Model Engine Maker

Engines => From Kits/Castings => Topic started by: AVTUR on August 02, 2019, 12:07:11 PM

Title: Hick Crank Overhead engine
Post by: AVTUR on August 02, 2019, 12:07:11 PM
My work on the Boulton & Watt Bell Crank engine is coming to an end with just a little painting and the base to finish. These will be done in the autumn and I will post pictures and comments on the forum before Christmas. To fill the gap between now and the return to the Maudslay Table engine design, when winter forces me out of the workshop, I am starting work on a model of a Hick Crank Overhead engine.

I bought the kit of castings six years and was not impressed with the quality of three of the castings. Also one small casting was also missing. I saw it as a difficult project with many fiddly bits so I wrapped it all up in anti-corrosion paper and bubble wrap, put it in a plastic box and found room for it on a shelf. Every so often I have taken a look at it, to see if anything had changed, and thought about having a go at it.

The original engine, a compact 10HP engine, was shown at the Great Exhibition of 1851 by Hick, Hargrave & Co of Bolton. In 1956 Geoffrey K King (A.M.I.C.E., A.M.I.Mech.E, A.M.I.E.I, Mem: Newcomen Society etc.) drew up a 1/12 scale drawing of the engine which is the basis of this model. I do not know if he ever made a model but some have featured on YouTube etc and one was displayed at the Bristol model engineering show a few years ago. As yet there are no instructions available for the engine build.

I find myself very critical of the quality of model engineering drawings. I have to admit that with the advent of CADs they have improved. Geoffrey King’s drawings are quite good but he has crammed an awful lot on small sheets of paper. I can forgive the use of fractions and first angle projection but I have never found the latter easy. I have got into the habit of redrawing all model parts to my satisfaction using decimal dimensions and third angle projection. This leads to a better, or at least quicker, understanding of parts and machining operations. So far, last year,  I have redrawn most of the castings.

It would be nice to show general arrangement drawings and pictures of a model of the engine but the only ones I have are copyrighted. I have found a picture of an engine, attached, on the internet which is in the public domain. It shows the top of the engine. The cylinder and steam valve are hidden by the plinth.

More will follow.

AVTUR
Title: Re: Hick Crank Overhead engine
Post by: b.lindsey on August 02, 2019, 02:51:31 PM
Should be a very interesting build to follow AVTUR.

Bill
Title: Re: Hick Crank Overhead engine
Post by: AVTUR on August 11, 2019, 05:13:16 PM
I have now inspected the castings:
1.   One bearing block cap casting is missing so I will have to machine one to shape from bar stock or an odd lump of gunmetal.
2.   One bearing block has been replaced by a lump of gunmetal. This is not a problem since the block can easily be machined from stock.
3.   The edge of the casting of one standard has run into the fancy Egyptian decoration, see attached photograph. I feel that this is important and needs correcting: Small models need something that catches the eye. An awful lot of models displayed at shows, however good, don’t have a “look at me” appeal. The only things that stand out on this model are the standards and the complexity of the small moving bits.
4.   Other than the above all the castings are above drawing/machining size.
5.   All the iron castings can be touched by a file.
6.   The bedplate is an aluminium casting and the fillets are messy, see attached photograph. This will require careful work with a file, Dremell or ball end cutter. I fear that the aluminium will be sticky and nasty to machine.

I am happy with the above and have painted the castings with marking out ink (sometimes I wonder why, I guess I wanted to). I have started filing the castings smooth, to get rid of mould lines, risers, etc. They will then be shot blasted to give a controlled rough finish.

The redrawing of parts, starting with the castings, is progressing. As stated earlier this leads to an understand of the parts. After the completion of each drawing the required tooling (drill, cutter, tap and die sizes), fixings and fixtures are recorded along with any obvious difficulties. Some problems have become apparent:
1.   Strange BA sizes, 9BA nuts and screws are required. Fortunately I have found a firm that stock these. 9BA taps and dies are also available from a few places.
2.   A 7/64” slot cutter is called for. I don’t think they exist but there is an obvious work round.
3.   There are a number of 3/64” wide slots. Although such slot cutters appear not to exist one can buy 1,0mm slot cutters for about £25 each (how many am I going to break). This is one reason for my interest in an EDM machine. Another option, as discussed elsewhere, is to use a piercing saw and a very small file.
4.   The layout of the cylinder to steam chest fixings is too large (the first drawing mistake).

On the plus side I have not found any fixings smaller than 10BA.

The original drawings were made before the advent of modern anaerobic adhesives. Quite a few fixings are captive and these can probably be replaced using Loctite. In addition keys have been used on shafts. I see no point in using them except for show.

More will follow

AVTUR
Title: Re: Hick Crank Overhead engine
Post by: Jo on August 11, 2019, 05:23:50 PM
I would use M2 rather than 9BA  ;)

Is this the same Hick Overcrank Engine that has recently become available from Hemmingway as a set of castings and drawings ? I have attached the Hemmingway GA so you can see if it is the same engine. In case anyone feels the need to build one of these engines the castings are available from Hemmingway here: http://www.hemingwaykits.com/acatalog/Hick___Son_Overhead_Crank_Engine___G_K_King.html

Jo
Title: Re: Hick Crank Overhead engine
Post by: AVTUR on August 11, 2019, 05:51:37 PM
Jo

It is the Hemingway kit. I do not know if they have had any castings made recently.

I did not post the picture for fear of copyright.

AVTUR
Title: Re: Hick Crank Overhead engine
Post by: Jo on August 11, 2019, 05:58:24 PM
I did not post the picture for fear of copyright.

Yes the image would be covered by copyright law. But copyright allows the sharing of a reasonable amount of a design for the purposes of discussion and I am sure Kirk will be more than happy if your documentation of your build results in additional sales of his castings, which I have provided a link to  ;)

Jo
Title: Re: Hick Crank Overhead engine
Post by: Jasonb on August 11, 2019, 06:47:33 PM
1.2mm milling cutters can be had fairly easily, MSC have several to choose from, I'm sure the extra 0.01mm over 3/64" won't be a problem.

As Jo says M2 fixings with old style hex proportions would be easier to source as well as taps & dies
Title: Re: Hick Crank Overhead engine
Post by: AVTUR on August 18, 2019, 01:27:04 PM
First: Many thanks to Jo and Jasonb concerning the picture of the model, 9BA threads and 3/64” cutters. I want to keep BA and ME threads since I do not like mixing different thread forms (or many forms on a project), seen too many bodged motorcycles. I am actively looking at the small cutters and have asked questions elsewhere on the forum. There may be more questions.

The fettling of castings has started. I got one fettled casting, the cylinder, shot blasted at “work”. I am just about happy with the result but filing marks will have to be finer (photographs attached). I do not have an air supply in my workshop so I have to rely on favours. The bedplate, its quality concerned me, is cleaning up very nicely. However I fear my Dremell may be reaching the end of its life. It was bought impulsively about 10 years ago and languished on the shelf for quite some time. About four years ago I found it made a good fettling tool and then, later, used it for parting-off very small items in a lathe.

During the fettling I found that the pump valve body casting (drawing attached) had a well-undersized dimension and that it was the mirror image of the drawing. The latter is of no consequence since it can be reversed without affecting anything. The undersized dimension has caused some thought:
1.   Do I try to squeeze the lost 0.05” into the remaining casting? I don’t really want to try.
2.   Do I machine a new one out of bronze bar? I don’t have any bar large enough although this is a sensible option.
3.   Do I build-up the casting by silver soldering a bronze pad onto the offending face? This is the likely option since I have small pieces of bronze and I like silver soldering.

This difficulty has uncovered a mirror drawing fault: the holes for the two studs that hold the valve body to the pump are also mirror imaged.

The drawing and understand of the components is continuing. More details and discoveries will be communicated later. I am itching to start machining.

AVTUR
Title: Re: Hick Crank Overhead engine
Post by: Jasonb on August 18, 2019, 03:24:10 PM
Depending on whether it is short at the bottom or top you could rearrange things so the error evens out a 0.025" top and bottom. As the part is not seen and I doubt you will be using it as a boiler feed pump that should not be an issue.

The soldering option would work too if you want to keep to the original sizes again depending on where the metal is missing either build up the top or bottom or if it is generally undersize all over then put a two bits top & bottom.
Title: Re: Hick Crank Overhead engine
Post by: AVTUR on August 26, 2019, 04:48:04 PM
It has been a week of minor disasters and difficulties.

The drawing of parts has progressed well enough for me to take a break and start making bits. I have not found any more errors other than one missing dimension.

Fettling is continuing and I have had a few more castings shot blasted [photographs attached]. The first “nasty” happened I tried to speed up the fettling of one of the two standards using the milling machine (I had to remove about 0.04” of material to get the correct outline of the casting). Holding the casting in the vice was difficult because of its shape. I convinced myself that it was held tightly and rigidly, even tried to dislodge it with a good tap from a small mallet. The cutter spat it out of the vice on the second cut resulting in some superficial cut/gouge marks on the casting. These will be filled with epoxy resin.

After shot blasting I skimmed the base of the bedplate [photograph of set-up attached] to get a flat base for the machining operations on the top surface. As feared, the aluminium was sticky and I had treated it as good aluminium bar. The finish was not good but no one will see it. Returning to it after three days I discovered two problems:

1.   The drawing distance across the bedplate for the model mounting holes could not be met. The drawing dimension is 3.250”, the maximum obtainable was 3.063” [see attached photograph]. So the holes were drilled 3.063” apart.

2.   The casting had bowed. On the long edges the mid-point was about 0.04” below the ends [see attached photograph]. Casting can stress relieve themselves and move when first machined but this magnitude was a surprise. Thinking about it the options were
a.   Make a second skimming cut – unwise, it might exacerbate the distortion since one is removing material from the stiffest part of the casting.
b.   Do nothing and see what happens (if the movement continues).
c.   Ignore the bowing since it can be lost by mounting the model only at the mounting holes. Skim the top pads carry which the cylinder and standards. Hopefully any resulting bowing will correct the shape. This will then require further skimming of the pads (the pads are thick enough to allow this). If there is no movement so much the better. Obviously the pads for the standards must be flat relative to each other so that the standards are parallel.
I decided on option c.

I skimmed of the pads (a largish diameter cutter, lower than normal speeds and white spirit gave an adequate finish), enlarged of the two major holes and drilled and tapped of small holes without any problems [see attached photographs]. I always use a guide for manual tapping, both for tapping and removing the tap. In this case the tapped holes are for studs so the small holes, 8 & 10 BA, were not through tapped. I could feel the tap tightening up as it approached the hard skin at the other end of each hole (discretion is the better part of valour, etc). Geoffrey King used trapped bolts to attach the standards to the bedplate. In this case I don’t why know he did this so I am using 4BA studs instead. The tapped holes are smaller than King’s square holes so I can revert to his design if necessary.

On inspection I found that the width of the large hole was well outside the nominal dimension. At work we had a 3Fs mantra – Fit, Form and Function. Function has not been compromised. Fit may improve the fitting of the cylinder. Form, very important on a model, may be slightly compromised at the base of the front, cylinder, standard. This can be hidden be a little bit of cosmetic machining [photograph of finished bedplate attached]. The studs, blacked, will be fitted later.

Now to clear up this morning’s silver solder session. There will be more next week.

I have to apologise for not including a scale in the photographs. Hopefully I will remember to do so from now on.

AVTUR
Title: Re: Hick Crank Overhead engine
Post by: AVTUR on September 01, 2019, 05:59:07 PM
I seem to have done very little this week. Part of this is due to me deciding that the week started on bank holiday Monday instead of Sunday.

I had a good silver soldering session. This I do outside on the garden patio because I do not want to incinerate the workshop and bikes due to the heat involved. Planning a session involves much watching of weather forecasts for a dry windless (less than 10 mph) few hours.

I soldered two parts for the model: the Valve Spindle Crosshead (details later) and the correction to the Pump Valve Body. I decided to pad out the face since I feel that if it can be seen, it will be seen and should look correct.

I have finished the basic Pump Valve Body but not the Screw Caps. The only difficult encountered was facing a valve seat. Again it was me being a bit gung-ho. I attach a drawing showing the passages in the body. Geoffrey King drew conical valve seats as shown in the drawing with an overall cone angle of 90°. I tried to work out a way of cutting these and almost started attacking a short rod of silver steel before wondering why he had used cones. Drawing the arrangement I found that the ball did not sit on the cone but on the lip formed by the cone and passage, just like a conventional arrangement. So I used the latter. The lip was formed by a slot cutter and machine reamer. The slot cutter bit on the first attempt, not badly. Once I had held it properly, not in a Jacobs chuck, removed the rake on the cutting edges and locked everything on the milling machine there were further difficulties.

The Bedplate has remained stable since the pads were skimmed eight days ago. I don’t think I will try to remove the bow in the bottom surface.

The workshop that does my shot blasting has a two week power outage starting in ten days time. Therefore fettling the Standards has become the priority.

AVTUR
Title: Re: Hick Crank Overhead engine
Post by: AVTUR on September 08, 2019, 06:21:07 PM
I have finished fettling the Standards. The damage from the cutter described a few weeks ago has been filled with epoxy resin and smoothed out. Now to get them shot blasted on Tuesday.

The weather forecast promised today would be nice, fine and windless. Therefore the last few days have been spent getting parts made and ready for silver soldering. Soldering was done this morning and I am happy with the results. I will give more details when I finish each part or assembly.

I am giving the assembly of the model, and the necessary data, much thought and will try to describe assembly sequence in the next few weeks.

AVTUR
Title: Re: Hick Crank Overhead engine
Post by: Jasonb on September 08, 2019, 07:23:00 PM
Do you find the filler is robust enough not to be removed by the shot blasting?
Title: Re: Hick Crank Overhead engine
Post by: AVTUR on September 10, 2019, 05:21:52 PM
Jason

About nine years ago I used JB Weld on an aluminium casting that was later shot blast. The JB Weld survived so I had some confidence. I had less in the actual stuff I used, it was nine years old. I believe epoxy has a shelf life.

The shot blasting was done this morning and again the JB Weld survived (photograph attached).

AVTUR
Title: Re: Hick Crank Overhead engine
Post by: Jasonb on September 10, 2019, 06:26:32 PM
Ah, yes the JBweld is a lot harder than the usual car body type epoxy filler so I can see why that was OK.

Funny enough I was looking through some old Model Engineer mags the other day from the '80s and the decorative pattern on the top of the standards was also poor on those just like yours, The builder milled them off and then used a small ball nose cutter to do new ones.
Title: Re: Hick Crank Overhead engine
Post by: AVTUR on September 10, 2019, 07:07:41 PM
The decorative feature on the top of the standards is a poor example of the casters' skills. It was one reason why I put the castings aside a few years ago.

I am not sure how, or even if, I am going to correct them. They have already been sharpened up with a file during fettling.

AVTUR
Title: Re: Hick Crank Overhead engine
Post by: Jasonb on September 10, 2019, 07:45:32 PM
I think I would mill off the raised vertical details and then go a bit deeper over the whole area. Then machine up a couple of flat strip to fit that can have a series of grooves cut into them and stick them in place with JBWeld. This gives nice square ends unlike the ball nosed cutter option.
Title: Re: Hick Crank Overhead engine
Post by: Johnmcc69 on September 10, 2019, 07:48:46 PM
That's a shame. Cool little feature.
 I like Jason's idea about using a ball end mill there.

 Good progress though!  :ThumbsUp:

 John
Title: Re: Hick Crank Overhead engine
Post by: AVTUR on September 16, 2019, 12:40:05 PM
After getting them shot blasted I have been giving the standards much thought. So much so that I put pen to paper (fingers to keyboard) so that I do not confuse myself. In the manner of a student to puts the longest, most complex equations into his/her presentation of work to hide the fact that he has done nothing, my ramblings are as follows:

The front standard has two bosses for the piston rod guide.

Function
1.   To hold the crankshaft assembly
2.   To locate the piston rod by means of a guide block
3.   To hold the governor spindle bracket
4.   To hold the rocker shaft

Fit: Datum 1 - Horizontal plane provided by base of standard, Datum 2 - Vertical plane provided by face of rear edging on standard, Datum 3 - Vertical plane of symmetry. These planes are orthogonal.
1.   The height from base to plummer block face must be 5.125” ± ?”. The faces must be flat and parallel.
2.   The shelf on the inner face of the standards must be flat for the governor spindle bracket mounting collars.
3.   The face of the piston rod guide bosses must be flat and square to the standard base.
4.   The face of the rocker shaft bearing pads must be flat and square to the standard base.
5.   Holes in bases and for plummer blocks must square or parallel to the datums.

Form is all important, looks count for everything. As far as possible both standards should be identical. I would like to have kept the finish as cast but the casting was so poor. Therefore I think they will be machined all over except for the large recessed surfaces which will remain as cast. I want to keep the height of the edging from the outside recessed surface constant if possible. The finished results may be shot blast again. The frieze at the top of the standards must be prominent. I do not intend to think about them for the moment but I like Jason’s suggestion.

Inspection showed that some dimensions are tight, importantly the height of the standards, while others allow quite a lot of room for machining. There are no critical undersize dimensions. However the rear standard is twisted with the bottom of the right leg forward of the left by about 0.030”.

Machining sequence will probably be as follows:
1.   Mount standard outer face downwards on milling table, using shims to account for the twist in necessary, and skim inside edging to provide Datum 2.
2.   Skim rear of base pads and top platform
3.   Face top and bottom of shelf for governor spindle bracket, rocker shaft bearing pads and top of base pads.
4.   Turn over and mount Datum 2 face against table (again using a suitable block of metal) and skim front of base pads and top platform.
5.   On front standard face piston rod bracket bosses.
6.   Clamp both standards together back to back using spacers and super glue if necessary.
7.   Mount vertically with feet upwards on an angle plate. [Think about Datum 3].

This is as far as I have got recording my thoughts. However it has given me the clarity to start work on the standards.


I have made some progress with the pump parts. The pump should be finished next week and I will give details.

I have also made the all important build stand.

AVTUR
Title: Re: Hick Crank Overhead engine
Post by: AVTUR on September 22, 2019, 06:53:53 PM
It has been a week of puzzlement and progress.

I have decided on the machining sequence for the standards which as follows:
1.   Mount standard outer face downwards on milling table, using shims to account for the twist in necessary, and skim inside edging to provide Datum 2.
2.   Skim rear of base pads and top platform
3.   Turn over and mount Datum 2 face against table (using a suitable block of metal) and skim front of base pads and top platform.
4.   On front standard face piston rod bracket bosses.
5.   Clamp both standards together, front edging to front edging, using some thickness spacers, shims and super glue if necessary. Use two clamps that sit inside the castings. Make sure that the top platform and the inner faces of each standard coincide. Check distance from inside edging to inside edging which should be constant (±0.010”?).
6.   Mount assembly vertically with feet upwards on an angle plate using same thickness spacers and two sets of clamping bolts. Make sure, taking numerous measurements, that the mean line between inner faces is square to the base of the angle plate. This gives Datum 3.
7.   Skim just enough metal off the underside of the feet to give nice flat surface. This is Datum 1.
8.   Skim sides of base pads.
9.   Drill mounting holes in base pads.
10.   Remove from angle plate.
11.   Mount assembly vertically with feet downwards on the angle plate using same thickness spacers and two sets of clamping bolts. Make sure the feet are firmly against the milling table.
12.   Skim the plummer block faces to height.
13.   Drill the holes for the plummer block and governor spindle bracket holes.
14.   Remove from angle block and separate the two standards.
15.   Mount standard outer face downwards on milling table, using shims to account for the twist in necessary [as operation 1] with Datum 1 parallel to the intending cuts.
16.   Face top and bottom of shelf for governor spindle bracket, rocker shaft bearing pads and top of base pads.
17.   Drill and tap stud holes [see below] for the rocker shaft bearing pads.
18.   Finish.
19.   NOTE. The drilling of holes for the piston rod guide bracket will be left for the moment. Likewise the decorative machining.

Geoffrey King used screws and nuts to hold the bearing pads to the standards. I feel it would be nice not the break the cast surfaces of the standards so I intend to use studs.

I hope to start machining the standards this coming week.


I have finished the water pump except for tidying up and polishing. None of the parts present any real problems.

I reduced the size of the spanner hexagon on the screw caps from 2BA to 3BA because it looks nicer. Because they were held by the thread I used an old filing rest that was made many years ago for a smaller lathe. If I tried to produce the flats by milling the cap would have unscrewed from the fixture so scrapping my work. Even so the caps had to be kept in place by a small bar mounted in the tailstock when I did the filing (see attachment).

I do not like turning long small diameter rod so I decided to produce the collars on the pump columns by silver soldering short sleeve over a rod and then turning back the excess metal and solder. The collar/rod gap for the capillary flow of the solder would be fixed by centre punch marks on the rod.  I have this technique very successfully in the past with stainless steel rods and sleeves. It appeared to work this time with mild steel but when I turned off the excess the punch marks were very visible, they had not filled with solder (see attachment). Much puzzlement – I can only think that they too deep for capillary action to work (mild steel being softer than stainless) or the wetting by the solder of the steels is different. The second attempt, this time raising a large, clumsy bur on the ends of the collars worked

AVTUR
Title: Re: Hick Crank Overhead engine
Post by: AVTUR on September 29, 2019, 06:56:23 PM
Slow but steady progress has been made.

I am machining the standards in the following stages:
1.   Mount standard outer face downwards on milling table, using shims to account for the twist in necessary, and skim inside edging to provide Datum 2. DONE.
2.   Skim rear of the feet and top platform. DONE – This was interesting since the clamping twisted the legs (see attached sketch) giving an odd rear face of the feet. Not a problem but a warning.
3.   Turnover and mount Datum 2 face against table (using a suitable block of metal) and skim front of base pads, DONE, and top platform, NOT DONE – I decided that this was not required.
4.   On front standard face piston rod bracket bosses. DONE.
5.   NEW STAGE – Front face against the table with suitable packing, correct the rear face of the feet. The finish was not good. The surface was slightly smeared which could suggest a blunt cutter, an end mill.
6.   Clamp both standards together, front edging to front edging, using some thickness spacers, shims and super glue if necessary. Use two clamps that sit inside the castings. Make sure that the top platform and the inner faces of each standard coincide. Check distance from inside edging to inside edging which should be constant (±0.010”?). CHANGE OF PLAN – I could not understand why I was clamping the two standards together. This is typical of carpentry and represents a lack of faith in repeatable machining. It struck me as being very cumbersome with too many clamps. The only possible gain would be the top platform heights might be the same. If you did them individually any difference in height of the crankshaft could be corrected when the plummer blocks were machined.
7.    Mount the standard vertically with feet upwards on an angle plate using same thickness spacers and two sets of clamping bolts. Make sure, taking numerous measurements, that the mean line between inner faces is square to the base of the angle plate. This gives Datum 3.DONE - for the rear standard [the front standard has yet to be machined]. I took the angles of the inner edges to set the datum (see attachment). Since I felt the part seemed very springy the top clamp was as close as possible to the feet.
8.   Skim just enough metal off the underside of the feet to give nice flat surface. This is Datum 1. DONE – Because of the above observations I did this slowly and carefully using a good sharp end mill, lowish cutter speed, low table feed speed and light cuts. It took time but I am happy with the result.
9.   Drill mounting holes in the feet. DONE – The hole in both legs comes out very close to the web of the structure. So more machining and a picture next week
10.   Skim sides of feet. DONE – I could not do the full face because the top of the angle plate was in the way. They will be finished off with a file.

The rear standard has been removed from the angle plate. The front standard and finishing the non-decorative machining on both is the next job. I would like to think that this will be done within the week, but next week is going to be busy.

AVTUR
Title: Re: Hick Crank Overhead engine
Post by: AVTUR on October 06, 2019, 06:05:30 PM
I have had a busy week outside the workshop.

As for machining the standards, it has been a case of two steps forward and one step back.

I skimmed the feet of both standards flat to give a good Datum 1. After successfully drilling the fixing holes (4BA clearance) in the feet of the rear standard I lost Datum 3 on the front standard. The holes were in the wrong place. I plug them with phosphor-bronze rod held by quick setting epoxy glue and re-drilled the holes. I am not totally happy but I understand why Geoffrey King slotted the mounting bolt holes in the plummer blocks (at least he foresaw the difficulty in keeping a vertical datum through the crankshaft).

The next difficulty became obvious when the holes were drilled. They are far too close to the main web of the casting (see attachment, only one this week); yet more machining. I have abandoned my elaborate work plans since they have served their purpose with the remaining non-ornamental machining operations are relatively simple – facing the top platform, drilling the associated holes and producing clearances and flat surfaces for fixtures. I have started doing the latter on the front standard. The bosses for the piston rod guide bracket will be drilled during assembly.

On Friday I just sat at my bench, looked at these castings and just wondered; would it have been less hassle to have made them from bar stock? If so, would they be carved from a single lump of metal or fabricated?

It is a short write-up this week and next week is likely to be similar. Like anyone who has a good workshop others want to give you work. I only consider neighbours and good friends (family live miles away). A friend’s job has been on the shelf for a couple of months and I cannot ignore it any longer.

AVTUR
Title: Re: Hick Crank Overhead engine
Post by: Admiral_dk on October 06, 2019, 08:29:00 PM
Well, progress is progress - even if it is not as fast as we could wish for ....
Title: Re: Hick Crank Overhead engine
Post by: AVTUR on October 14, 2019, 11:48:39 AM
A week of progress and I have even done some work on the “foreigner”.

Facing the platform top of each standard and the shelf underneath was simple. The heights of the platform tops from the base are within 0.002” of each other and 0.007” to 0.009” below the drawing. The latter can easily be corrected, if required, when machining the plummer blocks. The holes for the governor spindle bracket, in the shelves were drilled. Geoffrey King used captured screws for the plummer blocks, I do not understand why. Therefore I am replacing them with 8BA studs; their holes were drilled and tapped. On inspection I found that these had half broken through on the underside into the side of the web (see attachment). No problem since I am using studs, but it would make the use of captive screws very difficult.

The webs at the feet have been machined back to give clearance for the 4BA fixing nuts. I can now just about get them in and possibly tighten them. Access for my smallest 4BA spanner is too cramped and the spanner is too long to swing between the two standards (see attachments). There are a number of options:
1.   Carve out more room – I am loathe to do this, everything will just get messier.
2.   Use 4BA nuts with 5BA flats – I know such screws are available but whether nuts are?
3.   Buy another 4BA spanner and modify it – Will probably have to do this anyway.
4.   Use 4BA screws instead of studs and tighten them from the underside of the bedplate. The tapped holes in the bedplate would have to be drilled out – This may present assembly difficulties.

Tomorrow I should finish the non-ornamental machining with the skimming and drilling of the mounting for the rocker spindle bearings. The tolerance on their location is tight so I have produced a simple datum plate that would have bolted onto the feet had the screws not fouled the webs (see attachment).

My shopping list for Friday’s quick visit to the Midlands show is rapidly increasing.

AVTUR
Title: Re: Hick Crank Overhead engine
Post by: AOG on October 14, 2019, 02:44:26 PM
If you have a 4BA tap you can make nuts to of what ever size you need. If you don’t have a hex block you can use a pair of full size 4BA nuts to put in the facets or even go with square nuts..

Tony
Title: Re: Hick Crank Overhead engine
Post by: Jasonb on October 14, 2019, 03:12:33 PM
Easiest to drill out and tap some 5BA nuts with a 4BA tap
Title: Re: Hick Crank Overhead engine
Post by: AVTUR on October 15, 2019, 07:15:24 PM
Tony and Jason – Many thanks for the suggestions.

I found I had a 4BA – 6BA spanner pressed out of steel plate. Such spanners are just asking to be modified. After quite a bit of careful filing I am now able to tighten all four nuts without having to do further work on the standards. The 6BA end has been cut off so that I can swing it between the standards.

AVTUR