Here are the valve rod ends as they came out from the lathe, going to be drilled for their threaded holes.



 
Some tapping later, I?ve the problem of holding them for milling the elongated holes. My solution came through machining a push fit
holder, still in the vice, to hold them while plunge milling the holes.
No problems, here. They will come later.



 
The set of valve retainers, being drilled for the grub screws, then milled for the flats.  The brass screw I put as an indicator,
to have the flats square to the tapped hole. Useless.






In fact, I drilled them in a row, on the lathe. The drill bit, meeting the cross holes wandered into any direction.
Here?s the (poor) results.




Will do, in ?matching? sets of two.

The other retainers, I made on variations of the same way, with identical results: the only way that worked, besides making them one
at a time, was pre-drilling the axial hole first, then the cross holes.
 
A tool I?ve made from a piece of alu. tubing and a bit of steel from the scrap boxes.




Should help into shortening (quite) a few 4mm M3 grub screws to the length I need them without shortening my already clipped finger nails. 
I?ve no idea whether it would work or not, I?ve not used it yet.




Made a couple of valves (three to be exact: had to remake one of them  when I got too enthusiastic into turning the wheels when milling
the pocket, and stopped the table travel a couple of millimeters too late.


First test run.

(On the alu. Bernay).
Failure, however I timed the valves. ?That?s that one I screwed, obvious?. Remade it, fitted the new one.
Failure again.
Best I could get was a turn and a half, at full pressure. Providing I gave a strong start  to the wheel with my hand.
Ain?t particularly satisfied with my work. (That?s only four lines, but they took good part of the afternoon).

Decided to put aside the alu. and gain some prize out of the bronze one: ?it?s much smoother, when turned by hand?.

Dismounted the valves, fitted them to the other engine, played with the timings, the pipes the pressures, oil thickness, whatever?

The only positive result I got was two consecutive strokes when giving pressure in some carefully chosen positions of the crankshaft,
never a full turn.
Dinner time is long gone, now.  I?m in a mood for tears and a booze. Went to the pub.
(Got ?granita?, instead: crushed ice and mint syrup).
 

New valves

As they are shown below, made on different dimensions (they cover a wider area, and have a smaller pocket) out of C.I.




When looking for the edges of the wp. I held a tool blank in contact with the sides and moved the table till I felt the milling bit was
touching it: there?s no need for a precisely centered pocket here, as long as the offsets are  within reason. Ended with 3/100mm difference, btw.



 
New valves, new day, same results: a non runner. Two, TTTT.
 





Where the problem(s) were

Decided to dismount everything, add some (petr)oil, ..



 
..and clean it thoroughly, for a start.
 
While I had it apart, I took the occasion to add a few ?extra? features:
A  0.6mm hole, counterbored 3mm, then countersunk, on the insert, to act as oil reserve for the crankshaft. (The drawings show two diagonal
drills from the sides, but I should have drilled them before finishing the surfaces, now I won?t risk the look of the part.



 
Another 0.6mm drill into the crosshead insert, at the bottom of the already threaded hole. Here, there?s room for a small screwed in oil cup,
if I get around making it.



 
Piston grooves: made a square groove, then lunged a V at the bottom of it. Didn?t take measures, while making them, they should be about 2.5mm
wide and slightly deeper.
Being piston rings still out of scope, for me, I had ideas about fitting some cannabis into the groove: the type plumbers use to make joints.
Put some onto the piston and valve rods, too.
 



Then, made blade out of the ?china ink? end of a compass, the type we used in school times to drop wide stains of black undeletable ink on
already finished pencil drawings, for us to have a valid excuse to make them again.
 



Worked like charm, got all head gasket made in a few minutes. Other gaskets for steam chests and covers, I made with an ordinary knife cutter
and steel ruler.
The material is not the best, I agree, nor its colour. 

While looking for the causes of the malfunctions - it only worked with the pistons on the down strokes (now, it should work on the UP stroke,
if any! There would be less leaks, in it! -  I noticed the heads completely covered the cylinder ends of the lower steam passages. Being very
close to the cyl. dia. they made a nice seal, there.

All She was in need with, were gaskets, packings and 30 seconds work with a rotary file on a Dremel: re-mounting the parts, with no variations
into the valve timings, gave working results.
 




Marcello



This is a fitting job,
not a production job that can be measured in.